THE EFFECTS OF SULFIDE ON PULP AND PAPER WASTEWATER COLOR REVERSION Except where reference is made to the work of others, the work described in this thesis is my own or was done in collaboration with my advisory committee. This thesis does not include proprietary or classified information. ______________________________________ Jessica Marie Esty Certificate of Approval: ___________________________ ___________________________ Dongye Zhao Clifford R. Lange, Chair Assistant Professor Associate Professor Civil Engineering Civil Engineering ___________________________ ___________________________ Willie F. Harper, Jr. Stephen L. McFarland Assistant Professor Acting Dean Civil Engineering Graduate School THE EFFECTS OF SULFIDE ON PULP AND PAPER WASTEWATER COLOR REVERSION Jessica Marie Esty A Thesis Submitted to the Graduate Faculty of Auburn University in Partial Fulfillment of the Degree of Master of Science Auburn, Alabama December 16, 2005 iii THE EFFECTS OF SULFIDE ON PULP AND PAPER WASTEWATER COLOR REVERSION Jessica Marie Esty Permission is granted to Auburn University to make copies of this thesis at its discretion, upon the request of individuals or institutions and at their expense. The author reserves all publication rights. ______________________________ Signature of Author ______________________________ Date of Graduation iv VITA Jessica Marie Esty, daughter of Mark and Susan Esty, was born on August 27, 1979, in Waterville, ME. She graduated from Waterville Senior High School as Salutatorian in 1997. In 2001, she graduated from the University of Maine at Orono with a Bachelor of Science degree in Chemical Engineering. During her undergraduate studies, she gained cooperative experience at a local paper mill. From 2001-2002, she worked as an environmental engineer at a printed circuit board manufacturing company. Thereafter, from 2002 until 2004, she was employed at an environmental engineering consulting company. In 2004, she began graduate studies in Environmental Engineering in the Civil Engineering Department at Auburn University. v THESIS ABSTRACT THE EFFECTS OF SULFIDE ON PULP AND PAPER WASTEWATER COLOR REVERSION Jessica Marie Esty Master of Science, December 16, 2005 (B.S. Ch.E., University of Maine, 2001) 139 Typed Pages Directed By Clifford R. Lange More and more concern is being given to the aesthetics of wastewater, specifically the color of the resulting effluent. The underlying causes of colored wastewater suggest incomplete pollutant removal and unsuccessful overall treatment. Therefore, monitoring color will soon become a more commonly regulated parameter. Yet, in order to accomplish decolorization as effectively and efficiently as possible, understanding the mechanisms of color reversion, and thereby pin-pointing the color culprit, needs to be achieved first. But, minimal research has been conducted on the generation of color in pulp and paper wastewaters thus far. Therefore, a study of color reversion was conducted in order to observe the effects of sulfide dissolved in pulp and paper wastewater. Color reversion is the yellowing of pulp on exposure to air, heat, vi certain metallic ions, and fungi due to modification of residual lignin-forming chromophores. The rate and degree of color reversion has been hypothesized to be related to four main mechanisms: 1) anaerobic color reduction, 2) anaerobic color generation via sulfide reaction, 3) aerobic color reversion, and 4) aerobic decolorization. The major goal of this thesis is to elucidate the role sulfide has on color reversion of treated and untreated paper mill wastewater. Experimentation involving sulfide exposure, aeration, and individual lignin compounds all encompass the efforts of this research. Sulfide exposure yielded as great as 100% color increase in some cases; whereas, in other tests, the results suggested sulfide had relatively no effect on color reversion. The differences appeared to be associated with the initial color of the wastewater?lighter colored samples yielded higher color increases upon sulfide exposure, while the darker samples displayed generally no relationship to sulfide concentration, except at unrealistically high doses. Aeration appeared to have a reverse effect on sulfide color reversion. However, following this color reduction, other mechanisms became dominant which caused color reversion to recur. These results support the color phenomenon seen across ponds where at times color remains consistent while during other times, it has actually been reported to increase, suggesting another color generation mechanism is involved. As aforementioned, the underlying differences seen in color reversion appear to be related to the wastewater composition, given the extreme variability of pulp and paper wastewater. The concentrations of lignin derivatives (specifically humic substances) were hypothesized to have direct influences on sulfide color reversion. When different humic functional groups were tested, the catechol and anthraquinone solutions portrayed vii the greatest effects on sulfide color reversion. The results of this research increase the overall understanding of the color reversion phenomenon, but do not solve this problem in its entirety. viii ACKNOWLEDGMENTS The author wishes to express appreciation to Weyerhaeuser, Rayonier, and Georgia Pacific Pulp and Paper Mills for providing wastewater samples for the purposes of research and analysis. Additionally, thanks are due to my advisor, Dr. Clifford R. Lange, for his support and invaluable assistance during the course of my research. Moreover, I am much obliged to him for working under a rather tight timeline; for in doing so, he greatly enabled my expedited pursuit of completing graduate school. Finally, I would like to express my deepest appreciation to my family and friends for their support throughout the course of completing this challenging educational endeavor. ix Style manual or journal used: Guide to Preparation and Submission of Theses and Dissertations 2005___________________________ Computer software used: Microsoft Office (Word and Excel)_____________ x TABLE OF CONTENTS LIST OF FIGURES???????????????????????..??.....xii LIST OF TABLES???????????????????????...???xvii CHAPTER 1: INTRODUCTION??????????????????????1 CHAPTER 2: LITERATURE REVIEW??????????????????...11 General Information???????????????????????...12 Parameter Optimization??????????????????????.13 Biological Treatment Techniques??????????????????..15 Physiochemical Treatment Techniques????????????????.21 Summary?????????????????????????..??..25 CHAPTER 3: MATERIALS AND METHODS?????????.??????..26 Experimental Study Approach??????????????..?????.27 Sulfide Addition Testing????????????????????..?..28 NCASI Method 701??????????????????..??.28 Color Development in Sulfide Blanks?????????????...30 xi Colored Wastewater Samples?????????????????31 Mill Descriptions??????????????????????.??..32 Weyerhaeuser???????????????????????.32 Rayonier???????????????????????.??33 Georgia Pacific????????????????????...??34 Aeration Experimentation???????????????????.?.....34 Lignin Components Isolation Analysis????????????????..35 CHAPTER 4: RESULTS AND DISCUSSION??????????????.??36 Sulfide Color Reversion?????????????????????.?36 Weyerhaeuser???????????????????...???..36 Rayonier.??????????????????????..??..61 Georgia Pacific?...?????????????????????70 Aeration Experimentation??????????...??????.????..76 Lignin Components Isolation Analysis??????????????.??.83 CHAPTER 5: SUMMARY AND RECOMMENDATIONS???????...???.91 Summary?????????????????????????...??.91 Recommendations????????????????????????..94 REFERENCES????????????????????????????..97 APPENDIX?????????????????????????..????103 xii LIST OF FIGURES Figure 1.1: Some Proposed Chromophoric Structures?????????????...2 Figure 1.2: 4-Hydroxybenzaldehyde????????????????????..5 Figure 1.3: Phenol.???????????????????????????..5 Figure 1.4: Catechol???????????????????????????6 Figure 1.5: Vanillin???????????????????????????.6 Figure 1.6: Anthraquinone????????????????????????...6 Figure 1.7: Lignin Polymer Segment????????????????????..7 Figure 1.8: Humic Acid?????????????????????????..8 Figure 1.9: Fulvic Acid?????????????????????????...9 Figure 2.1: Chemical Reactions in the Lime Precipitation Process????????..23 Figure 3.1: Platinum Cobalt Color Standard Calibration Curve?????????...28 Figure 3.2: Blank Samples Color Results ??????????????????31 Figure 4.1: Grand Prairie, Alberta Weyerhaeuser Primary Clarifier Inlet Sample Color Results from 10-ppm Sulfide Solution Doses???????????37 Figure 4.2: Grand Prairie, Alberta Weyerhaeuser Primary Clarifier Inlet Sample Color Results from Crystallized Sulfide and Ammonium Molybdate Treatment????????????????????????...39 Figure 4.3: Grand Prairie, Alberta Weyerhaeuser Primary Clarifier Outlet Sample Color xiii Results from 10-ppm Sulfide Solution Doses???????????40 Figure 4.4: Grand Prairie, Alberta Weyerhaeuser Primary Clarifier Outlet Sample Color Results from both Crystallized Sulfide Exposure and with/without Ammonium Molybdate Treatment???????????????41 Figure 4.5: Grand Prairie, Alberta Weyerhaeuser Secondary Effluent Sample Color Results from 10-ppm Sulfide Solution Doses???????????42 Figure 4.6: Grand Prairie, Alberta Weyerhaeuser Secondary Effluent Sample Color Results from both Crystallized Sulfide and with/without Ammonium Molybdate Treatment????????????????????.43 Figure 4.7: Prince Albert, Saskatchewan Weyerhaeuser Primary Pond Inlet Sample Color Results???????????????????????..47 Figure 4.8: Prince Albert, Saskatchewan Weyerhaeuser Primary Pond Midpoint Sample Color Results???????????????????????..48 Figure 4.9: Prince Albert, Saskatchewan Weyerhaeuser Primary Pond Outlet Sample Color Results???????????????????????..49 Figure 4.10: Johnsonburg, PA Weyerhaeuser Pulp Sewer Sample Color Results from 10-ppm Sulfide Solution Doses????????????????.52 Figure 4.11: Johnsonburg, PA Weyerhaeuser Pulp Sewer Sample Color Results from Crystallized Sulfide Doses??????????????????.52 Figure 4.12: Johnsonburg, PA Weyerhaeuser Settling Pond Feed Sample Color Results from 10-ppm Sulfide Solution Doses??????????????53 Figure 4.13: Johnsonburg, PA Weyerhaeuser Settling Pond Feed Sample Color Results from Crystallized Sulfide Doses????????????????54 xiv Figure 4.14: Johnsonburg, PA Weyerhaeuser Aeration Pond Feed Sample Color Results from 10-ppm Sulfide Solution Doses??????????????55 Figure 4.15: Johnsonburg, PA Weyerhaeuser Final Discharge Sample Color Results from 10-ppm Sulfide Solution Doses??????????????57 Figure 4.16: Johnsonburg, PA Weyerhaeuser Aeration Pond Feed and Final Discharge Samples Color Results from Crystallized Sulfide Doses??????...58 Figure 4.17: Albany, OR Weyerhaeuser Mixed Composite Sample Color Results with Sulfide Doses???????????????????????.60 Figure 4.18: Rayonier Primary Clarifier Sample Color Results from 10-ppm Sulfide Solution Doses??????????????????????...62 Figure 4.19: Rayonier Primary Clarifier Sample Color Results from Crystallized Sulfide Doses??????????????????????????..63 Figure 4.20: Rayonier Influent Sample Color Results from 10-ppm Sulfide Solution Doses??????????????????????????..64 Figure 4.21: Rayonier Influent Sample Color Results from Crystallized Sulfide Doses??????????????????????????..65 Figure 4.22: Rayonier Effluent Sample Color Results from 10-ppm Sulfide Solution Doses????????????????????????..??66 Figure 4.23: Rayonier Effluent Sample Color Results from Crystallized Sulfide Doses??????????????????????????..66 Figure 4.24: Rayonier ASB #1 Effluent Sample Color Results from 10-ppm Sulfide Solution Doses??????????????????????...67 Figure 4.25: Rayonier ASB #2 Effluent Sample Color Results from 10-ppm Sulfide xv Solution Doses??????????????????????...68 Figure 4.26: Rayonier ASB #1 Effluent Sample Color Results from Crystallized Sulfide Doses??????????????????????????..69 Figure 4.27: Rayonier ASB #2 Effluent Sample Color Results from Crystallized Sulfide Doses??????????????????????????..69 Figure 4.28: Georgia Pacific Ponds 1 & 2 Samples Color Results????????...71 Figure 4.29: Georgia Pacific Ponds 3 & 4 Samples Color Results????????...71 Figure 4.30: Georgia Pacific Pond 2?Grab 1 Reproducibility Color Results????.73 Figure 4.31: Georgia Pacific Pond 2?Grab 1 Averaged Color Results????.??.74 Figure 4.32: Georgia Pacific Pond 2?Grabs 1 & 2 Samples Color Results?????75 Figure 4.33: Georgia Pacific Pond 2?Grabs 3 & 4 Samples Color Results?????75 Figure 4.34: Albany, OR Weyerhaeuser and Georgia Pacific Pond 2?Grab 4 Color Reversion / Aeration Results Comparison????????????.77 Figure 4.35: Albany, OR Weyerhaeuser and Georgia Pacific Pond 2?Grab 3 Color Reversion / Aeration Results Comparison????????????.78 Figure 4.36: Albany, OR Weyerhaeuser and Georgia Pacific Pond 2?Grab 2 Color Reversion / Aeration Results Comparison????????????.80 Figure 4.37: Catechol?Quinone Color-Producing Reaction??????????...82 Figure 4.38: 4-Hydroxybenzaldehyde Color Results??????????????84 Figure 4.39: Phenol Color Results?????????????????????84 Figure 4.40: Vanillin Color Results????????????????????.85 Figure 4.41: Humic Acid Color Results??????????????????...86 Figure 4.42: Fulvic Acid Color Results???????????????????87 xvi Figure 4.43: Catechol Color Results???????????????????.?88 Figure 4.44: Anthraquinone Color Results?????????????????...89 xvii LIST OF TABLES Table 4.1: Grand Prairie, Alberta Weyerhaeuser Color Results Summary (10-ppm Solution)?????????????????????????.44 Table 4.2: Grand Prairie, Alberta Weyerhaeuser Color Results (Crystallized Sulfide Doses & Ammonium Molybdate)???????????????..45 Table 4.3: Grand Prairie, Alberta Weyerhaeuser Color Results Summary (Crystallized Sulfide Doses)???????????????????????46 Table 4.4: Prince Albert, Saskatchewan Weyerhaeuser Results Summary?????..50 Table 4.5: Johnsonburg, PA Weyerhaeuser Samples?Initial Conditions?????...50 Table 4.6: Johnsonburg, PA Weyerhaeuser Results Summary??????????.59 Table 4.7: Albany, OR Weyerhaeuser Results Summary????????????.61 Table 4.8: Georgia Pacific Results Summary????????????????...72 Table 4.9: Georgia Pacific Aeration?Run 1 Results Summary?????????..79 Table 4.10: Georgia Pacific Aeration?Run 2 GC/FPD Results Summary?????.81 Table 4.11: Georgia Pacific Aeration?Run 2 Results Summary?????????83 Table 4.12: Catechol and Anthraquinone Results Summary???????????90 Table 5.1: Weyerhaeuser?Albany, OR Color Loadings????????????.94 Table A.1: Weyerhaeuser - Grand Prairie, Alberta Results Summary (from 10-ppm Sulfide Solution Doses)????????????????...........104 Table A.2: Weyerhaeuser - Grand Prairie, Alberta Results Summary (from Crystallized xviii Sulfide and Ammonium Molybdate Treatment)??????..???105 Table A.3: Weyerhaeuser - Grand Prairie, Alberta Results Summary (without Ammonium Molybdate, only Crystallized Sulfide Doses)?????..106 Table A.4: Weyerhaeuser ? Prince Albert, Saskatchewan Results Summary??..?..107 Table A.5: Weyerhaeuser ? Johnsonburg, PA Results Summary (from 10-ppm Sulfide Solution Doses)??????????????????????108 Table A.6: Weyerhaeuser ? Johnsonburg, PA Results Summary (from Crystallized Sulfide Doses)?????????????.?????????.109 Table A.7: Weyerhaeuser ? Albany, OR Results Summary??????????...110 Table A.8: Rayonier Results Summary (from 10-ppm Sulfide Solution Doses)???111 Table A.9: Rayonier Results Summary (from Crystallized Sulfide Doses)???.?..112 Table A.10: Georgia Pacific Results Summary (First Sample Set)????????113 Table A.11: Georgia Pacific Results Summary (Second Sample Set)?????........114 Table A.12: Georgia Pacific Results Summary (Second Sample Set-continued)??..115 Table A.13: Aeration Analysis (24-hour)???????????????..??.116 Table A.14: Aeration Analysis (4-day, Run 1)???????????????...117 Table A.15: Aeration Analysis (4-day, Run 2)???????????????...118 Table A.16: Lignin Components Isolation Analysis?????????????...119 Table A.17: Lignin Components Isolation Analysis (continued)????????...120 Table A.18: Lignin Components Isolation Analysis (continued)????????...121 1 CHAPTER 1 INTRODUCTION The brown colored effluents discharged by the pulp and paper industry result in poor water aesthetics as well as cause harm and disturbance to the surrounding aquatic environment. These colored compounds are released into the environment from an estimated two trillion gallon wastewater discharge per year and are attributable to various pulping and bleaching operational by-products, resulting from lignin degradation. The receiving waters can potentially experience an increase in temperature and a decrease in photosynthesis as a direct result of the addition of these brown colored effluents (Kringstad and Lindstrom, 1984). Moreover, while being unaesthetic, discharged color bodies can also create considerable problems in terms of contaminant transport as they can mimic chelating agents and form bonds with metallic ions (Dilek and Bese, 2001). Color reversion is the yellowing of pulp on exposure to air, heat, certain metallic ions, and fungi due to modification of residual lignin-forming chromophores (see Figure 1.1). 