STUDIES ON COLIFORM REMOVAL IN OXIDATION PONDS SYSTEMS

Abstract

Waste stabilization ponds are an efficient mean of wastewater treatment in many part of the world wherever suitable land is available at reasonable cost and solar energy is an abundant energy resource. This study evaluated the removal of total coliforms (TC), fecal coliforms (FC) and fecal streptococci (FS) in waste stabilization pond functioning at full scale system in the tropical climate of Rishikesh, North India. Sampling points are raw sewage and each pond effluent. In Oxidation Pond Lakkarghat (Rishikesh) 5 ponds are provided in series. Turbidity, pH and temperature are recorded. The average concentrations of TSS, BOD, COD in raw sewage are 265 mg/L, 170 mg/L, 445.73 mg/L and these concentrations in effluent are 70.5 mg/L, 37.42 mg/L and 104.52 mg/L respectively. The average concentration (Geometric mean) of TC, FC and FS at inlet and outlet are 2.7x108 and 6.5x104 MPN/100m1, 5.4x107 and 1.7x104 MPN/100m1, 7.7x106 and 1.6x103 MPN/100m1 respectively. The percentage removal of TSS, BOD, COD, TC, FC and FS are 73.38%, 78.02%, 76.81%, 99.973%, 99.971% and 99.981% respectively. In the present study correlations between Physico-chemical and indicator microorganisms are developed. Since the analysis of indicator microorganisms is very costly and time consuming. The correlation coefficient (R2) of TC vs. TSS, Turbidity, BOD and COD are 0.943, 0.773, 0.893 and 0.922 respectively. The correlation coefficient (R2) of FC vs. TSS, Turbidity, BOD and COD are 0.940, 0.774, 0.875 and 0.910 respectively. The correlation coefficient (R2) of FS vs. TSS, Turbidity, BOD and COD are 0.948, 0.7629, 0.864 and 0.910 respectively.