Nitrogen and Phosphorous Removal of Pilot-Scale Anaerobic-Anoxic-Aerobic Process Under Plateau Environmental Factors

Abstract

Considering the two unique factors of the plateau environment (i.e. water temperature and oxygen partial pressure), this paper explores the nitrogen and phosphorous removal of pilot-scale anaerobic-anoxic-aerobic (A2O) process. The experimental results show that none of the total phosphorous (TP), total nitrogen (TN) or NH4 + -N of the outlet water satisfied the Chinese national standard GB18918-2002, while COD only fulfilled the standard requirements under a few working parameters. The optimal values of the four working parameters were determined as: the optimal HRT=26.25 h, the optimal DO=3.0 mg/L, the optimal temperature=15°C. All these optimal values deviated greatly from the existing studies. The microbial densities corresponded poorly to the three working parameters, and were smaller than those under non-plateau environment; the number of indicator microorganisms had good correspondence with the optimal values of our experimental parameters.