Effects of anaerobic duration and dissolved oxygen on endogenous denitrification rate in AOA system
AN Ze-ming, DING Jing, GAO Xin-jie, PENG Yong-zhen
National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China
Abstract:The Anaerobic/Aerobic/Anoxic (AOA) process based on endogenous denitrification gained widespread attention in recent years with the benefits of carbon saving and consumption reduction. Nitrogen is mainly removed via the endogeous denitrification occurred in the post-anoxic phase of the AOA process. Therefore, increasing endogenous denitrification rate (EDNR) is the crucial to enhance the nitrogen removal efficiency. To explore the methods to improve the nitrogen removal efficiency of AOA process, the effects of the anaerobic duration and dissolved oxygen (DO) concentration in the aerobic phase on EDNR were investigated in this study. Results showed that the EDNR was the maximum when the anaerobic duration was 60min at the influent COD concentration of 155.1mg/L. Under different influent COD concentration, the accumulation of polyhydroxyalkanoates (PHAs) (a kind of intracellular carbon) reached the peak by controlling the appropriate anaerobic duration, and the EDNR was maximized. The EDNR was affected by excessive or insufficient DO in aerobic phase, and the highest EDNR was achieved when DO was controlled at 1mg/L. The EDNR was increased by 31.7% and 18.4% through anaerobic duration optimization and DO control, respectively. This paper provided a feasible strategy to enhance the EDNR in the post-anoxic phase of the AOA process, which is conducive to the optimization of the AOA process designs and operation strategies.
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