氯消毒对城市污水中DOM的三维荧光特性影响

在城市污水二级出水氯消毒过程中,通过对溶解性有机物(DOM)的三维荧光光谱(3DEEM)分析及反应过程中三卤甲烷(THMs)生成量的连续测定,分析各类荧光物质随加氯反应时间的变化规律,探讨其与THMs生成量之间的关系,以此来推测THMs的主要前驱物质。结果表明,加氯后0～6 h内,各反应时间点三维荧光光谱图的等高线的密集程度较原二级出水明显降低,荧光峰的荧光强度减少40%～70%,说明DOM与氯发生反应,芳香构造化程度及不饱程度降低,从而失去荧光特性。其中,简单芳香族蛋白质(酪氨酸类)、腐殖酸类及富里酸类物质在加氯前后荧光强度变化较大,是生成THMs的主要前驱物质。THMs的生成量随反应时间的增加呈现明显的上升趋势,15 min内各类荧光特性有机物的荧光强度减少约50%左右,同时生成了50.17%的THMs。

Effect of chlorination disinfection on three-dimension fluorescence characteristic of DOM in secondary effluent

During the process of chlorine disinfection of secondary effluent,continuous measurements of 3DEEM of secondary effluent DOM and the formation amount of THMs were used to investigate the relationship between variation of fluorescence matter and the formation amount of THMs,to infer the main precursors.The results showed that the fluorescence spectrogram of samples were varied with the time of 0~6 h after added NaClO,meanwhile the fluorescence intensity of each sample reduced by 40%~70%.It indicated that the reaction between DOM and chlorine disinfectant led to decrease the aromaticity and unsaturated rate of DOM,thereby lost their fluorescence characteristic.Particularly,the fluorescence intensity of aromatic protein(tyrosine-like),fulvic-like acid and humic-like acid changed apparently before and after chlorine disinfection reaction.That is to say these organic matters could be regarded as the principal THMs precursors.The formation amount of THMs increased obviously with reaction time,especially 15 min after reaction started the fluorescence intensity of DOM decreased about 50%,meanwhile 50.17% of total trichloromethane were formed.