Removal of metals in leachate from sewage sludge using electrochemical technology

Abstract Heavy metals in acidic leachates from sewage sludge are usually removed by chemical precipitation, which often requires high concentration of chemicals and induces high metallic sludge production. Electrochemical technique has been explored as an alternative method in a laboratory pilot scale reactor for heavy metals (Cu and Zn) removal from sludge leachate. Three electrolytic cell arrangements using different electrodes materials were tested: mild steel or aluminium bipolar electrode (EC cell), Graphite/stainless steel monopolar electrodes (ER cell) and iron‐monopolar electrodes (EC‐ER cell). Results showed that the best performances of metal removal were obtained with EC and EC‐ER cells using mild steel electrodes operated respectively at current intensities of 0.8 and 2.0A through 30 and 60 min of treatment. The yields of Cu and Zn removal from leachate varied respectively from 92.4 to 98.9% and from 69.8 to 76.6%. The amounts of 55 and 44 kg tds‐1 of metallic sludge were respectively produced...