Table_1_Water Treatment Effect, Microbial Community Structure, and Metabolic Characteristics in a Field-Scale Aquaculture Wastewater Treatment System.docx

Avoiding and mitigating the introduction of harmful effluent into the environment must be a key part of intensive industrial aquaculture development in order to minimize pollution impacts. We constructed a novel field-scale aquaculture wastewater treatment system (FAWTS) involving three-stage purification to efficiently remove nutrients from effluent wastewater. However, the mechanisms of nutrient attenuation in the FAWTS are still unclear. Since microbiota play an important role in the treatment of aquatic pollutants, we hypothesized that the different stages of FAWTS may have enriched various nutrient-metabolizing bacteria, with these promoting nutrient attenuation. We therefore tested microbial metabolic activity, microbial composition, and their metabolic potential using Biolog-GN2 microplate culture and high-throughput sequencing of prokaryotic 16S rRNA gene amplicons. Our results showed that the FAWTS displayed high removal efficiencies for chemical oxygen demand (COD, 74.4–91.2%), total nitrogen (TN, 66.9–86.8%), and total phosphorus (TP, 76.2–95.9%). Simultaneously, microbial metabolic activity for various carbon sources was significantly enhanced in FAWTS biofilms. Denitrifying and phosphorus-removing bacteria such as Rhodobacter were enriched in these biofilms, and genes participating in denitrification and the pathway from methylphosphonate to α-D-ribose-1,5-bisphosphate were increased in the biofilm communities. These results imply that the transformed multistep purification system effectively removed N, P, and COD from aquaculture wastewater by enhancing the bacterial communities involved in these processes. This suggests that contamination-free aquaculture is a feasible goal, and that microbial communities are central to pollutant removal.

为最大限度降低污染影响，规避并减缓有害养殖尾水进入环境，必须成为集约化工业水产养殖发展的核心环节之一。我们构建了一套新型现场规模水产养殖废水处理系统（field-scale aquaculture wastewater treatment system，FAWTS），采用三级净化工艺以高效去除尾水中的营养物质。然而，该FAWTS系统内营养物质消减的具体机制仍未明确。鉴于微生物群落在水生污染物治理中发挥关键作用，我们提出假说：FAWTS的不同处理阶段可能富集了不同的营养物质代谢细菌，从而促进营养物质的消减过程。为此，我们通过Biolog-GN2微平板培养法以及原核生物16S rRNA基因扩增子高通量测序技术，检测了系统内的微生物代谢活性、群落组成及其代谢潜能。研究结果表明，该FAWTS系统对化学需氧量（chemical oxygen demand，COD，74.4%~91.2%）、总氮（total nitrogen，TN，66.9%~86.8%）以及总磷（total phosphorus，TP，76.2%~95.9%）均具备较高的去除效率。与此同时，FAWTS生物膜中针对多种碳源的微生物代谢活性得到显著提升。此类生物膜中富集了脱氮除磷细菌，例如红杆菌属（Rhodobacter），且生物膜群落中参与脱氮作用以及甲基膦酸转化为α-D-核糖-1,5-二磷酸通路的功能基因丰度显著上调。上述结果表明，该多级净化系统通过强化参与相关代谢过程的细菌群落，实现了水产养殖废水中氮、磷与化学需氧量的高效去除。这一研究结果证实，实现无污染水产养殖是可行目标，而微生物群落正是污染物去除过程的核心驱动因素。