Advanced nitrogen removal of low C/N ratio sewage in an anaerobic/aerobic/anoxic process through enhanced
Xinjie Gao1, Ting Zhang2, Bo Wang1
1National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing, 100124, PR China.
Abstract:
Currently, it is a major challenge for waste water treatment plants (WWTPs) to achieve enhanced nitrogen removal economically and effectively from carbon-limited sewage to meet gradually stringent discharge quality standards. Enhanced nitrogen removal can be achieved by endogenous denitrification (ED) treatment of low C/N municipal sewage, but its application is limited by the slow reaction rate. In this study, a novel process of Sludge Double Recirculation-Anaerobic/Aerobic/Anoxic (SDR-AOA) was developed to improve nitrogen removal efficiency via ED. ED was successfully enhanced by an extra sludge recirculation to post-anoxic zone and the denitrification rate increased from 0.1 to 0.17 kgN/(m3·d). Moreover, the pre-anaerobic zone enhanced the intracellular carbon storage, which might also favor the ED process. Overall, under an influent C/N of 2.67, nitrogen removal efficiency of 97.7% was achieved with effluent total inorganic nitrogen (TIN) of 1.56 ± 1.77 mg/L and nitrogen removal rate (NRR) of 0.14 kgN/(m3·d). Therefore, this study provides a convenient approach to improve the nitrogen removal efficiency of municipal sewage with low C/N.
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