2 Figure 1.1: Some Proposed Chromophoric Structures (Sj?str?m, 1981) As paper product quality parameters have become more stringent, specifically brightness, the unwanted color bodies have increased in wastewater loadings. Moreover, while bleaching has decolorized pulp to meet final paper product standards, associated wastewater color has become intensified. Therefore, recognizing the source of these color-forming compounds is crucial to understanding color reversion. As pulp and paper wastewater is treated through various steps involving biological technologies which are geared towards biological oxygen demand (BOD) removal, color is at best partially reduced (Perez et al., 1997). High amounts of bio- resistant chlorinated lignin derivatives give kraft mill bleachery plants their highly 3 colored effluents. But despite chlorinated organics removal, these effluents keep their characteristic color by remaining stable and unaltered (Tarlan et al., 2002). Yet, while conventional wastewater contaminants such as biochemical oxygen demand (BOD) and suspended solids removal have been the main parameters targeted by environmental legislation, color has been and still is excluded because it is considered a non-conventional pollutant. However, disregarding the fact that official federal regulations have yet to be created, some countries have established permissible color limits for particular pulp mills. For instance, the Grand Prairie, Alberta kraft mill wastewater operating licenses have incorporated color standards such that mill operators are required to be proactively in search for color reduction strategies (Davies and Wilson, 1990). As color is often associated with contaminants arising during the production of paper (i.e., COD), these limits were created in order to protect fisheries and aesthetics. In addition, several Eastern European and Scandinavian countries as well as Japan have followed suit and are instituting chemical oxygen demand (COD) wastewater discharge limitations as this is tantamount to a color parameter. Additionally, a particular mill in Louisiana that discharges into a low flow stream has received much pressure from the state to reduce wastewater color loadings (Joyce and Petke, 1983). Therefore, it appears to be only a matter of time before color compliance is officially incorporated into the monitoring requirements under the U.S. National Pollutant Discharge Elimination System (NPDES). The rate and degree of color reversion has been hypothesized to be related to four main mechanisms: 1) anaerobic color reduction, 2) anaerobic color generation via sulfide reaction, 3) aerobic color reversion, and 4) aerobic decolorization. The major objective 4 of this thesis is to elucidate the role of sulfide generation during color reversion of treated and untreated paper mill wastewater. The results of this research increase the overall understanding of the color reversion phenomenon, but do not solve this problem in its entirety. To accomplish the goal of this thesis, several representative pulp and paper mill wastewaters were obtained. The pulp and paper plants that served as the source of the test samples included: three Weyerhaeuser mills, one Georgia Pacific mill, and one Rayonier mill. Samples were taken at various points in the wastewater treatment process including: before primary clarification, after primary clarification, and throughout aerobic biological treatment. It was hypothesized that the addition of sulfide, from biogenic generation in anaerobic portions of a pulp mill wastewater treatment process, could increase color intensity. This hypothesis was based on anecdotal information given by various wastewater treatment plant operators. Therefore, to validate this speculation, the wastewater samples were exposed to various concentrations of sulfide through the addition of sodium sulfide crystals, simulating biogenic sulfide production. Resulting changes in color were measured using Method 701 proscribed by the National Council of the Paper Industry for Air and Stream Improvement, Inc. (NCASI). A three phase approach was utilized to determine the effects of sulfide on pulp mill color. In the first phase, sulfide was added to the samples and changes in color were measured at various time intervals. This simulated the effect of biogenic sulfide production occurring in the anoxic zones of sewers, primary clarifiers, and when high organic loadings deplete aeration basin oxygen. Biogenic sulfide production can also 5 occur during lengthy holding periods and during shipping of samples if the temperature is above 4oC. The second phase of studies involved aeration of the wastewater following sulfide color development. The purpose of the second phase study was to determine if aeration, occurring subsequent to sulfide generation, could lessen or reverse the impacts of sulfide on the wastewater color. This phase would simulate processes occurring in the aerobic portion of the aeration basin, when sulfide is oxidized and stripped off. The third phase of studies involved exposing lignin, fulvic acid, and lignin monomer compounds to sulfide and measuring the resulting color changes. The goal of this study was to determine which compounds contributed to changes in color due to sulfide. Organic compounds appear to be associated with color in relationship to double bond resonance (Joyce and Petke, 1983). Therefore, several aromatic compounds were used in this experimentation in order to determine the sulfide influence associated with color reversion on various functional groups (see the molecular structures illustrated in Figures 1.2-1.6). The concentrations and amounts of organic matter (OM), specifically the residual carbon of lignin, appear to have a direct correlation to resulting wastewater color. The dark color that is characteristic of lignin is directly linked to the intricacy of its molecular structure which permits extensive double bond resonance. Figure 1.2: 4-Hydroxybenzaldehyde Figure 1.3: Phenol 6 Figure 1.4: Catechol Figure 1.5: Vanillin Figure 1.6: Anthraquinone Understanding the diversity of the papermaking process will provide much insight into the immense variability in the resulting wastewater composition. As all of the samples were collected from alkaline pulping and kraft processing mills, it is important to discuss these background technologies so as to provide a clear understanding of the wastewater composition and nature. Alkaline pulping is the pulping of wood using sodium hydroxide. A solution of sodium sulfide is utilized in the papermaking process along with sodium hydroxide in order to dissolve non-fibrous materials. This sulfide component is believed to be a major contributor to the effluent wastewater color. The kraft or sulfate process is labeled as such given that sodium sulfate is the original compound form involved in the process. Sodium sulfate is then converted to sodium sulfide, which becomes the active ingredient involved in the wood chip cooking process. Wood is comprised of three main substances: lignin, carbohydrates, and extractives. The intercellular material functioning as fibrous glue called the lamella is highly comprised of lignin. Lignin is an amorphous, highly polymerized substance 7 containing several linked phenyl propane units arranged into a three-dimensional structure (see Figure 1.7). Figure 1.7: Lignin Polymer Segment (Sj?str?m, 1981) 8 The amount of color associated with certain wastewaters can actually be traced back to the quantity of lignin discharged into the wastewater. Yet, pulp mill sewers do not produce the most color as would be expected considering the largest amount of lignin is released from this operation. This counterintuitive occurrence is due to the fact that the majority of this colored waste is actually recovered (Joyce and Petke, 1983). Yet, in examining the next largest lignin distributor, the bleach plant becomes identified as the major source of effluent color. In fact, more than two-thirds of the total color mass contained within the effluent can be attributable to the bleaching process. Moreover, it becomes even more remarkable when considering how concentrated this outlet is since it usually only makes up under half of the total wastewater volume. Nevertheless, while the amounts and concentrations may vary, the types of lignin derivatives are generally the same. Both humic and fulvic acids are found in wood pulp fibers and derivative components due to its organic composition. Humic acids are dark brown in color, whereas fulvic acids are light yellow to yellow-brown in color (see Figures 1.8 & 1.9). Figure 1.8: Humic Acid 9 Figure 1.9: Fulvic Acid Therefore, the hue of wastewater can be dominated by varying combinations of humic substances. The products of lignin transformation, primarily lignin peroxidase (LiP), are the main contributors of effluent color in paper mill wastewaters (Perez et al., 1997). Just as ligninase enzymatic competition between ?noncolored lignin? and ?colored lignin? affects decolorization (Yin et al. 1989), it would appear that the same should hold for color reversion. This competition affects the rate of color change in wastewater regardless of whether color generation or reduction occurs. The process of lignin transformation and related mechanisms serve as the reasoning behind including the third experimental phase in this thesis, which is discussed later in Chapters 3 & 4. The results of this research increase the overall understanding of the color reversion phenomenon as affected by sulfide. Various sulfide concentrations, combined aeration effects, and relationships between isolated lignin compounds were explored throughout this investigation and the results are presented herein. Solving the color reversion problem in its entirety and understanding all of the mechanisms and kinetics involved in color generation has only begun. Therefore, by uniting the knowledge obtained from past research, summarized in the following chapter (Chapter 2), and that 10 acquired by conducting this thesis, perceptive familiarity with sulfide color reversion should ensue, and hopefully will spark interest in connected research topics yet to be explored. 11 CHAPTER 2 LITERATURE REVIEW Color reversion is the technical term for increases in color that occur during the papermaking process, in wastewater treatment, and/or after release into the environment. While most accounts of color reversion are anecdotal, Lange et al. (2005) reported over 30% increase in color across an aerated lagoon system in Grand Prairie, Alberta (Canada), with similar increases replicated in the laboratory. Lange (2005) showed that aerobic color reversion, while occurring under abiotic conditions, appeared to be kinetically controlled by the treatment process microbiology. While few published accounts are available on the subject of this thesis?color reversion?much research has been conducted on the removal of color (decolorization) in wastewater treatment systems. The ultimate goal for resolving problematic wastewater color is by first understanding the mechanisms involved in color reversion, which is attempted in this thesis, and then by selecting the appropriate means for decolorization, which is discussed thoroughly in this chapter. The following paragraphs seek to provide insight into the available methods and tools that have been identified as successful means for color removal. 12 General Information The color problems associated with pulp and paper mill wastewater have become a subject of great importance and research in the last few decades (Dilek and Bese, 2001). High amounts of bio-resistant chlorinated lignin derivatives give kraft mill bleachery plants their highly colored effluents (Tarlan et al., 2002). These brown colored effluents discharged by the pulp and paper industry result in poor water aesthetics as well as cause harm and disturbance to the surrounding environment. For instance, the discharge of colored effluents can result in temperature increases and decrease photosynthesis activity in receiving waters (Kringstad and Lindstr?m, 1984). Therefore, several ecological problems can consequently develop, such as eutrophication. Yet, despite improved wastewater technology and efficiency over the years, the presence of color bodies has continued to occur in the final effluent of wastewater treatment. As pulp and paper wastewater is treated through various steps involving biological technologies which are geared towards removing biological oxygen demand (BOD), color is at best partially reduced (P?rez et al., 1997). Moreover, the lignin derivative color remains stable and unaltered despite chlorinated organics removal (Tarlan et al., 2002). A study conducted on bleached kraft pulp mills concluded that color originates from residual carbon left in solution after treatment (Kemeny and Banerjee, 1997). Additionally, major contributions to effluent color were determined to ensue from lignin transformation products (P?rez et al., 1997). Lignin derivatives comprise several aromatic compounds, specifically humic substances. Organic compounds appear to be associated with color in relationship to double bond resonance (Joyce and Petke, 1983). Additionally, along with posing several 13 drinking water problems in terms of taste, another integral part of many colored bodies are phenolic groups. As a result, several research projects involving the optimization of biological, chemical, and physical treatment techniques have been undertaken in an attempt to solve this persistent color problem. Some of the wastewater compositions explored include wastewaters from the olive oil, the textile, and the pulp & paper (including the following wastewaters: untreated and treated; bleached kraft and bleach plant effluent; chlorine bleaching treatment; sulfide-rich; wood-based; and bio-depurated) industries. In addition, a collaborative research effort summarizing various color removal technologies that were created and researched over a 15-year span prior to 1983 is included in the following paragraphs. Parameter Optimization The measurement of color, along with other parameters including trace pollutants, oxygen demand, and particulates, are conservative methods utilized in wastewater treatment systems to characterize OM content (Sonnenberg and Holmes, 1998). Non- mineralized OM was found to be the resulting cause for an increase in color across the lagoon pond (Kemeny and Banerjee, 1997). This phenomenon has been commonly seen across lagoons where a color increase occurs from influent to effluent. The effluent color and COD values provide a consistent correlation: residual carbon remaining in the wastewater that was not removed during treatment can offer conditions sufficient for color generation. Non-mineralized OM becomes converted into smaller, more chromophoric units (Kemeny and Banerjee, 1997), which adds to the color of the wastewater. Therefore, just as occurs with chlorolignin degradation, which can be 14 observed during quinone eradication due to hydrogen peroxide treatment, decolorization can result from the destruction of these chromophores (Chang et al., 1986). Pulp and paper mill wastewater lagoons and the surrounding forested hardwood wetland areas provide a suitable habitat for woody organic carbon decomposition by bacteria, algae, fungi, and other microbes. Hence, the process characteristics of dissolved organic carbon (DOC) were compared between that found in the lagoon ecosystem and that present in natural aquatic ecosystems (Sonnenberg and Holmes, 1998). It was found that untreated pulp and paper wastewater had similar DOC compounds to naturally occurring DOC; whereas, the treated wastewater consisted of hydrophilic and non-acidic material. Some relationships have been calculated for the media composition of bench scale analyses. While the results are associated with the related effects of decolorization percentages, these parameters could be considered in analyzing color reversion effects as well. With a glycerol carbon source and low nitrogen and manganese (Mn(II)) levels, decolorization is effectively increased (P?rez et al., 1997). The focus of the subject research of this thesis was not concerned with media nutrient optimization, etc., but these parameters could be considered and analyzed in solving color wastewater problems. A specific study on eucalyptus pulp explored the pollutants in kraft bleachery effluent using gas chromatographic determination. Phenol and catechol chlorinated derivatives were a few of the compounds detected during analysis of different wastewater treatment sampling points (primarily the chlorination and extraction stage effluents) (Sharma et al., 1999). These compounds have been known to contribute appreciably to color problems as well. The significance of this study was that the concentrations 15 detected were very close to their respective toxicity levels (96LC50), and therefore raises the potential concern for environmental effluent noncompliance in the situation of an untreated eucalyptus bleach liquor spill or release. Other parameters associated with color include the properties of macromolecular organic compounds known as humic substances. The fraction of humic acid in aquatic OM was studied for its relationship to pulp and paper mill effluents. The majority of DOC from stream waters is comprised of humic substances and plays an important role in terms of ionic metal and organic pollutant interactions (Santos and Duarte, 1998). Very little knowledge is known about humic substance composition and influence from pulp and paper wastewater interactions, therefore this investigation sought to provide more information on the subject. The study focused on the difference between two sampling sites?one upstream of a pulp mill effluent discharge outfall and one downstream. As the mill employs the sulfite pulping process, the DOC humic acid portion was characterized by lignosulfonic acid structures, as would be expected, being key sulfite process waste products (Santos and Duarte, 1997). Similarly, the fulvic acids from the samples contained high sulfur contents, suggesting the presence of sulfonic functional groups. The results from this work include the importance of anthropogenic sources of OM, the papermaking process being one of the most significant contributors. Biological Treatment Techniques Several biological solutions have been sought and tested related to decolorization, primarily using white-rot fungus (including the strains of Thiobacillus denitrificans, Phanerochaete flavido-alba, Trametes versicolor, Coriolus versicolor, Phanerochaete chrysosporium, Funalia trogii), although some more recent work using Trichoderma sp., 16 algae, and Rhizopus oryzae have been conducted as well. Each of these studies is discussed in detail in the following paragraphs. One case study delved into the technological aspects of sulfide-rich waters and its effect on microbial treatment (using Thiobacillus denitrificans). Substrate inhibition was found to have occurred with the sulfide, but the overall results indicated successful bio- treatment, effective deodorization and detoxification (Sublette et al., 1998). The white-rot fungus study involving the Phanerochaete flavido-alba (P. flavido- alba) organism was determined to be very successful as it ultimately reduced olive oil mill wastewater (OMW) color by 70%. As opposed to pulp mill wastewater color growth resulting from lignin and related derivatives, the presence of a polymerized pigment contributes to the dark color associated with OMW (Bl?nquez et al., 2002). The experiment was conducted using a laboratory-scale bioreactor, but the possibilities for large scale wastewater treatment application using P. flavido-alba seem very promising since mill environmental conditions are suitable circumstances for this organism to flourish and carry out its decolorizing activities. A study on kraft bleach effluents focused on treatment with a urethane prepolymer fluidized bed bioreactor for decolorization and dechlorination evaluation. The white-rot fungi, Trametes versicolor (T. versicolor), was found to successfully reduce color by 72-80% and adsorbable organic halides (AOX) by 52-59% (Pallerla and Chambers, 1995). Additionally, this study found that decolorization followed first order kinetics and was linearly dependent on glucose co-substrate concentration. Similar ranges of decolorization (70-80%) resulted from straw soda-pulping effluent treatment by T. versicolor as well (Mart?n and Manzanares, 1994). 