Influence of ultrasonic disintegration on sludge growth reduction and its estimation by respirometry

Excess biomass generation during wastewater treatment is a great threat to the ecology if it is not properly disposed. Sludge growth reduction is one of the best ways to alleviate the problem. The present study focused in this direction employs ultrasound to disintegrate the floc without causing cell disruption. It has been found that a major size reduction that takes place at a lower energy input (3000 kJ/kg) and a further increase in energy input results only in minor changes. Sludge growth reduction is found to be of the order of 29% and energy efficient under flow-through conditions. The effect of disintegration is substantiated by respirometric studies, microscopic examination, degree of inactivation, and degree of COD release.