溶藻菌及降解菌生物强化人工湿地在修复藻华及藻毒素污染中的应用

The prevalence of microcystis bloom and hepatotoxic microcystin(MCs) pollution caused by eutrophication poses serious problems to aquatic ecosystems and public health throughout the world. However, conventional water treatment technologies have some limitations on microcystis and MCs removal, such as low efficiency, high cost and secondary pollution. Recently, constructed wetlands have been introduced as a cost-efficient and sustainable system for water remediation. Therefore, in this study, we intend to enhance the performance of CWs on microcystis bloom and MCs remediation by bioaugmentation of cell-lysing and degrading bacteria in CWs, and establish suitable environments for these exogenous functional bacteria proliferation by substrates and plant screening. Two-staged CWs will be set up by combining cell-lysing bacteria fortified CWs with degrading bacteria enhanced ones. The removal efficiency of these two-staged CWs will be evaluated by repeat loading of microcystis cells and MCs. Moreover, compared with the CWs without bioaugmentation, the contribution of exogenous functional bacteria on pollutants removal will be investigated. In addition, degradation products of MCs will be identified to analyze the degradation pathway by CWs with bioaugmentaion. This study may provide new insights and methods on the remediation of eutrophic water with microcystis and MCs pollution.

因水体富营养化导致的微囊藻藻华频发及肝毒性藻毒素污染，已成为威胁到水生态系统安全及公共健康的全球性问题。考虑到传统的污水处理技术在去除微囊藻细胞及藻毒素方面存在效率低、成本高、或带来二次污染等局限，并基于人工湿地在污水处理中效率高、环境友好、可持续的优势，本项目拟通过外源添加具有溶藻功能和藻毒素降解潜力的功能性微生物对人工湿地进行生物强化，并通过基质及植物筛选来构建适应外源微生物繁殖并保持其活性的湿地环境，以此建立高效稳定的生物强化人工湿地。将溶藻菌生物强化与降解菌生物强化人工湿地进行组合建立两级强化湿地，考察其在多批次连续加载污染物条件下的去除潜力。此外，通过分子生物学技术探索外源功能微生物在污染物去除中的贡献，并通过降解产物分析了解其在生物强化人工湿地中的代谢途径，旨在为修复富营养化水体微囊藻污染提供新思路和新方法。

随着富营养化的加剧，微囊藻水华及其产生的微囊藻毒素污染是一个紧迫的全球性环境问题。人工湿地（CWs）是一种经济高效的污水处理技术，由湿地植物与基质构建的湿地环境，与藻毒素降解和碳氮磷循环功能微生物的富集与增殖密不可分。因此本研究通过基质与植物筛选，并结合外源功能菌PA14生物强化，微囊藻及藻毒素污染修复效率，及相关功能菌功能基因富集情况，从九种常见湿地基质与六种湿地植物中择优构建人工湿地微单元，并对该湿地单元的实际富营养水体修复能力进行评估。结果表明功能菌铜绿假单胞菌PA14可高表达参与吩嗪生物合成的相关基因，从而抑制微囊藻的生长；PA14对基质进行生物强化可显著提高微囊藻与藻毒素的去除效果。基质中高炉渣、生物质炭和木屑具有较功能菌富集及污染物去除潜力。植物筛选发现药用植物泽泻根际显著富集了潜在的藻毒素降解菌、降解基因mlrA以及碳水化合物和外源物质代谢途径，这可能有助于提高微囊藻分解和MC-LR降解的能力。据此，以木屑-泽泻湿地单元经组装构建微型人工湿地，用以处理富营养湖水，结果表明泽泻存在对叶绿素a、有毒微囊藻和MC-LR的去除效率分别为88.19%~98.97%、92.00~95.88%和86.48~94.82%。以木屑为基质的人工湿地，对氮、磷均具有良好的去除能力。植物存在对氨氮的去除作用较未种植的湿地明显提高。微生物群落组成及宏基因组分析发现，水体经CWs处理后，出水中微生物物种丰富度和多样性均有所增加，植物存在下增加趋势最为明显。研究发现木屑较适合作为湿地基质用于CWs构建当中；泽泻存在对微囊藻和MC-LR去除能力更强，且可富集mlrA、磷循环、碳循环及反硝化作用相关基因，可通过促进碳、氮、磷循环过程去除营养物质。综上所述，泽泻-木屑CWs及功能菌生物强化可作为高效手段，应用于微囊藻污染的富营养化水体修复当中。