Efficient partial denitrification-anammox process enabled by a novel denitrifier with truncated nitrite reduction pathway
Xiaoxu Zheng, Jialiang Zuo, Shengjun Xu, Jinglin Wang, Faqian Sun, Yawen Xie, Shuanglong Ma, Yunxiang Zhang, Xupo Zhang, Aibin Zhan, Cancan Jiang, Xuliang Zhuang
Abstract
Partial denitrification coupled with anaerobic ammonium oxidation (PD-anammox) is a promising technology for cost-effective nitrogen removal from wastewater. Nitrite availability is crucial to anammox performance but often limited by the slow partial denitrification process. Here we report an efficient PD-anammox system driven by the novel denitrifier Bacillus velezensis C1–3 with truncated nitrite reduction pathway. Whole-genome sequencing analysis revealed that the lack of nitrite reductase genes nirS/nirK and norBC in strain C1–3 enabled nitrite accumulation without the need for precise control of carbon dosage. By coupling it with anammox sludge, over 79 % total nitrogen (TN) removal was stably achieved, under a TN loading rate of 660 mg/L/d and a carbon/nitrogen ratio below 1.0. Mechanism explorations indicate that the niche differentiation of C1–3 and anammox bacteria facilitated their mutualism while avoiding nitrite competition. This study demonstrates a novel strategy for establishing efficient PD-anammox process by harnessing the unique metabolic deficiency of denitrifiers, shedding light on the development of stable and sustainable biological nitrogen removal technologies with minimal carbon footprint. • An efficient PD-anammox system driven by Bacillus velezensis C1–3. • The PD process enabled nitrite accumulation without the need for precise control of carbon dosage. • It demonstrates a novel PDA strategy for tolerating high nitrogen load. • It provides a biological nitrogen removal technology with minimal carbon footprint.