17 Another T. versicolor study determined that adsorbable organic halogen and color were reduced in conjunction with fungal and ozone combination treatment (Roy-Arcand et al., 1991). Ozone has been found to oxidize pulp and paper mill effluent color. This analysis was performed using samples from the alkaline extraction stage, the most colored and toxic portion of the entire kraft bleaching process. The concentration of ozone was tested in a later study and the results ranged from 90%+ of color destruction at very high doses to 79% at a lower level (210 ppm ozone per 2000 selector control units (scu)), and then to 71% decolorization at an even lower amount (180 ppm ozone per 2000 scu)?a substantial percentage of decolorization, even at the lowest reported level (Amero and Hilleke, 1993). Additionally, another ozone experiment indicated a strong correlation of decolorization to chromophoric lignin concentration (Joyce and Petke, 1983). One of the Fungi imperfecti, Trichoderma sp., was determined to be successful in lignin degradation and decolorization of hardwood extraction-stage bleach plant effluent (Prasad and Joyce, 1991). An 85% reduction in color and a 25% decrease in COD resulted from parameter optimization and a three-day cultivation duration. Additionally, decolorization was found to have been greatly stimulated with glucose as the fungal carbohydrate. Phanerochaete chrysosporium (P. chrysosporium) was found to effectively remove color from bleach plant effluent when treated in a rotating biological contractor (RBC), typically from 50-60% within one day (averaging 10,000-20,000 PCU removed / day) (Yin et al., 1989). Another study involving P. chrysosporium calculated that under 18 optimal conditions, up to 2,000 PCU / L / day of color removal from waste streams could be achievable (Joyce et al., 2002). Another white-rot fungal strain, Funalia trogii (from Malatya) showed 31% and 38% decolorization in OMW in static and agitated cultures, respectively (Yesilada et al., 1995). Phenol concentrations, a large contributor to wastewater color, were also reduced in this experiment, by 77% in the static culture and by 72% in the agitated culture. However, the major drawback in conducting white-rot fungal research is in the high glucose requirement and need for supplemental trace nutrients (i.e., yeast extract). Therefore, most of the organisms available for use in decolorization tactics do not appear to be economical for plant-scale size operation (Joyce et al., 2002). A zygomycete, Rhizopus oryzae, was observed to be more effective than basidiomycetes for bleach plant effluent decolorization, dechlorination, and detoxification as fewer nutrients were required. With one g/L of glucose as the co- substrate, a 92-95% color reduction was reported. Moreover, even without glucose, a 78% reduction in color was calculated (Nagarathnamma and Bajpai, 1998). When catalyzed by horseradish peroxidase, hydrogen peroxide treatment at a neutral pH was effective in color removal (Paice and Jurasek, 1983). Yet, compared with Coriolus versicolor (C. versicolor) mycelial color removal (MyCoR), the peroxide/peroxidase system was initially faster, but after two days, the fungal treatment surpassed this rate (suggesting that the fungus used another metabolic route in concurrence with the peroxidase pathway). A combined culture of white-rot fungi and C. versicolor was used in another study for kraft mill wastewater decolorization. In the presence of sucrose, a 60% 19 reduction in color was observed. Yet, 80% decolorization occurred when immobilizing this same sample in beads of calcium alginate gel (Livernoche et al., 1983). A unique opportunity with this method is that by recycling the beads, an efficient color removal system can be created. The decolorization potential of algae is being investigated more and more. A 70% reduction in AOX and 80% for color was seen in a wastewater treatment experiment using a mixed algal culture (Dilek et al., 1999). Furthermore, the algae was found to have reduced the color more efficiently when the sample was low in color initially (below 500 PCU) than for samples of a higher initial color (above 500 PCU). Other levels of wastewater constituents, TOC and lignin, were found to have been reduced considerably, indicating the possibility that the color removal mechanism might not be based on the colored-to-non-colored lignin molecular transformation (Dilek et al., 1999). For a wood-based pulp and paper industrial wastewater study, the treatment was determined to be dominated by some green algae (Chlorella) along with some diatom species. The main mechanism of color and organic removal was found to be a combination of basic metabolism processes and metabolic conversion of the colored and chlorinated molecules to non-colored and non-chlorinated products, respectively (Tarlan et al., 2002). Upon parameter optimization of light intensity and wastewater concentration strength, COD and color removal remained stable, but AOX removal rates were significantly affected. An anaerobic process is currently being developed by Lange et al. (2005b), which employs an anaerobic bacterial consortium on fibrous support material to reduce color. The process has been demonstrated to achieve over 85% reductions in highly colored 20 waste streams after 48 hours of treatment. Negligible reversion of color occurred upon reaeration of the anaerobic process effluent. The exact bacterial populations involved in the destruction of color bodies are unknown, but is the subject of ongoing studies. All of the biological species discussed above resulted in decolorization, though in varying degrees of success. Several factors, such as parameters tested, wastewater compositions, etc., can cause dissimilar results. Additionally, color rates can be affected by ligninase enzymes competition that exists between ?non-colored lignin? and ?colored lignin? (Yin et al., 1989). Ligninolytic activity of both lignin peroxidase (LiP) and manganese peroxidase (MnP) enzymes were analyzed using P. flavido-alba (P?rez et al., 1997). The activity of LiP was determined to play a principal role in paper mill wastewaters, more so than MnP activity. Correspondingly, similar tests were performed on OMW biodegradation by using white-rot fungi. While LiP appears to be the governing mechanism controlling decolorization rates in pulp and paper wastewater, laccase and MnP dominate this aspect in OMW (P?rez et al., 1998). A comparable study on OMW displayed that by using only concentrated extracellular fluids (MnP) results in unsuccessful removal of OMW pigment (Hamman et al., 1999). This signifies the crucial role mycelium binding plays in the decolorization process. The most efficient OMW decolorization occurred for the P. flavido-alba cultures prepared with 40 ?g/L Mn(II). Additionally, these results were accompanied by a 90% phenolic content reduction. Nevertheless, another study explored MnP relationships on pulp mill effluents by using MnP extracted from P. chrysosporium. Immobilized lignin and MnP were studied for decolorization effects on Amberlite IRA-400 resin. A 50% color reduction was 21 determined after the completion of a three-hour enzymatic treatment, but it was realized that a considerable fraction of the observed decolorization resulted from resin adsorption (Peralta-Zamora et al., 1998). Physicochemical Treatment Techniques The chemical methods highlighted during wastewater treatment decolorization research include such chemicals as activated petroleum coke, persulfates, lime and ferrous sulfate, alum and clay combinations, and iron/aluminum chloride/sulfate salts. Turbidity removal techniques, e.g. coagulation and flocculation, were analyzed for modification and improvement possibilities concerning the removal of color along with the main objective of removing colloidal particulates. Additionally, other work related to physical and photolytic techniques were explored as well. The remainder of this section elucidates the details of each of these topics. The main result of the petroleum coke work comprises the creation of isotherms for more accurate prediction of color removal and AOX (Shawwa et al., 2001). Since biological treatment proved to be ineffective for decolorization in pulp mill wastewater along with the fact that activated carbon is very expensive, a raw carbonaceous material abundant in much of Canada known as petroleum coke is utilized (?e?en et al., 1992). The experimental results indicated that using petroleum coke is very successful as greater than 90% color and AOX removal was achieved. Additionally, since the petroleum coke treatment oxidized the wastewater, this chemical treatment could serve as a pretreatment step prior to biological wastewater management (Shawwa et al., 2001). Certain dye decolorization was successful for chlorine-free wet strength paper repulping upon effective treatment with activated alkali metal persulfates. In addition, 22 this analysis was performed under optimal concentration, temperature, and pH conditions (Thorp et al., 1995). Lime and ferrous sulfate comprise another physicochemical treatment technique of color reduction that was researched and documented. This effort incorporated the mechanisms behind some of the color problems associated with cotton textile mill wastewater (Georgiou et al., 2003). The ferrous sulfate was used to stabilize pH for this treatment, which was regulated in the range of 9.0+0.5 (Georgiou et al., 2003). The lime coagulation/flocculation treatment resulted in 70-90% decolorization along with a 50% reduction in COD from the textile wastewater. Specifically for chlorination and extraction pulp and paper wastewaters, the significant groups associated with lime precipitation appeared to be enolic hydroxyl groups (Joyce and Petke, 1983). This conclusion supports the double bond relationship to color: as double bonds were broken through a series of reactions, color was effectively reduced (Figure 2.1). 23 Figure 2.1: Chemical Reactions in the Lime Precipitation Process (Bennett et al., 1971) Another coagulation/flocculation treatment technique was performed using various alum and clay combinations. While a 88% reduction in color resulted from the most effective coagulation treatment, it yielded poor settling characteristics (Dilek and Bese, 2001). Yet another coagulation and precipitation method was used for analysis on mechanical pulping effluent. This study focused on utilizing both chloride and sulfate salts of iron and aluminum. Decolorization was achieved at 90% while still effectively combating total carbon (TC) and turbidity, with respective reductions at 88% and 98% (Stephenson and Duff, 1996). During the mid 1970s, decolorization was evaluated for a sulfite, kraft, and thermo-mechanical pulping plant effluent by using ion exchange technology (Fitch, 24 1982). Yet, up until the turn of the century, no reported ion-exchange study had been performed on elementary chloride free (ECF) bleaching process effluents, commonly used in several mills. Thus, a Sustainable Forest Management Network Project was conducted which integrated ion-exchange resins and reactor design for the effective removal of color and chloride (Ikehata and Buchanan, 2000). This study resulted in effective color removal in all six of the Amberlite? strong base anion exchangers evaluated?each possessing a resin matrix in the hydroxide form, except for one which was in chloride-form. The five hydroxide-form resin exchangers were efficient in chloride removal as well, but the exchanger encompassing the chloride resin form was not successful in this venture. Therefore, in order for this latter resin to be effective in chloride removal, an additional treatment step would be necessary to achieve dechlorination. Photodegradation of organochlorine and color was investigated specifically for high molecular weight (HWM) bleachery effluent. These HMW fractions are very resistant to microbial degradation, but when subjected to artificial and natural sunlight, the wastewater can be effectively decolorized and dechlorinated (Archibald and Roy- Arcand, 1994). The results of this study indicated that a strong oxygen dependency was present with effective photo-decolorization, while this was not the case for AOX mineralization. In another study, ultraviolet (UV) light, derived from sunlight, catalyzed with oxygen and titanium oxide was tested for decolorization potential; but the results were discouraging as sunlight UV-dependency produced low decolorization rates. Yet, as this photocatalytic approach may not be promising, an electrochemical precipitation 25 process was trialed and consequently provided better results for color removal (Springer and Hand, 1992). Summary These decolorization studies aim at creating an understanding of the optimum parameters necessary for selection of the best color removal treatment method. Additionally, the different industrial wastewaters (OMW, textile, and pulp and paper) that were analyzed provide a good foundation for comparison, in terms of varying composition and suitable treatment. Furthermore, whether the appropriate treatment is chemical, physical, or something entirely different, the most important factors to incorporate into the selection process include the projected environmental impact and the financial and practical feasibility. Depending on the decolorization technique chosen, an additional papermaking cost of as much as $20/ton of pulp produced could result (Joyce and Petke, 1983). Nevertheless, before any of these can be implemented with success, the groundwork needs to be laid for appropriate identification and understanding of the underlying mechanisms involved in color generation and growth. 26 CHAPTER 3 MATERIALS AND METHODS The rate and degree of color reversion has been hypothesized to be related to four main mechanisms: 1) anaerobic color reduction, 2) anaerobic color generation via sulfide reaction, 3) aerobic color reversion, and 4) aerobic decolorization. The major goal of this thesis is to elucidate the role of sulfide generation during color reversion of treated and untreated paper mill wastewater. The results of this research increase the overall understanding of the color reversion phenomenon, but do not solve the problem of color reversion in its entirety. To accomplish the goal of this thesis, several representative pulp and paper mill wastewaters were obtained. The pulp and paper plants that served as the source of the test samples included: three Weyerhaeuser mills, one Georgia Pacific mill, and one Rayonier mill. Samples were taken at various points throughout wastewater treatment including: before primary clarification, after primary clarification, and throughout aerobic biological treatment. It was hypothesized that the addition of sulfide, from biogenic generation in anaerobic portions of a pulp mill wastewater treatment process, could increase color intensity. This hypothesis was based on anecdotal information given by various wastewater treatment plant operators. Therefore, to validate this speculation, the 27 wastewater samples were exposed to various concentrations of sulfide through the addition of sodium sulfide crystals, simulating biogenic sulfide production. Resulting changes in color were measured using NCASI method 701. The experimental study approach is outlined in the following section. Experimental Study Approach Three aspects of sulfide color reversion were investigated in this research. The first aspect involved adding sulfide to the samples and then measuring changes in color at various time intervals. This simulated the effect of biogenic sulfide production occurring within anoxic regions of sewers and primary clarifiers and also when high organic loadings deplete aeration basin oxygen. Biogenic sulfide production can also occur during lengthy holding periods and during sample shipment if the temperature is above 4oC. The second aspect of the study implicated aeration effects on the wastewater samples after sulfide color had developed. The purpose of the second phase study was to determine if aeration, occurring subsequent to sulfide generation, could lessen or reverse the impacts of sulfide on wastewater color. This phase would simulate processes occurring in the aerobic portion of the aeration basin, when sulfide is oxidized and stripped off. During the third aspect, lignin, fulvic acid, and lignin monomer compounds were exposed to sulfide and the resulting color changes were measured. The goal of this study was to determine which compounds contributed to the change in color due to sulfide. 28 Sulfide Addition Testing NCASI Method 701 For the color analysis, NCASI Method 701 was followed. Using the Fisher Scientific Platinum Cobalt Color Standard Apha No. 500 Color Standard for Water & Clear Liquids, a calibration curve was calculated (Figure 3.1). Platinum Cobalt Color Standard Calibration Curve y = 0.0003x + 0.0035 R2 = 0.9991 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0 100 200 300 400 500 600 Platinum Cobalt Color Units Ab so rb an ce Figure 3.1: Platinum Cobalt Color Standard Calibration Curve This calibration curve (linear equation) was then applied to the data in order to standardize the results in terms of platinum cobalt color units, PCU. Given the extreme diversity and variability of pulp mill wastewater, the individual color-causing compound concentrations are often very difficult to measure (Ikehata and Buchanan, 2000). Consequently, even though it is not an exact measurement, a color unit of the samples, 29 PCU, is used for conversion so as to represent all of the data on a universal scale for color comparison. Thirty-milliliter batch solutions were made up by adding increasing amounts of Fisher Scientific sodium sulfide reagent grade crystals. These solutions were made up in 40-mL glass vials with caps. A 10-ppm sodium sulfide solution was created in order to observe the effect of the lower sulfide range extremes. Increasing doses of this solution were administered to the first three sets of samples (which included those from the Grand Prairie, Alberta and Johnsonburg, PA Weyerhaeuser sites along with the sample set from Rayonier). Yet, no more samples were analyzed using this solution in an effort to minimize dosage dilution as well as to explore higher ranges of sulfide exposure. Hence, these samples and the rest of the entire data set were tested using pure crystal doses. Twenty milligrams of ammonium molybdate (Fisher Scientific lab grade, crystal, tetrahydrate) per liter of sample were added to the first three samples to hinder any color growth unrelated to the sulfide generation. Yet, upon analyzing the results, this chemical treatment was determined to have dramatically inhibited any color reversion increase at all. Therefore, this chemical addition was halted. Samples were analyzed initially at the time of make-up, but this was stopped after conducting a few experiments in order to ensure complete sodium sulfide crystal dissolution. Therefore, samples were made-up and then analyzed after one hour. Samples were tested at one-hr, four-hr, and 24-hr intervals. Some samples were only measured at the lower and higher end of the doses and/or at the one-hour and 24-hour time intervals, depending upon the volume of sample provided. Ten-milliliter aliquots were extracted at each of the time increments indicated and analyzed. 