Solids Retention Governs Nitrification of Poultry Processing Wastewater using an Algal-bacterial Consortium

Abstract

As water demand increases worldwide, the utilization of alternative water sources, such as wastewater, is becoming necessary. The poultry processing industry generates nutrient-rich wastewater that could be treated and reutilized as irrigation water for hydroponic systems. Unfortunately, antimicrobials are often found in poultry processing wastewater, which have been found to have a negative effect on the bacteria within wastewater treatment systems. Antimicrobial chemicals such as peracetic acid (PAA) have particularly acute effects on nitrifying bacteria. The function of nitrifiers is critical to repurposing this water for irrigation. In our lab, research has shown that the addition of algae can aid bacteria, and particularly nitrifiers, in the treatment of poultry wastewater. The objective of this work was to determine if and under what conditions algae promote nitrification during treatment of poultry processing wastewater in continuously operated reactors over a long (200 day) time horizon. Also, we aimed to test the resilience of nitrification to shock events such as the addition of the antimicrobial, PAA. In this study, two reactors were used, one containing bacterium and the other containing an algal-bacteria consortium. From this study, it was revealed that the effluent composition of the algal-bacterium reactor can be manipulated by the amount of solids retained (p-value <0.05). In the algal reactor, low solids retention led to a photosynthetic dominant system that had high nitrogen and phosphorous removal. A high solids retention led to a bacteria-dominated system, supported by algae, which helped oxidize nutrients and made the water suitable for hydroponic irrigation. Overall, both systems were negatively affected by stressor events, but the algal system exhibited greater resilience by continuing to remove phosphorous and transform ammonium to nitrate.