铜绿微囊藻对混凝除氟的促进作用及机理分析

Promotion effect of Microcystis aeruginosa on defluorination by coagulation and its mechanism analysis

以铜绿微囊藻、氯化铝(AlCl3·6H2O)为研究对象,通过三维荧光、场发射扫描电镜等表征,探究了藻类对氟化物混凝去除机制的影响.结果表明,在pH值为7.0,8.0,9.0,Al投加量在20.0~80.0mg/L的条件下,铜绿微囊藻对混凝除氟有明显的促进作用,其促进作用主要在于藻絮体对氟的表面吸附.铜绿微囊藻与氯化铝水解产物通过吸附架桥和网捕卷扫作用,聚集成较大较多的絮体.絮体粒径越大,除氟率越高.pH值为7.0,Al投加量为40.0mg/L时,絮体粒径达到最大值500μm,此时氟去除率最高,为77.37%;当Al投加量为80.0mg/L时,藻细胞破损严重,有机物过多释放,对混凝除氟起阻碍作用.絮体破碎吸附实验结果表明,对絮体进行一定强度破碎可以增加吸附位点,从而提高氟的去除率;但破碎强度过大,絮体粒径过小,对氟的吸附效率亦会降低.

Microcystis aeruginosa and aluminum chloride(AlCl3·6H2O)were chosen to research the effect of algae on the coagulation removal mechanism of fluoride through 3D-EEM,FE-SEM.The results showed that Microcystis aeruginosa had an obvious promotion effect on defluorination under the conditions of pH 7.0,8.0,9.0 and Al dosage of 20.0~80.0mg/L,which was mainly due to the surface adsorption of fluoride by algal flocs.Microcystis aeruginosa and the hydrolyzed products of coagulant aggregated into larger flocs by bridging and sweep flocculation.The larger the floc size was,the larger the fluoride removal rate was.When the pH value was 7.0 and the Al dosage was 40.0mg/L,the flocs reached the maximum particle size(500μm),and the fluoride removal rate was the largest(77.37%).When the Al dosage was 80mg/L,the algal cells were seriously damaged and the organic matter was released,which hindered the defluorination process.The results of floc breakage and adsorption experiments showed that certain strength breakage of algae floc could increase the adsorption site and thus improved the removal rate of fluoride.Excessive breakage led to too small particle size of algae flocs,resulting in the reduction of fluoride adsorption efficiency.