30 Using an ATI Orion Expandable Ion Analyzer EA 940 pH meter, the samples were adjusted to a pH value of 7.6 with phosphoric acid and/or sodium hydroxide depending upon the initial pH of the wastewater sample. A few specific instances during pH adjustment, the formation of white colloidal precipitates was observed specifically in the higher sodium sulfide dosage samples (typically in the 330, 660, and 1,650 mg/L doses). Metal hydroxide precipitation is believed to have been the cause for this phenomenon. This event was also observed during the ion-exchange experiments involving color and chloride removal (Ikehata and Buchanan 2000). After vacuum filtration using Whatman GF/C Circles 47 Diameter Glass Microfibre filters, color determination was accomplished by analyzing sample absorbance at 465 nanometers (nm) using a Hewlett Packard HP 8453 Ultraviolet-Visible Spectrophotometer. Color Development in Sulfide Blanks Increasing concentrations of sulfide were added to blank samples of water in order to determine the resulting color change attributed solely from sulfide dissolution (Figure 3.2). Sodium sulfide when dissolved in solution possesses a slightly yellowish tint. Therefore, the purpose of testing blanks was to ensure that the experimental data indicated a color increase as a result of interactions between sulfide and the pulp and paper wastewater and not just the resulting color increase of the sulfide solution alone. 31 03 7101 520253 07017033 06601650 1 24 0 30 60 90 120 Platinum Cobalt Color Units (PCU) Time (hr) Blanks (Crystals in Water) Color Development Sodium Sulfide Dosage (mg/L) Figure 3.2: Blank Samples Color Results It is important to note that while color development did occur in these samples, both with increasing doses and over time, the color increase (the highest value being less than 60 PCU) is significantly below the values displayed by the wastewater samples, graphically illustrated throughout Chapter 4. Therefore, the resultant color change of the blank solutions can be considered as negligible. Colored Wastewater Samples Wastewater samples were sampled and shipped to Auburn University by the Environmental Departments of Weyerhaeuser (Grand Prairie, Alberta, Canada; Prince Albert, Saskatchewan, Canada; Johnsonburg, PA; and Albany, OR), Rayonier (Jesup, Georgia), and Georgia Pacific (Palatka, Florida) Pulp and Paper Mills. Samples from Weyerhaeuser included the primary clarifier inlet and outlet and secondary effluent 32 sample set from Grand Prairie, Alberta; the primary pond inlet, midpoint, and outlet samples from the Prince Albert, Saskatchewan location; samples collected at the pulp sewer, settling and aeration pond feeds, and final discharge from the Johnsonburg site; and several grab samples from the Albany, OR dual-celled lagoon. Rayonier samples were collected from the primary clarifier, from the ?strong pond? influent and effluent, and from the associated effluents from parallel aerated stabilization basins (ASB) #1 and #2. Georgia Pacific provided samples from their lagoon of which is divided into four equivalently-sized ponds (Ponds 1, 2, 3, and 4) and additional grab samples were taken from Pond 2. Mill Descriptions Weyerhaeuser Samples from Weyerhaeuser included sample sets from three separate plants: the Prince Albert mill located in Canada, the Johnsonburg, PA operation, and the Albany, OR business unit. The Weyerhaeuser Canada Ltd., Alberta, Canada (Prince Albert, Saskatchewan, Canada) plant includes both the Grand Prairie, Alberta and Prince Albert, Saskatchewan mills. The Grand Prairie, Alberta mill is a softwood bleach kraft mill that is currently employing oxygen delignification and chlorine dioxide bleaching. A wastewater discharge of 13.1 million gallons per day is routed through a treatment process consisting of a pair of primary settling ponds, followed by two aeration cells with a total residence time of 25 days. At least half of the first aerated cell has no measurable oxygen concentration and moderate hydrogen sulfide generation (4-6 mg/L). There are two secondary settling cells, followed by discharge into the Wapiti River. 33 The Weyerhaeuser mill, located in Prince Albert, Saskatchewan, is a bleached kraft pulp mill with a wastewater flow of 19 million gallons per day. The wastewater treatment system consists of a primary clarifier, followed by a highly aerated-three cell aeration lagoon with a five-day residence time and two equally-sized final settling ponds. Final discharge of the effluent is into the Fraser River. The Johnsonburg, Pennsylvania Weyerhaeuser mill produces specialty paper for book publishing using a bleach kraft process. The wastewater treatment process consists of primary clarification, followed by a 13.8 million gallon per day activated sludge process with an average cell age of 25 days. After secondary clarification, discharge of the treated effluent is into the Clarion River. The Weyerhaeuser mill in Albany, Oregon is a bleached kraft mill with a wastewater flow of 5.2 million gallons per day. Wastewater treatment consists of a two- cell primary settling pond with a residence time of three days, followed by a two-cell aerated lagoon having an eight-day residence time. Final discharge is into the Willamette River. Rayonier The Jesup, GA Rayonier plant operates as a fluff-pulp mill, using an acidic digestion process followed by chlorine bleaching. The wastewater treatment includes a primary clarifier followed by an aerated strong pond where condensate is added to the waste stream. The wastewater is then divided into two aerated lagoons, each having a residence time of eight days. The front of each lagoon is highly aerated while the final half is not aerated or mixed and serves as the settling basin. The final discharge from both lagoons is into the Altamaha River. 34 Georgia Pacific Georgia Pacific located in Palatka, FL is a bleached kraft mill that produces specialty grade paper including toilet tissue and paper towels. The wastewater treatment system consists of a 360-foot diameter primary clarifier followed by a 1,000 acre - 900 million gallon aerated treatment lagoon. This lagoon is divided into four equally-sized basins (ponds), each with approximately 15 days of residence time. Ultimate discharge is into the Saint Johns River, which is regarded as sensitive. Aeration Experimentation Aeration was tested in order to observe the resulting effect on sulfide color reversion. This environment most closely represents the aerobic portion of the wastewater flow train in a treatment plant (aeration basins, lagoon, etc.); therefore, it was pertinent to incorporate this factor into the analysis. Two samples were employed in this analysis, one representative lightly colored sample (the Weyerhaeuser Albany, OR composite sample) and one of a darker color (the Georgia Pacific Pond 2 sample). Only the extreme doses of sulfide concentration (one ppm and 500 ppm) were tested during this experimentation. Aeration testing was conducted in 250-mL Erlenmeyer flasks using a volume of wastewater equal to 150 mL. The flasks were stoppered with foam to minimize evaporation. Aeration was accomplished with the use of aquarium aeration stones, an associated connection apparatus (holding five such stone connection ports), and the inlet and outlet plastic tubing. The manifold tube was then attached to the building air supply and adjusted to permit a slow stream of air to flow into the samples, allowing gentle 35 aeration (approximately 25 mL/L/minute). Ten-milliliter aliquots were extracted at various time intervals and analyzed using NCASI color method 701. Lignin Components Isolation Analysis Due to the composition of a variety of color-causing compounds, it is difficult to quantify the individual concentration of each of these wastewater components. As such, it also becomes difficult to ascertain the influence of any one lignin component and/or derivative involved in color reversion. Therefore, several single component solutions were created and analyzed in order to compare the results to that displayed by the wastewater samples. Such common components of lignin including 4-hydroxybenzaldehyde, phenol, vanillin, humic acid, fulvic acid, catechol, and anthraquinone were dissolved in solution, exposed to extreme sulfide concentrations, and analyzed for color. Solutions were created using chemicals from Avocado Research Chemical Ltd. (vanillin, 99% and 4-hydroxybenzaldehyde, 98%), from Fisher Scientific (phenol, reagent A.C.S., loose crystals), from Acros Organics (catechol, 99+%; anthraquinone-2,6-disulfonic, disodium salt; and humic acid, sodium salt.), and from Vital-Earth Minerals, LLC (fulvic mineral complex, ionic mineral supplement, 100% fulvic acid in solution). In addition to the sulfide and time variables, the effects of varying solution strength were also tested (one ppm and 50 ppm). 36 CHAPTER 4 RESULTS AND DISCUSSION Three factors affecting color reversion were investigated in this research. In this chapter, the effects of sulfide and subsequent aeration on color growth in wastewaters from various pulp and paper mills are addressed. Additionally, the effect of sulfide on color growth in solutions of humic acid, fulvic acid, and various lignin monomers was quantified. Sulfide Color Reversion It was hypothesized that the addition of sulfide, from biogenic generation in anaerobic portions of a pulp mill wastewater treatment process, could increase color intensity. This hypothesis was based on anecdotal information given by various wastewater treatment plant operators. To validate this hypothesis, the addition of sodium sulfide was used as a surrogate for biogenic sulfide production. The results of sulfide addition studies are presented in this section for each mill, and then summarized for all mills. Weyerhaeuser The first trends discussed are samples from the primary clarifier inlet/outlet and secondary effluent from the Weyerhaeuser - Grand Prairie, Alberta mill which is approaching its color discharge limits. For the primary clarifier inlet sample, an increase 37 in color was observed immediately after sulfide was added at time zero (Figure 4.1). Higher doses of sulfide resulted in higher increases of color. At the highest dose of five mg/L, over three times as much color was measured in comparison to the zero mg/L control. Minimal increases in color were observed over time, as seen by the one-hour and four-hour time intervals. However, after 24 hours, all samples had significantly lower colors, which may be attributable to stripping of the sulfide or biological anaerobic color removal processes, such as reduction of quinone moieties. 00 .4 0.8 2.0 5.0 0 1 4 24 0 500 1000 1500 2000 2500 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Primary Clarifier Inlet Figure 4.1: Grand Prairie, Alberta Weyerhaeuser Primary Clarifier Inlet Sample Color Results from 10-ppm Sulfide Solution Doses The clarifier inlet sample was analyzed again, this time being exposed to higher concentrations of sulfide along with ammonium molybdate treatment (Figure 4.2). As 38 this experimentation involved sulfide crystals, instead of the lower 10-ppm concentrations, the expected outcome was postulated to have been proportionally larger in terms of a color increase. Yet, much smaller initial increases in color reversion were observed at all concentrations. This counterintuitive result was believed to have been due to the chemical addition of ammonium molybdate. The samples containing ammonium molybdate demonstrated significantly lower colors at time zero hours and one hour (see Figure 4.2). This indicates that a portion of the rapid color change was inhibited by the presence of the molybdate. Molybdate is an inhibitor of sulfate reducing bacteria, and the reduction of color may be attributable to the decrease of microbial sulfide reduction and accompanying increases in the redox potential of the wastewater solutions. Alternatively, the molybdate could directly compete with sulfide for binding sites on the color bodies and may interfere with the rate and degree of color development. By the four-hour sampling interval, similar degrees of color reversion were observed in the lower sulfide concentration samples, but the color reversion was still much lower at the higher sulfide concentrations. A second variable appearing to contribute to changes in color was time. Immediately after sulfide addition (at time equaling zero hours), higher colors were measured for higher sulfide doses. These increases were many times the values measured for the sulfide blanks (see Chapter 3) and are likely the result of a rapid reaction between wastewater components and sulfide. Increases in time after sulfide addition resulted in additional increases in color, apparently independent of the ammonium molybdate addition. Thus, color development (color reversion) appears to have both a rapid component and a slower component. The highest percent increase in color occurred at 39 four hours and represented an approximate 280% increase from the original zero-mg/L, zero-hr sample (Figure 4.2). 02 510 1215 2025 4050 70751 30 0 1 4 24 0 1000 2000 3000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Primary Clarifier Inlet (with Ammonium Molybdate Treatment) Figure 4.2: Grand Prairie, Alberta Weyerhaeuser Primary Clarifier Inlet Sample Color Results from Crystallized Sulfide and Ammonium Molybdate Treatment Based on these preliminary results, it was apparent that sulfide had the potential to have a significant effect on color; however, the exact nature of the effect was not clear. Furthermore, the addition of molybdate altered both the rate and the degree of color reversion. Color development can be extremely rapid, with color appearing almost instantly. Additional color development occurs slowly over several hours of time. Color development does not appear to be long-lasting, with colors decreasing after 24 hours. The outlet sample for the Grand Prairie primary clarifier sample showed similar results to the clarifier inlet samples. The initial color of the primary effluent sample was 40 400 PCU which was somewhat lower than that of the 500 PCU measured for the primary influent. With increasing doses, color once again became more intense immediately after sulfide addition. Increases in color by 24 hours were similar at all sulfide doses and averaged a 30-40% increase (Figure 4.3). However, the degree of this color increase was somewhat smaller than that observed for the primary influent (Figure 4.1). The color increased slightly with increasing exposure times, but never achieved the colors measured for the primary influent. Since significant biological removal of organics is achieved during the 12-hour residence time in the primary clarifier, it is possible that color precursors are removed by biodegradation and/or settling in the clarifier. 00 .4 0.8 2.0 5.0 0 1 4 24 0 200 400 600 800 1000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Primary Clarifier Outlet Figure 4.3: Grand Prairie, Alberta Weyerhaeuser Primary Clarifier Outlet Sample Color Results from 10-ppm Sulfide Solution Doses 41 In Figure 4.4, the results from the ammonium molybdate addition can be seen. This chemical inclusion appeared to cause increased color reversion at lower doses. At higher doses, the color reversion was decreased as was observed for the influent sample. 037 10152 02530 7017033 06601650 1 4 24 1 4 24 0 700 1400 2100 2800 3500 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Primary Clarifier Outlet with Ammonium Molybdate without Ammonium Molybdate Figure 4.4: Grand Prairie, Alberta Weyerhaeuser Primary Clarifier Outlet Sample Color Results from both Crystallized Sulfide Exposure and with/without Ammonium Molybdate Treatment The secondary effluent sample had an initial color of less than 300 PCU which is likely reduced from the 400 PCU in the primary effluent due to the 25 days of biological action in the lagoons. For the secondary effluent samples, a color increase was observed immediately after sulfide addition, but was not as prominent as those measured for the 42 primary influent and effluent (Figure 4.5). Additional color reversion was observed as exposure time increased, achieving an approximate 10% increase ultimately after 24 hours. Since discharge permits are written in terms of pounds of color per day, which assumes one PCU is equal to one mg/L, a small increase in the color percentage may represent a significant mass of color in the effluent. In this specific case, based on a 13.1 million gallon per day (gpd) discharge, a 10% increase from 300 PCU of color equates to a color loading increase of 3,280 lbs/day! 00 .4 0.8 2.0 5.0 0 1 4 24 0 200 400 600 800 1000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Secondary Effluent Figure 4.5: Grand Prairie, Alberta Weyerhaeuser Secondary Effluent Sample Color Results from 10-ppm Sulfide Solution Doses 43 The addition of molybdate had similar effects as was seen for the primary clarifier samples, but color increases were somewhat more variable with increasing sulfide concentrations (Figure 4.6). This variability may be more pronounced in these samples due to the low starting color. Time did not appear to be as significant of a factor for the secondary effluent as it was for the primary clarifier samples. Most of the color increase occurred rapidly and was measured for the zero-hour samples. There was, however, some additional increase from slow development color reversion after one and four hours, though slight, measured at around 25%. 