填埋场中反硝化脱硫菌代谢行为对H2S的内源削减机理

The odor in landfill site arisen by H2S has seriously endangered human health and ecology safety, and has gained widely attention. Based on the mechanisms that nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) can affect H2S emission using nitrate and sulfide as electronic donor and acceptor, respectively, this proposed research aims to study the H2S endogenous mitigation mechanism by NR-SOB in landfill by traditional microbiological and molecular biological methods. Firstly, the phenomena of nitrate reducing and sulfate oxidizing coupled with the change of H2S emission rule in different cell during the landfill process will be investigated by isotopic tracing and electronic flow analyses. It expects to reveal the potential relationship between nitrate-reducing, sulfate-oxidizing and H2S emission reduction. Subsequently, dominated NR-SOB from simulated landfill bioreactor and real landfill site will be isolated by high-throughput sequencing, computer indexing and selective culturing, and the contribution of nitrate reducing and sulfide oxidation will also be figured out. Finally, scenarios of mini landfill circumstances with different electronic donor (sulfur) and acceptor (nitrogen) and their obligate metabolisms will be simulated and incubated with NR-SOB. The mediation effect by landfill circumstance and the corresponding H2S reduction mechanism will be elucidated. Results of this research will enrich the H2S odor source reduction technologies and methods, and also can provide more theoretical basis bioreactor landfill technologies.

填埋场H2S恶臭扰民已成为危害人类健康与生态安全的重大环境问题，基于反硝化脱硫菌（NR-SOB）能利用硝酸盐为电子受体、硫化物为电子供体进行代谢而影响H2S释放的原理，本项目以填埋场为载体，将NR-SOB的代谢与H2S的源头控制进行有机结合，深入开展填埋场内NR-SOB对H2S的内源削减行为及机理研究。首先通过同位素示踪和电子流向解析，动态研究模拟填埋场反应器运行过程中的反硝化脱硫行为与H2S释放的动态响应关系；随后通过高通量测序、计算机检索和选择性培养，筛选模拟填埋场和实际填埋场内不同填埋龄垃圾样品中优势NR-SOB菌群，并解析其反硝化硫氧化代谢贡献；最后通过界面分析，接种优势NR-SOB模拟填埋场微环境下硫、氮电子供受体及各自专性代谢过程，研究填埋环境对NR-SOB调控行为及H2S同步削减机理。项目研究结果将丰富源头削减填埋场H2S恶臭的技术，为完善生物反应器填埋理论体系提供依据。

填埋场H2S恶臭扰民已成为危害人类健康与生态安全的重大环境问题，基于反硝化脱硫菌（NR-SOB）能利用硝酸盐为电子受体、硫化物为电子供体进行代谢而影响H2S释放的原理，本项目以填埋场为载体，将NR-SOB的代谢与H2S的源头控制进行有机结合，深入开展填埋场内NR-SOB对H2S的内源削减行为及机理研究。首先，动态跟踪分析模拟填埋场内H2S的产排行为研究发现，填埋场内含硫有机物和/或无机物等H2S前驱体的氧化还原及迁移转化行为受水气调节影响差异显著，从而影响H2S末端覆盖层的释放行为。相比较而言，准好氧比渗滤液回灌调节更明显地改善了填埋场内H2S的释放行为。氧气的引入和渗滤液的回灌促进了硫酸盐理论贡献高达100%的还原，致使硫化物在填埋场内显著蓄积，但并未提升H2S的释放潜力。其次，水气调节前后关键时间节点的模拟填埋场内微生物结构研究表明，不同水气条件引起的环境变更对硫代谢微生物群落组成和分布有显著的影响，且硝酸盐的存在对填埋场内硫的转化的影响不容忽视。与厌氧填埋场相比，氧气的引入使得脱硫叶菌属（Desulfobulbus）等SRB的相对丰度提升了近30倍，但假单胞菌属（Pseudomonas）等NR-SOB则被削弱锐减至十分之一，硫酸盐还原的提升和其代谢产物转化的抑制致使硫化物明显累积而左右H2S的释放。最终，典型硫代谢微生物NR-SOB的批式培养研究进一步揭示，稳定的填埋场矿化垃圾中Thauera sp.和Paracoccus sp.等典型NR-SOB能在硝酸盐存在的情况下将硫化物彻底氧化为硫酸盐，同时使硝酸盐还原形成N2释放，有望降低填埋场内累积的硫化物转化为H2S释放的风险。项目研究结果丰富了源头削减填埋场H2S恶臭的技术，为完善生物反应器填埋理论体系提供了依据。