水中天然有机物混凝过程的光学在线监测及控制

Optical monitoring and control of coagulation process for the removal of aquatic organic matters

以腐殖酸为去除对象 ,用光散射颗粒分析仪 (PDA)对水中天然有机物的混凝过程进行在线监测 ,结果表明PDA输出信号 (FI曲线 )的特征值与絮凝体粒径和有机物去除率之间具有相关性 .在弱酸性 (pH =5 0 )和中性 (pH =7 0 )条件下 ,通过合理控制混凝剂投量 ,腐殖酸的TOC去除率可达 5 0 % ,UV2 54 去除率可达 80 %— 90 % ,但pH =7 0时的投量为pH =5 0的 5倍以上 .在pH =5 0的条件下 ,吸附电中和是有机物混凝的主要机理 ,但在混凝剂投量非常高的情况下 ,卷扫絮凝也起重要作用 .在pH =7 0条件下 。

Using a photometric dispersion analyzer (PDA), online monitoring and control of coagulation process was realized for the removal of aquatic organic matter. A correlative relationship was found among the PDA output (FI curve), floc size and TOC removal. At slightly acidic (pH=5\^0) and neutral (pH=7\^0) conditions, a TOC removal of 50% and UV 254 removal of 80%—90% can be achieved under optimum alum dosages, but the required Al dose at pH 7 is about 5 times of that at pH 5. At pH 5\^0, adsorption and charge\|neutralization is thought to be the main mechanism of coagulation for aquatic organic matter at moderate Al dose but sweep coagulation is the main mechanism at pH 7\^0 as well as at pH 5\^0 under an overdosing condition.