NOB suppression in pilot-scale mainstream nitritation-denitritation system coupled with MBR for municipal wastewater treatment

The high energy consumption associated with biological treatment of municipal wastewater is posing a serious impact and challenge on the current global wastewater industry and is also inevitably linked to the issue of global climate change. To tackle such an emerging situation, this study aimed to develop strategies to effectively suppress nitrite oxidizing bacteria (NOB) in pilot-scale mainstream nitritation-denitritation system coupled with MBR for municipal wastewater treatment. The results showed that stable nitrite shunt was achieved, while more than 90% of COD and NH₄⁺-N removal were obtained via nitritation-denitritation in the pilot plant fed with real municipal wastewater. Through adjusting aeration intensity in MBR in combination with the integrated control of dissolved oxygen (DO), sludge retention time (SRT) and sludge return ratio, NOB was successfully suppressed with a nitrite accumulation rate (NAR) of more than 80%.