Combined action of electro-osmotic drainage and mechanical compression on sludge dewatering

The efficiency of the implemented industrial means of sludge dewatering, at the present time, is not sufficient. Therefore, research of new techniques of advanced dewatering is necessary. Electro-osmotic drainage, notably used to consolidate soils, has recently been used to dewater sludges. In this work, a laboratory cell has been constructed. It permits one to superimpose a mechanical pressure adjustable to 7 kg/cm² to the electro-osmotic drainage. The application of an electrical field decreases the specific resistance of sludges to filtration with variable factor, which can result from both the electrical conductivity and the charge of the particles. However, in thickening, it enables organic sludges to reach very high solids concentration when compared to their dewatering by filtration under high mechanical pressure. The energy consumption does not seem to be an important constraint in sludge dewatering with this technique.