新型硫酸铝-壳聚糖助滤剂强化砂滤效能研究

将硫酸铝和壳聚糖复配作为微絮凝助滤剂（AS-CTS），考察其强化过滤性能.利用分子量分级、荧光光谱等手段分析有机物的去除特性，通过Zeta电位、絮体粒径、分形维数的变化分析其强化过滤机理.结果表明：AS-CTS较AS、CTS强化过滤效果明显，在AS/CTS复配比为2：1、CTS投加量0.3mg/L，转速300r/min，搅拌时间2min的条件下，砂滤出水浊度能达到0.1NTU、颗粒物125个/mL，残余铝浓度0.02mg/L；浊度和颗粒物去除率较未加AS-CTS分别提高了58%、61.7%.AS-CTS强化过滤可有效去除分子量>30KDa的腐殖酸和1~3KDa间的色氨酸类蛋白、溶解性微生物代谢产物、类富里酸.AS-CTS主要靠高分子吸附架桥作用和界面化学作用，增加胶体颗粒在滤料表面的粘附；通过形成较大粒径和分形维数的微絮体，增强絮体向滤料表面的迁移.

Enhancement sand filtration by an innovative filter aid: aluminum sulfate-chitosan (AS-CTS)

A combination of aluminum sulfate (AS) and chitosan (CTS) was used as an innovative filter additive, namely AS-CTS, to enhance the filtration. The properties of the trapped organics were analyzed by molecular weight fractionation and three-dimensional fluorescence spectroscopy, and the mechanism of enhanced filtration by AS-CTS was preliminarily investigated via the analysis of zeta potential, floc size, and fractal dimension. The results indicated that AS-CTS strengthened the filtration much more than AS or CTS alone. Under the optimum condition (AS/CTS mass ratio of 2/1, CTS dosage of 0.3mg/L, rotation speed of 300r/min, and stirring time of 2min) the effluent turbidity was 0.1NTU, particulate matter was 125/mL, residual aluminum concentration was 0.02mg/L. The turbidity and particulate matter removal rate was respectively 58% and 61.7% higher than that without AS-CTS. It was found that AS-CTS enhanced filtration could effectively remove hydrophobic humic acid with molecule weight > 30KDa, tryptophan protein with molecule weight between 1and 3KDa, soluble microbial metabolites, and fluvic-like acid. AS-CTS could increase the adhesion of colloidal particles on the surface of the filter media, mainly through the polymer bridging and interface chemistry, and enhanced the migration of particles to the surface of filter media by forming larger micro-flocculant in size and fractal dimension.