Full-scale study of removal effect on Cyclops of zooplankton with chlorine dioxide

Cyclops of zooplankton propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfections process like chlorination due to its stronger resistance to oxidation. In this paper, a full-scale study of chlorine dioxide preoxidation cooperating with routine clarification process for Cyclops removal was conducted in a waterworks. The experimental results were compared with that of the existing prechlorination process in several aspects: including the Cyclops removal efficiencies of water samples taken from the outlets of sedimentation tank and sand filter and the security of drinking water and so on. The results showed that chlorine dioxide might be more effective to inactivate Cyclops than chlorine and Cyclops could be thoroughly removed from water by pre-dosing chlorine dioxide process. The GC-MS examination and Ames test further showed that the sort and amount of organic substance in the treated water by chlorine dioxide preoxidation were evidently less than that of prechlorination and the mutagenicity of drinking water treated by pre-dosing chlorine dioxide was substantially reduced compared with prechlorination.

Pilot-scale study of removal effect on Chironomid larvae with chlorine dioxide

Chironomid larvae propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfection process like chlorination due to its stronger resistance to oxidation. In this paper, a pilot-scale study of chlorine dioxide preoxidation cooperating with routine clarification process for Chironomid larvae removal was conducted in Shenzhen Waterworks in Guangdong Province, China. The experimental results were compared with that of the existing prechlorination process in several aspects, including the Chironomid larvae removal efficiencies of water samples taken from the outlets of sedimentation tank, sand filter, the security of drinking water and so on. The results showed that chlorine dioxide might be more effective to inactivate Chironomid larvae than chlorine and Chironomid larvae could be thoroughly removed from water by pre-dosing chlorine dioxide process. The GC-MS examination and Ames test further showed that the sort and amount of organic substance in the treated water by chlorine dioxide preoxidation were evidently less than that ofprechlorination and the mutagenicity of drinking water treated by pre-dosing chlorine dioxide was substantially reduced compared with prechlorination.

Inactivation of Chironomid Larvae with Chlorine Dioxide and Chlorine

Chironomid larvae propagate prolifically in eutrophic water body and they cannot be exterminated by conventional disinfection process. The inactivation effects of chlorine and chlorine dioxide on Chironomid larvae were investigated and some bourdary values in practice were determined under .conditions of various oxidaat dosage, organic precursor concentmtion and pH value. In addition, removal effect of different pre-oxidation cambined with coagulation process on Chironomid larvae in raw water was evaluated. It was found that chlorine dioxide possessed better inactivation effect than chlorine. Complete inactivation of Chironomid larvae in raw water was resulted by 1.5 mg/L of chlorine dioxide with 30 min of contact ＇time. Additionally, the organic precursor concentration, pH value had little influence on the inactivation effect. The coagulation jar test showed that Chironomid larvae in the raw water could be completely removed by chlorine dioxide pre-oxidation in combination with the coagulation process at chlorine dioxide dosage of 0.8 mg/L.

Removal of benzene homologous compounds with chlorine dioxide

Chlorine dioxide composite disinfectant generator that produces a mixture of the oxidant gases comprising chlorine dioxide, chlorine, ozone and hydrogen peroxide through electrolyzing salt,is widely utilized in China presently.The experiments in the paper focused on the removal of benzene homologous compounds such as styrene, methyl and dimethyl benzene. The results indicated that pH value was the most crucial factor to influence the treatment effects while reaction time and input way were considered as the importance. The removal rate for benzene could reach 60% when above 80% for methyl, and 100% for styrene and dimethyl. The variation mechanisms between chlorine dioxide,chlorite and chloride which determine the drinking water quality also discussed.

Bench and Full Scale Study of Removal Effect and Mutagenicity on Mesocyclops Leukarti with Chlorine Dioxide

Mesocyclops Leukarti of zooplankton propagates excessively in eutrophic water body and it can not be effectively inactivated by the conventional process in drinking waterworks for its special surface structure. In this paper, a study of removal efficiency on Mesocyclops Leukarti with chlorine dioxide in a drinking waterworks was performed. Bench scale results showed that chlorine dioxide is more effective against Mesocyclops Leukarti. And Mesocyclops Leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation cooperated with the conventional process during the full scale study. The chlorite, by.product of prechiorine dioxide, was constant at 0.45 mg/L after filtration, which was lower than the critical value of the USEPA. GC-MS examination and Ames test showed that the quantity of organics and the mutngenicity in the water treated by chlorine dioxide is obviously less than that of prechlorination.

