2018—2022年辽宁省农村集中式供水单位消毒状况及效果分析

Analysis of disinfection status and efficiency in rural central water supply units in Liaoning Province,China,2018-2022

目的 了解辽宁省农村地区集中式供水消毒状况,并进一步了解不同方式消毒情况及效果,分析其影响因素,为保障农村饮用水卫生安全提供参考。方法 2018—2022年,在辽宁省14个市所有乡镇辖区范围内,每个乡镇设置2~4个监测点,收集集中式供水单位基本信息,每个水厂采集1份出厂水和1~2份末梢水,枯水期和丰水期各采集1次。按照《生活饮用水标准检验方法》(GB/T 5750-2006)进行微生物指标(总大肠菌群、大肠埃希氏菌和菌落总数)检验。采取消毒措施的水样检测消毒剂指标(游离氯或二氧化氯)。检测结果按照《生活饮用水卫生标准》(GB 5749-2006)进行评价,对微生物和消毒剂指标结果进行分析。结果 共调查供水单位5 384个,水源类型主要为地下水(94.42%);供水规模主要为小型集中式供水(96.34%)。消毒的供水单位739个(13.72%),其中消毒方式包括氯化消毒(69.68%)、二氧化氯消毒(27.60%)和紫外线消毒(2.72%);消毒设备按要求使用的占比60.35%。氯化消毒以漂白粉为主(81.55%),二氧化氯消毒以高纯二氧化氯为主(67.16%)。共采集检测水样23 427份,其中消毒水样3 389份(紫外线消毒水样84份,氯化和二氧化氯消毒水样3 305份)。游离氯和二氧化氯指标达标率为91.20%。二氧化氯消毒水样达标率(96.31%)高于氯化消毒水样(89.22%),达标率差异有统计学意义(χ^(2)=41.70,P<0.05)。丰水期游离余氯达标率高于枯水期;末梢水游离余氯的达标率高于出厂水;消毒设备按要求使用的水样游离余氯达标率高于偶尔使用和人工投加的情况,差异均有统计学意义(P<0.05)。不同水期、水样类型、水源、消毒剂投加方式,二氧化氯达标率的差异均无统计学意义(P>0.05)。消毒水样总大肠菌群、大肠埃希氏菌和菌落总数达标率高于不消毒水样,差异有统计学意义(P<0.05)。氯化消毒水样总大肠菌群和菌落总数达标率均高于二氧化氯消毒水样,且差异有统计学意义(P<0.05)。结论 辽宁省农村饮用水消毒状况有待加强,氯化消毒消毒效果优于二氧化氯消毒。今后应加强农村饮用水消毒的监管监测,保障饮用水安全。

Objective To investigate the disinfection status and efficiency of different disinfection method in central water supply units,to analyze the relevant influencing factors,and to provide a refence for ensuring the safety of drinking water in rural areas of Lia-oning Province,China.Methods From 2018 to 2022,2-4 monitoring points were set up in each town of 14 cities in Liaoning Prov-ince to collect basic information of central water supply units.One finished water sample and 1-2 tap water samples were collected from each water treatment plant for analysis of microbiological indicators(total coliform count,Escherichia coli count,and total bacterial count)in the dry and wet seasons,according to the Standard Examination Method for Drinking Water(GB/T 5750-2006).Water samples with disinfection were tested for the disinfectant indicators(free chlorine or chlorine dioxide).The results were evaluated ac-cording to the Standards for Drinking Water Quality(GB 5749-2006)in order to analyze microbial and disinfectant indicators.Results A total of 5384 centralized water supply units were investigated.The primary water source was groundwater(94.42%).The water supply was primarily from small-scale centralized systems(96.34%).Water disinfection was performed in 739(13.72%)water sup-ply units.The disinfection methods included chlorination disinfection(69.68%),chlorine dioxide disinfection(27.60%),and ultra-violet(UV)disinfection(2.72%).Disinfection equipment was used as required in 60.35%of all units.Bleaching powder(81.55%)was mainly used in chlorination disinfection.High-purity chlorine dioxide(67.16%)was the main method in chlorine dioxide disinfec-tion.A total of 23427 water samples were collected,including 3389 water samples with disinfection(84 water samples with UV disin-fection,and 3305 water samples with chlorination or chlorine dioxide disinfection).The qualified rate of free chlorine and chlorine di-oxide indicators was 91.20%.The qualified rate of water samples with chlorine dioxide disinfection(96.31%)was significantly higher than that with chlorination disinfection(89.22%)(χ^(2)=41.70,P<0.05).The qualified rate of free chlorine in wet season was higher than that in dry season.The qualified rate of free chlorine in the tap water was higher than that in the finished water.The qualified rate of free chlorine in water samples disinfected using equipment as required was significantly higher than that of water samples disinfected with occasional use of equipment and manual disinfectant addition(P<0.05).No significant differences in the qualified rates of chlo-rine dioxide were found between different seasons,different types of water samples,different sources of water,and different methods of adding disinfectant(P>0.05).The qualified rates of total coliform count,E.coli count,and total bacterial count were significantly higher in water samples with disinfection than in water samples without disinfection(P<0.05).The qualified rates of total coliform count and total bacterial count were significantly higher in water samples with chlorination disinfection than in those with chlorine diox-ide disinfection(P<0.05).Conclusion The disinfection status of rural drinking water in Liaoning Province needs to be strengthened.The disinfection efficiency of chlorination is higher than that of chlorine dioxide.In the future,we should strengthen the supervision and monitoring of rural drinking water disinfection to ensure the safety of drinking water.