Multi-strategy rehabilitation enhances nitrogen removal in a one-stage partial nitritation/anammox reactor
Xinyu Wan1, Zhicheng Zhao1, Yunpeng Zhao1
1National Engineering Research Center of Eco-Environment in the Yangtze River Economic Belt, China Three Gorges Corporation, Wuhan, 430014, PR China.
Abstract:
The one-stage granular PNA process is a promising low-carbon technology, yet its application is bottlenecked by unstable performance. In this study, a deteriorated granular sludge one-stage PNA reactor was rehabilitated using various operating strategies, resulting in an increase in total nitrogen removal rates from 0.2 to 0.8 kg N m3 d-1 and achieving a nitrogen removal efficiency of 80 %. Direct control of the airflow rate, rather than using dissolved oxygen (DO) as an indicator, successfully suppressed nitrite-oxidizing bacteria (NOB). Additionally, long-term addition of exogenous hydrazine (N2H4) effectively suppressed NOB, enhanced anammox activity, and strengthened the granulation process, with these effects persisting even after N2H4 addition ceased. The innovation lies in moving beyond conventional wastewater process parameters (like DO, FA, FNA) to implement practical control strategies (airflow rate, exogenous metabolite addition) that directly target and exploit the inherent properties of granular sludge ecosystems for effective, long-lasting system rehabilitation.
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