UF与PAC-UF工艺的微生物去除及消毒效能研究

研究对比了UF工艺与PAC-UF工艺在不同运行阶段的除污染和微生物截留效能,采用微生物和余氯等指标初步分析了超滤出水中微生物增长的可能原因及影响因素,以及PAC对超滤出水生物安全性的作用.结果表明,不同运行阶段PAC-UF工艺出水的CODMn和UV254都远低于UF工艺,氨氮的去除率也较高,但积累了较多的亚硝酸盐氮.两种工艺在启动运行阶段和膜清洗后运行初期的消毒效果较好,长时间运行过程可造成超滤出水微生物数量增加,影响消毒效果.PAC-UF工艺出水的细菌总数和大肠菌群数小于UF工艺,在相同加氯量时消毒效果更好.在运行初期,PAC-UF工艺出水的余氯高于UF工艺,运行后期会出现余氯低于UF工艺现象.微生物指标和余氯保持的情况表明,两种工艺出水的最佳加氯量均为1 mg/L.     

建筑生活热水二次消毒的微生物灭活效能及化学安全性研究

针对建筑生活热水系统水力停留时间长、余氯含量低、微生物超标等问题,采用二次加氯方式进行二次消毒,研究二次加氯的消毒效能、余氯衰减及消毒副产物生成特性等。结果表明,二次加氯消毒可有效保障生活热水的生物安全性,投加0.2～0.5 mg/L次氯酸钠均可完全灭活细菌总数和总大肠菌群,投加0.3～0.5 mg/L次氯酸钠在24～48 h内持续消毒效果良好。生活热水的余氯衰减速率和三氯甲烷生成量明显高于二次供水,存在消毒副产物超标的风险;随着水温和有机物含量的升高,余氯衰减速率、三氯甲烷生成速率和生成量均明显提高。综合考虑生活热水的生物和化学安全性、水力停留时间和持续消毒作用等方面的要求,0.3 mg/L次氯酸钠为二次加氯消毒的最适宜投加量。研究结果为生活热水系统二次加氯消毒技术的应用和水质安全保障提供了技术支持。     

高层建筑转输供水系统余氯衰减规律与补氯特点研究

针对高层建筑转输供水系统的二次供水水质安全问题,研究了水力停留时间、补氯量、水温、有机物等因素对余氯衰减特性的影响。结果表明,水箱中0.1mg/L余氯量的进水停留4h后余氯不达标并出现微生物滋生的问题,同时随着停留时间的延长,浊度升高,有机物含量下降;二次供水系统中余氯的衰减符合一级动力学模型,余氯衰减受补氯量、TOC含量和水温的影响,显著程度依次为水温补氯量TOC含量,其中补氯量、水温与TOC含量对余氯衰减的交互作用比较显著;补氯后余氯的衰减速率增大,且补氯量越低,TOC含量、水温越高,余氯的衰减速率越快;因此,在高层和超高层建筑的转输供水系统中进行补氯时,补氯点的设置和优化需要考虑二次供水水质、补氯量、余氯衰减速率、水温、有机物含量等因素。     

UV/H_2O_2/Cl_2组合工艺处理含2-MIB滤后水的中试研究

针对饮用水中二甲基异莰醇(2-MIB)污染和UV/H_2O_2高级氧化工艺H_2O_2残留问题,构建了UV/H_2O_2/Cl_2组合工艺,并以加标滤后水为原水开展了相关中试研究。基于响应曲面法对UV/H_2O_2工艺去除2-MIB进行参数优化,在此基础上对出水残留H_2O_2采用加氯中和处理,调整NaClO投加量以保证出水符合出厂水余氯要求。最终确定UV/H_2O_2/Cl_2组合工艺运行的最优工况为:当2-MIB为275ng/L时,UV为350mJ/cm~2,H_2O_2投加量6mg/L,NaClO投加量7.5mg/L,在确定的最优工况下连续稳定运行组合工艺,对工艺出水进行检测,结果表明UV/H_2O_2/Cl_2组合工艺对2-MIB去除率达到96.95%,出水余氯值0.4～0.5 mg/L,对TOC、UV_(254)去除率分别达到15.59%、65.71%,能够氧化去除水中大分子有机物,对色氨酸等5种溶解性有机物去除效果良好,且不会带来消毒副产物超标和生物毒性问题,最终出水符合《生活饮用水卫生标准》(GB 5749-2006)对水质的要求。     