Quantitative Detection of <i>Helicobacter pylori</i>by Real Time PCR in Drinking Water—Environmental and Public Health Risk Significance

Helicobacter pylori (H. pylori) is bacteria considered to be present in half of the population and it is a public health problem worldwide. Most patients infected with H. pylori show no clinical symptoms;nonetheless, approximately 10% to 20% of these patients will develop peptic ulcers and 1% will develop gastric cancer. The International Agency for Research on Cancer has classified H. pylori as a Group 1 carcinogen, recognized as the only bacteria capable of producing cancer. Samples of drinking water (n = 44) from aqueducts with chlorination treatment in selected areas with high prevalence of gastric cancer were analyzed in Costa Rica. Samples of drinking water from Panamá (n = 44) from aqueducts supplying untreated water for human consumption in the province of Chiriquí were also analyzed. The molecular marker of H. pylori, glmM, was used, and to optimize the Real Time PCR (qPCR) technique, annealing temperature, concentration of primers and probe were standardized;also, by analyzing different standard curves, the best reaction conditions that allowed detecting and quantifying the gene were determined. The LightCycler&reg 480 II (LC480II) equipment from Roche Diagnostics GmbH was used, as well as the Absolute Quantification Analysis by means of the Second Derivative Maximum Method. In the case of the samples from Costa Rica, it was determined that 79.5% were positive for H. pylori;removing outlier high average, quantification of bacteria was determined in 3.6 × 103 copies/100 mL. For Panamá it was determined that 86% of the samples were found positive for the presence of H. pylori;removing outlier high average quantification of bacteria was determined at 3.3 × 102 copies/100 mL. The difference in values between the aqueducts in both countries revealed an environmental distribution of the bacteria of epidemiological interest in each case.

复合型二氧化氯发生器工艺优化研究

生活饮用水的安全保障是中国所面临的较大民生问题之一。针对自主研发的国产复合型二氧化氯发生器发生效率低的现状以及消毒剂在应用过程中的各种问题,通过对复合型二氧化氯发生器的发生工艺进行条件参数优化,根据氯酸钠制备法的反应机理和条件,通过研究反应物加药比、反应温度和反应时间对反应效率的影响,最终得到最佳反应条件。

Treatment, residual chlorine and season as factors affecting variability of trihalomethanes in small drinking water systems

Seasonal variability in source water can lead to challenges for drinking water providers related to operational optimization and process control in treatment facilities. The objective of this study is to investigate seasonal variability of water quality in municipal small water systems （〈 3000 residents） supplied by surface waters. Residual chlorine and trihalomethanes （THM） were measured over seven years （2003-2009）. Comparisons are made within each system over time, as well as between systems according to the type of their treatment technologies. THM concentrations are generally higher in the summer and autumn. The seasonal variability was generally more pronounced in systems using chlorination plus additional treatment. Chloroform, total THM （TTHM） and residual chlorine concentrations were generally lower in systems using chlorination plus additional treatment. Conversely, brominated THM concentrations were higher in systems using additional treatment. Residual chlorine was highest in the winter and lowest in the spring and summer. Seasonal variations were most pronounced for residual chlorine in systems with additional treatment. There was generally poor correlation between THM concentrations and concentrations of residual chlorine. Further study with these data will be beneficial in finding determinants and indicators for both quantity and variability of disinfection byproducts and other water quality parameters.

基于吹扫捕集-气相色谱-质谱法探究单一/联合消毒剂消毒后生活饮用水中4种三卤甲烷生成量的变化

为探究次氯酸钠和二氧化氯+次氯酸钠消毒后生活饮用水中4种三卤甲烷[THMs,包括三氯甲烷(TCM)、二氯一溴甲烷(DCBM)、一氯二溴甲烷(DBCM)和三溴甲烷(TBM)]生成量以及生成比例的变化,进行了题示研究。将水样(稳定剂为抗坏血酸)充满40mL吹扫捕集瓶中,加入10.0mg·L^(-1)内标(氟苯)使用液10.0μL,旋紧瓶盖,振荡1 min后分取5 mL,在吹扫温度30℃、吹扫时间9.0min、吹扫流量40mL·min^(-1)、解吸温度225℃、解吸时间2.0min等条件下吹扫捕集,所得气体进入气相色谱-质谱仪,在DB-5MS石英毛细管色谱柱(60m×0.32mm,1.0μm)上进行程序升温分离(初始柱温为45℃),所得4种THMs用电子轰击离子(EI)源电离,以选择离子监测(SIM)模式检测,内标法定量。结果显示,4种THMs与内标的质量浓度比值均在一定范围内与其对应的峰面积比值呈线性关系,检出限(3s)为0.027~0.030μg·L^(-1);分别以无本底水和管网水为基质进行3个浓度水平的加标回收试验,回收率为88.1%~105%,测定值的相对标准偏差(n=6)为1.7%~4.7%。方法用于深圳市3家水厂76份生活饮用水样品中4种THMs的分析,各水厂水样中4种THMs的检出量和总量均未超过GB 5749-2022规定的限值;采用单一次氯酸钠消毒的水样中各THMs检出量占各THMs限值比值的加和(THMs*值)存在超标风险:采用二氧化氯+次氯酸钠消毒的水样中TCM的检出量和THMs总量均降低了近50%,TCM检出量占THMs总量的比值降低,其余3种溴代THMs的比值增加,并且次氯酸钠的投放量和投放次数显著降低,THMs*值超标风险降低,建议相关水厂在夏季高温多雨时,及时关注水源水质的变化,必要时采用二氧化氯+次氯酸钠联合消毒方式。

