强化种间电子传递促进垃圾焚烧渗沥液厌氧处理的效能及其机理研究

Anaerobic bio-methanogenic treatment of fresh leachate from municipal waste incineration plants is usually came across the problems of slow processing speed and low treatment efficiency, which will cause serious environmental pollution if not properly solved. The main reason for these problems is the degradation speeds of some intermediate metabolites (e.g. propionate) from the compounds of the leachate were hindered by the relative slow process of interspecies hydrogen transfer (IHT), according to our previous studies. Direct interspecies electron transfer (DIET) in anaerobic biosystems has recently been recognized as an alternative methanogenic route to IHT, with higher interspecies electron exchange efficiencies. Thus, this project presents a hypothesis that incorporating conducive materials into anaerobic bioreactors could enhance the incineration leachate treatment efficiency by facilitating DIET between microorganisms. The entire project contains three subsections: 1) explore the feasibility of enhancing incineration leachate treatment efficiency by incorporating conducive materials into bioreactors via DIET; 2) investigate the mechanisms of facilitating DIET through conductive materials to promote leachate treatment by molecular biology technology and defined co-cultures; 3) analyze the inhibitory factors and inhibitory mechanism for interspecies electron transfer processes by studying the inhibition effect on the DIET methanogenesis of typical inhibitors in leachate. The results expected from this project could significantly accelerate the methanogenic treatment of fresh leachate from municipal waste incineration plants.

采用厌氧产甲烷生物处理工艺处理城市生活垃圾焚烧渗沥液时经常出现处理效率低、处理效果差等问题，如不妥善解决，会造成严重的环境污染。前期研究分析其原因主要是由于厌氧处理过程中垃圾焚烧渗沥液的一些组分的中间代谢产物如丙酸等的降解速率受到了种间氢传递过程的限制。厌氧体系中的直接种间电子传递过程是一种比种间氢传递过程更高效的产甲烷过程，因此，本项目提出通过向体系中投加导电材料强化微生物的种间电子传递过程，来提高垃圾焚烧渗沥液的处理效能；通过分子生物学和纯菌共培养手段探究导电材料强化种间电子传递过程促进渗沥液处理效能的机理；通过考察渗沥液中典型抑制因子对导电材料介导的种间电子传递过程的抑制情况，解析种间电子传递过程的抑制因素及抑制作用机制。这些研究的成果，将为城市生活垃圾焚烧渗沥液的高效产甲烷资源化处理提供支持。

采用传统的厌氧产甲烷工艺对城市垃圾焚烧渗沥液进行处理时，经常出现处理工艺酸化崩溃的情况，处理效率和处理效果均不理想。本研究通过投加导电材料和施加阳极电势来强化厌氧产甲烷反应器中微生物间的直接电子传递过程（Direct interspecies electron transfer, DIET），实现了垃圾焚烧渗沥液的高效处理；探究了导电材料强化种间电子传递过程促进渗沥液处理效能的机理。研究结果表明：向厌氧反应器中投加导电材料并富集具有胞外电子传递能力的微生物种群，提升反应体系中有机污染物降解过程中的电子传递速率，进而提高厌氧体系的有机物代谢和产甲烷过程，使体系承受更高的有机负荷，并实现了直接渗沥原液处理。在有机负荷在25 kgCOD/(m3d)时，COD去除率可高达90%以上，有机负荷为36.7 kgCOD/(m3d)时，COD去除率也保持在85%左右，且反应体系没有酸化风险。颗粒活性炭表面的微生物群落中，与DIET有关的编码蛋白质的基因丰度大幅提高，来自Geobacter菌种的编码导电菌毛PilA，编码外膜c-型细胞色素OmcS和编码跨外膜孔蛋白—细胞色素复合体（pcc复合物）以及来自Methanosarcina菌种F420H2脱氢酶（Fpo复合物）和异二硫化物复合物（HdrABC）的相对丰度均显著增加。通过外加0.7V的小量阳极电势，可以有效强化垃圾焚烧渗沥液中的大分子有机物的降解，在进水COD为10,000 mg/L时，垃圾焚烧渗沥液经过微生物电解池处理后，出水中的大分子有机物比例比对照反应器降低25.4%，去除率提高15%。相关研究迄今在国际主流期刊发表SCI论文8篇（均为第一或通讯作者），包括Water Res.（1篇）、Bioresour. Technol.（4篇）和Chem. Eng. J.（1篇）等，为城市生活垃圾焚烧渗沥液的高效产甲烷资源化处理提供支持。