Development of the Membrane Filter Press for the Processing of Sewage Sludge

Abstract

The dewatering of sewage sludges using filter presses has been in common use for the past 80 years. The technology was mainly used in the UK for large waste water treatment plants especially where woollen grease was extracted from the sludge. It was also associated with the predrying of sludge prior to incineration in Multi Hearth Furnaces. To meet the growing demand for drier cakes and better capital productivity the membrane filter press has been developed. With the introduction of improved polyelectrolytes, polymer dosing systems, insitu cloth washing and computerised control the average pressing cycle has been reduced from 4-6 hours to under two hours. At the same time the dry solids content of the cake has become more consistent and for most waste waters in excess of 30%. The use of on-site pilot plant trails to determine the design criteria is now the accepted approach enabling sensible scale up and the setting of performance guarantees.