复合型二氧化氯发生器在饮用水消毒中的应用

生活饮用水的安全保障是我国所面临的较大民生问题之一,因此生活饮用水消毒剂品质和添加量对保障居民的身体健康有重要的意义。对二氧化氯性质、消毒机理、制备方法以及复合型二氧化氯发生器进行了深入分析,指出生活饮用水目前常用的消毒技术,并对复合型二氧化氯消毒剂的未来发展方向进行了展望。

Development of gradient boosting-assisted machine learning data-driven model for free chlorine residual prediction

Chlorine-based disinfection is ubiquitous in conventional drinking water treatment (DWT) and serves to mitigate threats of acute microbial disease caused by pathogens that may be present in source water. An important index of disinfection efficiency is the free chlorine residual (FCR), a regulated disinfection parameter in the US that indirectly measures disinfectant power for prevention of microbial recontamination during DWT and distribution. This work demonstrates how machine learning (ML) can be implemented to improve FCR forecasting when supplied with water quality data from a real, full-scale chlorine disinfection system in Georgia, USA. More precisely, a gradient-boosting ML method (CatBoost) was developed from a full year of DWT plant-generated chlorine disinfection data, including water quality parameters (e.g., temperature, turbidity, pH) and operational process data (e.g., flowrates), to predict FCR. Four gradient-boosting models were implemented, with the highest performance achieving a coefficient of determination, R2, of 0.937. Values that provide explanations using Shapley’s additive method were used to interpret the model’s results, uncovering that standard DWT operating parameters, although non-intuitive and theoretically non-causal, vastly improved prediction performance. These results provide a base case for data-driven DWT disinfection supervision and suggest process monitoring methods to provide better information to plant operators for implementation of safe chlorine dosing to maintain optimum FCR.

二氧化氯和液氯消毒饮用水致突变性的比较

本文运用国内外广泛应用的Ames试验,对二氧化氯与液氯消毒水样进行了致突变性的比较 结果表明,ClO_2消毒的水样未显示出致突变性,而液氯消毒的木样显示致突变性.研究结果为ClO_2在饮用水消毒中的应用提供了科学的依据.

二氧化氯与氯联合消毒对饮用水中消毒副产物的影响

为了研究二氧化氯与氯联合消毒工艺过程中消毒副产物的形成规律以及特点,探讨二氧化氯对氯化消毒副产物的控制效果,对我国北方某市使用同一水源的4家水厂消毒工艺进行全面的采样与检测,并对各项消毒副产物检测结果进行了全面的分析.结果表明,二氧化氯与氯联合消毒比单纯液氯消毒形成的三卤甲烷平均降低74.39%,卤乙酸平均降低40.65%.在控制氯酸盐及亚氯酸盐生成方面,使用纯二氧化氯发生器生成的氯酸盐要显著低于化学法复合二氧化氯发生器.

水体中不同相对分子质量有机质对饮用水消毒的影响

采用珠江广州河段一水源水作为研究对象 ,经预处理后 ,用AmiconYC 0 5 ,YM 1 ,YM 3 ,YM 1 0 ,YM 3 0 ,YM 1 0 0和ZM 5 0 0系列不同相对分子质量的超滤膜对其进行分离 ,分析各相对分子质量级别的可溶性有机物的DOC ,同时 ,对所分离出的各种相对分子质量级别的DOM与消毒剂Cl2 和ClO2 作用 .结果表明 ,在各个级别的DOM中 ,相对分子质量小于 5 0 0的DOM占总DOM的一半以上 ,这表明该水源水已经严重地受到人为的污染 ;而且该相对分子质量级别的DOM也是消毒过程形成三卤甲烷的主要前驱物质 .另外 ,这一类型的DOM在消毒过程中形成THMs与未分级的水源水也有较大的差别 .

