Electrocoagulation and Electrooxidation for Disinfecting Water: New Breakthroughs and Implied Mechanisms

Abstract

Electrochemical technology may present an option of treating water since they have proved some benefits over conventional techniques, like decreased handling and storage of chemicals and cost-effectiveness. Consecutive electrochemical techniques have yet to be tried for removing Escherichia coli in potable waters. In this review, a brief discussion of the work of Lynn [1] is presented. Lynn [1] studied electrocoagulation (EC) and electrooxidation (EO) employing two model surface waters and two model groundwaters to define the performance of consecutive EC-EO for removing E. coli. At a current density of 1.67 mA/cm2 for 1 min, bench-scale EO alone attained 4-logs reduction of E. coli in the model shallow aquifer. Elevating the EO current density to 6.67 mA/cm2 for 1 min presented similar levels of E. coli reduction in the model deep aquifer. Employing a current density of 10 mA/cm2 for 5 min EC attained 1-log or bigger E. coli removal in all model waters. No supplementary reduction beyond EC alone was reached employing consecutive EC-EO. Diminutions in the initial pH of the surface waters in order to reach bigger natural organic matter elimination did not improve E. coli cells killing with EC-EO comparatively with EC alone. De facto, around 64% of NOM was eliminated regardless of the variation in pH, which possibly restricted E. coli removal. More causes for the shortage of enhancement in E. coli disinfection may have comprised the existence of iron after EC or deficient EO current density. Diminishing the initial water pH did enhance E. coli reduction employing EO when pretreated via EC compared to the baseline water matrix pH. Despite the breakthroughs obtained throughout the Lynn [1] research in both EC and EO processes for disinfecting water in terms of mechanisms and optimization, great research remains to be accomplished with a view to largely accept these electrochemical techniques in the water treatment industry. Finding the correct hybridization and appropriate combination of such methods, and probably introduce other physical techniques like adsorption and magnetic treatment, would open large perspectives in implementing electrochemical engineering in water treatment.