OPTIMIZATION OF HUMIC SUBSTANCE REMOVAL FROM WATERS BY COAGULATION WITH TAGUCHI METHOD

摘要

In this study, Taguchi method was implemented in order to optimize the humic substance removal from aqueous solution by coagulation using aluminum and ferric ions. An orthogonal array (OA_(25)) experimental design having five levels and six parameters (initial pH of the water, initial humic substance concentration, rapid mixing rate, slow mixing rate, alkalinity, and coagulant dosage) was employed in order to evaluate the effects of experimental parameters. Humic substance removal efficiency was taken as performance criteria. The obtained data were evaluated via Taguchi's 'the larger the better' performance formula. By implementing ANOVA on performance criteria, their effects on result were determined. While the optimum conditions were found to be 8 for initial pH of the water, 40 mg/L for initial humic substance concentration, 125 rpm for rapid mixing rate, 30 rpm for slow mixing rate, 50 mgHCC_3~-/L for alkalinity, and 5 mgAl~(+3)/L of coagulant dosage for aluminum; and similarly 7 for initial pH of the water, 150 mg/L for initial humic substance concentration, 300 rpm for rapid mixing rate, 40 rpm for slow mixing rate, 0 mgHCC_3~-/L for alkalinity, and 10 mgFe~(+3)/L of coagulant dosage for Ferric. Under optimum conditions, removal efficiencies are 96.42% for Al~(+3) and 88.74% for Fe~(+3).