南方城市水厂次氯酸钠代替液氯和投碱工艺的可行性研究

通过对次氯酸钠的消毒效果以及提升pH方面进行小试和中试,研究了次氯酸钠代替液氯和投碱工艺的可行性,研究结果表明:投加1.0mg/L、1.5mg/L、2.0mg/L次氯酸钠(以有效氯计),搅拌1h后其pH分别可提高至7.5、7.8、8.0左右,余氯分别保持在0.5 mg/L、0.7 mg/L、1.1mg/L左右,能够在提高pH的同时保持出水的余氯浓度。次氯酸钠消毒产生的消毒副产物三卤甲烷和三氯乙醛浓度与液氯的相比略低,并无明显的优势。次氯酸钠的灭菌效果明显,能保证出水的细菌总数和总大肠菌群达标,同时能够保持48h后的管网末梢水的余氯要求,满足持续消毒灭菌的效果。次氯酸钠投加可以取代液氯和加碱系统,且改造方便,能实现良好的经济和社会效益。     

次氯酸钠消毒再生水的效果和副产物生成量研究

采用次氯酸钠在实验室对配制再生水进行消毒试验研究,同时考察次氯酸钠对粪大肠菌群灭活效果和消毒副产物（三卤甲烷）的生成量。研究结果表明,微生物的灭活率随着次氯酸钠的浓度和接触时间的增加而增大,当次氯酸钠浓度为8 mg/L且接触时间为20 min以上时,水样中粪大肠菌群的灭活率可达6 lg以上;同时得到,消毒副产物三卤甲烷的含量虽然随次氯酸钠浓度和接触时间的增大而增加,但是即使次氯酸钠浓度达到20mg/L,且接触时间达3h时,产生的三氯甲烷最大量为27.6μg/L ,也是低于我国生活饮用水卫生标准中对三氯甲烷含量的限值（60μg/L ）要求,因此,对再生水采用次氯酸钠消毒在能满足水质微生物安全性的CT 值下,产生消毒副产物三氯甲烷的风险是可以接受的。     

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。     

次氯酸钠消毒剂的分解特性及氯酸盐副产物形成规律探讨

分析了水厂消毒剂商品次氯酸钠在储存过程中的分解特性。结果表明,次氯酸钠在储存过程中会发生歧化反应,导致有效氯持续降低并大量产生副产物氯酸盐。实地取样检测水厂使用的次氯酸钠,发现在10d储存期内有效氯衰减率高达15.48%,其中的氯酸盐浓度达到9 667.8mg/L。实验室模拟试验结果表明,有效氯的衰减量和氯酸盐的生成量均与储存时间成正比;温度是影响次率氯酸钠反应速度的重要因素,温度越高,反应速度越快。因此,采用次氯酸钠消毒也应关注氯酸盐副产物的水质风险。     

预处理及深度处理改造后D水厂消毒副产物跟踪分析

W市D水厂于2011年和2012年完成了深度处理和预处理改造,形成了预臭氧-曝气氧化-沉淀-砂滤-后臭氧-活性炭-消毒工艺,运用了多点加氯技术。通过跟踪调研改造前后D水厂太湖水净化过程中臭氧消毒副产物和液氯消毒副产物情况,发现改造后D水厂出厂水中臭氧消毒副产物溴酸盐检出率为1.18%,达标率为100%,出水甲醛无检出;氯耗降低了19.1%,出厂水中春、夏、秋、冬季的三卤甲烷比值相较于改造前下降了55%、23%、28%、61%。     

东太湖水源臭氧-活性炭工艺消毒副产物的生成规律与控制

对以东太湖水为水源的臭氧—活性炭处理工艺和常规处理工艺净水厂的消毒副产物生成情况进行了一年的检测,研究了臭氧—活性炭和常规处理工艺各处理单元对消毒副产物生成势的作用情况。结果表明,臭氧—活性炭和常规处理工艺的出厂水中均含有三卤甲烷、卤乙酸、卤乙腈等消毒副产物;与常规处理工艺相比,臭氧—活性炭处理工艺出水中的消毒副产物种类少、总量低,但三溴甲烷、二溴乙酸的生成量高;臭氧氧化能使消毒副产物生成势提高,砂滤工艺对消毒副产物生成势的去除效果稳定,混凝—沉淀工艺比其他工艺单元对消毒副产物生成势的去除效果好,活性炭工艺在夏季对消毒副产物生成势的处理效果比其他季节好。     

