中文摘要：

混凝是降低水体中天然有机物浓度的有效手段．本研究旨在了解天然有机物的存在对混凝效果及絮体特性产生的影响．实验以PACl25作为混凝剂来模拟含有一定量天然有机物的典型代表物质腐殖酸或柠檬酸配水的水处理混凝过程．分析了混凝过程中这两种有机物的存在对絮体颗粒大小、分形维数、Zeta电位和水中剩余铝浓度的影响．结果表明，在一定浓度范围内，随着溶液中腐殖酸、柠檬酸浓度的增加，絮体颗粒的大小及其成长速率、Zeta电位以及分形维数均呈现出下降的趋势（腐殖酸质量浓度从0mg·L-1增加到10mg·L-1、柠檬酸浓度从0μmol·L-1增加到7μmol·L-1，破碎前絮体大小分别降低34．2％、53．1％；絮体Zeta电位从10mV左右分别下降到-10mV及-2．5mV左右；絮体成长速率分别下降了42．6％、77．5％；分形维数分别降低了0．08和0．094），表明有机物占据了微絮体表面从而导致絮体活性及致密性的降低；而在此有机物浓度范围内溶液中剩余铝的浓度却不因絮凝能力的下降而变化．

英文摘要：

Coagulation is an efficient way to remove the natural organic matter in water. Our works primarily focused on the effect of natural organic matter on coagulation and the properties of the flocs formed. PACl25 was used as the coagulant in this research to simulate the process of coagulation, and typical substance of NOM, humic acid and citric acid were used to prepare the model water. The impact of NOM on the size, fractal dimension, Zeta potential of the floes and residual aluminum in solution was explored. The experiment results showed that as the concentration of humic acid and citric acid increased in the experimental range, the size and growth velocity of flocs, Zeta potential and fractal dimension showed a tendency of decrease （ when the concentration of humic acid increased from 0 mg.L-1 to 10 mg.L-1,citric acid increased from 0 μmol.L-1 to 7 μmol. L-1, the size of floes before breakage was decreased by 34.2% and 53.1% , respectively, the Zeta potential decreased from about 10 mV to approximately - 10 mV and -2.5 mV, the growth velocity of the flocs was decreased by 42.6% and 77.5% , and the fractal dimension declined by 0. 08 and 0. 094） , which showed the occupying of the floc surface by NOM resulted in the decrease of its activity and compactivity. However, the residual aluminum was not affected by the decrease of coagulation efficiency.