Processing of sewage sludge: Dependence of sludge dewatering efficiency on amount of flocculant

Paper presents results of experimental dewatering of stabilized sludge analysis and study. The experiments were carried out at a small waste water treatment plant (15,000 population equivalent). Experiment focused on impact of consumption of flocculant and centrifuge load on quality of dewatered sludge and centrate. Dry solids in dewatered sludge and content of undissolved particles in the centrate were observed in particular for proper evaluation of the experiment. It was proven that specific consumption of flocculant has greater impact on centrate quality than on dry solids content in dewatered sludge. It was possible to increase dry solids content in dewatered sludge only by 10% at most. However, amount of undissolved particles dropped more than ten-fold. Regarding quality of dewatered sludge and centrate, optimum specific consumption of flocculant during the experiment amounts to 8 g/kg of dry solids of sludge with flocculant concentration being 0.16% and centrifuge load reaching 110 kg/h of dry solids. Specific consumption of flocculant amounting to 5.4 g/kg of dry solids of sludge (calculated value) under identical operational conditions proves to be the best economical option.