CHANGES OF SOME SEWAGE-SLUDGE PARAMETERS PREPARED WITH AN ULTRASONIC-FIELD

Studies of sewage sludge conditioning by ultrasonic field concentrate on determination of the increase of water removal effect, which depend s on kind of sludge and chemical compounds used in the dewatering proc ess. An attempt was made to find new methods of sludge preparation bef ore dewatering. Tests presented here focused on digested and difficult dewatered sludge. The sludge was dewatered on a vacuum filter after c onditioning with polyelectrolytes and the ultrasonic field. The micros copic analysis was an additional criterion to evaluate changes in the sludge structure after preparation. The polyelectrolyte dose of 3 mg/g d.m. sonicated within 15 sec. resulted in the 50% decrease of sludge volume. Results presented confirmed our previous experiences, concerni ng the relation between conglomerates of sludge and the effect of dewa tering. (C) 1997 IAWQ. Published by Elsevier Science Ltd.