MFC脱氮产电性能及电导率研究

发布时间：2018-09-14 13:55

【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。
[Abstract]:With the development of economy and the improvement of people's living standard, the total amount of nitrogen discharged into nature increases rapidly, which destroys the original nitrogen cycle in nature, leads to the accumulation of intermediate products (mainly ammonia, nitrite and nitrate) in the nitrogen cycle, causes environmental pollution and endangers human beings and ecosystems. Nitrification, denitrification and anaerobic ammonia oxidation in nitrogen Nitrification process, denitrification process and anaerobic ammonia oxidation process are the main technologies for biological denitrification of wastewater. Process control is the basis for efficient operation of biological denitrification process. Ammonia is a potential energy source for microbial fuel cell (MFC). Ammonia-oxidized microbial fuel cell (AO-MFC) and anaerobic ammonia-oxidized microbial fuel cell (ANAMMOX-MFC) can be constructed, which can not only control pollution and generate electricity at the same time, but also can be real-time reversed by the change of electrical signal of MFC. In view of the above, the relationship between the performance of biological denitrification process and the change of conductivity was investigated, AO-MFC and ANAMMOOX-MFC were developed, and their denitrification and electricity production performance were studied.
1) The relationship between the performance of nitrification, denitrification and anaerobic ammonia oxidation process and the ionic strength and conductivity was established.The results showed that the ionic strength of the simulated wastewater was approximately proportional to the conductivity and the concentration of the main components was significantly linear. With the effluent concentration, conductivity can be used to indicate the change of biological nitrogen removal process performance, and also can be used to assist biological nitrogen removal process control.
2) The reason for the change of conductivity in denitrification process is found. The denitrification process consumes N03-, and produces HC03-, or CO32-, with the same charge number, which does not cause the decrease of conductivity in theory. CaC03 precipitation is formed by the reaction of C032-produced in denitrification with Ca2+ in wastewater, which further reduces the conductivity of the reaction solution.
3) Ammonia-oxidizing microbial fuel cells were developed to investigate the effects of dissolved oxygen (DO) on nitrification and electricity production. The results show that the maximum ammonia-nitrogen conversion rate of AO-MFC is 99.7%. The output voltage of AO-MFC is 98.5 (+ 1.41 mV) and the power density is 9.70 (+ 0.27 mW m-2). Ammonia monooxygenase (AMO), Cyt aa3 oxidase and electrodes, in turn, are used to trigger ammonia oxidation, synthesize ATP and generate current. Molecular oxygen controls the distribution of electrons among the three. Excessive or low DO concentration will weaken the power generation performance.
4) Anaerobic ammonia oxidation microbial fuel cell was developed, and Its Denitrification and electricity production performance were investigated. The results showed that using anaerobic ammonia oxidation enrichment culture (AEC) as catalyst, using ammonium salt and nitrite as reaction substrate, / ANAMMOX-MFC could produce electricity successfully. The removal rates of NRRs were 1.72-2.57 kg N m-3d-1,1.64-2.38 kg N m-3d-1,88.9% -98.3% for ammonia nitrogen and 88.7% -97.2% for nitrous nitrogen respectively. When the substrate supply was stopped, the power generation performance of ANAMMOX-MFC decreased sharply, the substrate supply was restored, and the power generation performance was restored rapidly.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：X703;TM911.45

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