以实验设计法评估不同因子对三卤甲烷形成之影响

Using Experimental Design to Evaluate the Effects of Different Factors on Trihalomethane Formation

本研究采实验设计方式,初步筛选重要三卤甲烷(Trihalomethane,THM)形成控制参数,包括溴离子、加氯量/有机物、温度及反应时间,并配合净水厂实际操作状况,进行参数范围设定,再利用统计软件比较各参数对THM物种形成之影响。研究结果显示含氯较高之THM物种(氯仿及二氯-溴仿),主要受溴离子及温度影响,其中溴离子属负效应,温度则属正效应,当低溴离子浓度存在时,其生成含氯较高之THM物种高于低溴离子浓度者。至于二溴-氯仿之形成主要受溴离子及温度影响,但两参数均属正效应。在溴仿形成之控制参数与另三种THM物种不同,主要受溴离子及加氯量/有机物含量影响,前者属正效应,后者则属负效应,当高溴离子浓度存在时,高加氯量/有机物之比值者,其生成之溴仿,小于低加氯量/有机物比值者。

In this study, four parameters, including bromide ion, chlorine dosage added/organic content, temperature and time were well discussed their effects on the trihalomethane formation using experimental design with statistical software. The ranges of all parameters were operated with the consideration in full-scale plant. It indicates that the formation of higher chloride in THM species （chloroform and bromodichloromethane） was mainly affected by the bromide ion and temperature. Bromide showed negative effect while temperature showed the positive effect. It implies that the content of higher chloride in THM exceed in that of lower chloride in THM in a condition of low bromide ion in water sample. As for the formation process of dibromochloromethane, both parameters of bromide ion and temperature had positive and important contribution. The important parameters for affecting bromoform formation were changed into bromide ion and chlorine dosage added/organic content. Bromide had a positive effect in contrast with the negative effect of chlorine dosage added/organic content. The content of bromoform was decreased with the increase of the ration of chlorine dosage added to organic content at high bromide ion.