再生水中亚硝酸盐对余氯衰减的影响及其控制

根据华北地区某再生水厂的实际水质特点，通过实验比较了加氯消毒后水中TOC、NO2-对余氯消耗的影响；使用平行一级反应模型分析实验结果，发现折点氯化后亚硝酸盐耗氯反应的速率常数显著高于有机物耗氯反应，亚硝酸盐成为再生水中重要耗氯物质．为稳定再生水中余氯浓度，提出了2个方案：再生水中加氨或调节pH值，分别进行了模型拟合和实验效果分析．通过对比加氨和调pH值方案的余氯成分和所需药剂投量，得出调节水体至弱碱性（pH值为8．3）是更好的途径．本研究对再生水厂消毒工艺的设计、运行具有一定的借鉴意义，对保证再生水水质安全具有较高的实用价值．

Influence and Resolution of Nitrite-Leaded Chlorine Decay in Reclaimed Water

Based on the water samples collected from a reclaimed water treatment plant （RWTP） in North China, the effect of nitrite and TOC on chlorine decay was investigated and a parallel first-order decay model was used to simulate the experimental data. The result indicated that the reaction constant between nitrite and chlorine was higher than that between organic matter and chlorine; and nitrite consumed much more chlorine than organic matter after break- point chlorination. In order to stabilize the chlorine concentration in reclaimed water, two methods were proposed to restrain nitrite-leaded chlorine decay： adding ammonia and adjusting water to be alkaline before chlorination, each of which was tested by experiments and simulated with parallel first-order decay models. It is proven that the two meth- ods were both effective in stabilizing residual chlorine concentration. And then the residual-chlorine composition and chemical dosage of the two proposed methods were compared, and the result showed that adjusting water to be alkalescent （pH=8.3） was better than ammonia addition, and thus the former method was recommended to be applied in the plant.