2016—2018年贵阳市饮用水消毒效果及其影响因素

Disinfection effects and influencing factors of drinking water in Guiyang,2016-2018

目的了解贵阳市饮用水消毒效果状况,并探讨其影响因素。方法分别于2016—2018年枯水期(3—5月)和丰水期(8-10月),采集贵阳市出厂水和末梢水水样,检测消毒剂指标和微生物指标。结果共监测经消毒处理的水样2 230件,以消毒方式分类,氯化消毒的有1 759件(占78.88%),二氧化氯消毒的有471件(占21.12%);消毒剂指标合格的有1 562件(占70.04%),浑浊度合格的有1 909件(占85.61%);净化方式为常规处理的有1 300件(占58.30%),仅消毒的有930件(占41.70%)。二氧化氯消毒水样消毒剂指标合格率[85.13%(401/471)]高于氯化消毒[66.00%(1 161/1 759)],差异有统计学意义(P<0.001)。消毒剂指标合格率依次为液氯[95.49%(656/687)]>复合二氧化氯[86.78%(210/242)]、高纯二氧化氯[83.41%(191/229)]>次氯酸钠[64.91%(74/114)]>漂白粉[44.99%(431/958)],差异均有统计学意义(P<0.05)。在1 759件氯化消毒水样中,消毒副产物三氯甲烷浓度超标的有56件,超标率为3.18%;在471件二氧化氯消毒水样中,消毒副产物氯酸盐和(或)亚氯酸盐超标的有4件,超标率为0.85%。氯化消毒水样的副产物超标率高于二氧化氯消毒水样,差异有统计学意义(P=0.005)。在2 230件水样中,菌落总数的合格率为86.14%,总大肠菌群的合格率为79.51%。在检出总大肠菌群的457件水样中,检出耐热大肠菌群的有437件,检出率95.62%。3项微生物指标均合格的水样有1 724件,合格率为77.31%。不同消毒方式微生物指标合格率依次为液氯[98.40%(676/687)]>复合二氧化氯[86.36%(209/242)]>高纯二氧化氯[74.67%(171/229)]、次氯酸钠[73.68%(84/114)]>漂白粉[60.96%(584/958)]。经logistic回归分析结果显示,消毒剂指标不合格(OR=27.50,95%CI:19.50~38.80)、二氧化氯消毒(OR=3.10,95%CI:2.09~4.59)、浑浊度不合格(OR=1.64,95%CI:1.17~2.27)、农村饮用水(OR=3.53,95%CI:2.35~5.28)、以地下水为水源的饮用水(地面水与地下水比较,OR=0.64,95%CI:0.46~0.90)、末梢水样(OR=2.73,95%CI:2.01~3.72)以及仅消毒的饮用水(OR=2.08,95%CI:1.50~2.87)微生物指标不合格率较高。结论贵阳市饮用水消毒效果存在一定问题,仍需进一步完善饮用水消毒处理。

Objective To known about the status and the influencing factors of drinking water disinfection in Guiyang. Methods During the dry season(March to May) and wet season(August to October) of 2016-2018,the samples of finished water and tap water in Guiyang were collected to detect disinfectant and microbial indicators. Results A total of 2 230 monitored water samples were collected. According to the way of disinfection,there were 1 759 samples(78.88%) disinfected with chlorination and 471 samples(21.12%) disinfected with chlorine dioxide.A total of 562(70.04%) samples were qualified in disinfection index,and 1 909(85.61%) samples were qualified in turbidity.A total of 1 300(58.30%) samples were treated with conventional method and 930(41.70%) samples were disinfected only. The qualified rate of disinfection index of water samples disinfected by chlorine dioxide [85.13%(401/471)] was higher than that of water samples disinfected by chlorine[66.00%(1 161/1 759)],the difference was statistically significant(P <0.001).The qualified rate of disinfection index of water samples according to disinfection methods ranked as liquid chlorine [95.49%(656/687)] > compound chlorine dioxide [86.78%(210/242)],highpurity chlorine dioxide [83.41%(191/229)] > sodium hypochlorite [64.91%(74/114)] > bleaching powder [44.99%(431/958)],with significant difference(P<0.05). Among the 1 759 chlorinated water samples,the levels of chloroform in 56 water samples exceeded the standard with over standard rate of 3.18%. Among the 471 water samples disinfected by chlorine dioxide,the levels of chlorate and/or chlorite in four samples exceeded the standard with over standard rate of 0.85%.The over standard rate of disinfection by-products in chlorinated water samples was significantly higher than that in water samples disinfected by chlorine dioxide(P=0.005). In 2 230 water samples,the qualified rate was 86.14% for total count of bacteria,79.51% for total coliform respectively.Total coliform bacteria were detected in 457 water samples,437 among which revealed presence of thermotolerant coliform with detection rate of 95.62%.A total of 1 724 samples were qualified for all of the three microbial indexes with qualified rate of 77.31%.The qualified rates of microbiological indicator in water samples according to disinfection methods ranked as liquid chlorine [98.40%(676/687)] > compound chlorine dioxide [86.36%(209/242)] > high purity chlorine dioxide [74.67%(171/229)],sodium hypochlorite [73.68%(84/114)] > bleaching powder [60.96%(584/958)]. Logistic regression analysis showed that the water samples with unqualified disinfection index(OR=27.50,95%CI:19.50-38.80),the water samples disinfected by chlorine dioxide(OR=3.10,95%CI:2.09-4.59),the water samples with unqualified turbidity(OR=1.64,95%CI:1.17-2.27),rural drinking water(OR=3.53,95%CI:2.35-5.28),drinking water supplied from groundwater source(OR=0.64,95%CI:0.46-0.90),tap water(OR=2.73,95%CI:2.01-3.72) and disinfected drinking water without other treatment(OR=2.08,95% CI:1.50-2.87) had higher unqualified rate in microbiological indicator.Conclusion There are some problems in the disinfection effects of drinking water in Guiyang,which still need to be further improved.