0371 015202 5307017 0330660165 0 1 4 24 1 4 24 0 400 800 1200 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Secondary Effluent with Ammonium Molybdate without Ammonium Molybdate Figure 4.6: Grand Prairie, Alberta Weyerhaeuser Secondary Effluent Sample Color Results from both Crystallized Sulfide and with/without Ammonium Molybdate Treatment 44 It should be noted that an increase of color occurred in the control samples (zero mg/L of sulfide added) samples. It is likely that biogenic sulfide production may have contributed to these increases. In similar samples from this mill, Lange (2004) measured up to 22 mg/L of sulfide production in a 24-hour period. Therefore, sample data was compared against the related zero-mg/L, zero-hour values for each sampling location to account for any biogenically-created color (refer to Tables 4.1 - 4.3). Table 4.1: Grand Prairie, Alberta Weyerhaeuser Color Results Summary (10-ppm Solution) Weyerhaeuser Grand Prairie, Alberta Color Results (PCU) from 10-ppm Solution Sulfide Dosage Primary Clarifier Inlet Primary Clarifier Outlet Primary Clarifier Secondary Effluent (mg/L) 24 hr % Color Change 24 hr % Color Change 24 hr % Color Change 0 392 -56 731 35 527 53 0.1 416 -53 696 28 517 50 0.2 434 -51 711 31 546 58 0.4 418 -53 634 17 526 53 0.5 387 -56 676 24 575 67 0.6 393 -56 691 27 549 59 0.8 442 -50 648 19 567 64 1.0 495 -44 712 31 504 46 1.5 456 -49 707 30 411 19 2.0 523 -41 715 32 505 47 2.5 553 -38 630 16 465 35 3.0 564 -36 680 25 424 23 5.0 697 -21 797 47 893 159 45 Table 4.2: Grand Prairie, Alberta Weyerhaeuser Color Results (Crystallized Sulfide Doses & Ammonium Molybdate) Weyerhaeuser Grand Prairie, Alberta Color Results (PCU) with Ammonium Molybdate Sulfide Dosage Primary Clarifier Inlet Sulfide Dosage Primary Clarifier Outlet Secondary Effluent (mg/L) 24 hr % Color Change (mg/L) 24 hr % Color Change 24 hr % Color Change 0 1719 159 0 2794 82 641 44 2 1473 122 3 3057 99 457 2 5 1499 126 7 3009 96 388 -13 10 1525 130 10 3358 118 335 -25 12 1650 149 15 3159 106 862 93 15 1307 97 20 2269 48 394 -12 20 1487 124 25 2423 58 357 -20 25 1190 79 30 1841 20 342 -23 40 1143 72 70 1757 14 341 -24 50 881 33 170 1544 0 354 -21 70 815 23 330 707 -54 344 -23 75 930 40 660 924 -40 1008 126 130 536 -19 1650 974 -37 486 9 46 Table 4.3: Grand Prairie, Alberta Weyerhaeuser Color Results Summary (Crystallized Sulfide Doses) Weyerhaeuser Grand Prairie, Alberta Color Results (PCU) without Ammonium Molybdate Sulfide Dosage Primary Clarifier Inlet Primary Clarifier Outlet Secondary Effluent (mg/L) 24 hr % Color Change 24 hr % Color Change 24 hr % Color Change 0 880 6 661 -7 237 25 3 736 -11 1193 69 341 52 7 721 -13 1091 54 516 90 10 735 -11 1116 58 507 56 15 798 -3 1222 73 303 54 20 801 -3 1221 73 320 55 25 824 0 1141 61 346 63 30 892 8 1111 57 317 53 70 753 -9 1399 98 325 55 170 757 -8 1182 67 492 57 330 663 -20 1151 63 325 62 660 594 -28 779 10 489 108 1650 749 -9 794 12 498 142 The next set of data relates to a set of wastewater samples obtained from the Prince Albert, Saskatchewan mill. These samples were taken from the primary pond inlet, midpoint, and outlet where significant sulfidogenic activity was measured, resulting in sulfide increases from 15 ppm to 38 ppm. For the primary pond influent, negligible rapid color increases were observed for sulfide doses at or below 70 mg/L (see Figure 4.7). At sulfide concentrations of 170 mg/L and above, there was an immediate increase in color that approached 200% of the original color. Little additional color change was observed after four hours had passed. However, after 24 hours had elapsed, all of the samples displayed the same color value (averaging 400 PCU). This reduction may be a 47 result of sulfide stripping or biological anaerobic color removal processes, specifically quinone degradation or transformation. 03 710 1520 2530 701703 3066016 50 1 4 24 0 400 800 1200 1600 2000 2400 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Primary Pond Inlet Figure 4.7: Prince Albert, Saskatchewan Weyerhaeuser Primary Pond Inlet Sample Color Results For the midpoint sampling location of the clarifier, the color increases at one hour were observed for all sulfide doses, being most dramatic at the highest dosage levels (Figure 4.8). At sulfide doses of three mg/L and higher, the color change ranged from 30% to 300%. Once again, very little additional color change was noted after the initial one hour of sulfide exposure. In general, the results for the mid-pond sample were very consistent with the pond influent. However, after 24 hours, color reversion remained prominent (averaging about 40%) for the midpoint sample; whereas, color reduction was 48 observed at 24 hours for the inlet sample (Table 4.4). This later color increase could potentially support the aerobic color reversion mechanism as this pond is a highly aerated lagoon. Furthermore, color increases have been commonly purported to occur across aeration ponds. 03 710 1520 2530 701703 3066016 50 1 4 24 0 500 1000 1500 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Primary Pond Midpoint Figure 4.8: Prince Albert, Saskatchewan Weyerhaeuser Primary Pond Midpoint Sample Color Results The effluent from the primary settling pond showed similar results as given by the influent and mid-pond samples. The one-hour data set displayed a color increase for all sulfide doses: as dose increased, so did resulting color (Figure 4.9). The most significant increases in color occurred for sulfide doses of 330 mg/L and higher. The color change for these sulfide concentrations ranged from 10% to 100% (see Table 4.4). As for the influent and mid-point samples, very little additional color change was noted after the 49 initial one hour of exposure. Therefore, the supposed theory of color reversion becoming intensified as a result of aeration and/or other mechanisms is further deduced by this data set. Table 4.4 clearly shows increasing color percentages from inlet to midpoint to outlet. Though not proven, quinone production is likely to have occurred here. 03 710 1520 2530 701703 306601 650 1 4 24 0 200 400 600 800 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Primary Pond Outlet Figure 4.9: Prince Albert, Saskatchewan Weyerhaeuser Primary Pond Outlet Sample Color Results 50 Table 4.4: Prince Albert, Saskatchewan Weyerhaeuser Results Summary Weyerhaeuser Prince Albert, Saskatchewan Color Results (PCU) Sulfide Dosage Primary Pond Inlet Primary Pond Midpoint Primary Pond Outlet (mg/L) 24 hr % Color Change 24 hr % Color Change 24 hr % Color Change 0 480 11 388 29 413 16 3 418 -3 401 34 449 26 7 429 -1 386 29 481 35 10 369 -14 557 86 397 12 15 408 -5 402 34 405 14 20 426 -1 372 24 464 31 25 527 22 381 27 457 29 30 327 -24 409 36 733 106 70 413 -4 396 32 451 27 170 368 -15 419 40 474 33 330 420 -3 408 36 379 7 660 206 -52 239 -20 564 59 1650 383 -11 229 -24 460 29 The Johnsonburg samples were collected at the pulp sewer, settling pond feed, aeration pond feed, and the final discharge locations. The initial conditions for the samples are provided below in Table 4.5: Table 4.5: Johnsonburg, PA Weyerhaeuser Samples?Initial Conditions Pulp Sewer Settling Pond Feed pHp Cond. Sulfide (ppm) pHp Cond. Sulfide (ppm) 11.4 3880 4 11.1 2920 3 Aeration Pond Feed Final Discharge pHp Cond. Sulfide (ppm) pHp Cond. Sulfide (ppm) 9 2400 16 7.8 2500 0 51 The wastewater samples from the pulp sewer have high BOD, small chlorine residual, highly positive redox, and high pH. Even though a small sulfide residual was reported for this sample, it should not have a long history of sulfide exposure. Because this sample represents wastewater from bleaching, it typically has a low color (approximately 200 PCU) and is believed to be most susceptible to color reversion. The pulp sewer (often referred to as the alkaline sewer) showed a strong correlation to the mechanistic anaerobic color generation via the sulfide reaction (see Figures 4.10 & 4.11). For the lower ranges of sulfide exposure (Figure 4.10), the initial samples (zero-hour) taken immediately after sulfide addition showed an increase in color. The observed trend provided increasing color with increasing sulfide dose, approaching 400% by the highest dose of five mg/L. Additionally, color reversion was supported by the slower mechanism in that by the 24-hour interval, close to a 1,000% color increase had been reached. The highest immediate color change for the higher dosage ranges was 180% (Figure 4.11). A further increase in color was observed after four and 24 hours of exposure to sulfide. The highest increases for color ranged from 140% in the 330 mg/L sample to 220% in the 1,650 mg/L sample during the four-hr sampling interval. The high change in color percentage was not unexpected due to the bleached state of the waste and the high potential for non-sulfide reacted color bodies. 52 0 0.4 0.8 2.0 5.0 0 1 4 24 0 500 1000 1500 Platinum Cobalt Color Units (PCU) Time (hr) Weyerhaeuser Pulp Sewer Sulfide Dosage (mg/L) Figure 4.10: Johnsonburg, PA Weyerhaeuser Pulp Sewer Sample Color Results from 10-ppm Sulfide Solution Doses 03 710 1520 2530 701703 3066016 50 1 4 24 0 200 400 600 800 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Pulp Sewer Figure 4.11: Johnsonburg, PA Weyerhaeuser Pulp Sewer Sample Color Results from Crystallized Sulfide Doses 53 The feed to the settling pond includes the pulp sewer material, condensate, and other process wastewater from throughout the mill. Higher initial color was noted, as well as similar color reversion trends as seen for the pulp sewer sample (Figure 4.12). 00 .4 0.8 2.0 5.0 0 1 4 24 0 500 1000 1500 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Settling Pond Feed Figure 4.12: Johnsonburg, PA Weyerhaeuser Settling Pond Feed Sample Color Results from 10-ppm Sulfide Solution Doses The settling pond influent is maintained at a high pH to counter the effects of organic acid production by anaerobic organisms in the pond. The settling pond influent had an initial color of 640 PCU which was somewhat higher than the pulp sewer sample and may be due to some reversion in the pulp sewer wastewater and color contributions from other wastewater streams (Figure 4.13). 54 03 710 1520 2530 701703 3066016 50 1 4 24 0 300 600 900 1200 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Settling Pond Feed Figure 4.13: Johnsonburg, PA Weyerhaeuser Settling Pond Feed Sample Color Results from Crystallized Sulfide Doses As shown by Figures 4.12 & 4.13, a rapid increase in color was observed in the settling pond samples immediately after sulfide addition. However, unlike the pulp sewer samples, the increase in color seemed to only rise slightly with increasing sulfide dose. For the higher sulfide exposure doses, the initial increase in color ranged from 30% in the 20 mg/L sample to 50% in the 25 mg/L sample. Additional color reversion was measured after four and 24 hours, reaching final colors that were slightly higher than those observed in the pulp sewer samples. At highest dosage levels, sulfide saturation could have resulted causing color reversion to lessen in value. 55 Tracking the wastewater further along its treatment path shows that the color in the aeration pond feed stage is similar to the primary settling pond influent (approximately 400 PCU). The aeration basin feed is the effluent from the settling pond that is fed into the aeration basin of the Johnsonburg activated sludge process. Some immediate increases in color were observed in the aeration feed (Figure 4.14). However, these increases were smaller than observed for the upstream samples and did not correlate well to the sulfide dose. Some additional growth was measured after 24 hours, with color growth ranging from four percent in the 0.2-mg/L samples to over 100% in the five-mg/L sample. 00 .4 0.8 2.0 5.0 0 1 4 24 0 200 400 600 800 1000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Aeration Pond Feed Figure 4.14: Johnsonburg, PA Weyerhaeuser Aeration Pond Feed Sample Color Results from 10-ppm Sulfide Solution Doses 56 The final discharge sample represents the wastewater after treatment in the activated sludge process and from final clarification. The color in this discharge was 470 PCU, which is slightly lower than the aeration influent and indicates that some removal of color was accomplished by aerobic treatment. To regulators, this sample would be most important since this is discharged to the environment. Very little immediate color increase was observed in this sample as illustrated by the zero-hour data (Figure 4.15). But then at a concentration of 2.5 mg/L of sulfide and after 24 hours of exposure, the color increased significantly, supporting the slower color development mechanism. While the initial conditions (Table 4.5) suggest that zero ppm of sulfide is characteristic of the final discharge, note that 16-ppm is indicated as a typical concentration seen in the aeration pond feed. As the aeration pond feed wastewater precedes the treatment stage for the final discharge, the potential for color problems seems to be present. Therefore, color reversion seen at these higher levels of five mg/L at the 24-hour interval mark suggests the problematic possibility of color loading upon low sulfide exposure levels. 57 0 0.4 0.8 2.0 5.0 0 1 4 24 0 500 1000 1500 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Final Discharge Figure 4.15: Johnsonburg, PA Weyerhaeuser Final Discharge Sample Color Results from 10-ppm Sulfide Solution Doses Moreover, color reversion seems to be most sensitive to lower amounts of sulfide doses which are the realistic exposures wastewater would actually encounter. Additionally, the higher sulfide levels achieved through the addition of sulfide crystals resulted in sporadic color increases, suggesting another color mechanism was involved (Figure 4.16). Saturation could be a possible explanation for the sudden decline in color values seen in the highest sulfide levels. Furthermore, color change seemed to suggest an independent relationship to sulfide dosage. Yet, it is important to note the higher color increase seen for the final discharge sample as opposed to the aeration pond feed 58 samples. This observation provides further indication of the possibility of color being augmented across the treatment process train. 03 7101 5202 5307 017033 0660165 0 1 24 1 24 0 200 400 600 800 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Aeration Pond Feed & Final Discharge Aeration Pond Feed Final Discharge Figure 4.16: Johnsonburg, PA Weyerhaeuser Aeration Pond Feed and Final Discharge Samples Color Results from Crystallized Sulfide Doses The Johnsonburg, PA mill results propose the importance of the color source: the pulp sewer. Color lessened as the wastewater progressed toward its final discharge location (see Table 4.6). Yet, the residual effects of color reversion from the pulp sewer could still be seen. Therefore, understanding the pulp sewer relationships concerning color reversion should be one of the first steps of any decolorization tactic. 59 Table 4.6: Johnsonburg, PA Weyerhaeuser Results Summary Pulp Sewer Final Discharge Color Results (PCU) Color Results (PCU) Sulfide Dosage Sulfide (ppm) = 4 Sulfide (ppm) = 0 (mg/L) 0 hr % Color Change 24 hr % Color Change 0 hr % Color Change 24 hr % Color Change 0 115 0 398 246 443 286 437 280 0.1 270 135 1228 969 501 335 440 283 0.2 364 217 1303 1034 527 358 497 332 0.4 443 285 1145 897 545 374 517 350 0.5 192 67 981 753 528 359 538 368 0.6 158 37 1029 795 482 319 565 392 0.8 120 4 1058 821 565 391 658 472 1.0 202 76 1123 877 549 377 646 462 1.5 416 262 984 756 456 296 593 416 2.0 436 279 1363 1086 444 287 489 325 2.5 664 477 1083 843 534 365 918 699 3.0 459 299 1071 832 473 312 1238 977 5.0 625 443 1146 897 665 478 1223 964 The last set of samples from Weyerhaeuser consisted of seven grab samples taken throughout the Albany, OR mill wastewater lagoon. Equal volumes of these samples were combined to form one composite wastewater that was employed in sulfide experimentation as well as in the aeration tests described later in this chapter. These samples appeared to be a suitable representation of lightly colored samples in pulp and paper wastewater treatment. Furthermore, the mill reported problems with increases in both sulfide concentrations and color in this pond system. Due to a series of pulp spills, the front of the lagoon had become anoxic, and sulfide levels had increased from less than one mg/L to over ten mg/L. The initial color of the composite wastewater sample was just under 200 PCU. After one hour of sulfide exposure, increases in color were apparent, with the highest 60 colors linked to the highest sulfide doses (Figure 4.17). After four and 24 hours of exposure, color increased further resulting in a final increase of about 100%. This substantiates the correlation between sulfide and color reported for this pond. 03 710 1520 2530 701703 306601 650 1 4 24 0 100 200 300 400 500 600 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Weyerhaeuser Mixed Sample Figure 4.17: Albany, OR Weyerhaeuser Mixed Composite Sample Color Results with Sulfide Doses 61 Table 4.7: Albany, OR Weyerhaeuser Results Summary Weyerhaeuser Albany, OR Mixed Sample Color Results (PCU) Sulfide Dosage (Composite of seven grab samples from the dual-celled lagoon) (mg/L) 1 hr % Color Change 4 hr % Color Change 24 hr % Color Change 0 191 0 192 1 239 25 3 232 21 267 40 443 132 7 230 20 279 46 381 100 10 248 30 280 46 401 110 15 244 28 223 17 339 78 20 239 25 240 26 400 109 25 258 35 248 30 297 56 30 281 47 303 59 266 40 70 282 48 289 51 400 109 170 473 148 412 116 442 131 330 344 80 372 95 327 72 660 580 204 449 135 271 42 1650 281 47 374 96 378 98 Rayonier Samples from Rayonier included the primary clarifier inlet, the influent and effluent of an under-aerated ?strong pond,? and the effluent from two parallel-configured aerated stabilization basins (ASB #1 & #2). These wastewaters were highly colored (around 1000-2000 PCU), compared to the previously discussed waste streams. This may be due to the high-temperature acid digestion process used to produce cellulose and fluff-pulp at this mill. There was little immediate change in color in the primary clarifier inlet sample as shown by the zero-hour data of Figure 4.18. There was no measurable increase in color over time for this sample except when exposed to the highest sulfide dosage level of five 62 mg/L. Upon looking at sulfide concentrations above five mg/L (Figure 4.19), color growth continues to occur, though most dramatic at unrealistically high sulfide levels. 00 .4 0.8 2.0 5.0 0 1 4 24 0 500 1000 1500 2000 2500 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier Primary Clarifier Figure 4.18: Rayonier Primary Clarifier Sample Color Results from 10-ppm Sulfide Solution Doses 63 03 710 1520 2530 701703 3066016 50 1 4 24 0 400 800 1200 1600 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier Primary Clarifier Figure 4.19: Rayonier Primary Clarifier Sample Color Results from Crystallized Sulfide Doses The higher initial color of the sample is believed to mask the effects of any sulfide color reversion. The high color of this sample may be indicative of a long history of previous exposure to sulfide. The primary influent has nearly 20 mg/L of sulfide resulting from anaerobic processes in the acid sewer from the hot acid pulping process. Alternatively, the nature of this highly colored wastewater may be variable. The wastewater contains high levels of furfuraldehyde due to the pulping process, which may contribute significantly to color. Furfuraldehyde is not commonly found in bleach kraft processes and is highly colored between 450 and 470 nm. 64 Due to the high initial color possessed by the combination of primary effluent and bleach plant filtrate of the strong pond influent, little immediate color increase was observed (Figures 4.20 & 4.21). Additionally, little color increase over time due to sulfide was seen. Sulfide exposure even at the highest levels of concentration appeared to be rather negligible. Once again, this higher initial color (above 500 PCU) in comparison to what was seen for the Weyerhaeuser samples seems to overwhelm the color effect that sulfide would be expected to cause. Additionally, a color reduction seen in the higher sulfide doses (Figure 4.21) suggest sulfide saturation as previously discussed. 