Method of treating dilute phase sludges by applying electric field before dewatering

摘要

Disclosed is a method of treating dilute phase sludges having a concentration between 0.5% DS to 4.0% DS by adjusting the pH to between 5 and 6 and thereafter applying a DC voltage between 2 volts to 20 volts in a cell having electrodes of carbon, graphite, carbon fibre or stainless steel, and whilst the sludge is continuously flowing though the cell, the current density is held to between 10 amperes per square metre to 80 amperes per square metre, the temperature of the sludge is controlled to between 15 Deg. C and 37 Deg. C and the flow rate of the sludge is such that a residence time of 2 minutes to 10 minutes is achieved and thereafter, after the sludge leaves the cell, a cationic polymer is added to the sludge at a dose rate of between 4 kg/t DS to 20 kg/t DS and then subjected to further dewatering to achieve a final DS of the sludge between 25% DS to 40% DS.