Dewatering of bio-sludge from industrial wastewater plant using an electrokinetic-assisted process: Effects of electrical gradient

Abstract

An electrokinetic-assisted sludge dewatering (EASD) process was used to evaluate the dewaterability of the bio-sludge cake with moisture content of 68.9%. The cake sample was collected immediately after a belt filter press of an industrial wastewater treatment plant. Results showed that an average of electro-osmosis permeability of 2.2×10−5cm2/V-s was observed. After treatment, the sludge pH values near the anode and cathode were in the range of 6.5–7.5 and 9.5–10.8, respectively. The effectiveness of the EASD process was directly related to the magnitude of the electric current in the system. Increasing the potential gradient would enhance the extent of dewatering efficiency. As a constant electrical gradient of 1.25V/cm was applied, the moisture content of sludge decreased to 63.6% after 4-h treatment. The moisture content of sludge decreased further to 48.8% as the process operated at an applied potential gradient of 5.0V/cm. Energy requirement per unit ton of sludge treated was 17.7–86.5kWh/ton (dry weight). Preliminary cost analysis of the EASD dewatering process showed that approximately a saving of 23% sludge disposal cost could be realized. Results indicated that the EASD process is an economic, viable and effective technology in assisting sludge dewatering.