Temperature effect on settling velocity of activated sludge

Batch settling tests performed at most of the plants and the settling velocity was generally correlated to MLSS concentration. The majority of these MLSS settling test not include any form of temperature compensation. The present work was done to prove that temperature was an important factor on activated sludge settling. Batch settling test was taken at different temperature for the sludge extracted from a Tunisian wastewater treatment plant. The results were shown that a high temperature increases the settling velocity but it can increase the turbidity of supernatant. The evolution of settling velocity function the temperature was not linear. A low temperature also has increased a settling velocity. The Vesilind settling model parameters was also influenced by temperature. Increasing temperature from 21°C to 40°C has increased initial settling velocity from 0.143 m/h to 0. 9 m/h and decreased the hindered mass coefficient from 1.107 to 0.556 L/g.