【作者】 谢作甫；

【导师】 郑平；

【作者基本信息】 浙江大学 ， 环境工程， 2014， 博士

【摘要】 随着经济的发展和人们生活水平的提高,排入自然界的氮素总量迅猛增加,破坏了自然界原有的氮素循环,导致氮素循环中间产物(主要为氨、亚硝酸盐和硝酸盐)积累,造成环境污染,危害人类及生态系统。硝化、反硝化和厌氧氨氧化在氮素循环中发挥着重要作用,以此为基础的硝化工艺、反硝化工艺和厌氧氨氧化工艺是废水生物脱氮的主要技术。过程控制是生物脱氮工艺高效运行的基础。生物脱氮过程伴随着离子种类和数量的改变,可导致反应液电导率的改变。因此,有望以电导率指示生物脱氮过程性能,辅助过程控制。氨是微生物燃料电池(MFC)的潜在能源,构建氨氧化微生物燃料电池(AO-MFC)和厌氧氨氧化微生物燃料电池(ANAMMOX-MFC),不但能够同时实现治污和产电,还有望通过MFC的电信号变化实时反映生物脱氮过程性能,为过程控制提供信息。鉴上所述,笔者考察了生物脱氮过程性能与电导率变化的关系,研发了AO-MFC和ANAMMOX-MFC,并研究了其脱氮产电性能,主要结论如下：1)建立了硝化、反硝化、厌氧氨氧化过程性能与离子强度及电导率变化的关系。研究结果表明：电导率与模拟废水的离子强度近似成正比,与主要成分浓度呈显著的线性关系；电导率能反映生物脱氮工艺容积负荷与容积效能、进水浓度与出水浓度的大小；电导率可用于指示生物脱氮过程性能的变化,也可用于辅助生物脱氮的过程控制。2)探明了反硝化过程电导率变化的原因。反硝化过程消耗N03-,同时生成相同电荷数的HC03或CO32-,理论上反应后不引起电导率降低。碱度衡算发现：反硝化中产生C032-可引起反硝化过程电导率变化；相同离子电荷数的Na2CO3溶液电导率明显小于NaNO3溶液；反硝化中产生的部分C032-与废水中的Ca2+反应形成CaC03沉淀,进一步降低反应液电导率。3)研发了氨氧化微生物燃料电池,探明了溶解氧(DO)对硝化和产电性能的影响及其机理。研究结果表明：AO-MFC的最大氨氮转化率为99.7%。稳定产电期的输出电压为98.5±1.41mV,功率密度为9.70±0.27mW m-2。在AO-MFC系统中,氨释放的电子分别流向氨单加氧酶(AMO)、 Cyt aa3氧化酶和电极,依次用于触发氨氧化、合成ATP和产生电流,分子氧控制着三者之间的电子分配。DO浓度过高或过低都会削弱产电性能。4)研发了厌氧氨氧化微生物燃料电池,探明了其脱氮和产电性能。研究结果表明：以厌氧氨氧化富集培养物(ANAMMOX Enrichment Culture, AEC)作为催化剂,以铵盐和亚硝酸盐作为反应基质,／ANAMMOX-MFC可成功产电。ANAMMOX-MFC容积负荷(NLRs)和容积去除速率(NRRs)分别为1.72-2.57kg N m-3d-1、1.64-2.38kg N m-3d-1,氨氮和亚硝氮去除率分别为88.9%-98.3%、88.7%-97.2%。随着基质浓度的提高,ANAMMOX-MFC工作电压从12.8mV逐步增大至131mV,其面积功率密度和体积功率密度分别从0.17mWm-2、1.08mWm-3上升至183mW m-2、115mW m-3。停止基质供给,ANAMMOX-MFC产电性能急剧下降,恢复基质供给,产电性能迅速恢复。／ANAMMOX-MFC产电性能易受阴极表面MnO2沉积所影响。更多还原

