基于废弃植物质为碳源的波形流生态池正负效应及其微生物机制研究

Being an important pollution source in surface and underground water bodies, nitrate has being one of target pollutants urgently required reduction and control. Superiorities including low costs, easy operation, wide applicable range, etc. can be presented when treating nitrate pollution in water bodies using ecological technologies, but nitrate reduction is always restricted by insufficient of available organic carbon. .Recently, the effectiveness of addition of plant biomass as carbon source to improve nitrate removal in ecological technologies has been proven. However, to date, these studies were mostly just focused on nitrogen removal performance, and the systematic investigation on the negative effects of ecological technologies and the mechanisms after the plant biomass addition under different operation conditions are still lack..Accordingly, in the project we desired, nitrate-laden wastewater was treated using two types of wavy-flow ecological chambers, with waste plant biomass added as carbon source. The positive effect of nitrate removal performance and negative effects of discharges of carbon and nitrogen by-products with different plant biomass type, combination, dosage and nitrate loading rate will be investigated to assess and compare their application performance. .Furthermore, the activities, abundances and community structures of total microorganisms and denitrifying bacteria in the chambers will be investigated and analyzed to preliminarily reveal the response mechanisms of the positive and negative effects after the carbon source addition, and to illustrate the functioning mechanisms of plant biomass carbon combining the alterations of their properties. The final goals are to provide theoretical basis and technical support for the reduction and control of nitrate pollution employing the integrated ecological technologies, and to recycle the waste plant biomass.

硝氮是地表及地下水的重要污染源，长期以来都是水体亟需削减和控制的目标污染物之一。利用生态技术治理水体硝氮污染具有成本低、易操作、应用范围广等优势，但可用有机碳源常成为其脱硝限制因子。近年来的研究表明外加植物生物质作为碳源是解决这一问题的有效手段，然目前的研究多关注系统脱氮效能，对于其负效应在不同工况下对植物生物质碳源投加的响应及其作用机制还缺乏系统研究。由此本研究拟采用两种波形流生态池处理硝氮废水，并外加废弃植物生物质为碳源，通过考察不同碳源种类和组合、投加量和污染负荷下两种系统的硝氮去除效能和碳、氮副产物排放等正负效应综合评估和比较其应用性能；同时通过解析不同种类碳源投加对系统微生物及反硝化菌活性、数量及群落结构的影响初步揭示正负效应的响应机理，并结合碳源性质变化探寻其作用机制，旨在为应用该方法削减和治理水体硝氮污染提供理论依据和技术支撑，同时达到废弃植物质资源化的目的。

硝氮作为地表及地下水的重要污染源，长期以来都是较受关注、需进行削减和控制的目标污染物之一。在诸多污水硝氮去除方法中，利用基于微生物反硝化作用的生态技术具有成本低、易操作、可大规模应用等优点，但可供给反硝化反应的有机碳源的缺乏常成为限制其脱硝效能的关键因子。自然界大量存在的植物质可作为外加碳源有效解决这一问题，而关于植物质投加的负面效应、基于正负效应合理评价下的运行工况优化及植物质作用的微生物机制还缺乏系统研究。本项目构建了小试潜流生态池处理含硝氮污水，并外加废弃植物质为碳源，通过长期动态运行考察不同碳源种类、投加量、投加方式和污染负荷下系统脱氮效能和碳、氮副产物排放等效应综合评价和比较其应用性能，提出系统优化运行方式。结果表明植物质投加可有效提高生态池的脱氮效能，芦苇秸秆是相对较优的碳源，植物质的分解消耗水中溶解氧，为反硝化创造适宜的还原环境条件。植物质的不均匀释碳导致投加初期有机污染较大，碳源不充足时出现亚硝氮累积，投加后期则脱氮效能下降。碳源有效期随水力负荷的增加而下降，植物质碳源的投加应依据生态池负荷采用适当的频率进行。生态池脱硝效率可用出水无机碳浓度进行很好地指示和预测。考察了植物质碳源投加下生态池微生物活性和群落结构响应，表明植物质投加系统中与反硝化作用和有机物分解相关的几种酶活性显著高于对照，微生物的多样性和均匀性增加，一些功能微生物的比例显著上升，这有利于植物质的分解利用和系统脱氮功能的发挥。研究成果可为应用废弃植物质碳源投加下的生态池净化低碳高硝氮污水、削减水体硝氮污染提供理论和实践依据。