Evaluation of effective conditioners for enhancing sludge dewatering and subsequent detachment from filter cloth

Various types of materials (including ferric chloride, alum polymers, acids , wood chips, wheat dregs, diatomite, and coal ash) were used individually to condition a digested sludge from a brewery to investigate how adding the se materials affected the dewaterability and adhesion of the sludge. Specif ic resistance (SR) to filtration, as an index of sludge dewaterability, and the mass of residue (MR) on the filter cloth after cake detachment, as an index of sludge adhesion, were measured to evaluate the effectiveness of co nditioners. Among these additives, ferric chloride, alum, commercial organi c polymers, and acids proved to be effective chemicals in reducing SR. Howe ver, only ferric chloride addition effectively decreased sludge adhesion. T he optimum dosage of ferric chloride is around 15%, based on the original d ry solids content of the sludge. Wood chips and wheat dregs were verified a s suitable physical conditioners for both improving dewaterability and also reducing adhesion of sludge. These two inert materials also satisfy the re quirements that conditioners be biodegradable, easy to obtain, and low cost , to maintain the potential utilization value of the resulting sludge cake.