Physicochemical pretreatment and dewaterability of septage

In this study, chemical treatability of septa-e was investigated. The septa ge, taken from the equalization tank of an existing septa-e treatment plant , was coagulated by different chemicals such as alum, alum plus polyelectro lite (PE) and lime plus PE in varying dosages. After coagulation-flocculati on and sedimentation TSS, COD and total phosphorus (TP) parameters of the l iquid phase were measured. Capillay suction time (CST) was measured as an i ndication of the dewaterability of the sludge generated from coagulation. T he best results were obtained by alum plus PE and the optimum dosages for a lum and PE were found to be 200 mg/l and 2 mg/l, respectively. The COD and TSS removal efficiencies were satisfactory and the phosphorus concentration of the liquid phase was appropriate for the nutrient balance required by a ctivated sludge microorganisms. Dewaterability of sludge was also at satisf actory levels. These results imply that dewaterability of sludge could be c onsidered as an additional parameter for the determination of optimum coagu lants.