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摘要：城市污水二级生化处理尾水中含有大量病原微生物，消毒是保证出水安全性的重要措施。鉴于氯消毒存在氯化消毒副产物、紫外消毒存在光复活现象的不足，研究开发可有效灭活水中微生物的新技术十分重要。

论文以粪便污染指示菌大肠杆菌为研究对象，考察二价铁/过硫酸氢钾（Fe2+/PMS）体系及紫外/过硫酸钾（UV/PDS）体系对大肠杆菌的灭活效果，并对灭活过程进行动力学拟合，同时初步分析各体系对大肠杆菌的灭活机理，在此基础上将两种体系应用于污水处理厂二级生化处理尾水深度处理中，研究结论如下：

（1）Fe2+/PMS体系能够有效灭活大肠杆菌，灭活过程遵循Weibull模型。Fe2+/PMS摩尔比为1/1时适当降低初始pH或增加PMS初始浓度能提高大肠杆菌的灭活效果；在Fe2+及PMS初始浓度均为0.3mmol·L-1、初始pH为7的条件下，反应30 min后大肠杆菌对数去除率达到6.3 log；络合剂柠檬酸及EDTA对灭活存在抑制作用，适量的焦磷酸钾则具有促进作用；死/活荧光染色及电镜扫描实验结果证实大肠杆菌在Fe2+/PMS体系灭活期间失去了细胞完整性，表明体系产生的〖〖"SO"〗_"4" ^"∙" 〗^"-" 氧化了细胞壁和细胞膜造成细胞内有机质的释放，同时氧化破坏其内容物。

（2）PDS能够有效提高UV对大肠杆菌的灭活效果，灭活过程遵循Chick-Waston模型。适当增加PDS初始浓度能提高大肠杆菌的灭活效果，中性条件更有利于大肠杆菌的灭活，Fe2+对灭活存在抑制作用，在20 mJ·cm-2的紫外剂量下，0.3 mmol·L-1 PDS的加入较单独UV灭活时大肠杆菌对数去除率增加1.1 log；经UV/PDS体系灭活后大肠杆菌光复活能力明显下降，仅在较强的复活光照下才会产生一定的光复活；死/活荧光染色及电镜扫描实验结果证实UV/PDS体系较单独UV灭活对大肠杆菌细胞形态破坏更为严重，大肠杆菌在UV/PDS体系灭活期间失去了细胞完整性，表明体系产生的〖〖"SO" 〗_"4" ^"∙" 〗^"-" 氧化了细胞壁和细胞膜造成细胞内有机质的释放，同时氧化破坏其内容物，在UV及〖〖"SO" 〗_"4" ^"∙" 〗^"-" 的共同作用下，大肠杆菌细胞遭到严重破坏。

（3）两种体系均对二级生化处理尾水中残留有机物及病原微生物有降解及去除效果。Fe2+/PMS体系在最佳药剂量：Fe2+及PMS均为1.0 mmol·L-1时，反应30 min后，二级生化处理尾水COD和TOC去除率为16.62%、19.35%；类富里酸、腐殖酸等腐殖质及色氨酸类芳香族蛋白质的降解率为27.51%、20.44%、10.08%；菌落总数及粪大肠菌群数下降至1.3×105 CFU·L-1、380 CFU·L-1。UV/PDS体系在紫外光强0.104 mW·cm-2，PDS投加量为1.0 mmol·L-1时，反应30 min后，二级生化处理尾水COD和TOC去除率为15.48%、17.89%；类富里酸、腐殖酸等腐殖质及色氨酸类芳香族蛋白质降解率为16.86%、15.42%、7.99%；在紫外剂量为20 mJ·cm-2、PDS投加量1.0mmol·L-1时，菌落总数及粪大肠菌群数下降至4.0×104 CFU·L-1、200 CFU·L-1，均能达到《城镇污水处理厂污染物排放标准》中一级A排放标准。经计算，Fe2+/PMS及UV/PDS两种体系灭菌单位成本分别为5.33 元·t-1及3.16 元·t-1。

