CSIRO Environment, 147 Underwood Avenue, Floreat, WA, 6014, Australia; College of Environmental Science and Engineering, Nanjing Tech University, Nanjing, 211816, China; Department of Environmental Engineering, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
CSIRO Environment, 147 Underwood Avenue, Floreat, WA, 6014, Australia; School of Engineering & Energy, Murdoch University, WA 6150, Australia.
Chemosphere. 2024 Sep;364:143224. doi: 10.1016/j.chemosphere.2024.143224. Epub 2024 Aug 30.
Biological fluidized bed reactor (FBR) is a promising treatment option for removing selenium oxyanions from wastewater by converting them into elemental selenium. The process can achieve high rates and be efficiently operated at low hydraulic retention times (HRT). However, the effects of HRT on the changes in microbial community in the FBR process have not been previously explored. In this study, dynamic changes of microbial communities both on biofilm carrier and in suspension of a selenate-reducing FBR were explored at various HRTs (0.3-120 h). Based on partial 16S rRNA gene sequencing of the microbial communities, alpha diversity of microbial communities in suspension rather than in the biofilm were impacted by low HRTs (0.3 h-3 h). Members from genera Geobacter, Geoalkalibacter, and Geovibrio were the main selenate-reducing bacteria on carrier throughout the FBR process. Genus Geobacter was dominant in FBR carrier at HRT of 24 h-120 h, whereas Geoalkalibacter and Geovibrio dominated at low HRT of 0.3 h-6 h. Suspended microbial communities detected in the FBR effluent were more sensitive to HRT changes than that in biofilm. "Shock loading" at HRT of 0.3 h had a great impact on microbial community compositions both in the biofilm and effluent. Reactor operation in batch mode and long HRT of 24 h helped recover the community from "shock loading" and improved selenite reduction and ethanol oxidation. Redundancy analysis revealed that HRT, influent pH and selenate loading were key operational parameters impacting both the FBR performance and the composition of microbial communities associated with both the FBR carrier and effluent. Overall, the microbial communities in FBR biofilm flexibly responded to the changes of HRT and showed resilience to the temporary shock loading, enabling efficient selenate removal.
生物流化床反应器（FBR）是一种很有前途的处理方法，可将硒酸盐转化为元素硒，从而去除废水中的硒酸盐阴离子。该工艺可以实现高去除率，并在低水力停留时间（HRT）下高效运行。然而，HRT 对 FBR 工艺中微生物群落变化的影响尚未得到探索。在这项研究中，研究了不同 HRT（0.3-120 h）下，硒酸盐还原 FBR 的生物膜载体上和悬浮液中微生物群落的动态变化。基于微生物群落的部分 16S rRNA 基因测序，悬浮液中微生物群落的α多样性而不是生物膜中的α多样性受到低 HRT（0.3 h-3 h）的影响。在整个 FBR 过程中，属 Geobacter、Geoalkalibacter 和 Geovibrio 是载体上主要的硒酸盐还原菌。在 HRT 为 24 h-120 h 时，属 Geobacter 在 FBR 载体上占优势，而在 HRT 为 0.3 h-6 h 时，Geoalkalibacter 和 Geovibrio 占优势。FBR 出水中检测到的悬浮微生物群落对 HRT 变化比生物膜中的微生物群落更敏感。在 HRT 为 0.3 h 时进行“冲击负荷”对生物膜和出水的微生物群落组成都有很大的影响。在批处理模式下运行反应器和 HRT 长为 24 h 有助于从“冲击负荷”中恢复群落，并提高亚硒酸盐还原和乙醇氧化。冗余分析表明，HRT、进水 pH 值和硒酸盐负荷是影响 FBR 性能和与 FBR 载体和出水相关的微生物群落组成的关键操作参数。总的来说，FBR 生物膜中的微生物群落灵活地响应 HRT 的变化，并对暂时的冲击负荷具有恢复能力，从而实现高效的硒酸盐去除。