【Abstract】 Greatly developed economy and improved quality of people’s life have led to the rapid increase of nitrogen discharge into the nature. The natural balance of nitrogen cycle has been broken due to the accumulation of intermediate products in nitrogen cycle (such as ammonium, nitrite and nitrate), hence polluting the environment and threatening the security of human beings and ecosystem. Nitrification, denitrification and ANAMMOX play key roles in nitrogen cycle, and the nitrification process, denitrification process and ANAMMOX process based on these biological reactions are the main nitrogen removal processes. Process control is the basis of high performance of nitrogen removal processes. In the process of biological nitrogen removal from wastewater, the type and quantity of ions change as the reaction progresses, which further results in the variation of conductivity. Therefore, the conductivity can serve as an indicator that reflects the process performance and assists in the process control of biological nitrogen removal. Ammonium is the energy substance of nitrifiers and ANAMMOX bacteria, and ammonium oxidation can release electrons, for this reason, ammonia can be a potential fuel for MFC. With the development of MFCs which are based on ammonium oxidation or ANAMMOX, we can not only achieve the goal of simultaneous biological nitrogen removal and electricity generation, but also take the advantage of the electrical signal of MFC as an potential indicator to reflect the process performance of biological nitrogen removal. In this study, the relationship of process performances of biological nitrogen removal and conductivity variation was investigated, and MFCs which are based on ammonium oxidation and ANAMMOX were developed to investigate the performance of simultaneous biological nitrogen removal and electricity generation. Some innovative finding have been made as follows:1) The relationships between process performance of biological nitrogen removal and the variations of conductivity and ionic strength were investigated. The conductivity could be used as an indicator to reflect the volumetric loading and volumetric efficiency, as well as the concentrations of influent and effluent. The conductivity was a suitable parameter for the process performance variation and could assist process control of biological nitrogen removal.2) The reasons of conductivity variation in the process of denitrifiction was investigated. As NO3-was transformed to N2in denitrification, HCO3-or CO32-, which carried the same charge number as NO3-, were produced. Therefore it might not result in the conductivity variation. By investigating the alkalinity balance, the production of CO32-was found to be the main reason of conductivity variation in the process of denitrifiction. Firstly, the conductivity of Na2CO3solution was evidently smaller than that of the NaNO3solution which had the same ion charge number. Secondly, part of CO32-produced in denitrification could react with Ca2+in the wastewater which resulted in the formation of CaCO3precipitation, the conductivity was therefore further reduced.3) Based on inorganic fuel, an Ammonia-Oxidation Microbial Fuel Cell had been developed, and the influence and mechanism of dissolved oxygen (DO) on the performance of nitrification and electricity generation were investigated. The results showed that the maximum conversion percentage of ammonium-nitrogen (NH4+-N) was99.7%. The output voltage and the power density were98.5±1.41mV and9.70±0.27mW m-2in the stable phase of electricity generation. In the AO-MFC,the electrons originated from ammonia and flowed to ammonia monooxygenase (AMO, which catalyzes the conversion of ammonia to hydroxylamine),Cyt aa3oxidase (which catalyzes the reduction of oxygen) and electrode, which were used for triggering ammonia oxidation, synthesizing ATP and generating electricity. Molecular oxygen played a key role in the electron distribution among these three acceptors.DO concentration too high (>6.45mg L-1) or too low (<0.5mg L-1) could exert a great negative influence on the performance of electricity generation.4) An ANAMMOX-MFC based on anaerobic ammonium oxidation was developed, and its nitrogen removal and electricity production performance was tested. The results showed as follows:with ammonium and nitrite as substrates and ANAMMOX Enrichment Culture (AEC) as catalyst, the ANAMMOX-MFC could generate electricity. The volumetric nitrogen loading rates (NLRs) and volumetric nitrogen removal rates (NRRs) were1.72-2.57kg m-3d-1and1.64-2.38kg m-3d-1respectively, and most of the ammonium (88.9%-98.3%) and the nitrite (88.7%-97.2%) were removed. With the increasing substrates concentration, the output voltage of ANAMMOX-MFC went up from12.8mV to131mV, and the power density increased from0.17mW m-2(1.08mW m-3) to18.3mW m-2(115mW m-3). The output voltage dropped sharply after the breakoff of substrate supply, but once the substrate supply continued, its power generation performance recovered. The performance of electricity generation were found to be greatly influenced by the MnO2deposition on the cathode surface.更多还原