混凝和活性炭吸附去除微污染水源水中DON的研究

溶解性有机氮(dissolved organic nitrogen,DON)作为饮用水中新兴氮消毒副产物(nitrogenous disinfection by-products,N-DBPs)的前体物逐渐受到国内外学者的关注.为探讨混凝和活性炭吸附对微污染水源水中DON的去除机制,首先测定原水中DON、溶解性有机炭(dissolved organic carbon,DOC)、NH4+-N、UV254、pH和溶解氧(dissolved oxygen,DO)等指标和DON、DOC分子量分布;接着通过混凝和活性炭吸附试验来考察原水中DON、DOC和UV254变化,并应用三维荧光光谱对原水中DON变化进行表征.结果表明,微污染水源水中DON、DOC和UV254分别为1.28 mg.L-1、8.56 mg.L-1和0.16 cm-1,DOC与DON比值(DOC/DON)为6.69 mg.mg-1,SUVA为1.87 m-1.(mg.L-1)-1;小分子量(<6 000)DON占较高比例约为68%,大分子量(>20 000)DON占的比例为22%;当混凝剂投加量为10 mg.L-1,DON的去除率大约为20%,DOC和UV254去除率约26%、70%;当活性炭投加量为1.0 g,DON、DOC和UV254的去除率大约为60%、35%、100%;混凝和活性炭吸附组合试验时,对DON、DOC的去除率大约为82%和64%;三维荧光光谱证实,原水中DON变化与3个主要峰有关,分别代表物质为色氨酸类蛋白质、芳香族类蛋白质和富里酸类物质.

Removal of DON in Micro-polluted Raw Water by Coagulation and Adsorption Using Activated Carbon

Dissolved organic nitrogen as a precursor of new type nitrogenous disinfection by-products in drinking water attracted gradually the attention of scholars all over the world. In order to explore the mechanism of DON removal in micro-polluted raw water by coagulation and adsorption, water quality parameters, such as DON, DOC, NH₄⁺-N, UV₂₅₄, pH and dissolved oxygen, were determined in raw water and the molecular weight distribution of the DON and DOC was investigated. The variations in DON, DOC and UV₂₅₄ in the coagulation and adsorption tests were investigated, and the changes of DON in raw water were characterized using three-dimensional fluorescence spectroscopy. The results showed that DON, DOC and UV₂₅₄ were 1.28 mg·L^-1, 8.56 mg·L^-1, 0.16 cm^-1, and DOC/DON and SUVA were 6.69 mg·mg^-1, 1.87 m^-1·(mg·L^-1)^-1 in raw water, respectively. The molecular weight distribution of the DON in raw water showed a bimodal distribution. The small molecular weight (<6000) fractions accounted for a high proportion of 68% and the large (>20000) fractions accounted for about 22%. The removal of DON, DOC and UV₂₅₄ was about 20%, 26% and 70%, respectively, in the coagulation test and the dosage of coagulant was 10 mg·L^-1. The removal of DON, DOC and UV₂₅₄ was about 60%, 35% and 100%, respectively, in the adsorption test and the dosage of activated carbon was 1.0 g. In the combination of coagulation and adsorption, the removal of DON and DOC reached approximately 82% and 64%, respectively. 3DEEM revealed that the variation of DON in the coagulation and adsorption tests depended intimately on tryptophan protein-like substances, aromatic protein-like substances and fulvic acid-like substances.