0 0.4 0.8 2.0 5.0 0 1 4 24 0 500 1000 1500 2000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier Influent Figure 4.20: Rayonier Influent Sample Color Results from 10-ppm Sulfide Solution Doses 65 03 710 1520 2530 701703 3066016 50 1 4 24 0 400 800 1200 1600 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier Influent Figure 4.21: Rayonier Influent Sample Color Results from Crystallized Sulfide Doses The strong pond effluent was associated with somewhat of a higher color than the influent, but this may be due to color reversion in the pond. Some immediate increase with sulfide dose was seen (Figures 4.22 & 4.23). Significant color growth after 24 hours, seen by an approximate 175% increase in the five-mg/L, 24-hr sample, may indicate formation of color precursors in the pond system. Moreover, sulfide saturation could be a result of the color decrease seen in the highest dosage levels (Figure 4.23). 66 0 0.4 0.8 2.0 5.0 0 1 4 24 0 1000 2000 3000 4000 5000 6000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier Effluent Figure 4.22: Rayonier Effluent Sample Color Results from 10-ppm Sulfide Solution Doses 03 710 1520 2530 701703 3066016 50 1 4 24 0 1000 2000 3000 4000 5000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier Effluent Figure 4.23: Rayonier Effluent Sample Color Results from Crystallized Sulfide Doses 67 The two aerated stabilization basins (ASB #1 & #2) were reported to have high effluent color values, but little or no increases in color either immediately or after time resulted from the sulfide experimentation (Figures 4.24 & 4.25). This minimal color change supports the theory that the high degree of initial color appears to be masking any color change due to sulfide. 00 .4 0.8 2.0 5.0 0 1 4 24 0 500 1000 1500 2000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier ASB #1 Effluent Figure 4.24: Rayonier ASB #1 Effluent Sample Color Results from 10-ppm Sulfide Solution Doses 68 00 .4 0.8 2.0 5.0 0 1 4 24 0 500 1000 1500 2000 2500 3000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier ASB #2 Effluent Figure 4.25: Rayonier ASB #2 Effluent Sample Color Results from 10-ppm Sulfide Solution Doses The same color decline depicted at the higher sulfide concentrations for the other preceding treatment stages resulted for these two ASB samples as well (Figures 4.26 & 4.27). Once again sulfide saturation appears to be responsible for this trend. Little potential for sulfide reversion appears to be present in these wastewater treatment stages. Yet, it is important to note that the initial color values are appreciably different between the two basins, ABS #2 being around 400 PCU higher. The difference between the initial colors of the two basin samples could be attributable to differences in residence times of the basins, aeration, and other design variations. 69 03 710 1520 2530 701703 3066016 50 1 4 24 0 400 800 1200 1600 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier ASB #1 Effluent Figure 4.26: Rayonier ASB #1 Effluent Sample Color Results from Crystallized Sulfide Doses 03 710 1520 2530 701703 3066016 50 1 4 24 0 400 800 1200 1600 2000 2400 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Rayonier ASB #2 Effluent Figure 4.27: Rayonier ASB #2 Effluent Sample Color Results from Crystallized Sulfide Doses 70 Georgia Pacific The samples from Georgia Pacific were collected from each of the lagoon system divides referred to as Ponds 1, 2, 3, and 4. One effluent sample from each pond was collected and sent for participation in this experiment. The initial color of the wastewater increased slightly as the water passed through the series of ponds, indicating that color reversion was occurring in this system. In Pond 1, the initial color was 1,160 PCU, and after treatment through all four ponds, was discharged at almost 3,000 PCU, a 150% increase. According to Georgia Pacific personnel, significant hydrogen sulfide (H2S) generation occurs in this lagoon, ranging from 12 ppm in Pond 1 to 20 ppm in Pond 4. For Pond 1, increases in color were observed with increasing sulfide dose after one hour of exposure (see Figure 4.28). The color growth trend observed as sulfide doses were increased was apparent for this sample, especially at higher sulfide doses. There was no significant change in color between the one and 24-hour color readings. The results for Pond 2 were similar to those for Pond 1, the most prominent color change occurring at the highest sulfide doses. For Ponds 3 and 4, there was little change in color except at the 2,500 mg/L sulfide dose (Figure 4.29), which is unrealistically high for an actual treatment process scenario. 71 05 1020 252505 002500 1 24 1 24 0 400 800 1200 1600 2000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Georgia Pacific Pond 1 Pond 2 Figure 4.28: Georgia Pacific Ponds 1 & 2 Samples Color Results 05 1020 252505 002500 1 24 1 24 0 600 1200 1800 2400 3000 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Georgia Pacific Pond 3 Pond 4 Figure 4.29: Georgia Pacific Ponds 3 & 4 Samples Color Results 72 Also, while the results indicate color growth across the ponds, color reversion was minimal when the samples were exposed to concentrations up to 250 mg/L (Table 4.8). Table 4.8: Georgia Pacific Results Summary Georgia Pacific Color Results (PCU) Sulfide Dosage Pond 1 Pond 2 Pond 3 Pond 4 (mg/L) 24 hr % Color ? 24 hr % Color ? 24 hr % Color ? 24 hr % Color ? 0 1165 0 1342 1 1240 -17 1456 8 5 1347 16 1355 2 1199 -20 1207 -11 10 1370 18 1298 -2 1132 -24 1178 -13 20 1205 4 1259 -5 1157 -22 1175 -13 25 1259 9 1237 -7 1200 -19 1193 -12 250 1173 1 1244 -6 1119 -25 1187 -12 500 1700 46 1412 7 890 -40 1083 -20 2500 1798 55 1677 27 2418 62 2933 117 The conclusion from this observation is that color reversion that results from the sulfide mechanism appears to be affected at extreme levels of sulfide. Lower values of sulfide have a minimal affect on color generation. One of these ponds (Pond 2) was sampled again at a later date (nearly two months later) and provided dissimilar results than those previously presented for this pond. The second sample set (four grab samples from Pond 2) reflected a previous exposure history of 40-50 ppm of sulfide. Thus, any reversion would have already occurred. The underlying difference was that the second sample set exhibited the effects of having no primary clarifying treatment as it had been previously taken offline. Therefore, the resulting effect on color was actually expected 73 given the treatment conditions. Therefore, to test this theory, the four grab samples from the same pond were analyzed individually. As with any grab sample, including every sample used throughout this entire experiment, they represent a ?snapshot? of the current wastewater characteristics present upon sample collection. Any spills, releases, upsets, etc. can therefore cause sample variation. Therefore, to ensure that variation was not caused by experimental variation, one of the grab samples (Grab 1) was analyzed in triplicates for a reproducibility analysis (Figure 4.30). 0510 202550 09902500 1 24 1 24 1 24 0 500 1000 1500 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Georgia Pacific Pond 2-Grab 1 Run 1 Run 2 Run 3 Figure 4.30: Georgia Pacific Pond 2?Grab 1 Reproducibility Color Results Furthermore, the resulting error bars calculated on the three samples did not indicate dramatic variation and illustrated consistent color trends (Figure 4.31). Hence, it 74 was concluded that the data for an individual sample was reproducible and the discrepancy seen in the color results between two samples from the same source was due to process modifications. Georgia Pacific Pond 2-Grab 1 (Reproducibility) 0 200 400 600 800 1000 1200 1400 1600 1 10 100 1000 10000 Sodium Sulfide Dosage (mg/L) Pl ati nu m C ob alt C ol or U ni ts (P CU ) 1 hr 24 hr *NOTE: All dosage values = value + 1 for graphical representation (since log(0) = nonexistent value) Figure 4.31: Georgia Pacific Pond 2?Grab 1 Averaged Color Results Color appeared to remain relatively stable for Grabs 2 and 3, while slight color growth was seen in Grabs 1 and 4 (Figures 4.32 & 4.33). The data from Run 1 was used for the Grab 1 sample set plotted in Figure 4.32. 75 037 10152 02530 7017033 06601650 1 24 1 4 24 0 400 800 1200 1600 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Georgia Pacific Pond 2 Grab 1 Pond 2 Grab 2 Figure 4.32: Georgia Pacific Pond 2?Grabs 1 & 2 Samples Color Results 0371 015202 5307017 0330660165 0 1 4 24 1 4 24 0 400 800 1200 1600 Platinum Cobalt Color Units (PCU) Sulfide Dosage (mg/L) Time (hr) Georgia Pacific Pond 2 Grab 3 Pond 2 Grab 4 Figure 4.33: Georgia Pacific Pond 2?Grabs 3 & 4 Samples Color Results 76 As previously shown for the other Georgia Pacific samples, time was not apparently an important factor on color development. Additionally, color reduction was evident at the highest dosages, reflecting sulfide saturation. Sulfide saturation seems to be dependent on initial wastewater color. For the lighter samples, as sulfide dosages increased, so did the resulting degree of color reversion; yet, for the darker samples, a decline or saturation point was reached when exposed to the highest sulfide concentrations. Aeration Experimentation The aforementioned Georgia Pacific Pond 2 sample (the latter sample set of four grabs from Pond 2) was selected as the representative darkly colored sample. Therefore, this darkly colored sample along with the representative lightly colored sample previously discussed as the Weyerhaeuser-Albany, OR composite sample were used in a bench scale aeration study. The goal of this study was to ascertain if color increases due to sulfide were reversible by stripping and/or oxidation of the sulfide by aeration. Samples were first analyzed based on the effects of aeration on prior color generation (Figure 4.34). Only the higher sulfide doses of 330-ppm, 660-ppm, and 1,650-ppm were tested in this aeration experiment based on the hypothesis that the greatest color generation occurs at these higher sulfide levels. Color was measured at one- hour and four-hour intervals in the same manner as previously described for the sulfide experimentation (seen by the first two points of each line on the plot in Figure 4.34). Then the samples were aerated overnight and analyzed the following day for any resulting color change. Color was reverted in both sample sets as shown by the upward trend for each line in Figure 4.34. It is likely that aeration was not sufficient to reduce the 77 sulfide concentration during the 24-hour aeration period, since these sulfide doses are much higher than would be expected in actual treatment systems. Therefore, it was deemed necessary to examine the affects of aeration on lower sulfide doses as well. Color Growth & Aeration Results Comparison Between Samples of Different Initial Color 0 400 800 1200 1600 0 5 10 15 20 25 30 Time (Hours) Pl ati nu m C ob alt C ol or U ni ts (P CU ) Light 330 mg/L Light 660 mg/L Light 1650 mg/L Dark 330 mg/L Dark 660 mg/L Dark 1650 mg/L overnight aerationno aeration Figure 4.34: Albany, OR Weyerhaeuser and Georgia Pacific Pond 2?Grab 4 Color Reversion / Aeration Results Comparison Additional aeration tests were performed on these representative samples (the lighter colored sample from the Albany, OR Weyerhaeuser mill (less than 500 PCU) and the darker one from Georgia Pacific (greater than 500 PCU)) in two duplicate trials. For the first run, one-mg/L and 500-mg/L sulfide doses were added to each of the two sample sets (100-mL batches). One hour was allowed to pass before beginning aeration to ensure complete sodium sulfide crystal dissolution and rapid phase color formation. 78 Aeration was then begun and 10-mL aliquots were taken and tested at the following times (after one, four, and twenty-four hours of aeration and then on each additional day of aeration, ending on the fourth day). The sample with one mg/L of sulfide showed a significant decrease in color during the first 10 hours of aeration. The color increased slightly over the remainder of the aeration period. The 500-mg/L sulfide-treated sample showed a small decrease in color during the first 10 hours of aeration, but thereafter an increase during the remainder of the 4-day aeration experiment (Figure 4.35). Aeration Results Comparison Between Samples of Different Initial Color (First Run) 0 200 400 600 800 1000 1200 1400 1600 1800 0.00 1.00 2.00 3.00 4.00 Time (Days) Pl ati nu m C ob alt C ol or U ni ts (P CU ) Light 1 mg/LLight 500 mg/L Dark 1 mg/L Dark 500 mg/L Figure 4.35: Albany, OR Weyerhaeuser and Georgia Pacific Pond 2?Grab 3 Color Reversion / Aeration Results Comparison It is possible, but unproven, that the aerobic increase of color observed during the experiment reflects aerobic color formation of quinones resulting from catechol 79 compound precursors. The large degree of color growth seen in the one-mg/L dosage for the lighter sample was believed to have been primarily attributable to high turbidity. Over the duration of the experiment it was noted that the sample was increasing in turbidity visibly, and these conspicuous particles were not effectively removed during the vacuum filtration step of analysis. Therefore, the large PCU values for this data set (associated with the one-mg/L light sample) in particular could be influenced by turbidity and not accurately reflect the true color value. Nevertheless, the overall development of color for the samples is noteworthy (Table 4.9). Table 4.9: Georgia Pacific Aeration?Run 1 Results Summary ALL VALUES X TIME AFTER AERATION Weyerhaeuser (Albany, OR) Light Sample* Color Results (PCU) Sulfide Dosage (mg/L) 1 hr % Color Change 4-day % Color Change 1 292 0 581 99 500 1027 252 590 102 Georgia Pacific, Pond 2 Grab 3 Dark Sample Color Results (PCU) 1 1155 0 1309 13 500 1023 -11 1200 4 Notes: *High Turbidity, even after filtration for the lighter sample at 1 mg/L of sulfide exposure; it appeared as though precipitation was occurring throughout the aeration duration, specifically at the 2 and 3-day time periods. This experiment was run for comparison purposes, but this time each sample set included a control sample (containing zero sodium sulfide crystals), and also a more 80 frequent sampling schedule was followed during the first day of aeration. Furthermore, the sulfide concentration was measured using gas chromatography (GC) / flame photometric detector (FPD) to establish the actual corresponding sulfide concentration for each color measurement. Aeration was again started after one hour of time was allowed to pass to promote rapid phase color development; thereafter, samples were taken at the start of aeration (at zero hours), at the one-hour mark, after two hours had elapsed, and then on increments of two hours up until 10 hours of aeration had been reached. Subsequent samples were drawn from the aeration batch as before on each successive day up until the fourth day had been attained. During the first 10 hours of aeration, color decreased by the following percentages: 13% for the zero-mg/L sample, 36% for the one- mg/L, and 26% for the 330-mg/L samples (Figure 4.36). Aeration Results Comparison Between Samples of Different Initial Color (Second Run) 0 200 400 600 800 1000 1200 1400 1600 1800 0.00 1.00 2.00 3.00 4.00 Time (Days) Pl at in um C ob alt C ol or U ni ts (P CU ) Light 0 mg/L Light 1 mg/L Light 330 mg/L Dark 0 mg/L Dark 1 mg/L Dark 330 mg/L Figure 4.36: Albany, OR Weyerhaeuser and Georgia Pacific Pond 2?Grab 2 Color Reversion / Aeration Results Comparison 81 These color reductions corresponded to the decreasing sulfide concentration detected by (GC) / (FP) (Table 4.10). Therefore, removal of sulfide by stripping and/or oxidation can reverse the affects of sulfide. Table 4.10 supports this as it displays how after only one day of aeration, all of the sulfide had been removed. Also, note the presence of a small amount of sulfide (2-3 ppm) in the ?zero? mg/L samples (no sulfide was added to these samples during experimentation). This suggests the presence of sulfide in both samples initially and further validates the reasoning behind comparing the resulting color changes against the zero-mg/L, zero-hour sample. Table 4.10: Georgia Pacific Aeration?Run 2 GC/FPD Results Summary Sample I.D. Time Light (0 mg/L) Light (1 mg/L) Light (330 mg/L) Dark (0 mg/L) Dark (1 mg/L) Dark (330 mg/L) 0 hr 2.1 3.4 479 3.0 4.7 349 1 hr 1.6 2.5 341 2.2 3.1 290 2 hr 0.4 0.6 138 0.3 0.8 16 4 hr 0.1 0.2 56 0.2 0.3 2.5 6 hr 0 0.1 8.5 0 0.2 0.9 8 hr 0 0 0.7 0 0 0.2 10 hr 0 0 0.3 0 0 0 1 day 0 0 0 0 0 0 2 day 0 0 0 0 0 0 82 The remaining duration of aeration demonstrated that after sulfide was depleted, color was again reverted. This is likely due to mechanistic aerobic oxidation of catechols to quinones and the oxidation of reduced quinones to more colored oxidized forms as reported by Lange et al. (2005) (see Figure 4.37). Figure 4.37: Catechol?Quinone Color-Producing Reaction Therefore, aeration did in fact reverse the effects of sulfide color reversion, but color growth became consequential of other dominant mechanisms. Table 4.11 provides the initial and final color values from the four-day aeration test (second trial). Overall, it appears that aeration has negligible effect on color reversion for the lighter sample, but provided a significant outcome for the darker sample. However, in looking closely at the aforementioned aeration spectrum of color reversion (Figures 4.36 & 4.37), the results were characteristically cyclical in nature and suggested other color mechanisms were at work. 83 Table 4.11: Georgia Pacific Aeration?Run 2 Results Summary ALL VALUES X TIME AFTER AERATION Weyerhaeuser (Albany, OR) Light Sample Color Results (PCU) Sulfide Dosage (mg/L) 0 hr % Color Change 4-day % Color Change 0 324 0 283 -13 10 228 -30 220 -32 330 390 21 254 -22 Georgia Pacific, Pond 2 Grab 2 Dark Sample Color Results (PCU) 0 966 0 1645 70 10 1130 17 1128 17 330 1127 17 953 -1 Lignin Components Isolation Analysis As explained in the previous chapters of this thesis, lignin degradation products have been known to highly contribute to color reversion. In order to provide some additional analysis of color reversion regarding the subject sulfide reaction, several solutions were created for color analysis using the same experimental variables as before: sodium sulfide crystal dosages and time, while adding a third factor?solution strength (one-ppm and 50-ppm). Compounds were selected based on their relationship with humic functional groups and included 4-hydroxybenzaldehyde, phenol, vanillin, humic and fulvic acid, catechol, and anthraquinone (as a surrogate for the array of quinones found in color bodies). The color increases observed for phenol and 4?hydroxybenzaldehyde are close in magnitude to those reported earlier for the sulfide blanks (see Chapter 3) and may not be 84 a result of color development due to sulfide-lignin derivative interactions (Figures 4.38 & 4.39). 