The Fate of Recalcitrant Nutrients Through an Anaerobic Digester and Anammox Sidestream Treatment Process

The objective of this research is to investigate anaerobic sludge digestion in a biological nutrient removal (BNR) treatment plant context. A detailed characterization was made of effluent from a bench-scale anaerobic digester (AD) fed waste sludge from the existing City of Kelowna Wastewater Treatment Facility (KWTF), located in the Okanagan Valley, Canada. In parallel to the AD piloting, an ANaerobic AMMonia OXidizing (anammox) sidestream treatment reactor was operated to assess its efficacy for removing various nutrient species from dewatering centrate, including dissolved organic nitrogen (DON) and non-reactive dissolved phosphorus (NRDP). For comparison, dissolved nutrient characterization was also made of sidestream and mainstream flows from the KWTF. The KWTF data are intended to serve as a baseline for the research and to understand the mass flux of DON and NRDP through a full-scale process. The results show that the anammox process is able to degrade a large fraction of the DON (90%) and to a lesser extent the NRDP (12%). The research suggests that additional removal of sidestream dissolved phosphorus (orthophosphate and NRDP) would be required to allow an anaerobic digester to be incorporated into the KWTF without compromising effluent quality.