Removal of CaCO3 scales on a filter membrane using plasma discharge in water

In modern wastewater treatment, filters are routinely used for removing unwanted particles from water. The present study investigated if a pulsed spark discharge in water can be used to remove deposits from the filter membrane for its potential application in drinking and industrial water treatment. The test setup included a circulating water loop and a pulsed power system. The present experiments used artificially hardened water with hardness of 1000 mg/L of CaCO3 made from a mixture of calcium chloride (CaCl2) and sodium carbonate (Na2CO3) in order to produce calcium carbonate deposits on the filter membrane. Spark discharge in water was found to produce strong shockwaves in water, and the efficiency of the spark discharge in cleaning filter surface was evaluated by measuring the pressure drop across the filter over time. Results showed that the pressure drop could be reduced to the value corresponding to the initial clean state and after that the filter could be maintained at the initial state almost indefinitely, confirming the validity of the present concept of pulsed spark discharge in water to clean dirty filter. (C) 2009 Elsevier Ltd. All rights reserved.