Role of Organic/Sulfide Ratios On DNRA Cultivation And The Microbial Community Structure of A Co-Driven Sequencing Biofilm Batch Reactor

Abstract

Denitrification and dissimilatory nitrate reduction to ammonium (DNRA), are two competing pathways in nitrate reducing process. In this study, a series of C/S ratios from 8:1 to 2:4 was investigated in a sequencing biofilm batch reactor (SBBR) to determine the role of reducers (sulfide and acetate) on their competition. The results showed the proportion of DNRA increased in high electron system, either in organic rich or in sulfide rich system. The highest DNRA ratio increased to 16.7% at the C/S ratio of 2:3. Excess electron donors, particularly sulfide, were favorable for DNRA in a limited nitrate environment. Moreover, a higher reductive environment (ORP <-400 mV) can be used as an indicator for the occurrence of DNRA. 16s RNA analysis demonstrated that Grobacter was the main functional bacteria of DNRA in the organic rich system, while Alphaproteobacteria and Desulfomicrobium were dominant DNRA bacteria in the sulfide rich system. DNRA cultivation could enrich nitrogen conversion pathways in conventional denitrification systems. This provides the great insight into nitrogen removal in high nitrogen containing sewage with low C/N.

CS2 increasing CH4-derived carbon emissions and active microbial diversity in lake sediments

“…Li (2020) also found that Methylomonas koyamae could secrect more EPS into the culture under the CH3SH stress of 200-1000 mg m -3 than the group without CH3SH. Moreover, CH3SH and CS2 could be converted between each other (Li, 2020). Previous studies have also reported that microorganisms could secrete EPS to improve resistance under harsh environments in the presence of heavy metals, chemicals and antibiotics (Fang et al, 2002;Coburn et al, 2016).…”