Investigation into alternative sludge conditioning prior to dewatering

Abstract

The principal objective of this work is to provide a more effective alternative for sludge conditioning prior to mechanical dewatering. The common use of polyelectrolytes often results in the final cake solids concentration not sufficiently high for the sludge to be beneficially reused or safely disposed. The pyrolysed domestic refuse (char) was used to increase the structural strength and permeability of biological sludges in order to increase final cake solids concentration. The laboratory experiments have proven that the mixture of char and a small quantity of polyelectrolyte (0.5 to I kg per ton of dry solids), used as a conditioner prior to centrifugation and filtration tests, produced cake solids concentration superior to that obtained by using polyelectrolyte on its own. Laboratory dewatering by filtration with admixture of char and polymer, resulted in cake solids concentration of 30 and above 40 per cent.