水源更换对给水管网水质的影响研究

为了研究水源更换对给水管网水质的影响，对北方A市水源更换过程中管网水质理化指标进行了监测分析.通过33 h的监测发现，由于水源水质不同造成管网水质化学不稳定，管网水水质部分指标发生了明显的下降，pH从7.54降到7.18，碱度从188　mg·L^-1降到117 　mg·L^-1，氯化物从310 　mg·L^-1降到132 　mg·L^-1（以Cl^-计），电导率从0.176　S·m^-1降到0.087 　S·m^-1，钙离子和镁离子略有下降分别为15 　mg·L^-1和11 　mg·L^-1，这些都是由于滦河水质与黄河水质不同造成的；余氯在换水过程中发生了较复杂的变化，主要是由于水源更换造成耗氯量增加以及夜间用水量少造成管网水输配时间长引起的；pH、碱度、余氯的变化使得管网水中铁的含量增加，最高达到0.4 　mg·L^-1，超出饮用水标准规定的0.3 　mg·L^-1.通过分析水源更换过程中水质的变化，提出了控制管网水质稳定的方法主要有提高pH、增加碱度、投加缓蚀剂和严格保证出厂水及管网水水质指标特别是余氯等.

Influence of Water Source Switching on Water Quality in Drinking Water Distribution System

This study investigates the regularity of the change on the physical and chemical water qualities in the distribution system during the process of water source switching in A city. Due to the water source switching, the water quality is chemical-astable. Because of the differences between the two water sources, pH reduced from 7.54 to 7.18, alkalinity reduced from 188 mg x L(-1) to 117 mg x L(-1), chloride (Cl(-)) reduced from 310 mg x L(-1) to 132 mg x L(-1), conductance reduced from 0.176 S x m(-1) to 0.087 S x m(-1) and the ions of calcium and magnesium reduced to 15 mg x L(-1) and 11 mg x L(-1) respectively. Residual chlorine changed while the increase of the chlorine demand and the water quantity decreasing at night, and the changes of pH, alkalinity and residual chlorine brought the iron increased to 0.4 mg x L(-1) at the tiptop, which was over the standard. The influence of the change of the water parameters on the water chemical-stability in the drinking water distribution system is analyzed, and the controlling countermeasure is advanced: increasing pH, using phosphate and enhancing the quality of the water in distribution system especially the residual chlorine.