Investigation of electrochemical treatment processes as a novel technology for municipal wastewater reuse: A parametric and a kinetic study

This work is an attempt to contribute to the development of advanced and cost effective technologies for wastewater purification, which plays a crucial part in achieving the goals of the new millennium for safe access to water and sanitation services by the year 2025. The electrochemical process is one technology that can be used effectively in treating wastewater. In this work raw municipal wastewater was electrochemically treated for the removal of BOD, using stainless steel electrodes. Electro-oxidation and electro-coagulation were investigated separately as the two mechanisms of soluble and particulate BOD removals, respectively. The maximum soluble BOD removal of 61.34% occurred at a current of 0.2A, beyond which the removal was adversely affected. The decrease of removal efficiencies for soluble BOD at higher currents was attributed to the increase in pH, which resulted in hindering the production of hypochlorous acid and other oxidizing agents. The removal efficiency of particulate BOD through the electro-coagulation mechanism was shown to increase as the current and contact time increased. This increase in removal efficiency was attributed to the increase in the amount of coagulant released as the current and contact time increased. The removal efficiency of total BOD, through the combined effects of the electro-oxidation and electro-coagulation processes, showed similar trends as the soluble BOD removal. The maximum removal efficiency of total BOD was 84.5%, which occurred at a current of 0.2A and a contact time of 30 minutes. The kinetic model that best simulates the removal efficiency trend of soluble and total BOD was found to follow the Exponential Association Model, which is part of the Growth-Saturation Models.