Elevated nitrogen concentrations in wastewater effluent discharged to surface waters is a problem for fish toxicity and eutrophication. Anaerobic ammonium oxidation (anammox) is an environmentally friendly and cost-effective alternative to traditional wastewater treatment methods that utilize processes like nitrification and denitrification for nitrogen removal. Anammox bacteria are able to convert ammonia directly into nitrogen gas in the presence of nitrite. However, anammox bacteria grow slowly and require specific temperature, pH, redox and other growth conditions. The goals of this project were to develop a low maintenance and low cost means of growing anammox bacteria, using an anaerobic baffled reactor (ABR) tank, regularly fed with a nutrient-rich solution. We performed weekly measurements of dissolved oxygen, pH, electric conductivity, and temperature to evaluate ABR performance and optimal conditions for anammox growth. We tracked nutrient (ammonium, nitrite, and nitrate) concentrations, which showed > 98% removal of ammonium and nitrite after ~100 days. Anammox activity tests, performed for each chamber of the ABR, demonstrated N removal under anaerobic conditions.. Through collaboration with the Los Angeles Sanitation County District, qPCR analysis was performed that confirmed the presence of anammox bacteria, among a mixed consortium of bacteria, in the ABR. Future experiments include transferring our anammox bacteria into smaller, more portable ABR tanks for wider use in decentralized or small-scale applications.
