【作者】 王翠华；

【导师】 吴彦；

【作者基本信息】 大连理工大学 ， 环境工程， 2008， 博士

【摘要】 随着水资源短缺和饮水水质的不断恶化,如何在不产生二次污染的情况下,去除水中微生物以及微生物产生的有毒物质是水处理工作的重点与难点,但目前现有的处理方法难以满足这样的要求。作为高级氧化技术之一的脉冲放电技术因操作简单、处理效率高、无二次污染等优点而日益受到国内外研究者的普遍关注。本论文利用脉冲放电等离子体杀灭大肠杆菌、灭活铜绿微囊藻并去除铜绿微囊藻死亡后或细胞破裂后产生的微囊藻毒素。论文首先考察了双向窄脉冲放电灭活大肠杆菌过程中影响大肠杆菌存活率、灭活速率常数的电气参数和气液参数,发现加电时曝气使大肠杆菌存活率明显降低,灭活速率常数明显提高,且系统的最佳曝气量为0.75 m³/h;提高脉冲峰值电压和脉冲重复频率均能降低大肠杆菌的存活率和灭活速率常数;溶液初始电导率的改变对大肠杆菌存活率和灭活速率常数的影响不明显,弱碱性系统大肠杆菌存活率低于弱酸性的。在脉冲峰值电压54 kV,频率50 Hz,曝气量0.75 m³/h,放电处理25 min时,大肠杆菌细胞数下降了4.00个对数,存活率低于0.01%,灭活速率常数为1.36×10^-1min^-1。详细考察了气液两相和气液固三相放电反应系统对放电特性、铜绿微囊藻灭活效果和过氧化氢浓度的影响,并讨论双电介质层位置、单双电介质层、放电电极直径、材料和数目对藻灭活的影响,确定了多电极三相脉冲放电系统灭活铜绿微囊藻。在多电极三相脉冲放电系统中,延长藻细胞在放电系统中的处理时间在一定程度上提高了藻的灭活效果;增加脉冲峰值电压、脉冲重复频率和曝入气体量（小于0.75 m³/h）均能提高藻的灭活效果;在藻适宜生长的pH范围内,放电处理弱碱性藻液的灭藻效果好于弱酸性的;在脉冲峰值电压40 kV,频率50 Hz,气量0.75 m³/h,放电处理40 min后的第5天,铜绿微囊藻的光密度去除率达到93.4%,细胞数和叶绿素a的去除率达到100%。通过测定脉冲放电对铜绿微囊藻生物量（细胞数、光密度和叶绿素a）、细胞形态、藻灭活的剩余效应、MDA含量、细胞膜通透性、吸收光谱以及溶液DOC的变化,探讨了脉冲放电等离子体灭活铜绿微囊藻的机理。通过比较微囊藻毒素MC-LR的提取方法与提取液浓缩富集方法,确定乙酸法提取藻毒素MC-LR,低浓度甲醇溶液梯度淋洗、高浓度甲醇洗脱富集在固相萃取柱上的藻毒素MC-LR。研究了影响脉冲放电去除藻毒素MC-LR的电气参数和气液参数,结果表明提高脉冲峰值电压和脉冲重复频率或降低溶液初始电导率均能提高MC-LR的去除效率和去除速率常数;碱性条件下放电去除MC-LR得到的去除效率稍好于酸性的。在脉冲峰值电压40 kV,频率50 Hz,曝气量0.75 m³/h,放电处理20 min时,0.20 mg/L的MC-LR完全被去除。溶液中TOC和TC值降低,IC值增加说明了放电产生的过氧化氢、臭氧以及·OH破坏了MC-LR原有的分子结构。更多还原

【Abstract】 With the shortage of water resources and deterioration of drinking water quality, the removal of microorganism and toxic substances produced by microorganism is a key point and also a difficult point in water treatment without secondary pollution, but the existing processing method can not meet the requirements. Pulsed discharge technology, one of advanced oxidation technologies, has aroused more and more concerns by researchers in the world for its simplicity of operator, efficient treatment, non-secondary pollution and so on.This paper discussed the inactivation of Escherichia coli （E. coli）, Microcystis aeruginosa （MA） and removal of Microcystins-LR （MC-LR） by plasma generated by pulsed discharge. The effects of electric parameters and gas-liquid parameters on the survival efficiency and inactivation rate constants of E. coli by bipolar pulsed discharge were studied. The results show that the gas bubbling can obviously improve the survival efficiency and inactivation rate constant under the discharge condition and the optical gas bubbling rate is 0.75 m³/h. The survival efficiency of E. coli decreases and the inactivation rate constants of E. coli increases by the upgrading peak pulse voltage and pulse repetitive rate. The initial conductivity has no marked effect on the survival efficiency and the inactivation rate constants of E. coli and the survival efficiency in alkalescent solution is higher than that in the acidulous solution. The cell density of E.coli decreased 4.001g, the survival efficiency of E. coli is lower than 0.01% and the inactivation rate constant of E. coli is 1.36×10^-1 min^-1 under the condition of 54 kV peak pulse voltage, 50 Hz pulse repetitive rate, 0.75 m³/h gas bubbling rate and 25 min treatment time.The effects of gas-liquid two-phase and gas-liquid-solid three-phase discharge reaction system on the discharge characteristic, inactivation of MA and hydrogen peroxide concentration were studied. The effects of location of the double dielectric layers, single or double dielectric layers, discharge electrode diameter, material and number on the inactivation of MA were discussed and the multi-electrodes three-phase discharge reaction system was confirmed to inactivate MA. In the multi-electrodes three-phase discharge reaction system, the inactivation efficiency of MA increases with the upgrading of discharge time, peak pulse voltage, pulse repetitive rate and gas bubbling rate （be below 0.75 m³/h）. In the range of optimum growth pH, the inactivation efficiency of MA in the alkalescent algal solution is higher than that in the acidulous algal solution. More than 93.40% of optical density, 100% of cell density and Chlorophyll-a of MA are removed at the end of the fifth day incubation as a function of 40 min treatment under the condition of 40 kV peak pulse voltage, 50 Hz pulse repetitive rate, 0.75 m³/h gas bubbling rate. To determine the mechanism of inactivation of MA by plasma generated by pulsed discharge, the biomass of MA （cell density, optical density, Chlorophyll-a）, cellular morphology, the residual effect, content of MDA, electrolysis on the membrane permeability, absorption spectrum and changes in DOC were measured.Comparing extractive methods of MC-LR and enrichment methods of extract, MC-LR is extracted by acetic acid and extract of MC-LR is gradually rinsed by light concentration of methanol and eluted by high concentration of methanol from solid phase extraction cartridge. Electric parameters and liquid parameters of MC-LR removal by pulsed discharge were studied. The results show that the removal efficiency and removal rate constants of MC-LR increases with the increasing of the peak pulse voltage and pulse repetitive rate or the decreasing of initial conductivity. The removal efficiency of MC-LR in the alkalescent solution is higher than that in the acidulous solution. MC-LR at a concentration of 0.2 mg/L is totally removed at a treatment time of 20 min under the condition of 40 kV peak pulse voltage, 50 Hz pulse repetitive rate, 0.75 m³/h gas bubbling rate. The value of TOC and TC was decreased and IC was increased, showing that the intrinsic structure of MC-LR is destroyed by hydrogen peroxide, ozone and hydrogen radicals generated by pulsed discharge.更多还原