A large number of pathogenic microorganismsstill exist in urban sewage from the sewage treatment plant after secondarybiochemical treatment. Traditional disinfection techniques have variousshortcomings, such as disinfection by-products in chlorine disinfection andphotoreactivation in UV disinfection. So it is very important to research anddevelop new technologies that can effectively inactivate microorganisms inwater. In this paper, Escherichia coli, a fecal contamination indicator, wasused as the research object. The E.coli inactivated by Fe2+/PMS and UV/PDSsystems was investigated. And the inactivation process was kinetically fitted.Based on the inactivation mechanism, the two systems were applied in the actualsewage treatment. The main research conclusions were as follows:

(1) E.coli could be effectively inactivatedin the Fe2+/PMS system and the inactivation process followed the Weibull model.The inactivation effect of E.coli was enhanced when the initial pH and theinitial concentration of PMS were lowered at the ratio of 1/1 of Fe2+ and PMS.Under the conditions of initial concentration of 0.3 mmol·L-1 of Fe2+ and PMSand initial pH of 7, the reaction was carried out. After 30 min, thelogarithmic removal rate of E.coli reached 6.3 log. The complexing agent(citric acid and EDTA) inhibited the inactivation. But the appropriate amountof potassium pyrophosphate promoted the inactivation effect. The results ofdead/live fluorescent staining and electron microscopy showed that cellintegrity of E.coli was lost during the Fe2+/PMS system treatment, indicatingthat the system produced 〖〖"SO" 〗_"4" ^"∙" 〗^"-"  that oxidizedthe cell wall and cell membrane. This caused the release of intracellularorganic matter. And then its contents and DNA were oxidatively destroyed.

(2) The inactivation of E.coli by UV couldbe effectively improved by PDS. And the inactivation process followed theChick-Waston model. The inactivation effect of E.coli could be improved whenthe initial concentration of PDS was appropriately increased. It was moreconducive to the inactivation of E.coli under neutral conditions. Fe2+ couldinhibited the inactivation effect. At an ultraviolet dose of 20 mJ·cm-2,compared with UV inactivation, the addition of 0.3 mmol·L-1 PDS increased thelogarithmic removal rate of E.coli by 1.1 log. The photoreactivation ability ofE.coli was significantly decreased after inactivation by UV/PDS system. Andonly certain light was produced under strong resurrection illumination.Dead/live fluorescent staining and electron microscopy experiments showed thatthe cell integrity of E.coli was also lost during UV/PDS treatment, indicatingthat the system produced 〖〖"SO" 〗_"4" ^"∙" 〗^"-"  that oxidizedcell walls and cell membranes. This caused the release of intracellular organicmatter. And then its contents and DNA were oxidatively destroyed. The cells ofE.coli were severely damaged under the joint action of UV and 〖〖"SO" 〗_"4" ^"∙" 〗^"-" .

(3) Organic matter and pathogenicmicroorganism could be effectively removed in secondary effluent in theFe2+/PMS and UV/PDS systems. Under the optimal conditions of initialconcentration of 0.3 mmol·L-1 of Fe2+ and PMS in the Fe2+/PMS system. After 30min, the removal rates of COD and TOC in the secondary effluent reached 16.62%,19.35%. Fluorescence of humic acids such as fulvic acid and humic acid andtryptophan aromatic proteins were observed. The degradation rates of thesesubstances were 27.51%, 20.44%, 10.08%. The total numbers of bacteria coloniesand fecal coliforms were decreased to 1.3×105 CFU·L-1, 380 CFU·L-1. Under theoptimal conditions of ultraviolet light intensity of 0.104 mW·cm-2 added 0.3mmol·L-1 PDS in the UV/PDS system, the removal rates of COD and TOC in thesecondary effluent reached 15.48%, 17.89%. The degradation rates offluorescence of humic acids such as fulvic acid and humic acid and tryptophanaromatic proteins were 16.86%.

关键词：过硫酸盐；硫酸根自由基；大肠杆菌；二价铁；紫外线；消毒

persulfate; sulfate radical; Escherichiacoli; ferrous iron; ultraviolet; disinfection