常规工艺对消毒副产物及前体物的去除

以西南某市L水厂为测试对象 ,研究了常规水处理工艺过程对消毒副产物及其前体物的去除特性 ,并且提出了控制饮用水中消毒副产物的几点对策。研究结果表明 :常规水处理对三卤甲烷前体物 (THMsFP)和卤乙酸前体物 (HAAsFP)具有很好的去除效果 ,去除率分别为 50 %以上、4 3%～ 6 4 % ,但对卤乙酸和三卤甲烷却无去除作用 ;预氯化是生成出厂水中THMs、HAAs的主要原因。     

桐乡水务集团次氯酸钠投加系统改造情况介绍

针对液氯消毒存在的安全性问题,桐乡市水务集团有限公司下属果园桥水厂和运河水厂对消毒工艺进行了改造,由液氯投加改为次氯酸钠投加。结果表明,改造后的次氯酸钠投加系统安全系数高,设备故障率低,出厂水水质良好,可节约大量压力水和用电,同时药剂存储安全可靠,可较大程度地降低重大节日、重要会议期间的供水安保压力。     

村镇饮用水不同次氯酸钠消毒模式对比研究

为探讨村镇供水工程的适宜次氯酸钠消毒模式,本文采用室内试验的方法从消毒液品质及其对水质的影响、消毒效果及运行成本三方面对不同应用模式开展对比分析。研究结果表明:离子膜法电解次氯酸钠发生器所产次氯酸钠溶液的有效氯浓度高,分别是无隔膜法、隔膜法电解设备产物和商品次氯酸钠溶液的10.75倍、4.51倍和1.41倍,其杂质氯酸盐和亚氯酸盐浓度极低,投入水体后对水质的影响程度最小;对大肠杆菌的消毒效果表明,4种次氯酸钠消毒应用模式均能在10 min内有效灭菌,采用离子膜法发生器消毒产生的副产物三卤甲烷最少;离子膜法发生器的电耗、盐耗相对较低,运行成本比无隔膜法、隔膜法、商品次氯酸钠溶液分别低46%、56%和81%。由于上述优势,在村镇供水中采用离子膜电解次氯酸钠发生器消毒具有较好的应用前景。     

常规处理工艺中加氯方式与三氯甲烷变化规律研究

以南方某市S给水厂为研究对象,试验研究了在常规处理工艺条件下对水中三氯甲烷的生成量进行控制。研究结果表明,饮用水中三氯甲烷随前、后加氯量以及余氯量的增加而增加,而随氨氯比的增加而减少。分次投加前氯0．5mg／L和后氯1mg／L要比一次性投加1．5mg／L氯明显降低出厂水中的三氯甲烷。合理采用加氯方式,严格控制消毒剂用量,可以把出厂水中的三氯甲烷生成量控制在最低水平。     

Disinfection by-products and microbial contamination in the treatment of pool water with granular activated carbon.

