Abstrait

EVALUATION OF OPTIMAL DOSE AND pH OF AN IN-LINE ALUM FACILITY TO INLETS IN KUKKARAHALLI LAKE, MYSORE

Roopa .C , Sadashiva Murthy .B .M

In-line Alum injection facility is an innovative application technology in restoring lakes. In this technology, guidelines for dose calculation and application are lacking. In this study, Jar tests are carried out to optimize alum dose and study alum effect on pH. Four major inlets to lake are taken for study of water quality and application of alum treatment. This treatment resulted in immediate and substantial improvements to water quality in Kukkarahalli Lake. Tests showed that alum dose between 15-20 mg/L is sufficient to decrease phosphorus from around 0.1 mg/L to below 0.025 mg/L which is the limiting value for eutrophication. Alum doses of up to 20 mg/L did not depress pH below the recommended minimum pH of 6. Test study were conducted to see the effect of pH on alum treatment, it is seen that at a pH of 6, alum dose application can be reduced to between 5-10 mg/L.