二氧化氯作为消毒剂在饮用水处理中的应用

二氧化氯作为饮用水消毒剂受到广泛关注。二氧化氯具有强氧化性,在饮用水消毒中对杀菌,灭活病毒和原生动物具有良好的效果。二氧化氯-液氯/二氧化氯-氯胺等联合消毒工艺也具有优良的消毒特性,研究结果表明,其处理效果优于单一二氧化氯消毒。

复合二氧化氯发生器对饮用水消毒的适用性研究

对采用氯酸钠／盐酸法的复合二氧化氯发生器进行了测评和调查，并对其消毒液的成分及消毒后的副产物进行了定量分析。结果表明，复合二氧化氯发生器在实际运行中的转化率仅为30％左右，而在试验模拟条件下的最高转化率也仅为41％左右；在其产生的消毒液中，Cl2量约占Cl2和ClO2总量的30％-48％；由于消毒液中存在大量氯气和残留的氯酸盐，生成的消毒副产物已经给饮用水安全带来了新的威胁。

几种消毒剂对饮水致突变活性的影响

本研究应用Ａｍｅｓ致突变试验对武汉东湖水分别经氯、二氧化氯和臭氧消毒处理后的致突变活性进行了检测与比较。结果表明。东湖水以及臭氧消毒处理水样未呈现致突变性，氯与二氧化氯处理的水样致突变性检测结果为阳性，这３种消毒剂处理的各水样致突变比活性强度顺序由强至弱依次为氯＞二氧化氛＞臭氧；同时对东湖水用高锰酸钾预处理，以降低氯化消毒饮水致突变活性的效果也进行了比较，结果发现用高锰酸钾预处理东湖水，可降低氯化消毒饮水的致突变活性，而且高锰酸钾较高投加量的处理效果要优于低投加量。

二氧化氯、次氯酸钠及其联合消毒模拟水样效果的比较

目的比较不同剂量二氧化氯（CIO2）、次氯酸钠（NaCIO）及其联合（CIO2＋NaCIO）消毒模拟水样的效果。方法以实验室配制含大肠杆菌5．0×10^4～5．0×10^5cfu／100ml的模拟水样为研究对象，应用不同剂量CIO2、NaCIO、CIO2＋NaCIO进行消毒试验，分别消毒60、60、30＋60min后，以滤膜法和电位滴定法检测并比较模拟水样中大肠杆菌的杀灭率、CIO2残留量、CIO2^-生成量和总余氯量。结果0．4mg／L CIO2、0．5mg／LNaCIO，CIO2＋NaCIO联合配比为0．1mg/L＋0.3mg／L或0.2mg／L＋0.2mg／L时，为消毒模拟水样的最低有效剂量；与CIO2、NaCIO各自单独消毒相比，在CIO2＋NaCIO联合消毒的模拟水样中，CIO2的残留量增加13．43％～166．67％，CIO2^-的生成减小13．11％～19.97％，总余氯量增加9．34％～40．15％。结论二氧化氯、次氯酸钠二者联合消毒饮用水既可提高消毒效果，又可减少消毒剂使用剂量及消毒副产物的生成量。

二氧化氯对剑水蚤类浮游动物的灭活与去除

进行了氯气和二氧化氯灭活剑水蚤的对比试验，并分析了pH值、有机物含量等对二氧化氯灭活剑水蚤的影响．在此基础上，对预氧化与混凝过程的协同除蚤效能进行了考察．结果表明，与氯气相比二氧化氯对剑水蚤具有更显著的灭活作用，在较低的投加量（1．0mg／L）下，接触30min就可以达到100％的灭活率．当水体pH值为5．7—8．0，灭活效果不受影响，但pH值为9．8可以导致灭活率降低10％．有机物含量对灭活率产生显著影响，有机物含量增加，则灭活率降低．混凝烧杯试验表明，二氧化氯投加量为O．9mg／L时，二氧化氯预氧化与混凝沉淀的协同作用将完全去除原水中的剑水蚤．

桶装水空桶和桶盖的杀菌消毒和清洗技术研究

在国内首次研究了二氧化氯对桶装水空桶和桶盖中微生物的杀灭效果.研究结果表明,高纯二氧化氯是最有效的杀菌剂,二氧化氯投加质量浓度为0.5 mg/L即可获得满意的杀菌效果;高纯二氧化氯对桶装水水桶和桶盖中的细菌均具有很好的杀菌效果,且20 mg/L的ClO2溶液冲洗1～3 min左右空桶和桶盖获得很高的杀菌率,所以二氧化氯是一种有效的适用于桶装水水桶和桶盖的清洗剂和杀菌剂.