Advanced nutrient removal from ammonia and domestic wastewaters by a novel process based on simultaneous partial nitrification-anammox and modified denitrifying phosphorus removal

A novel process combined simultaneous partial nitrification-anammox (SPNA) with modified denitrifying phosphorus removal (DPR) in two sequencing batch reactors (terms as SPNA-SBR and mDPR-SBR) was proposed for treating ammonia (NH4+-N) and domestic wastewaters. Firstly, NH4+-N contained wastewater was fed into SPNA-SBR for autotrophic nitrogen removal. Meanwhile, domestic wastewater was introduced to mDPR-SBR for anaerobic phosphorus release and intracellular carbon storage. Then, nitrate (NO3--N) produced in SPNA-SBR was discharged to mDPR-SBR, where NO3--N was reduced to dinitrogen gas (N-2) via anoxic denitrifying phosphorus removal. Finally, the residual NH4+-N and PO43--P in mDPR-SBR were removed via aerobic simultaneous nitrification, endogenous denitrification and phosphorus removal (SNEDPR). The long-term operation (235-day) suggested that a desirable nutrient removal performance was achieved in the SPNA-mDPR process, and the final effluent NH4+-N, total nitrogen and PO43--P concentrations were 1.5, 5.0 and 0.2 mg.L-1, respectively. In the SPNA-SBR, SPNA contributed to similar to 90% of NH4+-N removal at low aeration intensity (dissolved oxygen (DO): 0.1 mg.L-1); in the mDPR-SBR, similar to 70% of PO43--P and similar to 100% of NO3--N were simultaneously removed via anoxic DPR, and post-aerobic SNEDPR further reduced similar to 30% of PO43--P and similar to 70% of NH4+-N. Stoichiometry-based microbial activity analysis demonstrated that, in the mDPR-SBR, high activity of denitrifying phosphorus accumulating organisms (DPAOs) over denitrifying glycogen accumulating organisms (DGAOs) in anoxic NO3--N removal (71.1% > 28.9%) facilitated DPR, and high percentage of SNEDPR via nitrite (89.6%) over nitrate saved 52% intracellular carbon demand to realize the deep-level nutrient removal without external carbon addition.