The high concentration, complexity and refractory of organic pollutants in actual starch wastewater are becoming major obstacles to realizing efficient water purification. Herein, bentonite was selected from four kinds of clay minerals (i.e. kaolin, zeolite, attapulgite and bentonite) as coagulant aids, and chitosan-modified bentonite combined with polyglutamic acid was used for enhanced coagulation treatment for starch wastewater. Among them, bentonite can adsorb soluble pollutants in starch wastewater, chitosan modification can enhance the coagulation effect, and the flocculant of polyglutamic acid is conducive to the removal of particulate matter through bridging effects. The combination of the three can effectively and deeply remove pollutants in starch wastewater. Under the optimal conditions, the removal rates of chemical oxygen demand, total nitrogen, total phosphorus and turbidity can reach 86.2 %, 80.3 %, 52.3 % and 98.2 %, respectively, which are far higher than that of the vast majority of coagulants currently reported. Density functional theory calculation was carried out to reveal the mechanisms for the enhanced coagulation-flocculation system and explained the adsorption and coagulation mechanism, respectively. The electrostatic potential around aluminum in bentonite of 14.248 kcal.mol⁻¹ is more conducive to the adsorption of negatively charged organic pollutants, and that bentonite has lower adsorption energy (-1.43 eV) than chitosan and polyglutamic acid.

实际淀粉废水中有机污染物的高浓度、复杂性和难降解性正成为实现高效水质净化的主要障碍。本文选用高岭土、沸石、凹凸棒石和膨润土四种粘土矿物中的膨润土作为助凝剂，采用壳聚糖改性膨润土联合聚谷氨酸对淀粉废水进行强化混凝处理。其中，膨润土可吸附淀粉废水中的可溶性污染物，壳聚糖改性可增强混凝效果，聚谷氨酸絮凝剂有利于通过架桥作用去除颗粒物。三者结合可有效深度去除淀粉废水中的污染物。在最优条件下，化学需氧量去除率、总氮、总磷和浊度分别可达86.2%、80.3%、52.3%和98.2%，远高于目前报道的绝大多数混凝剂。进行了密度泛函理论计算，揭示了强化混凝-絮凝体系的机理，并分别解释了吸附和混凝机理。膨润土中铝周围的静电势为14.248 kcal.mol^-1更有利于吸附带负电荷的有机污染物，膨润土的吸附能（-1.43 eV）低于壳聚糖和聚谷氨酸。