Enhancement of Nutrient and Organic Removal from Poultry Litter Using Anaerobic Digestion and Subsequent Algal Growth

Abstract

Research has indicated anaerobically digesting poultry litter can recover energy and reduce pathogen concentrations, which can be used as a nutrient rich media to support algal growth and simultaneously further treat the effluent of ammonium, phosphate, and COD. However, interactions between wastewater microbes and algae are only partially understood. To further understand algal-microbial interactions, algal growth was tested on digestate treatments in 300mL indoor batch reactors. There were three treatments – algae grown on sterile digestate, algae grown on non-sterile digestate, and digestate grown alone. Digestate bacteria did not significantly affect the growth of two Chlorella sorokiniana strains, but it did enhance Auxenochlorella protothecoides growth. Starch content in both C. sorokiniana strains increased 17 to 38% when grown on digestate, regardless of microbial presence. Adding aerobic bacteria to algae and digestate microbes facilitated COD removal and increased the capacity of aerobic bacteria to remove COD as well as carry out nitrification reactions. Combining aerobic and digestate microbes with algae enhances nutrient and COD removal through nitrification.