壳聚糖絮凝分离豆腐废水蛋白的研究

Chitosan-Based Coagulating Agents Effective for Treating Tofu Wastewater

研究了采用生物絮凝法处理豆腐废水的可行性。探讨了絮凝剂的种类、添加量、废水的前处理、絮凝时间及pH对絮凝效果的影响,并重点比较了复合絮凝剂对废水中蛋白质和低聚糖的絮凝作用。单一絮凝剂试验结果显示壳聚糖的絮凝效果明显优于聚合硫酸铁、聚合三氯化铝、海藻酸钠、聚丙烯酰胺。较优的添加量为0.6～0.8 mg/mL,添加量过高浊度会不降反升。絮凝前废水-18℃冷冻处理有利于蛋白质的分离,絮凝后的沉降是必要的,时间以12 h为宜。复合絮凝剂中所有组合都表现出明显的协同增效作用,尤以0.5mg/mL壳聚糖＋0.3mg/mL海藻酸钠效果最佳,pH 4.5条件下絮凝后浊度降低97.8%,原液中蛋白脱除率高达76.842%,而低聚糖（减少6.56%）几乎不受影响,是较为理想的豆腐废水絮凝剂组合。

Tofu wastewater was treated by using the biocoagulation separation method.The turbidity of coagulate supernate was investigated in relation to the kinds of coagulating agent,addition dosage,preservation temperature of wastewater,coagulation time and pH,focusing on the synergistic effect of coagulating agent complexes.Results on experiments with single coagulating agent suggest that chitosan at 0.6~0.8 mg/L shows a maximal turbidity reduction than poly ferric sulfate,poly aluminum trichloride,sodium alginate,and polyacrylamide.Freezing treatment of waste water at-18 ℃ before coagulation is fit for protein separation.Coagulation time plays a significant role in adsorption,and it is necessary for at least 12 h.All complex coagulating agents show noticeable synergistic effect.Especially,chitosan/alginate complex（monomeric mixing ratio of 1.67） at 0.8 mg/mL,under condition of pH 4.5 exhibits optimum coagulation effects with turbidity reduction of 97.8%,protein removal rate of 76.84%,whereas hardly has any significant effect on soy oligosaccharide（6.56%）.Chitosan/alginate complex is an ideal coagulating agent for protein separation from Tofu wastewater.