COLUMN SETTLING TESTS FOR HINDERED BATCH SETTLING IN ACTIVATED SLUDGE

摘要

Sedimentation experiments under hindered settling were performed at steady state on dairy activated sludge using settling columns of dimensions (2.25 cm ID x 65 cm Ht), (2.25 cm ID x 90 cm Ht), (2.25 cm ID x 120 cm Ht) for MCRT of 5, 7 and 9 days for initial MLSS concentration ranging from 2 g/L to 20 g/L. Zone settling velocities were determined to analyze the effect of initial height of settling column on biofloc settling. A program was developed in MATLAB to interpolate the zone settling velocity values obtained for a known height of settling column to get the zone settling velocity at unknown height of the clarifier. To check the accuracy of the program the velocities were also calculated by using Work & Kohler approach. No appreciable change in zone settling velocity was observed with respect to height of the settling column. The results indicate that the variation of zone settling rate of the suspension with respect to height of the settling column is insignificant.