Dewatering of Anaerobic Digested Sludge with Oil Palm Biomass as Novel Physical Conditioner

This study investigated the use of oil palm biomass, namely empty fruit bunch (EFB), palm kernel shell (PKS), and the biomass residue, palm ash (PA), as physical conditioner, to improve the dewaterability of anaerobic digested sludge. The dewatering performance of the conditioned sludge in this work was evaluated with four common measurements i.e. the capillary suction time (CST), specific resistance to filtration (SRF), net sludge solids yield (YN), and moisture content of the sludge cake. Amongst all the biomass samples, the ground EFB passing through a 0.6-mm mesh sieve indicated the highest reduction in SRF and the highest gain in YN at solids mass ratio of conditioner to sludge of 1.6. When the conditioned sludge was subjected to filtration dewatering, the presence of oil palm biomass in sludge may act as a skeleton builder to provide a porous, permeable and rigid lattice sludge cake structure which allows the passage of water and consequently enhances water removal from sludge.