Microbially mediated molecular transformations of dissolved organic matter in bioelectrochemical systems treating beer brewery wastewater

Abstract

Microbial communities can grow as anodic and cathodic biofilms and in suspended form (planktonic) in a single-chamber bioelectrochemical system (BES). However, the roles of these microbial communities at different niches on dissolved organic matter (DOM) transformations remain largely unknown. Herein, microorganisms and DOM during beer brewery wastewater (BBW) treatment by the BESs were characterized using a combination of high-throughput sequencing and high-resolution mass spectrometry analyses. The BESs showed promising in degrading the DOM in BBW with over 80% and 90% of COD and TOC removal efficiencies, respectively. The BES treatments significantly increased the aromaticity and unsaturation of DOM by degrading preferentially those molecules with low O/C and high H/C ratios, and also enhanced chemodiversity of DOM due to the generation of thousands of N- and S-containing compounds. The co-occurrence networks displayed that the molecular composition of DOM was shaped by the combination of anodic, planktonic and cathodic microbial communities, but those microorganisms in the anodic biofilms and planktons played more significant roles. Furthermore, the network analyses identified those keystone taxa in each niche responsible for the DOM transformations, showing that some microorganisms situated in different microbial communities would cooperate to drive the transformation of the same DOM patterns. The unveiled interactions between bacterial diversity and chemical diversity of DOM will deepen our understanding of DOM transformations during bioelectrochemical wastewater treatment, which may guide to advance this technique for more efficient DOM control.