Denitrification and Phosphorus Removal from Low C/N Urban Sewage Based on a Post-Partial Denitrification AOA-SBR Process

This study focuses on the investigation of the nitrogen (N) and phosphorus (P) removal characteristics of a combination of enhanced phosphorus removal (EBPR) with simultaneous partial nitrification endogenous denitrification (SPND) and post-partial denitrification process. An anaerobic/aerobic/anoxic (A/O/A) operated sequencing batch reactor (SBR) fed with urban sewage was optimized by regulating the aeration rate and anoxic time. Based on this optimization, deep-level nitrogen and phosphorus removals from low C/N urban sewage could be realized. The experimental results show that the effluent PO 4 3- -P concentration decreased from 0.06 mg•L -1 to 0 mg•L -1 , the effluent NH 4 + -N, NO 2 - -N, and NO 3 - -N concentrations gradually decreased from 0.18, 18.79, and 0.08 mg•L -1 to 0, 16.46, and 0.05 mg•L -1 , respectively, and the TN removal efficiency increased from 72.69% to 77.97% when the aeration rate decreased from 1.0 L•min -1 to 0.6 L•min -1 and the anoxic duration was 180 min. With the reduction of the aeration rate, the SPND phenomenon became notable and the SND rate increased from 19.18% to 31.20%. When the anoxic duration was extended from 180 min to 420 min, the effluent PO 4 3- -P, NH 4 + -N, and NO 3 - -N concentrations stabilized at~0, 0, and 0.03 mg•L -1 , respectively. The effluent NO 2 - -N concentration was as low as 3.06 mg•L -1 , the SND rate was~32.21%, the TN removal performance gradually improved, and the TN removal efficiency was as high as 99.42%. Thus, deep-level nitrogen and phosphorus removals could be realized with the SPNDPR-PD system. © 2019, Science Press. All right reserved.