For swimming pools, it is generally agreed that free chlorine levels have to be maintained to guarantee adequate disinfection. Recommended free chlorine levels can vary between 0.3 and 0.6 mg/L in Germany and up to 3 mg/L in other countries. Bathers introduce considerable amounts of organic matter, mainly in the form of such as urine and sweat, into the pool water. As a consequence, disinfection byproducts (DBPs) are formed. Regulations in Germany recommend levels of combined chlorine of less than 0.2 mg/L and levels of trihalomethanes (THMs) of less than 20 microg/L. Haloacetic acids (HAAs), haloacetonitriles (HANs), chloropicrin and chloral hydrate are also detected in considerable amounts. However, these compounds are not regulated yet. Swimming pool staff and swimmers, especially athletes, are primarily exposed to these byproducts by inhalation and/or dermal uptake. In Germany, new regulations for swimming pool water treatment generally require the use of activated carbon. In this project, three different types of granular activated carbon (GAC) (one standard GAC, two catalytic GACs) are compared for their long time behaviour in pool water treatment. In a pilot plant operated with real swimming pool water, production and removal of disinfection byproducts (THMs, HAAs, AOXs), of biodegradable substances (AOC), of bacteria (Pseudomonas aeruginosa, Legionella, coliforms, HPC) as well as the removal of chlorine and chloramines are monitored as function of GAC bed depth. Combined chlorine penetrates deeper in the filter bed than free chlorine does. However, both, free and combined chlorine removal efficiencies decrease over the time of filter operation. The decreases of removal efficiencies are also observed for parameters such as dissolved organic carbon, spectral absorption coefficient, adsorbable organic carbon and most of the disinfection byproducts. However, THMs, especially chloroform are produced in the filter bed. The GAC beds were contaminated microbially, especially with P. aeruginosa. The contamination was not removable by backwashing with chlorine concentrations up to 2 mg/l free chlorine.     

饮用水中余氯对大型蚤的急性和慢性毒性

目前我国饮用水生产过程中普遍采用氯消毒,在去除一些有害微生物的同时,会形成一定浓度的余氯。为了监测余氯对用于在线监测的水生生物产生的毒性效应,讨论了饮用水中余氯对大型蚤的急性和慢性毒性。当余氯为0.16 mg/L时,大型蚤24 h存活率为100%,48 h存活率为90%;当余氯达到0.32 mg/L时,大型蚤48 h存活率为30%。在最小致死剂量(MLD=0.16 mg/L) 暴露下,40 d慢性毒性结果显示水中余氯对大型蚤生长和生殖影响显著。因此,可用于实现在线连续监测过量投加后水中高浓度的余氯。而当大型蚤用于毒性的在线生物监测(如突发性事故监测), 或用于监测水质大幅度变化时,应考虑首先消除水中余氯对动物行为生态的影响。     

RESEARCH ON MATHEMATICAL SIMULATION OF RESIDUAL CHLORINE DECAY AND OPTIMIZATION OF CHLORINATION ALLOCATION OF URBAN WATER DISTRIBUTION SYSTEM

The concentration of Residual Chlorine (RC) frequently violates the standard in situations of urban water distribution system with large water supply area and long time of distribution. If chlorine dosage increases within water treatment plant, although RC in distribution system could meet water quality standard, Disinfection By-Products (DBPs) such as hydrocarbon halide rises. In the paper, a mathematical model of chlorine allocation optimization was presented based on reaction kinetics mechanism and optimization theory to solve the problem. The model includes the objective function of minimizing annual operation cost and constraints of RC standard and rational chlorination station distribution, and solving by 0-1 Integer Programming (IP). The model had been applied to a real water distribution system. The simulation results of the model showed that adding chlorine in‘ water distribution system remarkably improved water quality and reduced the operation cost by 49.3% per year less than chlorine dosed only in water treatment plant to meet RC standard. The results prove adding chlorine in water distribution system based on the model can bring both technological and economic advancement.     

MF与次氯酸钠协同处理微污染水试验研究

通过在一体式膜反应器(MF)中投加强氧化剂次氯酸钠,考察MF与次氯酸钠协同处理微污染饮用水的处理效果。通过从浊度、色度、CODMn和UV410这4个指标,研究不同剂量的次氯酸钠对MF与次氯酸钠协同处理微污染饮用水的处理效果。结果表明,从处理效果和经济两个角度,确定在原水浊度在3-8 NTU、色度30°-50°、CODMn5~8mg/L、UV2542.0-4.5cm-1时,反应器中强氧化剂次氯酸钠最佳投量为10mg/L。     

原水管道中淡水壳菜足丝的溶解性能研究

淡水壳菜依靠足丝附着在管道内壁,并快速大量繁殖,会导致管道、阀门等堵塞。研究了足丝在强酸、强碱、水处理氧化剂中的溶解性能。结果表明:除次氯酸钠外,其他试验药剂都不能溶解淡水壳菜的足丝。导致足丝溶解的有效成分是次氯酸根。水中余氯达到1mg/L的次氯酸钠溶液,可在36h内完全溶解分泌24h后的足丝,127h内完全溶解老化的足丝。因此,可以通过投加次氯酸钠降低足丝的附着能力,从而去除管道中的贝壳。     

