【作者】 张士汉；

【导师】 施耀； 李伟；

【作者基本信息】 浙江大学 ， 环境工程， 2010， 博士

【摘要】 生物还原耦合化学吸收法处理烟气中氮氧化物具有处理效果好、经济成本低等优点,在烟气脱硝领域具有巨大的应用前景。本文研究了Fe(Ⅱ)EDTA-NO还原途径及机理,分析了氧气等因素对络合吸收剂再生的影响；论证了生物填料塔内生物还原耦合化学吸收工艺的可行性；通过分析生物还原耦合化学吸收法处理NO的过程,建立涉及气、液、固三相传质-反应动力学模型。论文取得以下一些有价值的结果：(1)根据化学计量数和中间产物分析,探明了络合态NO的还原途径为以N2O为中间产物,终产物为氮气。微生物还原络合态NO时能同时利用葡萄糖和Fe(Ⅱ)EDTA作为电子供体,葡萄糖作为优先电子供体能使微生物还原过程获取更快还原速率。(2)NO2-和NO3-作为竞争性电子受体阻碍了Fe(Ⅲ)EDTA还原时的电子传递,NO2-同Fe(Ⅱ)EDTA因化学反应生成部分Fe(Ⅱ)EDTA-NO的生成抑制了微生物的活性。氧气影响Fe(Ⅲ)EDTA的表观还原速率,由以下两方面的原因造成的：1)化学氧化过程使得Fe(Ⅲ)EDTA生成量增加；2)氧气对微生物毒害作用,降低了微生物的活性。(3)利用生物填料塔反应器能有效的去除烟气中的氮氧化物,在连续稳态条件下具有持续去除模拟烟气中氮氧化物的能力；分析了总铁浓度、进气NO、SO2、氧气浓度、进气流量、液体循环量、填料塔高度以及反应器停运闲置等工艺参数对反应器运行的影响；利用PCR-DGGE技术初步分析了不同填料层微生物群落结构。(4)以生物填料塔内NO传质-反应过程为研究对象,基于双膜理论,通过气相、液相以及固相(生物膜)的质量衡算,结合微生物降解动力学分析,在生物填料塔建立了NO传质-反应模型,利用该模型来预测NO的去除效率。根据该模型可知,吸收液中Fe(Ⅱ)EDTA浓度是维持生物填料塔高去除效率的关键参数。当络合吸收液中Fe(Ⅱ)EDTA浓度高于3.4 mM时,生物填料塔对NO的去除效率即可达到90%以上。更多还原

【Abstract】 A chemical absorption-biological reduction integrated approach is employed to achieve the removal of nitrogen monoxide (NO) from the simulated flue gas with the advantages of low cost, completely reduction of NO and high removal efficiency. In this dissertation, the stoichiometry and mechanism of Fe(II)EDTA-NO reduction was investigated; the effect of environmental factors, such as oxygen, on the complex sorbent regeneration was discussed; the feasibility of biological packed column with the integrated process was studied; through the analysis of biological reduction of NO process, involving the gas, liquid, solid three-phase mass transfer, the kinetic model was established. The main original conclusions of this dissertation are:(1) According to stoichiometry and intermediate product analysis, reduction of NO to N2 was found to be biologically catalyzed with nitrous oxide (N2O) as an intermediate. The main product of complexed NO reduction was N2. Fe(II)EDTA and Glucose can be Simultaneously served as electron donor for complexed NO reduction. In addition, glucose is the preferred and primary electron donor.(2) NO2-, NO3- and oxygen had a certain inhibition of biological Fe(III)EDTA reduction. NO2- and NO3-, mainly as a competitive electron acceptor, prevented the electron transfer to Fe(III)EDTA. Formation of Fe(II)EDTA-NO also resulted in the inhibition of Fe(III)EDTA reduction. Oxygen affected Fe(III)EDTA reduction rate mainly due to both reasons:1) chemical oxidation process increasing the Fe(III)EDTA loading; 2) the toxic effects of oxygen on microorganisms decreasing the microbial activity.(3) Biological packed tower could effectively remove nitrogen oxides from flue gas, steady state removal efficiency under continuous operation could be maintained for a long term operation. Effect of several key parameters such as Total iron concentration, inlet NO, SO2, oxygen concentration, gas flow rate, liquid flow rate, packed column height, and reactor shutdown idle on the NO removal have been investigated in the biological packed tower. Additionally, the microbial community structure in the biological packed tower was analyses with the PCR-DGGE technology.(4) Based on the analysis of biological reduction of NO process and two-film theory, involving the gas, liquid, solid three-phase mass transfer, the kinetic model was established. According to the developed model, Fe(II)EDTA is a key parameter affecting the operation of the integrated prcoss. The biological packed tower can achieve 90% of NOx removal when the Fe(II)EDTA concentration in the liquid phase was up to 3.4 mM.更多还原