Achieving Energy and Chemical Savings in Sidestream Treatment through Reliable Nitritation of High Strength Ammonia Liquors Using Novel Biocatalysts

The Microvi MNETM biocatalyst technology for introducing and retaining a highly effective organism for ammonia oxidation was evaluated for achieving ammonia removal in high strength ammonia liquors from the dewatering process of anaerobic digestors. First, the MNE technology was evaluated in a laboratory bench-scale reactor and then in a 567 L continuous stirred tank reactor (CSTR) pilot system commissioned at Oro Loma Sanitary District (OLSD) in San Lorenzo, California. The laboratory bench-scale reactor removed 99.9% of the ammonia in filtrate water. It achieved ammonia concentrations below 5 mg-N/L from influent concentrations of approximately 600 mg-N/L. More than 95% ammonia removal was observed running the pilot system at a 15-hour hydraulic retention time (HRT) from volumetric ammonia loads ranging between 0.7 kg-N/m3∙d and 0.9 kg-N/m3∙d. The MNE biocatalysts operated under numerous stress conditions and recovered to steady state performance within 24 hours. This work demonstrated that the MNE technology is effective for sidestream treatment and also well-suited nitrite shunt applications in Annamox systems or as a standalone process. As a result of this work, the MNE technology is currently undergoing full-scale implementation at Oro Loma Sanitary District as the first sidestream treatment technology in the San Francisco Bay Area.