SLUDGE ACCUMULATION IN PONDS FOR WASTEWATER TREATMENT USING ALUM PRECIPITATION
Sludge accumulation techniques in pond systems for wastewater treatment, particularly those using chemical precipitation, were reviewed. The chemical sludge at Bruksvallarna treatment plant, a ten year old chemical precipitation pond using alum (AVR), was investigated with respect to volume and content of total solids and its volatile fraction. The volume of the primary sludge was also estimated. The overall sludge accumulation was 11 l/m3 of wastewater treated. The organic content of the solids in the chemical sludge was approximately 50 %, and was independent of the sludge sampling depth, A simple relationship, originally developed for deposited lake sediments, was shown to adequately describe the compression of the chemical sludge.