紫外线消毒在给水处理中的应用

紫外线(UV)的消毒效果取决于紫外线的波长、辐射强度和辐射时间,并与水层深度、微生物的种类和数量以及其他水质指标有关。介绍了紫外灯管选择,UV剂量和微生物灭活的关系,给水处理厂UV消毒系统设计时需注意的问题及UV消毒的费用等。特别指出,现有常规给水处理厂采用UV消毒,其装置可设在滤池和清水池之间的管(渠)中。     

影响供水管网中余氯与浊度的因素及相关性分析

余氯与浊度是管网水质中有效反映水质状况的参数,以太仓市某小区供水管网为研究对象,通过对该小区供水管网14个取样点进行水质监测,分析供水管网中余氯与浊度之间的的相关性及其影响因素。研究结果表明:余氯在管网中总体呈下降趋势,浊度总体呈上升趋势;当管网中余氯在0.05~0.2mg/L时,余氯与浊度之间呈明显负相关,浊度越小,耗氯量越小,管网中自由余氯保持在较高浓度,消毒效果显著;当余氯高于0.2mg/L时,浊度对余氯消毒效果没有显著影响,余氯与浊度无明显相关性。     

饮用水UV/TiO_2光催化消毒技术研究进展

UV/TiO_2光催化消毒技术具有高效、无二次污染的优点,研究其应用于饮用水消毒具有现实意义。UV/TiO_2光催化产生活性基团氧化微生物的细胞结构,破坏其细胞功能,特别对细胞选择透过性的破坏,使细菌死亡。TiO_2特性、UV光照条件、水质条件和细菌特性都能不同程度影响光催化消毒的效率。UV/TiO_2光催化对实际生产水质条件下细菌的灭活效能及消毒后细菌复活的问题需要更多的研究。光催化反应器的优化设计、TiO_2膜的制备、TiO_2对可见光的响应的改性和在使用中TiO_2光催化活性的稳定性研究也有待深入开展。     

常州市供水管网余氯分布规律研究

以常州市供水管网为例,通过人工取样检测水厂、补氯站、管网、二供采样点的余氯浓度,从时间和空间角度对常州市供水管网余氯分布均匀性进行了初步评估。结果表明,水厂-补氯站两级消毒方案改善了常州市政管网余氯浓度分布均匀性,应加强对冬夏两季水质敏感点的监控。同时,应综合考虑经济因素,采用增设补氯点、改造管网、改变消毒方案等方式提高供水管网余氯分布时空均匀性。     

紫外C消毒技术在某医院屋顶水箱中的应用

介绍了水箱紫外 C 消毒技术及其在重庆医科大学附一院外科大楼屋顶水箱供水中的应用,并对紫外 C 消毒设备的主要设计性能参数,屋顶水箱紫外 C 消毒效果,以及与氯消毒的效果进行了比较。     

余氯对发光菌法检测再生水生物急性毒性的影响及消除

利用发光菌检测了4座污水处理厂再生水的生物急性毒性,并分析了余氯对其的影响。结果表明,毒性随着余氯的增加而增强,这主要是由于消毒副产物所引起的。加入脱氯剂可减小由消毒副产物引起的毒性。分析了曝气和脱氯剂(硫代硫酸钠、亚硫酸钠)的脱氯效果及推荐浓度,以消除在用发光菌检测再生水的生物急性毒性时余氯对其造成的干扰。     

紫外线消毒对水中余氯衰减规律的影响研究

对经紫外线消毒后水中余氯的衰减规律进行了研究,考察了pH、有机物含量、紫外线强度及剂量等因素对氯衰减速率的影响。结果表明:紫外线剂量低于40mJ/cm2时紫外线消毒对氯衰减基本没有影响,而当紫外线剂量大于40mJ/cm2时会加速氯的衰减速度,紫外线剂量从40mJ/cm2提高到1 000mJ/cm2时,水中余氯由3.2mg/L下降到2.8mg/L;低紫外线强度下氯的衰减速度低于高紫外线强度情况,如紫外线剂量为100mJ/cm2,紫外线强度为0.113 00mW/cm2和0.028 25mW/cm2时,水中余氯分别为2.31mg/L和2.63mg/L;在同一紫外线剂量下,pH偏酸性时氯衰减速度高于高pH情况;增加水中有机物浓度会加快氯的衰减速度。在实际应用低紫外线强度进行消毒时,如降低投氯量将不能有效保证管网水中的余氯量。     

UV disinfection of wastewater effluents for unrestricted irrigation.

