基于耐高温硝化菌群和硫氧化菌群强化原位控制污泥堆肥系统中NH3与H2S臭气的机理研究

Sewage sludge composting is the mainstream technology of sludge treatment at home and abroad, due to the low investment and low operating costs. The release of NH3 and H2S odors during the thermophilic phase is an serious problem that has not been solved for a long time in practical application. To develop a new technology for in-situ control of NH3 and H2S, it ia necessary to solve the problems of low activity of nitrifier under high temperature and lack of electron acceptor in the process of sulfur oxidation during thermophilic phase. At present, there are few studies on thermophilic nitrifying bacteria (TNB) and its mechanism of enhancing the nitrification at high temperature is unclear. The mechanism of synergistic control of NH3 and H2S by TNB and sulfur-oxidizing bacteria (SOB) is still blank. Based on the screening of TNB and SOB, the biological characteristics of two kinds of bacteria will be studied by enzymology, molecular biology and other techniques. The efficiency of TNB will be investigated. The mechanism of enhancing nitrification during the thermophilic phase by TNB will be illuminated. The competitive relationship between denitrification and sulfur oxidation on NO3- will be clarifed. The radial diffusion of NO3- into the sludge particle will be explored when it is involved in the oxidation of sulfur as an electron acceptor.The effects of synergistic control of the two kinds of bacteria and the activities of key enzymes will be analyzed to reveal the mechanism of synergistic in-situ conversion of NH3 and H2S. In this way, a new method and theory for the in-situ control of odor during sewage sludge composting can be developed.

污泥堆肥工艺投资少、运行费用低，是国内外污泥处理的主流技术。但污泥堆肥高温期NH3和H2S大量释放是该工艺在实际应用中长期未能解决的重要问题。开发污泥堆肥原位控制NH3和H2S等臭气的新技术，需解决堆肥高温期硝化菌活性低、硫氧化过程缺少电子受体等难题，目前对耐高温硝化菌群强化高温期硝化作用的研究较少，耐高温硝化菌群与硫氧化菌群协同控制NH3和H2S的作用机制尚属空白。本项目在筛选出耐高温硝化菌群和硫氧化菌群的基础上，利用酶学、分子生物学等技术手段，研究两类菌群的生物学特性；考察耐高温硝化菌群效能，阐明其强化高温期硝化作用的机理；明确反硝化作用与硫氧化作用对NO3-的竞争关系，探讨NO3-径向扩散到污泥颗粒内部作为电子受体参与硫氧化作用的规律；分析两类菌群协同控制的作用效能及其关键酶活性的变化特征，揭示其协同原位转化NH3和H2S的作用机制；从而完善污泥堆肥系统臭气原位控制的新方法和新理论。

污泥堆肥高温期NH3和H2S的大量释放是该工艺在实际应用中长期未能解决的重要问题，开发污泥堆肥原位控制NH3和H2S等臭气的新技术，是解决堆肥高温期时含氮含硫臭气排放问题的关键。本课题利用筛选纯化和菌株鉴定等手段，从堆肥物料中分别筛选获得3株硝化能力和3株硫氧化能力较强的菌株，并明确了两类菌群的优化发酵条件和在高温条件（≥50℃）下的硝化和硫氧化代谢途径。将获得的耐高温硝化菌群应用于污泥堆肥，分析了堆肥过程中氮素形态的转化过程及不同工艺条件下NO3--N的分布特征，并研究了耐高温硝化菌群强化硝化效能的作用机制；将构建的耐高温硫氧化菌群投入到污泥堆肥中，明确了硫基反硝化和土著反硝化作用对于NO3--N电子受体的竞争机制。通过应用优化投加条件后的耐高温硝化菌群和硫氧化菌群，发现两类菌群对NH3和H2S臭气的协同控制效果较为明显，可将堆体中NH3和H2S臭气的累积释放量分别降低31.52%和48.82%；并从种群结构、功能基因表达和酶学角度阐述了两类菌群原位协同转化NH3和H2S的作用机理。上述研究成果可为污泥堆肥工艺中原位控制NH3和H2S臭气的复合菌剂应用提供技术支撑，同时对于污泥堆肥技术的推广和工程化应用也具有重要的理论意义。