REMOVAL OF ZINC AND NICKEL FROM WASTEWATER TREATMENT SLUDGE BY COMBINED MAGNETIC SEPARATION AND LEACHING WITH ENHANCED ELECTROKINETIC PROCESS

Heavy metals are among the most serious environmental pollutants. Contamination of industrial waste water treatment sludge with heavy metals represents a potential threat to human and animal health. Electrokinetic remediation is one way of removing pollutants such as heavy metals from the contaminated soils. This technique is also highly cost-eective and practical for remediation of industrial sludge. In electrokinetic remediation a low-intensity electrical current is made to ow through electrodes (cathode and anode) embedded in the contaminated soil. Small ions and charged particles migrate between the electrodes encased with water. Due to electrical potential dierences, pollutants, such as heavy metals in uenced by the ow of electric current, move into the electrolytic solution. The main objective of this study is to investigate the eect of magnetic separation and sulfuric acid leaching pretreatment asawayofboostingzincandNickelremovalfromindustrial wastewater sludge through an electrokinetic process. This laboratory-scale study uses real sludge samples taken out from a wastewater treatment plant of industrial park. In this study, changes in pH, electrical current, electro-osmosis ow and energy consumption in dierent processes have been studied and the ability of each processes for the removal of zinc and nickel from sludge is determined. The results of pre test showed that enhanced electrokinetic process (the use of EDTA andcitricacidastheelectrolyte)comparedwithconventional electrokinetic (the use of water as the electrolyte) has a better performance in the removal of metals from thesludge. Inthisstudy, removalofzincusingenhanced electrokinetic process was 31% more than that in conventional method. The results revealed that leachingelectrokinetic combined process increases the removal eciency of zinc and nickel to 94% and 82%, respectively. Decreasing pH and removing unwanted elements by leaching were the major factors to improve the electrokinetic performance. The results also showed that themagneticseparation-electrokineticcombinedprocess has no considerable eect on heavy metal removal from sludge.