Wastewater reuse in arid regions is important for the production of a water resource to be utilised for non-potable purposes and to prevent the environmental transmission of disease-causing agents. This study was conducted to evaluate the effect of water quality on the comparative disinfection efficiency of viruses, bacteria and spores by UV irradiation. Furthermore, the microbial quality of effluent produced by coagulation, high rate filtration (HRF) and either UV irradiation or chlorination was determined. Using low pressure collimated beam, a UV dose of 80 mWs/cm2 was needed to achieve a 3-log10 inactivation of either rotavirus SA-11 or coliphage MS2, whereas over 5-log10 inactivation of E. coli was reached with a dose of only 20 mWs/cm2. B. subtilis inactivation was found to be linear up to a dose of 40 mWs/cm2 and then a tailing up to a UV dose of 120 mWs/cm2 was observed. It is worth noting that effluent turbidity of < 5 NTU did not influence the inactivation efficiency of UV irradiation. Operation of a pilot plant to treat secondary effluent by coagulation, HRF and UV disinfection at a UV dose of 80 mWs/cm2 resulted in the production of high quality effluent in compliance with the Israel standards for unrestricted irrigation (< 10 CFU/100 mL faecal coliform and turbidity of < 5 NTU). Sulphite reducing clostridia (SRC) were found to be more resistant than coliphages and F coliform for UV irradiation. The results of this study indicated that UV disinfection is suitable for the production of effluents for unrestricted irrigation of food crops.     

金门水厂原水中臭味物质去除的中试研究

金门地区水库富营养化严重影响饮用水水质。夏天藻类所产生的臭味以土霉味为主。土霉味主要来自于藻类代谢物二甲基异冰片和土臭素。利用活性炭处理工艺分别使二甲基异冰片、土臭素及嗅值的去除率达92%、83%及72%;而利用臭氧一生物活性炭工艺则可使二甲基异冰片、土臭素及嗅值的去除率分别达96.3%、100%及96.7%。组合工艺可有效去除臭味物质,但清水池加氯消毒所产生的氯臭味,使嗅值无法达到台湾地区的饮用水水质标准,因此要特别注意控制加氯量。     

Toxicity screening and evaluating in chlorination disinfection of wastewater reclamation processes.

Reclamation and re-use of wastewater is one of the most effective ways to alleviate the shortage of water resources, while the safety of reclaimed water becomes one of the critical problems for protecting human health and the ecosystem. While a toxicity test can vividly reflect biological effects of chemicals as a whole, in this study, the Microtox test was used to screen toxicity changes of wastewater during conventional reclamation processes. The results showed that toxicities of water samples decreased continuously along reclamation processes except chlorination/dechlorination in which the toxicity increased significantly. Furthermore, as for different forms of residual chlorine, toxicity of wastewater was quite different with increasing chlorine dosage. NH3-N had a trend to decrease toxicity of disinfected wastewater, while UV254 had a trend to increase toxicity. It was found that there was a good linear relationship between toxicity formation and UV254/NH3-N ratio for wastewater after disinfection with combined chlorine form before peak-point.     

饮用水消毒副产物的去除途径及进展

饮用水使用氯消毒产生的消毒副产物对人类健康带来了极大危害。本文介绍了饮用水消毒副产物的形成原因及影响因素,并从选择优质水源、降低消毒副产物的前体物质、替换传统的消毒剂、去除已生成的消毒副产物四个方面论述和比较了饮用水中消毒副产物的各种去除途径及进展,指出了在去除消毒副产物方面存在的问题。     

A dispersed-ozone flotation (DOF) separator for tertiary wastewater treatment.

A dispersed-ozone flotation (DOF) separator was devised for a pilot study of tertiary wastewater treatment for re-use purposes. As a compact device combining coagulation, ozonation and flotation in an integrated unit, the DOF separator achieved a very high removal of SS, TOC, UV254 and colour, as well as effective inactivation of coliform and total bacteria within a short hydraulic retention time of 30 min. The finished water quality is comparable to or better than that by a conventional tertiary treatment process using coagulation, sedimentation, filtration and chlorine disinfection, and meets the quality standards for non-drinkable domestic reuse.     

