壳聚糖改性蛭石絮凝除藻效果研究

Research on flocculation to remove cyanobacteria by chitosan modified vermiculite

以水华微囊藻为对象,研究壳聚糖改性蛭石对蓝藻的絮凝去除效果,考察藻密度、初始pH值和藻类生长期对除藻效果的影响且分析了改性蛭石表面Zeta电位的变化.结果表明,投加比m(壳聚糖)∶m(蛭石)=1∶15且蛭石投加量为18 mg/L时,除藻效果最佳,浊度、藻密度和叶绿素a(chl-a)的去除率分别达到95.16%、96.67%和100%.在最佳除藻工艺条件下,壳聚糖改性蛭石的抗藻密度冲击负荷能力强;初始pH值为2.1~6.0时,除藻效果较好;衰亡后期的藻细胞较其他生长期的DOC值较高,藻去除率仅在30%左右.低浓度EOM宏观上对混凝有促进作用,高浓度干扰混凝.壳聚糖可改变蛭石的Zeta电位为正值,压缩双电层与藻体电性中和,使得藻体脱稳、聚集.

In this study, Microcystis flos-aquae was selected to explore the effects of chitosan modified vermiculite on algae removal of flocculation. The influences of algae density, initial pH and algae growing period were investigated and the change of zeta potential of modified vermiculite was analyzed. Results show that the effect of cyanobacteria removal is best when the ratio of chitosan and vermiculite is 1 ： 15 and the vermiculite addition amount is 18 mg/L, and turbidity, algal density, chl-a removal rates reach 95.16 %, 96.67 %,100 %. Under the best conditions mentioned above, the anti-algae density of chitosan modified vermiculite has a strong load capacity. The effect of algae removal is better when initial pH value between 2.1 and 6.0; The algae cells in the later stage of decline are higher than those in other growth stages, and the algae removal rate is only about 30%; Low concentration of EOM promotes coagulation, and high concentration disturbs coagulation. Chitosan can change zeta potential of vermiculite to positive, and the double electric layer is neutralized with the algae, thus the algae is destabilized and aggregated.