Application of Yellow Clay Powder for Efficient Treatment of Cyanobacterium Microcystis sp. - Laden Source Water in Drinking Water Treatment Facility

Abstract

Objectives : This study evaluated the effect of dosing yellow clay powder as a sedimentation aid when Microcystis sp. bloomed.Methods : Pre-oxidation (chlorination and ozonation) treatment and coagulation/precipitation experiments of Microcystis sp. - laden source water were performed with a jar-tester. Treatment efficiency was evaluated by analyzing the turbidity and particulate matter of the supernatant after sedimentation according to the presence or not of pre-oxidation, the concentrations of yellow clay powder, and polyamine dosing.Results and Discussion : As a result of evaluating the turbidity and particulate matter of the supernatant after coagulation/sedimentation according to the dosing concentrations of yellow clay powder, the turbidity of the supernatant decreased as the dosing concentrations of yellow clay powder increased regardless of the presence or not of pre-oxidation. In particular, when pre-oxidation was not performed, both turbidity and particulate matter of the supernatant after sedimentation were significantly reduced. In addition, without pre-oxidation, when yellow clay powder (50 mg/L) and polyamine (1.0 mg/L) were dosed together, turbidity was reduced by 25% and the amount of particulate matter by 41% compared to utilizing pre-oxidation. Regarding the concentrating efficiency of sedimentation sludge, when yellow clay powder was added, concentrating efficiency increased by more than 31~38% regardless of pre-oxidation treatment compared to when yellow clay powder was not added. However, with pre-oxidation, the concentrating efficiency decreased by about 27~34% under the same yellow clay powder and polyamine dosing conditions compared to without pre-oxidation.Conclusion : When yellow clay powder was added to Microcystis sp. - laden source water, turbidity and particulate matter were effectively reduced after coagulation/sedimentation regardless of the presence or not of pre-oxidation. In particular, when pre-oxidation was not performed, the turbidity and particulate matter after coagulation/sedimentation were significantly reduced as compared with utilizing pre-oxidation, and using yellow clay powder together with a polyamine reduced turbidity and particulate matter the most. In addition, the sludge concentration of Microcystis sp. - containing sludge with low concentrating efficiency was increased by dosing yellow clay powder.