Particle size distribution and property of bacteria attached to carbon fines in drinking water treatment

The quantitative change and size distribution of particles in the effluents from a sand filter and a granular activated carbon （GAC） filter in a drinking water treatment plant were investigated. The average total concentration of particles in the sand filter effluent during a filter cycle was 148 particles/mL, 27 of which were larger than 2 μm in size. The concentration in the GAC effluent （561 particles/mL） was significantly greater than that in the sand filter effluent. The concentration of particles larger than 2 μm in the GAC filter effluent reached 201 particles/mL, with the amount of particles with sizes between 2 μm and 15 μm increasing. The most probable number （MPN） of carbon fines reached 43 unit/L after six hours and fines between 0.45 μm and 8.0 μm accounted for more than 50%. The total concentration of outflowing bacteria in the GAC filter effluent, 350 CFU （colony-forming units） /mL, was greater than that in the sand filter effluent, 210 CFU/mL. The desorbed bacteria concentration reached an average of 310 CFU/mg fines. The disinfection efficiency of desorbed bacteria was lower than 40% with 1.5 mg/L of chlorine. The disinfection effect showed that the inactivation rate with 2.0 mg/L of chloramine （90%） was higher than that with chlorine （70%）. Experimental results indicated that the high particle concentration in raw water and sedimentation effluent led to high levels of outflowing particles in the sand filter effluent. The activated carbon fines in the effluent accounted for a small proportion of the total particle amount, but the existing bacteria attached to carbon fines may influence the drinking water safety. The disinfection efficiency of desorbed bacteria was lower than that of free bacteria with chlorine, and the disinfection effect on bacteria attached to carbon fines with chloramine was better than that with only chlorine.     

生活饮用水二氧化氯消毒副产物检测技术的研究与应用

建立生活饮用水中二氧化氯消毒副产物氯酸盐、亚氯酸盐及氟化物、氯化物、硝酸盐、硫酸盐等6种无机阴离子的同时测定方法。以离子色谱法为测试手段,对采用二氧化氯消毒的生活饮用水出厂水及管网水中氯酸盐、亚氯酸盐含量进行测定。结果:分析方法的线性相关系数在0.9990-0.9994之间,,测试值的相对标准偏差RSD为1.49%-4.12%,各组份的检出限在0.0050-0.0225mg/L之间,回收率为96.0%-102.0%。方法简单、快速、准确、灵敏,适于大批量水样分析。出厂水及末梢水中二氧化氯消毒产生的消毒副产物均符合国标。     

小型农村安全饮水工程使用稳定二氧化氯进行消毒的可行性

论述了二氧化氯的物理和化学特性及其用于饮水消毒的方法和特点。分析了二氧化氯发生器不适用我区小型农村饮水安全工程的原因,对使用稳定二氧化氯进行了可行性分析。     

小型间歇式次氯酸钠发生器的设计参数研究

为提高小型间歇式次氯酸钠发生器的适用性和可靠性,综合考虑农村小型供水工程特点,结合两端式板式电极,采用单因子试验方法开展电极结构、阴极材质、电极安装高度、盐水浓度、配盐水质、盐水体积、电流密度等设计参数的试验研究。试验结果表明: 小型间歇式次氯酸钠发生器的最佳设计参数为: 电极左右间距 6 cm,阴、阳极采用相同涂层,电极板间距 5 mm,电极板中心距电解槽底部 20 cm,盐水浓度3% ,盐水体积30 L,电流密度480 ～ 640 A /m2,电解时间300 ～ 360 min,有效氯浓度 8. 50 ～ 8. 80 g /L,有效氯产量 255 ～ 264 g,运行成本 7. 16 ～ 7. 20 元/ kg。此外,亦可结合实际供水工程规模、消毒剂需求量、电解时间等多个因素,选择适宜的电解参数。试验结果为下一步设备定型和实际应用奠定了良好基础。