DEWATERING OF SLUDGE USING SUPERCRITICAL CARBON DIOXIDE

Traditional sludge disposal methods pose environmental concerns and are economically expensive due to high moisture content. Dewatering is an important step to address these concerns. Conventional dewatering technologies include thermal drying and mechanical compression of sludge. Recently, dewatering with supercritical CO2 has started gaining attention as a potential low-cost alternative to these conventional technologies. While many published studies on supercritical CO2 dewatering are usually in a small reactor volume (similar to 0.1 L), sludge dewatering in a relatively large reactor volume (similar to 1 L) is demonstrated here as a feasible alternative to existing methods. Influence of equilibrium/ sCO(2) residence time and wet-sludge loading rate on the dewatering performance was determined from three-staged experiments. Within the first stage of dewatering, 40-60% dewatering was noticed. Preliminary techno-economic analysis showed a 5-50% reduction in sludge dewatering cost with supercritical CO2 in comparison to thermal drying.