03165 0 1 4 24 1 4 24 0 30 60 90 120 Platinum Cobalt Color Units (PCU) Time (hr) 4-Hydroxybenzaldehyde Color Results 1-ppm Solution 50-ppm Solution Sulfide Dosage (mg/L) Figure 4.38: 4-Hydroxybenzaldehyde Color Results 03165 0 1 4 24 1 4 24 0 30 60 90 120 Platinum Cobalt Color Units (PCU) Time (hr) Phenol Color Results 1-ppm Solution Sulfide Dosage (mg/L) 50-ppm Solution Figure 4.39: Phenol Color Results 85 Vanillin showed intriguing results. In these samples, as time elapsed, the solutions actually resulted in reduced color (Figure 4.40). The highest color associated with vanillin was its initial hue resulting from the 1,650-mg/L dosage in the 50-ppm solution. Therefore, color mechanisms independent of sulfide appear to be controlling this particular outcome. As a result, no significant connection between vanillin and sulfide color reversion appears to be present. 03165 0 1 4 24 1 4 24 0 40 80 120 160 200 Platinum Cobalt Color Units (PCU) Time (hr) Vanillin Color Results 1-ppm Solution 50-ppm Solution Sulfide Dosage (mg/L) Figure 4.40: Vanillin Color Results Since humic acids and fulvic acids are the likely products of lignin degradation and have been implicated as chief sources of color in pulp mill wastewater, sulfide studies were conducted on humic and fulvic acid solutions. Humic acid, being the darker colored humic substance in comparison to fulvic acid, resulted in a greater color effect in the one-ppm solution than for the solution having 86 a 50-ppm concentration. This latter solution strength had such high initial color that it would have been difficult to observe even moderate magnitudes of color change (as was true for highly colored wastewaters) (Figure 4.41). As the amounts of sodium sulfide crystals were increased in the one-ppm solution, the color correspondingly rose. Additionally, for the one-ppm solution, color increased over time as well. The 50-ppm solution reflected a relatively stable color effect with respect to the sulfide doses and time increments. The high initial color present in the 50-ppm solution is believed to have masked any sulfide color reversion. 03165 0 1 4 24 1 4 24 0 1000 2000 3000 4000 5000 6000 Platinum Cobalt Color Units (PCU) Time (hr) Humic Acid Color Results 1-ppm Solution Sulfide Dosage (mg/L) 50-ppm Solution Figure 4.41: Humic Acid Color Results Fulvic acid yielded a much lower colored solution than the humic acid. For the fulvic acid solution, the experiment resulted in a somewhat different outcome than was 87 given in the analysis of its associated humic substance complement (humic acid). Sulfide contributed to color development with rapid increases of color of 400% being observed for the one percent solution, 60% for the 20% solution, and 30% for the 50% solution (Figure 4.42). Unlike humic acid, for which color development occurred slowly, no additional color increase was observed for fulvic acid after the initial one hour. Trends were proportionally related for the three fulvic acid concentrations. 031650 1 4 24 1 4 24 1 4 24 0 200 400 600 800 1000 Platinum Cobalt Color Units (PCU) Time (hr) Fulvic Acid Color Results 1% Solution Sulfide Dosage (mg/L) 20% Solution 50% Solution Figure 4.42: Fulvic Acid Color Results It is imperative to note that both humic and fulvic acids are reported as having large numbers of catechol and quinone functional groups. And as these compounds have been known to contribute significantly to wastewater color, concentrated solutions of catechol and anthraquinone were subsequently tested in order to further isolate the related sulfide color effects. 88 For the compound catechol, time appeared to be the greatest factor involved in the ultimate development of color. For both catechol concentrations, sulfide addition resulted in minimal rapid color increase, but yielded some slow development color growth. The solution strength did not appear to result in any major differences, except when time was factored in. For the 1650-mg/L, 24-hr, 50-ppm solution, a 20-fold increase of color production resulted, denoted by practically 3,000 PCU in value (Figure 4.43). Additionally, an intense yellow color became visible upon adjusting the pH to 7.6. 03165 0 1 4 24 1 4 24 0 300 600 900 1200 1500 1800 2100 2400 2700 3000 Platinum Cobalt Color Units (PCU) Time (hr) Catechol Color Results 1-ppm Solution Sulfide Dosage (mg/L) 50-ppm Solution Figure 4.43: Catechol Color Results Anthraquinone yielded undoubtedly the most extraordinary results of all of the compounds tested during this experimental phase. Time was the key factor in these results as was true for the catechol solutions. Likewise, sulfide interactions and solution 89 strength contributed to the color generation (as the amount of sulfide and anthraquinone went up, so did color) (Figure 4.44). Visually, these solutions actually took on a very different hue than any of the other samples analyzed throughout this thesis. As color grew during this experiment, the solution took on a slightly pinkish color followed by a bright pinkish orange hue and finally to a deep shade of wine red, respective with the time intervals. As shown in Figure 4.44, the presence of sulfide and anthraquinone led to the development of extremely high color in the solution. The measured PCU values of all of the results throughout this investigation only represent the yellow band of color present in these solutions as this wavelength (color) is characteristic of pulp and paper wastewater. Therefore being as high as 2,000 PCU initially for the 1,650-mg/L and then as high as 9,000 PCU after four and 24 hours had elapsed is quite remarkable, considering only a partial color value is thus reported. 03165 0 1 4 24 1 4 24 0 2000 4000 6000 8000 10000 Platinum Cobalt Color Units (PCU) Time (hr) Anthraquinone Color Results 1-ppm Solution 50-ppm Solution Sulfide Dosage (mg/L) Figure 4.44: Anthraquinone Color Results 90 Based on the results of the lignin monomer studies, it is apparent that quinones and catechols are the two moieties that are most affected by sulfide color reversion. Therefore, wastewaters containing these compounds have the potential to cause large changes in color upon sulfide exposure (Table 4.12). Table 4.12: Catechol and Anthraquinone Results Summary Sulfide Dosage Catechol Color Results (PCU) Sulfide Dosage Anthraquinone Color Results (PCU) Solution Strength (mg/L) 24 hr % Color Change Solution Strength (mg/L) 24 hr % Color Change 0 745 523 0 11 -69 3 463 287 3 92 168 1 ppm 1650 198 65 1 ppm 1650 1726 4917 0 177 48 0 163 373 3 565 373 3 147 326 50 ppm 1650 2785 2229 50 ppm 1650 8731 25274 91 CHAPTER 5 SUMMARY AND RECOMMENDATIONS The research presented in this thesis supports the hypothesis that sulfide plays a role in color reversion observed in pulp and paper mill wastewater treatment processes. Color reversion does not appear to be a common subject for research and the mechanisms are poorly understood. The results of this thesis will contribute to the understanding of one aspect of this phenomenon. In this chapter, a summary of the findings along with overall conclusions and recommendations for further work are presented. Summary Given the extreme diversity of wastewater, sample-based, specific case-based results need to be sought for accurate inference. The role of sulfide generation in color reversion of treated and untreated paper mill wastewater appears to be important but highly variable. Color reversion was observed to be mediated by sulfide. While some ranges of increases were considerable, sometimes being quadruple of the initial color, other samples showed no increase at all. As such, the degree of sulfide effects differs due to highly variable conditions and wastewaters from mill to mill. The initial color of wastewater appears to have a direct relationship with sulfide color reversion: the lighter the initial wastewater color, the greater the resulting color generation. Additionally, while samples can be variable from process to process, the most significant treatment 92 stages appear to occur earlier on in the wastewater process train (i.e., sewers, primary clarifiers, and ponds). Additionally, sample color as well as related conditions can be variable with time for the same process ? as was seen with the Georgia Pacific samples that were both from Pond 2, but from different collection timeframes. This was attributable to process/equipment changes which therefore needed to be incorporated into the analytical conclusions. From the other two experimentation results, the aeration and lignin solution color tests, the results successfully provided some insight into these color relationships. Sulfide color reversion appears to be reversible when sulfide is removed by aeration. Quinones and catechols are groups causing color reversion when sulfide is added. This coincides with sulfide addition to humic acid and fulvic acids which also can result in large color increases. Other lignin degradation products that were tested ? specifically phenols, vanillin, and 4-hydroxybenzaldehyde ? do not contribute much to color and are not significantly affected by sulfide. As demonstrated by the lignin components isolation analysis, the degradation of lignin can contribute significantly to color depending on the amount at which the derivatives are present in a certain wastewater, the degree of double bond resonance, and the types of related functional groups linked to such compounds. While aeration can reverse the effects of sulfide color reversion, subsequent aerobic mechanisms take over and cause a relapse of color reversion to ensue. In exploring initial color relationships, if a lighter sample is characterized by fulvic acid and a darker sample by humic acid, color growth might only be notable in the lighter sample, as demonstrated by the previously 93 depicted tests results involving synthesized solutions. Yet, as observed, aeration can reverse the effects and cause a recurrence of color in the darker sample. Therefore, many variables need to be considered and factored in when considering color reversion mechanisms. The objective of this thesis seeks to provide meaningful information to aid in the understanding and eventual solution of color reversion. The effects of sulfide on pulp and paper wastewater color reversion are deemed significant, but need to be combined with the other key pieces of the wastewater color puzzle in order to accurately and effectively recognize color generation and eradicate its progression. In relation to wastewater treatment plants in general, these findings are significant in that they can supplement the understanding of color reversion and the search for its ultimate solution for removal (decolorization). Pinpointing the optimal conditions and environments for color reversion can result in more effective and efficient means for developing and implementing color reduction technologies. Color generation in sewers, primary clarifiers, and anoxic portions of the biological treatment processes can lead to color formation if sulfidogenic activity is present. Additionally, some color decreases in aerobic wastewater treatment processes may be due to stripping/oxidation of sulfide. Furthermore, in shipping/storage of color samples, care should be taken to prevent sulfide generation conditions so that representative and accurate results can be obtained and reported. Based on the Weyerhaeuser (Albany, OR) color results (refer back to Figure 4.17 and Table 4.7), specific color loadings can be calculated. Based on an initial color value of 200 PCU and a 5.2-mgd flow rate, percentage increases can be linked to consequent color loads (Table 5.1). For every five percent increase in color, close to 200 lbs/day of 94 color would be discharged into nearby receiving water. For a worst case scenario, consequential to spills or equipment failure for example, a 100% color increase could develop which equates to more than 4,000 lbs/day of color that would be discharged into a particular water body, in this case Willamette River. Table 5.1: Weyerhaeuser?Albany, OR Color Loadings Color Increase Color Loading ? Color Loading (%) (lbs/day) (lbs/day) 1 8765 87 3 8939 174 5 9112 174 10 9546 434 15 9980 434 20 10414 434 25 10848 434 50 13017 2170 100 17357 4339 Recommendations In order to solve pulp and paper wastewater color reversion problems, the mechanisms underlying color formation need to be identified and understood. Whether the dominant cause of the color generation is deemed aerobic, anaerobic, and/or sulfide- driven, these factors need to be recognized in order for effective removal applications to be performed. Therefore, it is recommended that several factors undergo testing and analysis to determine and provide more information regarding color reversion. More knowledge of the sulfur cycle in pulp mill wastewater treatment processes needs to be obtained in order to fully solve the color reversion problem and understand 95 this phenomenon. Additionally, more samples, including mills with sulfite process, coated fiber board processes should be tested for comparison to these results. This request also coincides with the need for temporal studies to be conducted with the purpose of observing color reversion changes as affected by certain seasonal conditions. Throughout the course of this thesis, better redox control and sulfide measurements during studies was recognized as a potential area for improvement and therefore, should be obtained in further studies. For instance, it should be determined if sulfide decreases over longer time periods can lead to lower color in the 24-hour samples. Moreover, similarities and differences need to be verified for biogenic sulfide production versus sodium sulfide addition. The dissociation of sodium sulfide in water should produce similar ions as observed for biogenic sulfide production, but more support on this topic should be sought. The time factor needs to be tested more in relation to color change also, including sample shipping time. Additionally, reproducibility studies should be performed numerous times (10-20 trials) to achieve true statistical significance. This could provide more insight into the influence of sample holding time as well. More kinetic studies should be included in this research topic in order to establish instant or immediate color change?rate models. Additionally, relationships involving nutrient concentrations and compositions should be explored. Moreover, the results of a study using P. Flavido-alba displayed that the highest color reduction occurred when the culture media was low in nitrogen and manganese (Mn (II)) and contained a sufficient amount of glycerol (P?rez et al., 1997). These conditions could be tested for color reversion to determine if the opposite set of parameters holds in 96 the case of color growth. Similarly, additional tests utilizing isolated LiP and MnP could be tested to determine relationships to color growth as was performed for decolorization. More work with aeration and lignin solutions could be very beneficial work as well. More aeration tests could be conducted to observe optimal parameters and describe more of the role between aeration and sulfide color generation. Another suggested study would be to test various combinations of catechol and anthraquinone with humic substances, as well as with other solutions, in order to further implicate the color relationship to individual lignin components. Numerous topics could serve as research topics regarding color reversion. In fact, as color generation continues to pose problems, understanding the root cause and identifying a solution could soon become mandatory. 97 REFERENCES Amero, B. and Hilleke, J. (1993), Advancement in Effluent Decolorization Using Ozone, 1993 Environmental Conference Proceedings. Archibald, F. and Roy-Arcand, L. (1995), Photodegradation of High Molecular Weight Kraft Bleachery Effluent Organochlorine and Color. Wat. Res., Vol. 29, No. 2, pp. 661-669, 1995 Bennett, D. J., Dence, C. W., Kung, F.-L., Luner, P., Ota, M., The Mechanism of Color Removal in the Treatment of Spent Bleaching Liquors with Lime, TAPPI, Vol. 54, No. 12, p. 2019, 1971. Bl?nquez, P., Caminal, M. Sarra, M., Vicent, M. T., and Gabarrell, X. (2002), Olive Oil Mill Waste Waters Decoloration and Detoxification in a Bioreactor by the White Rot Fungus Phanerochaete flavido-alba. Biotechnol. Prog. 2002, 18, 660-662. Davies, J. S., and Wilson, M. A. (1990), Biological Treatment and Color Reduction in Alberta Bleached Kraft Effluents, 1990 TAPPI Environmental Conference Proceedings. Dilek, F. B. and Bese, S. (2001), Treatment of Pulping Effluents by Using Alum and Clay ? Colour Removal and Sludge Characteristics. Water SA, Vol. 27, No. 3, July 2001. 98 Dilek, F. B., Taplamacioglu, H. M., Tarlan, E. (1999), Colour and AOX removal from pulping effluents by algae. Appl. Microbial. Biotechnol (1999) 52: 585-591. Georgiou, D., Aivazidis, A., Hatirras, J., Gimouhopoulos, K. (2003), Treatment of Cotton Textile Wastewater Using Lime and Ferrous Sulfate. Water Research 37 (2003) 2248-2250. Hamman, O. B., Rubia, T. De La, Mart?nez, J. (1999), Decolorization of Olive Oil Mill Wastewaters by Phanerochaete Flavido-alba. Environmental Toxicology and Chemistry, Vol. 18, Issue. 11, pp. 2410-2415. Ikehata, K. and Buchanan, I. D. (2000), Colour and Chloride Removal from Pulp Mill Effluent Using Ion-Exchange Resins. Sustainable Forest Management Network Project. Joyce, T. W., Chang, H.-M., Campbell, Jr., A.G., Gerrard, E. D., and Kirk, T. K. (2002), A Continuous Biological Process to Decolorize Bleach Plant Effluents. Joyce, T.W. and Petke, W.H. (1983), Effluent Decolorization Technologies for the Pulp and Paper Industry, Water Resource Research Institute of the University of North Carolina Kemeny, T. E. and Banerjee, S. (1997), Relationships Among Effluent Constituents in Bleached Kraft Pulp Mills. Wat. Res. 31(7), 1589-1594. Lange, C.R. (2004). Aerobic Color Reversion in the Grand Prairie Lagoon System: Final-Report, submitted to Weyerhaeuser, Environmental Technology Center, Federal Way, Washington, December, 2004. 