不同水体溶解性有机物的混凝去除特性

The removal of dissolved organic matter in different water by coagulation

采用硫酸铝、工业氯化铁、无机高分子絮凝剂(PAC)3种无机混凝剂,对广州珠江、北京密云、天津滦河不同原水进行了混凝实验,分析了不同混凝剂去除水体有机物的特性以及不同水体溶解性有机物(DOM)的内在分级特征与其混凝去除率的关系.实验结果表明,①珠江水体由于碱度低,pH较易下降,高投药浓度下此水体DOM更易被氯化铁去除;中低投药下,在南方水体中,PAC与盐类絮凝剂对去除DOM的混凝性能差别不如在北方水体中明显,表明南北方水体DOM的内在特性存在一定差异,即北方水体DOM中可混凝去除部分的有机物易发生电中和作用,带有较多负电基团,南方珠江水体DOM含带电基团的有机物相对较少,而中性有机物含量相对较高,这与进一步分级结果一致.②所有水体从混凝收敛点看,总溶解性有机碳(DOC)去除率都是工业PAC最高,显示电中和(憎水化)-沉淀(吸附)可能为这些水体DOM的主要去除机理.③从不同水体的DOC平均去除率看,珠江水体高于密云水体,它们又明显高于滦河水体.对水体DOM进一步的化学分级研究结果表明,DOC去除率越高的水体,其中的憎水中性物质(HoN)含量也越高.这表明,除了碱度、总有机碳(TOC)外,原水DOM的内在化学分级特征也是影响水体DOC混凝去除率的重要因素.

The removal of DOM, which are from natural waters of Guangzhou Zhujiang River, Beijing Miyun Reservoir and Tianjin Luan River, by coagulation was investigated using aluminium sulfate, industrial ferric chloride and industrial polyaluminum chloride （PAC）, respectively. The relationship between water quality and the process of coagulation was investigated as well. The removal of DOM from Zhujiang water by Ferric chloride with higher dosage is the best because of the lower alkalinity of the water and the rapid decrease of pH. The difference of coagulation process between polyaluminum ehloride （PAC） and salt coagulant with lower dosage was less notable in south water than in north water. It showed that there must be some differences between the characteristics of south and north water. The part of removed DOM in north water would have more charged groups and be easier to be neutralized than in south water. Polyaluminum chloride （PAC） showed the best efficiency in the removal of DOM for all waters if compared by the efficiency at the convergent point of coagulation process. It indicated that charge neutralized-hydrophobilization or adsorption-precipitation may be the primary mechanism. The average DOC removal of Zhujiang River was higher than Miyun water and they were both higher than Luan River remarkably. The further fractionation of DOM indicated that the higher content of HoN was in the water, the higher DOC removal. The kind of relationship between the characteristics of DOM and the DOC removal showed that the fraction distribution of DOM was also an important factor influencing DOC removal in addition to alkalinity and TOC.