次氯酸钠与液氯消毒在农村供水中的应用效果对比研究

为明确次氯酸钠消毒在农村供水工程中的实际应用效果,考察了南方某省以同一地表水为水源、水处理工艺相同、分别采用液氯和次氯酸钠消毒的具有一定代表性的两处农村供水工程(T水厂和H水厂)的余氯衰减、消毒效果和副产物生成情况。结果显示:在有效氯投加量分别为1.0 mg/L和2.0 mg/L时,2.4 h后H水厂出厂水的余氯值衰减率比T水厂分别低6.53%和3.30%,两者的消毒效果均较好,H水厂的管网末梢水菌落总数值比T水厂低40.62%,微生物安全性更高;当有效氯投加量由1.0 mg/L增至2.0 mg/L时,T水厂和H水厂出厂水的三氯甲烷生成量分别增长97.36%和59.35%,三卤甲烷分别增长122.64%和91.43%,而二氯乙酸和三氯乙酸生成量增长率相差不大。研究结果表明,次氯酸钠的稳定性及消毒效果略好于液氯,且消毒副产物三氯甲烷和三卤甲烷的生成量较小。由于两水厂在水源类型、水源水质特征、工程规模及水处理工艺方面具有一定代表性,经与其他研究进行对比分析认为,次氯酸钠消毒在农村供水中具有较好的应用前景。

Comparative study on application of sodium hypochlorite and liquid chlorine disinfectionstorural water supply

In order to clarify the effect of the practical application of disinfection with sodium hypochlorite to rural water supply project, the residual chlorine decay, disinfection effect, by-product production of two rural water supply projects ( plant T and H) with certain representativeness and with the same water source and same water treatment technology in a province in South China, for which the disinfections with sodium hypochlorite and liquid chlorine are adopted respectively, are investigated. The result shows that when the available chlorine dosages are 1. 0 mg/L and 2. 0 mg/L respectively, the residual chlorine decay rates of the treated water from the plant H are lower than the plant T by 6. 53% and 3. 30% respectively after 2. 4 h and both the disinfection effects are better, while the value of the total bacterial count of the treated water at the end of the pipeline network of the plant H is lower than that of the plant T by 40. 62% with a higher microbial safety. When the available chlorine dosage is increased from1. 0 mg/L to 2. 0 mg/L, the productions of chloroform from the treated water of both the plant T and the plant H are increased by97. 36% and 59. 35% and the trihalomethanes are increased by 122. 64% and 91. 43% respectively, while there is no significant difference between the productions of dichloroacetic acid and trichloroacetic acid. The study result shows that the stability and disinfection effect of sodium hypochloriteare a little bit better than those of liquid chlorine with less productions of the disinfectant by-products of chloroform and trihalomethanes. As both the plants have certain representativeness in the aspects of water source type, water quality characteristics of water source, project scale and water treatment technology, it is considered that after the comparative analysis made with the other studies, the disinfection with sodium hypochlorite has a better application prospect for the rural water supply.