ELECTRO-OSMOSIS DEWATERING OF COAL SLUDGE

In waste treatment process, decreasing of water load from the coal sludge is economical and feasible before disposal. Electroosmosis dewatering (EOD) is more energy saving and effective process over other conventional dewatering process. Draining of water from the sludge by generating potential gradient in between two electrodes which were placed in the sludge; is called electro-osmotic dewatering process. A direct current (DC) was used to create that potential difference. This experiment was done by dewatering fine coal sludge using two copper disks as electrodes. It is reported that the flow rate of dewater is proportional to the potential difference between two electrodes and the zeta potential of the sludge particle [2] . In this study, the voltage is increased from 40V to 100V with constant current (1.1 Amp) supply. The zeta potential of the coal particle is increased by adding 1%, 2% and 5% (w/v) sodium hydroxide (NaOH) solution, respectively. The volume of water removed, % moisture content of coal slurry after EOD, volume of water evaporated from the hot electrode surface, and energy consumption are measured for each case. It is observed that as the increasing NaOH concentration and the potential difference in the slurry, the % moisture content of slurry is reduced after EOD. The moisture content of the slurry is measured at 5% NaOH for 100V is around 19.7% which is approximately 6% lower than as compared to without using caustic solution under same operating condition. The energy used for the removal of above moisture content (19.7%) is around 5KWh/Kg of dewater, which is 54% less than the thermal processing of sludge.