Abstract

Given the toxicity and widespread occurrence of hexavalent chromium [Cr(VI)] in aquatic environments, we investigated the feasibility of a down-flow hanging sponge (DHS) biofilm reactor for the enrichment of microbial communities capable of Cr(VI) removal. In the present study, a laboratory-scale DHS reactor fed with a molasses-based medium containing Cr(VI) was operated for 112 days for the investigation. The enrichment of Cr(VI)-removing microbial communities was evaluated based on water quality and prokaryotic community analyses. Once the DHS reactor began to operate, high average volumetric Cr(VI) removal rates of 1.21–1.45 mg L-sponge⁻¹ h⁻¹ were confirmed under varying influent Cr(VI) concentrations (approximately 20–40 mg L⁻¹). 16S rRNA gene amplicon sequencing analysis suggested the presence of phylogenetically diverse prokaryotic lineages, including phyla that contain well-known Cr(VI)-reducing bacteria (e.g., Bacteroidetes, Firmicutes, and Proteobacteria) in the polyurethane sponge media of the DHS reactor. Therefore, our findings indicate that DHS reactors have great potential for the enrichment of Cr(VI)-removing microbial communities.

摘要

鉴于六价铬[Cr（VI）]在水生环境中的毒性和普遍存在，我们研究了下流悬挂式海绵（DHS）生物膜反应器用于富集能够去除Cr（VI）的微生物群落的可行性。在本研究中，实验室规模的DHS反应器装有含Cr（VI）的糖蜜基培养基，运行112天进行调查。基于水质和原核生物群落分析，评估了去除Cr（VI）的微生物群落的富集程度。一旦DHS反应器开始运行，在变化的进水Cr（VI）浓度（约20-40 mg L ^-1）下，可以确定1.21–1.45 mg L海绵^-1 h ^-1的高平均体积Cr（VI）去除率。）。16S rRNA基因扩增子测序分析表明，DHS反应器的聚氨酯海绵介质中存在系统发育多样的原核世系，包括含有众所周知的Cr（VI）还原菌（例如拟杆菌，硬毛菌和变形杆菌）的种系。因此，我们的发现表明DHS反应器具有丰富的去除Cr（VI）微生物群落的潜力。