二级出水溶解性有机物与铝盐混凝剂反应特性研究

Reactivity characteristics of dissolved secondary effluent organic matter with aluminum coagulants

以污水处理厂二级出水溶解性有机物(EfOM)为考察对象,研究了EfOM与铝盐混凝剂的反应特性及混凝过程中EfOM组分的变化。通过不同投药量下COD和TOC的去除效果比较确定氯化铝混凝剂的最佳投药量为11 mg/L。在此投药量下进行混凝实验,结合原水和混凝水的1H NMR、三维荧光光谱和分子质量分布分析可得:混凝过程中,脂肪族和芳香族的有机物很容易被混凝去除,而消毒副产物的前驱体只能被部分去除;原水中低激发区蛋白类物质荧光强度高于高激发区蛋白类物质,混凝对低激发区蛋白类物质有一定的去除效果,但基本不会改变高激发区蛋白类物质的分子质量分布。铝盐和EfOM络合时有2个结合位点,分别位于203 nm和350 nm,二维紫外相关光谱揭示了铝盐混凝剂和EfOM结合位点的络合顺序,络合首先发生在较长的波长(350 nm)位点,其次是较短的波长(203 nm)位点。

Taking the dissolved secondary effluent organic matter(EfOM)of waste water treatment plant as research object,the coagulation characteristics of EfOM with aluminum coagulants and changes of organic components dur⁃ing coagulation were studied.The optimal aluminum chloride coagulant dosage was set at 11 mg/L by comparing the removal effects of COD and TOC at different dosage.Based on this condition,jar-text experiments were carried out combined with the analysis of 1H NMR,three dimensional fluorescence spectrum and molecular weight distribution of raw and coagulated water.It was concluded that aliphatic and aromatic organic compounds could be easily re⁃moved,while the precursors of disinfection by-products could only be partially removed.The fluorescence intensity of protein-like substances in low excitation region of raw water was higher than that in high excitation region.Coagu⁃lation had a certain removal effect on protein-like substances in low excitation region.However,the molecular weight distribution of the protein-like substances of high excitation region was not changed by coagulation.It re⁃vealed that EfOM exhibited two binding sites(203 nm and 350 nm)for Al complexation.Two-dimensional correla⁃tion ultraviolet spectroscopic indicated the binding sequences of EfOM during coagulation with aluminum.The re⁃sults demonstrated that EfOM binding to Al first took place at longer wavelengths(350 nm)site,followed by the shorter wavelengths(203 nm)site.