Abstract: The impacts of recycling 2%, 5% or 8% by volume of filter backwash waters (FBWWs) blended with corresponding raw water W1 (synthesized water) and W2 (‘Longtan’ lake water), as compared to control trials where FBWW was not added on specific bulk water parameters, i.e. DOC, UV254 and specific ultraviolet absorbance (SUVA) removal in coagulation-sedimentation processes were evaluated The fluorescence characteristics of dissolved organic matter (DOM) in source waters, FBWWs and treated water samples were identified, and the comparisons of various recycling ratios were conducted. Results indicated fluorescent components in raw water and corresponding untreated FBWWs DOM were mainly humic-like fluorophore (Peak A) and protein-like fluorophore (Peak T), with the Ex/Em wavelengths at 245.0~265.0nm/400.0~435.0nm, 280.0~305.0nm/305.0~345.0nm, respectively. Additionally, the relatively lower fluorescence intensity, board Peak C was observed in all fluorescence spectra. Organics removal rates in settled water were improved with FBWW1 at observed recycling rates, while the comprised removal efficiencies were achieved in W2 samples. Fluorescence EEM spectra in the DOM of treated water samples were analogous to that of source water accordingly. The process of recycling FBWW could improve humic-like substances (Peak A) removal, but the protein-like matters were resistant to be eliminated or even be enriched with unvaried structure. The DOM removal in the coagulation process of recycling filter backwash water could be well reflected by the reduction of fluorescence intensity, therefore the three-dimensional excitation emission matrix (3D-EEM) fluorescence technique will be used in wide applications.

摘要： 选定两种水样（模拟水样W1和龙潭湖水W2）以及相应滤池反冲洗水（FBWW1和FBWW2），对比考察回流体积比为0%（空白）、2%、5%和8% FBWW直接与相应原水混合后，混凝-沉淀出水中DOC、UV254和比紫外吸光度（SUVA）去除效果及溶解性有机物（DOM）的荧光特性。结果表明：未经预处理的FBWW与相应原水中DOM荧光光谱中均出现A峰Ex/Em=245.0~265.0nm/400.0~435.0nm，T峰Ex/Em=280.0~305.0nm/305.0~345.0nm，分别代表类腐殖质和类蛋白质物质，此外有一个荧光强度较弱的峰带-C峰。FBWW1回流均可强化W1中DOM去除，FBWW2回流混凝去除DOM效果不明显。不同回流比出水中DOM三维荧光光谱与各自原水中DOM光谱图较为相似。FBWWs回流工艺可强化类腐殖质（A峰）去除，而对类蛋白物质（T峰）没有去除甚至有所富集，且结构变化不明显。荧光强度的削减可以有效地反映滤池反冲水回流混凝-沉淀工艺中DOM去除情况，荧光技术将具有广阔应用前景。

关键词: 滤池反冲水, 回流, 溶解性有机物, 三维荧光, filter backwash water, recycling, dissolved organic matter, 3D-EEM