The Removal Of Algae In Water Body By Modified Clay

In recent years, algae blooms which caused by eutrophication occurred more andmore frequently. The outbreak of cyanobacterial blooms caused a serious impact topeople’s lives. Cyanobacterial blooms also happened in Shijiazhuang circular water systemwhich have a serious impact on the ornamental of landscape water. It has been found thatthe advantage algae species caused water bloom is Oscillatoria Agardhii through theanalysis of microscopic samples. This paper aims to develop efficient algae removalmaterial for emergency controlling of algal bloom in landscape water. The bestflocculation condition of Oscillatoria has been researched which can be used as theguidance for actual water body governance.The technology of removal algae by modified clay is an effective way to removealgae blooms in water body, how to improve the efficiency of modified clay and algaeremoval rate has become the main research direction of this technology. The removal ofOscillatoria by montmorillonite modified by inorganic polymer flocculantspolyaluminium chloride (PAC) and cetyl trimethyl ammonium bromide (CTAB) wasstudied in this experiment. The changes of turbidity as well as the chlorophyll (a) beforeand after the treatment were used to characterize the algae removal performance. Theappropriate component proportion and suitable operation condition of Oscillatoria removalby compound modified montmorillonite were investigated by signal factor and orthogonalexperiments. The results show that the suitable flocculation conditions for removal ofOscillatoria by modified clay are70mg/L montmorillonite with160mesh particle size,9mg/L PAC,0.875mg/L CTAB and pH8.0. Under these conditions the removal rate ofturbidity and chlorophyll(a) can reach96.02%and93.90%.The results showed that if purifying water with polyaluminum chloride(PAC) alone,the formed floccules are too incompact to subside. The flocculation effect could beimproved by adding montmorillonite, but the flocculating constituents may floating upbecause of the oxygen that released by algae photosynthesis. The condition can beimproved by adding surfactant CTAB. Modified clay has a good removal effect on algalcells in various periods and has a role in removal of algal toxins.The algae removal mechanism of the modified clay was analyzed by Zeta potential ofalgae removal material and morphological characterization of floc by biomicroscope SEM. The modified clay flocculate algal cells by charge neutralization absorption, gathering andunwrapping. The surface charge of montmorillonite change from electronegativity toelectropositivity after being modified by PAC and CTAB, and the rate and effect of algaecells flocculation-settling. Modifying agent CTAB inactivate the algal cells which inhibitsthe re-suspension of algae flocs and improves the effect of algae removal.The pH, turbidity, COD, chlorophyll a and other indicators of circular water systemwere measured and analyzed through regular sampling to study the relationship beteenmain indicators of water quality and water bloom. Based on the best conditions onlaboratory-derived coagulation treatment applied to the actual body of water, it found thatthe treatment effect is quite effective, it provides a scientific basis for cyanobacterialblooms treatment.