济南鹊华水厂深度处理改造工程设计及运行分析

济南鹊华水厂以引黄调蓄水库为水源,原水存在低浊高藻高臭味等问题,水厂原有工艺难以有效处理。为适应国家《生活饮用水卫生标准》(GB 5749—2006)要求,水厂将"混凝—沉淀—过滤—液氯消毒"工艺改造为"中置式高密度沉淀—臭氧催化氧化—上向流生物活性炭吸附—V型砂滤—液氯消毒"工艺,改造后的净水工艺对有机物、臭味等特征污染物去除效果明显,出厂水水质稳定达标。     

农村供水系统不同贮水材质水质变化特性分析

针对西部地区农村供水系统管线长、用水量小,水在调节池中停留时间较长而易造成供水系统二次污染的问题,选取工程上常用的混凝土、瓷砖、塑料和不锈钢材质,分别研究了不同环境条件下各贮水材质水体中余氯、pH、电导率和溶解氧等水质参数随时间的变化特征。结果表明:一定温度下不同材质调节池中,贮存水余氯衰减系数由大到小依次为混凝土、塑料、瓷砖、不锈钢;水体pH值变化也较为明显,其中混凝土及瓷砖内壁调节池pH值随储存时间增加呈现明显的上升趋势,不锈钢材质pH上升趋势平缓,而塑料材质pH值未发生显著变化;混凝土、瓷砖及不锈钢材质蓄水池电导率在初始阶段随时间的变化上升较快,而在后期随时间的变化趋势较为平稳;混凝土及不锈钢材质调节池溶解氧随时间的变化较为平稳,而瓷砖及塑料材质调节池溶解氧随时间的变化有升高的趋势。通过本研究进一步明确了不同材质调节池对水质的影响及其随环境因素变化的时间效应,以期为农村供水系统规划设计及运行管理提供一定参考。     

Exploring the potential synergistic effects of chemical disinfectants and UV on the inactivation of free-living bacteria and treatment of biofilms in a pilot-scale system

The main objective of this study is to explore possible synergistic or additive effects of combinations of chemical disinfectants (sodium hypochlorite, peracetic acid, hydrogen peroxide, chlorine dioxide) and UV in their efficacy in inactivating free-living bacteria and removing biofilms. In contrast to most studies, this study examines disinfection of municipal water in a pilot-scale system using a mixed bacterial suspension, which enables a better simulation of the conditions encountered in actual industrial environments. It was shown that the combination of either hypochlorite, hydrogen peroxide, peracetic acid, or chlorine dioxide with UV yielded additive effects on the inactivation of free-living bacteria. Actual synergy was observed for the combination of UV and 5 ppm hydrogen peroxide. Regarding biofilm treatment, additive effects were observed using the combination of hydrogen peroxide and UV. The promising results obtained in this study indicate that the combination of UV and chemical disinfectants can considerably reduce the amount of chemicals required for the effective disinfection and treatment of biofilms.     

Penalty-Free Multi-Objective Evolutionary Approach to Optimization of Anytown Water Distribution Network

This paper describes the development and application of a new multi-objective evolutionary optimization approach for the design and upgrading of water distribution systems with multiple pumps and service reservoirs. The optimization model employs a pressure-driven analysis simulator that accounts for the minimum node pressure constraints and conservation of mass and energy. Pump scheduling, tank siting and tank design are integrated seamlessly in the optimization without introducing additional heuristic procedures. The computational solution of the optimization problem is entirely penalty-free, thanks to pressure-driven analysis and the inclusion of explicit criteria for tank depletion and replenishment. The model was applied to the Anytown network that is a benchmark optimization problem. Many new solutions were achieved that are cheaper and offer superior performance compared to previous solutions in the literature. Detailed and extensive simulations of the solutions achieved were carried out. Spatial and temporal variations in water quality were investigated by simulating the chlorine residual and disinfection by-products in addition to water age. The hydraulic requirements were satisfied; efficiency of pumps was consistently high; effective operation of the new and existing tanks was achieved; water quality was improved; and overall computational efficiency was high. The formulation is entirely generic.