Boosting industrial bio-denitrification through gene activation: the micro-nano-MoS2 enhanced bioprocess

Abstract High levels of nitrates and nitrites not only threaten aquatic ecosystems and drinking water safety but also impair the biodegradation efficiency of industrial wastewater. In this study, micro-nano-MoS2-1013 (0.04 g/L) enhanced denitrification by 56.9% and 29.6% in steel pickling and meat processing wastewaters, respectively, and improved chemical oxygen demand (COD) removal by 136.7% in refinery cooling wastewater under continuous-flow conditions using a 3.5 L upflow anaerobic sludge blanket (UASB) reactor. The catalytic effect of micro-nano-MoS2 on denitrification was achieved by stimulating an increase in the abundance of denitrification genes and the transcript levels of narL (93.82 times), narG (16.34 times), and nirK (12.27 times) within the bacterial cells, which led to an increase in the expression levels of denitrifying enzymes. These findings have significant implications for the design and optimization of biodegradation processes and bio-denitrification systems, particularly for the treatment of high-concentration nitrate wastewater.