DEVELOPMENTS IN LABORATORY EVALUATION OF SEWAGE SLUDGES DEWATERABILITY

Literature review shows that particle size distribution, water distrib ution and rheological properties can play an important role in the eva luation of dewatering performance. Following a previous study on relat ionships between rheological parameters and filterability parameters, work has been addressed to the understanding of the influence of parti cle size and water distribution on specific resistance to filtration. Tests were carried out on different types of sludge (raw, digested, co nditioned). Two substantially different techniques for measuring the p article size distribution were used, showing that the mechanical techn ique (sieving) resulted in larger particle sizes than the optical (las er diffraction). Results showed that particle size distributions play a role in describing sludge filterability.