不同有机物对含藻水体混凝效果和絮体特性的影响

Effects of different organic substances on the coagulation effect and floc properties of water containing algae

为了解不同有机物对含藻水体混凝过程的影响,以含铜绿微囊藻水体作为实验对象,考察牛血清蛋白(BSA)和腐殖酸(HA)2种有机物及其质量浓度对含藻水体浊度、藻类有机物的去除效果以及絮体形成、破碎、再絮凝的影响。结果表明,少量的BSA对混凝反应起促进作用,当BSA的投加量超过1 mg·L^(-1)转为抑制作用,因为投加量升高时,BSA抢占混凝剂活性位点,抑制混凝反应。HA不利于混凝反应的进行,因为HA中的官能团优先与混凝剂结合,从而导致混凝效果变差。提高混凝药剂投加量可缓解有机物质量浓度增加对混凝效果的影响。当BSA投加量为5 mg·L^(-1),PACl投加量为0.06 mmol·L^(-1)时,能达到出水浊度小于1 NTU,藻细胞去除率大于90%的混凝效果,HA添加量为5 mg·L^(-1),PACl投加量为0.12 mmol·L^(-1)时,也能达到相同的混凝效果。混凝更容易去除分子质量较大的BSA和HA,而对小分子亲水性有机物的去处效果较差,如藻类有机物或HA中小分子有机物。少量的BSA和HA增加了混凝絮体的生成速率和初始粒径。本研究结果可为天然水体混凝除藻工艺优化运行提供参考。

In order to understand the influence of different organic substances on the coagulation process of algal water,this study took the water containing Microcystis aeruginosa as the experimental object,and investigated the influence of two kinds of organic substances,bovine serum albumin(BSA)and humic acid(HA),and their mass concentrations on the turbidity of the algal water,the removal of algal organic matter,and the formation of flocs,fragmentation,and re-flocculation.The results showed that:1)a small amount of BSA promoted the coagulation reaction,and when the dosage of BSA exceeded 1 mg·L^(-1),it turned into an inhibition,because when the dosage was elevated,the BSA seized the active sites of the coagulant and inhibited the coagulation reaction.2)HA was detrimental to the coagulation reaction because the functional groups in HA preferentially bound with the coagulant,which led to the deterioration of coagulation effect.3)Increasing the dosage of coagulant could alleviate the effects of organic matter mass concentration and floc formation.The dosage can alleviate the effect of increasing organic mass concentration on the coagulation effect.When the dosage of BSA was 5 mg·L^(-1)and the dosage of PACl was 0.06 mmol·L^(-1),the coagulation effect of effluent turbidity less than 1 NTU and algal cell removal rate more than 90%can be achieved,and the same coagulation effect can be achieved when the dosage of HA was 5 mg·L^(-1)and the dosage of PACl was 0.12 mmol·L^(-1).4)Coagulation was more likely to remove molecular weights BSA and HA,while it was less effective in removing small hydrophilic organics,such as algae organics or small molecule organics in HA.5)Small amounts of BSA and HA increased the generation rate and initial particle size of coagulated flocs.The results of this study can provide a reference for the optimal operation of coagulation and algal removal processes in natural waters.