99 Lange, C. ?Color Reversion at the Grand Prairie Mill ? Final Report? submitted to Weyerhaeuser, Inc., Federal Way, Washington. January 2005. Lange, C., Christiansen, J, Rogers, D., and DeWitt, G. ?Development of a Biological Color Removal Process for Selected Pulp and Paper Mill Waste Streams. NCASI Effluent Color Management Workshop, Baltimore, Md., March 21, 2005. Lange, C., Pagoria, P, Lincoln, D, McIlveen, L, ?Weyerhaeuser - Grand Prairie Effluent Color Growth?, NCASI Effluent Color Management Workshop, Baltimore, Md., March 21, 2005. Livernoche, D., Jurasek, L., Desrochers, M., Dorica, J., and Veliky, A. (1983), Removal of color from kraft mill wastewaters with cultured of white-rot fungal and with immobilized mycelium of Coriolus versicolor. Biotechnology and Bioengineering. Mart?n, C. and Manzanares, P. (1994), A Study of the Decolourization of Straw Soda-Pulping Effluents by Rametes versicolor. Bioresource Technology, Vol. 47, Issue 3, 1994, pp. 209-214. Nagarathnamma, R. and Bajpai, P. (1999), Decolorization and Detoxification of Extraction-Stage Effluent from Chlorine Bleaching of Kraft Pulp by Rhizopus oryzae. Applied and Environmental microbiology, March 1999, pp. 1078-1082, Vol. 65, No. 3. National Council for Air and Stream Improvement, Inc. (NCASI). 2000. Methods Manual ? NCASI Method Color 253: Color Measurement in Pulp Mill Wastewaters by Spectrophotometry. Research Triangle Park, NC: 100 National Council for Air and Stream Improvement, Inc. Paice, M. G. and Jurasek, L. (1983), Peroxidase-catalyzed color removal from bleach effluent. Pallerla, S. and Chambers, R. P. (1995), New Urethane Prepolymer Immobilized Fungal Bioreactor for Decolorization and Dechlorination of Kraft Bleach Effluents. Vol. 79: No. 5 TAPPI Journal. Peralta-Zamora, P., de Moraes S. G., Esposito, E., Antunes, R., Reyes, J., Dur?n, N. (1998), Decolorization of Pulp Mill Effluents with Immobilized Lignin and Manganese Peroxidase from Phanerochaete chrysoporium. Environmental Technology, Vol. 19, No. 5, 1998, pp. 521-528(8). P?rez, J., Saez, L., Rubia, T. De La, and Mart?nez, J. (1998), Phanerochaete Flavido-alba Laccase Induction and Modification of Manganese Peroxidase Isoenzyme Pattern in Decolorized Olive Oil Mill Wastewaters. Applied and Environmental Microbiology, July 1998, pp. 2726-2729. P?rez, J., Saez, L., Rubia, T. De La, and Mart?nez, J. (1997), Phanerochaete Flavido-alba Ligninolytic Activities and Decolorization of Partially Bio- Depurated Paper Mill Wastes. Wat. Res. 31(3), 495-502. Prasad, D. Y. and Joyce, T. W. (1991), Color Removal from Kraft Bleach-Plant Effluents by Trichoderma sp. January 1991 TAPPI Journal. Roy-Arcand, L., Archibalc, F. S., and Briere, F. (1991), Comparison and Combination of Ozone and Fungal Treatments of a Kraft Bleachery Effluent. September 1991 TAPPI Journal. Santos, E. B. H. and Duarte, A. C. (1998), The Influence of Pulp and Paper Mill 101 Effluents on the Composition of the Humic Fraction of Aquatic Matter. Wat. Res. Vol. 32, No. 3, pp. 597-608, 1998. Sharma, C., Mohanty, S. K., and Rao, N. J. (1999), Gas Chromatographic Determination of Pollutants in Kraft Bleachery Effluent from the Eucalyptus Pulp. Analytical Sciences, November 1999, Vol. 15, 1115-1121. Shawwa, A. R., Smith, D. W., Sego, D. C. (2001), Color and Chlorinated Organics Removal from Pulp Mills Wastewater Using Activated Petroleum Coke. Wat. Res. Vol. 35, No. 3, pp. 745-749, 2001. Sj?str?m, Eero, Wood Chemistry ? Fundamentals and Applications, Academic Press: New York, 1981. Sonnenberg, L.B. and Holmes, J.C. (1998), Physicochemical Characteristics of Dissolved Organic Matter in Untreated and Treated Pulp and Paper Mill Wastewaters. Proceedings 1998 TAPPI International Environmental Conference, Vancouver, BC, April 1998. Springer, A. M. and Hand, V. C. (1992), Analysis of the Potential of Photochemical and Electrochemical Techniques for Decolorization of Bleached Kraft Mill Effluent, 1992 Environmental Conference Proceedings. Stephenson, R. J. and Duff, S. J. B. (1996), Coagulation and Precipitation of a Mechanical Pulping Effluent?I. Removal of Carbon, Colour and Turbidity. Wat. Res. Vol. 30, No. 4, pp. 781-792, 1996. Sublette, K. L., Kolhatkar, R., and Raterman, K. (1998), Technological Aspects of the Microbial Treatment of Sulfide-rich Wastewaters: A Case Study. Biodegradation 9: 259-271, 1998 102 Tarlan, E., Dilek, F. B., and Yetis, U. (2002), Effectiveness of Algae in the Treatment of a Wood-bases Pulp and Paper Industry Wastewater. Bioresource Technology 84 (2002), 1-5. Thorp, D. S., Tieckelmann, R. H., Millar, D. J., and West, G. E. (1995), Chlorine-Free Wet Strength Paper Repulping and Decolorizing with Activated Persulfates, 1995 Papermakers Conference Proceedings. Yesilada, ?, Fiskin K., and Yesilada, E. (1995), The Use of White Rot Fungus Funalia trogii (Malatya) for the Decolourization and Phenol Removal from Olive Mill Wastewater. Environmental Technology, Vol. 16, No. 1, 1995, pp. 95-100(6). Yin, C.-F., Joyce, T.W., and Chang, H.-M. (1989) Kinetics of Bleach Plant Effluent Decolorization by Phanerochaete chrysosporium. Journal of Biotechnology, 10, 67-76. 103 APPENDIX EXPERIMENTAL DATA Table A.1: Weyerhaeuser - Grand Prairie, Alberta Results Summary (from 10-ppm Sulfide Solution Doses) Weyerhaeuser - Grand Prairie, Alberta Color Results (PCU) from 10-ppm Sulfide Solution Doses Sulfide Dosage Primary Clarifier Inlet Primary Clarifier Outlet Secondary Effluent (mg/L) 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 886 981 672 392 543 648 597 731 345 474 478 527 0.1 1383 396 954 416 619 593 707 696 461 482 388 517 0.2 728 535 1019 434 601 662 704 711 448 532 423 546 0.4 1100 20 946 418 640 620 697 634 495 529 407 526 0.5 1442 862 636 387 664 593 746 676 467 478 358 575 0.6 1084 1226 922 393 663 668 688 691 425 491 361 549 0.8 1188 683 1033 442 705 648 722 648 534 433 405 567 1.0 905 1006 673 495 675 745 797 712 542 513 395 504 1.5 1104 1121 1169 456 622 676 759 707 471 475 313 411 2.0 1795 1419 872 523 705 780 806 715 537 427 341 505 2.5 1558 1726 1395 553 744 762 855 630 554 484 432 465 3.0 1529 1807 1618 564 740 819 773 680 521 503 354 424 5.0 2017 1824 1858 697 708 984 904 797 736 533 397 893 104 Table A.2: Weyerhaeuser - Grand Prairie, Alberta Results Summary (from Crystallized Sulfide and Ammonium Molybdate Treatment) Weyerhaeuser - Grand Prairie, Alberta Color Results (PCU) with Ammonium Molybdate Sulfide Dosage Primary Clarifier Inlet Sulfide Dosage Primary Clarifier Outlet Sulfide Dosage Secondary Effluent (mg/L) 0 hr 1 hr 4 hr 24 hr (mg/L) 1 hr 4 hr 24 hr (mg/L) 1 hr 4 hr 24 hr 0 663 872 2237 1719 0 1537 2084 2794 0 446 765 641 2 770 890 2475 1473 3 1339 2041 3057 3 510 527 457 5 776 908 2486 1499 7 1480 2093 3009 7 643 548 388 10 748 971 2550 1525 10 1210 1727 3358 10 432 445 335 12 711 876 1898 1650 15 1316 1860 3159 15 931 1065 862 15 680 795 1943 1307 20 834 1625 2269 20 562 612 394 20 724 926 2277 1487 25 1011 1670 2423 25 661 800 357 25 604 692 1416 1190 30 1223 1453 1841 30 471 444 342 40 690 727 1229 1143 70 1574 1827 1757 70 517 510 341 50 756 808 1099 881 170 1689 2095 1544 170 423 442 354 70 766 816 1165 815 330 725 832 707 330 553 572 344 75 723 638 743 930 660 906 970 924 660 1007 981 1008 130 482 575 657 536 1650 760 1018 974 1650 639 824 486 105 Table A.3: Weyerhaeuser - Grand Prairie, Alberta Results Summary (without Ammonium Molybdate, only Crystallized Sulfide Doses) Weyerhaeuser - Grand Prairie, Alberta Color Results (PCU) without Ammonium Molybdate Sulfide Dosage Primary Clarifier Inlet Primary Clarifier Outlet Secondary Effluent (mg/L) 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 0 872 2237 1719 1537 2084 2794 446 765 641 3 890 2475 1473 1339 2041 3057 510 527 457 7 908 2486 1499 1480 2093 3009 643 548 388 10 971 2550 1525 1210 1727 3358 432 445 335 15 876 1898 1650 1316 1860 3159 931 1065 862 20 795 1943 1307 834 1625 2269 562 612 394 25 926 2277 1487 1011 1670 2423 661 800 357 30 692 1416 1190 1223 1453 1841 471 444 342 70 727 1229 1143 1574 1827 1757 517 510 341 170 808 1099 881 1689 2095 1544 423 442 354 330 816 1165 815 725 832 707 553 572 344 660 638 743 930 906 970 924 1007 981 1008 1650 575 657 536 760 1018 974 639 824 486 106 Table A.4: Weyerhaeuser ? Prince Albert, Saskatchewan Results Summary Weyerhaeuser ? Prince Albert, Saskatchewan Color Results (PCU) Sulfide Dosage Primary Pond Inlet Primary Pond Midpoint Primary Pond Outlet (mg/L) 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 0 432 438 480 300 351 388 355 279 413 3 339 2127 418 378 459 401 408 395 449 7 339 405 429 405 428 386 526 463 481 10 317 442 369 495 535 557 369 359 397 15 361 615 408 416 438 402 391 375 405 20 428 449 426 389 414 372 390 372 464 25 417 449 527 475 417 381 397 364 457 30 387 526 327 402 425 409 410 382 733 70 368 475 413 393 402 396 389 358 451 170 673 728 368 1501 584 419 402 403 474 330 800 253 420 606 503 408 401 616 379 660 584 587 206 294 284 239 416 568 564 1650 1303 1487 383 1251 339 229 599 692 460 107 Table A.5: Weyerhaeuser ? Johnsonburg, PA Results Summary (from 10-ppm Sulfide Solution Doses) Weyerhaeuser - Johnsonburg, PA Color Results (PCU) from 10-ppm Sulfide Solution Doses Sulfide Dosage Pulp Sewer Settling Pond Feed Aeration Pond Feed Final Discharge (mg/L) 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 115 369 167 398 560 533 331 593 407 455 460 752 443 438 506 437 0.1 270 925 243 1228 855 647 719 913 673 593 603 731 501 471 520 440 0.2 364 802 350 1303 994 733 1089 1227 611 536 415 423 527 582 599 497 0.4 443 731 395 1145 851 456 1015 1197 448 357 323 529 545 611 607 517 0.5 192 689 167 981 906 778 1025 1451 455 409 310 480 528 582 722 538 0.6 158 666 224 1029 1014 740 1041 1263 348 322 357 484 482 634 735 565 0.8 120 724 273 1058 783 948 1090 1127 324 385 328 389 565 685 829 658 1.0 202 612 433 1123 941 648 1206 1003 398 415 370 465 549 505 865 646 1.5 416 812 754 984 1045 495 1297 1419 422 361 370 413 456 499 679 593 2.0 436 547 372 1363 836 553 1410 1120 509 339 334 412 444 489 760 489 2.5 664 616 578 1083 998 779 1172 1173 454 377 349 375 534 508 671 918 3.0 459 608 668 1071 1044 833 1303 1172 532 447 432 450 473 436 449 1238 5.0 625 705 626 1146 916 700 1399 1286 614 492 436 853 665 435 694 1223 108 Table A.6: Weyerhaeuser ? Johnsonburg, PA Results Summary (from Crystallized Sulfide Doses) Weyerhaeuser - Johnsonburg, PA Color Results (PCU) Sulfide Dosage Pulp Sewer Settling Pond Feed Aeration Pond Feed Final Discharge (mg/L) 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 24 hr 1 hr 24 hr 0 224 253 153 640 759 572 580 480 470 548 3 145 222 98 762 731 977 333 408 707 396 7 246 248 147 719 727 729 599 511 437 385 10 202 231 224 752 767 793 492 379 666 424 15 381 221 121 798 748 853 599 464 906 386 20 219 227 153 834 761 834 343 719 819 404 25 220 170 187 953 826 957 324 769 871 421 30 203 177 496 850 740 917 363 569 683 613 70 198 321 236 765 1048 472 302 366 477 580 170 408 261 228 186 1066 552 351 186 495 352 330 632 535 305 431 903 869 297 259 325 244 660 449 421 288 407 502 213 306 194 340 1016 1650 650 714 621 393 532 551 351 252 443 458 109 Table A.7: Weyerhaeuser ? Albany, OR Results Summary Weyerhaeuser (Albany, OR) Color Results (PCU) Sulfide Dosage Mixed Sample (different grab points) (mg/L) 1 hr 4 hr 24 hr 0 191 192 239 3 232 267 443 7 230 279 381 10 248 280 401 15 244 223 339 20 239 240 400 25 258 248 297 30 281 303 266 70 282 289 400 170 473 412 442 330 344 372 327 660 580 449 271 1650 281 374 378 110 Table A.8: Rayonier Results Summary (from 10-ppm Sulfide Solution Doses) Rayonier Color Results (PCU) from 10-ppm Sulfide Solution Doses Sulfide Dosage (Before) Primary Clarifier Strong Pond Influent Strong Pond Effluent ASB #1 Effluent ASB #2 Effluent (mg/L) 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 hr 1 hr 4 hr 24 hr 0 1119 1121 997 1048 1181 1021 1383 1252 2404 3091 3546 4236 1507 1436 1419 1443 2081 2031 2087 2103 0.1 1373 1145 1114 925 1099 1075 1454 1349 2909 3138 3742 4622 1475 1500 1299 1539 2172 2051 2261 2375 0.2 1322 1277 1225 1191 1163 1135 1306 1209 3080 3141 3691 5589 1446 1477 1477 1396 2141 2197 2293 2205 0.4 1218 1148 1130 1128 1154 1373 1398 1172 3143 4835 3696 4609 1553 1574 1568 1443 2127 2143 2500 2154 0.5 1914 1078 1132 1043 1132 1199 1303 1304 3083 3469 3875 4161 1583 1481 1372 1529 2119 2093 2107 2267 0.6 1115 1031 1674 1077 1167 1479 1332 1174 3238 3520 3787 4139 1558 1436 1474 1433 2226 1945 2104 2060 0.8 1159 1074 1463 1024 1208 1340 1237 1134 3232 3528 3734 4494 1493 1534 1490 1392 2200 2286 2084 2242 1.0 1196 1133 1203 1026 1139 1104 1360 1109 2539 3501 3770 4064 1499 1507 1492 1472 2107 2114 1850 1738 1.5 1277 1134 1256 1096 1269 990 1354 1200 3249 3855 3942 5294 1466 1436 1452 1506 2110 1972 2221 1971 2.0 1572 1050 1043 1153 1350 1195 1323 1068 3177 3381 3932 5044 1469 1370 1493 1328 2282 2408 2089 2167 2.5 1104 1183 1270 1127 1119 1125 1358 1270 3104 3687 3915 4022 1444 1320 1510 1449 2167 2116 2397 2254 3.0 1225 1287 1255 1063 1292 1276 1345 1392 3179 3534 3979 5195 1476 1340 1491 1263 2005 2097 1997 2294 5.0 1389 1789 2351 1084 1412 1394 1323 1505 3117 3393 3722 4367 1546 1461 1487 1372 2105 2259 2143 2107 111 Table A.9: Rayonier Results Summary (from Crystallized Sulfide Doses) Rayonier Color Results (PCU) from Crystallized Sulfide Doses Sulfide Dosage (Before) Primary Clarifier Influent (Pond) Effluent (Pond) Effluent ASB #1 (Pond) Effluent ASB #2 (Pond) (mg/L) (or ppm) 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 0 1018 1069 1028 1368 1143 1230 2198 2058 2074 1552 1371 1595 3519 4747 3718 3 1054 946 1080 1177 1175 1381 2232 2054 2158 1499 1516 1440 3351 3871 4223 7 978 1008 1104 1272 1079 1328 2236 2178 2197 1491 1303 1496 3533 3988 3911 10 1121 966 1372 1412 1229 1423 2206 2155 2126 1470 1380 1512 3198 3866 4006 15 1051 767 1140 1385 1290 1451 2187 2102 2147 1441 1471 1481 3456 4237 3950 20 906 957 1087 1369 1230 1484 2042 2077 2181 1470 1468 1466 3183 4037 3980 25 920 888 1312 1301 1243 1338 2108 2130 2201 1392 1448 1482 3318 4091 3840 30 939 863 1228 1247 1203 1429 2090 2106 2140 1243 1479 1457 2830 3904 4227 70 1174 909 1204 1218 1144 1287 1977 2098 2148 1226 1383 1711 3026 3602 3407 170 1507 772 969 1143 1014 1277 1881 2000 2052 1155 992 1354 2396 3565 2800 330 925 1236 760 969 1238 1069 1629 2000 1985 977 1066 1308 2377 3319 2852 660 1401 1087 905 1378 1419 1034 1819 1700 1814 1137 1169 1140 1105 2422 1886 1650 1618 1273 965 792 1035 1101 1230 1718 1857 1124 1118 1200 1968 3315 2362 112 Table A.10: Georgia Pacific Results Summary (First Sample Set) Georgia Pacific Color Results (PCU) Sulfide Dosage Pond 1 Pond 2 Pond 3 Pond 4 (mg/L) 1 hr 24 hr 1 hr 24 hr 1 hr 24 hr 1 hr 24 hr 0 1160 1165 1324 1342 1490 1240 1348 1456 5 1173 1347 1164 1355 1283 1199 1187 1207 10 1167 1370 1067 1298 1221 1132 1169 1178 20 1155 1205 1149 1259 1246 1157 1165 1175 25 1151 1259 1134 1237 1213 1200 1141 1193 250 1286 1173 947 1244 910 1119 830 1187 500 1574 1700 1558 1412 1308 890 1201 1083 2500 1672 1798 1618 1677 1923 2418 2397 2933 113 Table A.11: Georgia Pacific Results Summary (Second Sample Set) Georgia Pacific Color Results (PCU) Sulfide Dosage Pond 2 Grab 1-Run 1 Pond 2 Grab 1-Run 2 Pond 2 Grab 1-Run 3 (mg/L) (or ppm) 1 hr 24 hr 1 hr 24 hr 1 hr 24 hr 0 1197 1150 1198 1203 948 828 5 1336 1298 1252 1244 1247 1200 10 1393 1289 1240 936 1259 1222 20 1119 1131 1214 1194 1320 1213 25 1239 1189 1206 1240 1216 1203 500 767 995 937 986 822 831 990 1050 1208 912 1164 1099 1112 2500 1094 1219 896 1089 1025 927 114 Table A.12: Georgia Pacific Results Summary (Second Sample Set-continued) Georgia Pacific Color Results (PCU) Sulfide Dosage Pond 2 Grab 2 Pond 2 Grab 3 Pond 2 Grab 4 (mg/L) (or ppm) 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 0 1115 1120 1211 1089 1065 959 1174 872 925 3 1127 1159 1186 1256 1300 1178 1301 1088 1225 7 1127 1181 1240 1332 1470 1221 1258 1177 1246 10 1403 1450 1326 1287 1546 1369 1238 1195 1163 15 1311 1542 1435 1133 1180 1151 1300 1177 1236 20 1169 1150 1244 1105 1457 1300 1269 1176 1215 25 1229 1343 1385 1120 1482 1390 1240 1195 1206 30 1170 1337 1371 1098 1370 1400 1211 1137 1190 70 1121 1193 1258 981 1310 1206 1152 1133 1319 170 1174 1234 1503 1133 1326 1232 1140 1302 1225 330 779 1136 793 1043 884 1248 1190 1124 1139 660 924 1002 1080 819 1066 1092 1244 1262 1352 1650 832 883 977 835 1126 936 1311 1293 1370 115 Table A.13: Aeration Analysis (24-hour) Aeration Analysis Color Results (PCU) Sulfide Dosage "Light" Sample "Dark" Sample (mg/L) (or ppm) 1 hr 4 hr 24 hr (overnight aeration) 1 hr 4 hr 24 hr (overnight aeration) 330 135 229 204 732 861 1173 660 284 393 402 1132 1161 1146 1650 288 343 458 1185 1190 1270 116 Table A.14: Aeration Analysis (4-day, Run 1) ALL VALUES X TIME AFTER AERATION Weyerhaeuser (Albany, OR) Light Sample Sulfide Dosage Mixed Sample (different grab points) (mg/L) (or ppm) 1 hr 4 hr 24 hr 2 day 3 day 4 day 1 292 420 217 1317 1520 581 500 1027 217 221 194 391 590 Georgia Pacific, Pond 2 Grab 3 Dark Sample 1 1155 945 957 1025 1240 1309 500 1023 900 1103 1006 1088 1200 117 Table A.15: Aeration Analysis (4-day, Run 2) ALL VALUES X TIME AFTER AERATION Weyerhaeuser (Albany, OR) Light Sample Sulfide Dosage Mixed Sample (different grab points) (mg/L) (or ppm) 0 hr 1 hr 2 hr 4 hr 6 hr 8 hr 10 hr 1 day 2 day 3 day 4 day 0 324 269 363 314 278 289 281 277 325 304 283 1 228 289 287 196 219 334 205 231 271 294 220 330 390 403 496 579 262 237 238 231 314 228 254 Georgia Pacific, Pond 2 Grab 2 Dark Sample 0 966 1290 972 939 967 967 936 926 1104 1119 1645 1 1130 1033 1004 959 991 991 925 980 1210 1017 1128 330 1127 964 986 1046 1005 982 950 987 1025 982 953 118 Table A.16: Lignin Components Isolation Analysis Lignin Components Isolation Analysis Color Results (PCU) Sulfide Dosage 4-Hydroxybenzaldehyde Phenol Vanillin Solution Strength (mg/L) (or ppm) 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 0 22 11 46 32 6 10 187 33 77 3 26 15 31 25 0 22 61 28 51 1 ppm 1650 64 75 108 54 65 68 82 48 36 0 1 12 16 22 -3 14 59 21 81 3 24 5 14 25 3 18 31 19 55 50 ppm 1650 51 112 122 96 45 -6 198 158 94 119 Table A.17: Lignin Components Isolation Analysis (continued) Lignin Components Isolation Analysis Color Results (PCU) Sulfide Dosage Catechol Anthraquinone Humic Acid Solution Strength (mg/L) (or ppm) 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 1 hr 4 hr 24 hr 0 120 414 745 34 9 11 239 222 232 3 259 353 463 35 10 92 213 266 294 1 ppm 1650 126 198 198 1025 1712 1726 543 591 1410 0 225 121 177 86 112 163 5335 5463 5394 3 113 197 565 102 79 147 4617 5546 5786 50 ppm 1650 193 338 2785 4181 9008 8731 4918 5258 4132 120 Table A.18: Lignin Components Isolation Analysis (continued) Lignin Components Isolation Analysis Color Results (PCU) Sulfide Dosage Fulvic Acid Solution Strength (mg/L) (or ppm) 1 hr 4 hr 24 hr 0 46 38 32 3 30 29 37 1% 1650 241 74 114 0 194 157 174 3 312 470 301 20% 1650 44 225 272 0 552 504 579 3 556 556 574 50% 1650 738 911 738 121