壳聚糖/羧甲基纤维素钠复凝聚体系处理高浊度水体中污染物研究

Treatment of pollutants in high turbidity water by chitosan/sodium carboxymethyl cellulose complex coagulation system

混凝工艺因成本低廉、操作简单而成为地表水处理的常见工艺,但现有混凝剂存在对地表水中溶解性有机物去除率较低的问题。针对我国地表水体普遍存在的有机微污染问题,设计一种通过壳聚糖/羧甲基纤维素钠于水中原位生成的复凝聚絮体以代替传统混凝剂并去除污染物的新工艺,进而将复凝聚技术原位生成网状絮体应用于水污染处理中。选取高岭土和盐酸四环素分别模拟黄河水中的无机胶体和有机微污染物,探究初始浊度、壳聚糖/羧甲基纤维素钠投加质量浓度对两类污染物的去除效率和机理,并进一步对混凝后产生污泥的吸附性能进行研究。结果显示,壳聚糖/羧甲基纤维素钠对不同模拟污染水的浊度去除率都在99%以上,对盐酸四环素-高岭土和黄河水-盐酸四环素中盐酸四环素的最佳去除率分别为40.02%和56.72%,效果明显优于聚合氯化铝(Polyaluminium chloride,PAC)。壳聚糖/羧甲基纤维素钠和高岭土共沉淀产生的污泥能够对水中盐酸四环素进行化学吸附,最高吸附质量比达4.81 mg/g。壳聚糖/羧甲基纤维素钠复凝聚体系对地表水中的无机污染物和有机污染物均有较好的去除效果,且所得污泥具有回用价值,具有良好的应用前景。

Coagulation is a common process for surface water treatment due to its low cost and simple operation,but existing coagulants have the problem of a low removal rate of dissolved organic matter in surface water.In response to the widespread organic micro-pollution in surface waters in China,this paper designs a new process to remove pollutants by replacing traditional coagulants with complex coagulation flocs generated in situ by sodium chitosan/carboxymethylcellulose in water.Kaolinite and tetracycline hydrochloride were selected to simulate inorganic colloids and organic micro-pollutants in the Yellow River water respectively,and the initial turbidity and the amount of sodium chitosan/carboxymethylcellulose dosing were investigated on the removal efficiency and mechanism of the two types of pollutants,and the adsorption performance of the sludge produced after coagulation was further investigated.The experiments show that the turbidity removal rate of sodium chitosan/carboxymethyl cellulose was above 99% for different simulated polluted water and the best removal rates of tetracycline hydrochloride-kaolin and yellow river water-tetracycline hydrochloride were 40.02% and 56.72% respectively.Compared with PAC,the coagulation time of CS/CMC was shorter,the dosage was less and the coagulation effect was better.The sludge produced by co-precipitation of chitosan/sodium carboxymethylcellulose and kaolin was able to chemisorbed tetracycline hydrochloride in water with a maximum removal rate of 98.46% and a maximum adsorption capacity of 4.81 mg/g.This indicates that the flocs produced by coagulation were able to adsorb dissolved organic pollutants,enabling the sludge to be reused.The adsorption kinetic fitting shows that the adsorption of tetracycline hydrochloride by the sludge produced by co-precipitation of chitosan/sodium carboxymethylcellulose and kaolin clay was more in line with the quasi-secondary kinetic model.It is also consistent with the Freundlich adsorption isotherm model,which is a spontaneous and disordered heat absorption reaction.In conclusion,the chitosan/sodium carboxymethylcellulose co-collocation system has good potential to remove both inorganic and organic pollutants from surface water and the resulting sludge has good reuse value.