Simultaneous Nitrogen and Phosphorus Removal Characteristics of An Anaerobic/Aerobic Operated SPNDPR System Treating Low C/N Urban Sewage

Abstract

This study focused on the nitrogen (N) and phosphorus (P) removal performance optimization of simultaneous partial nitrification-endogenous denitrification and phosphorus removal (SPNDPR) systems. An anaerobic (180 min)/aerobic operated sequencing batch reactor (SBR) fed with domestic wastewater was used for investigating the startup and optimization of SPNDPR by regulating the aeration rate and aerobic duration time. The experimental results showed that at an aerobic aeration rate of 0.8 L·min-1 and aerobic duration time of 150 min, the effluent PO43--P concentration was about 1.5 mg·L-1, with the effluent NH4+-N and NO3--N concentrations gradually decreasing from 10.28 and 8.14 mg·L-1 to 0 and 2.27 mg·L-1, respectively, and effluent NO2--N concentration increasing to 1.81 mg·L-1. When the aeration rate was increased to 1.0 L·min-1 and the aerobic duration time was shortened to 120 min, the phosphorus removal and partial nitrification-endogenous performance of the system gradually increased, but the total nitrogen (TN) removal performance initially decreased and then gradually increased. The final effluent PO43--P and NH4+-N were stably below 0.5 and 1.0 mg·L-1, respectively, aerobic nitrite accumulation and simultaneous nitrification-endogenous denitrification (SND) efficiencies were 98.65 and 44.20%, respectively, and TN removal efficiency was 79.78%. The concurrence of aerobic phosphorus absorption, denitrifying phosphorus removal, partial nitrification, and nitrification-endogenous in the aerobic stage of the SPNDPR system ensured the simultaneous removal of N and P from low C/N wastewater.