Electrochemical Corrosion Prevention in Oilfield Wastewater for Effective Dissolved Oxygen Removal Using a Novel Upflow Bioelectrochemical System

Abstract

Towards the corrosion issues of oilfield wastewater for water recycling, the dissolved oxygen (DO) is a subsequent corrosive factor after the air desulfurization tower for high-efficiency removal of sulfides. However, an in situ biological technology for efficient DO removal has not been well developed by using organics in oilfield wastewater. A novel upflow bioelectrocatalytic system assembled with three electrodes (cathode-anode-cathode) was designed in this study, in which waste organic matter of oil wastewater was degraded by a bioanode for electron production and dissolved oxygen was efficiently reduced by a biocathode under an assistant external voltage. The results showed that the average current was kept over 6 mA by applying a fixed voltage of 0.8 V to treat oil wastewater with DO as high as 3-5 mg/L. The bottom cathode contributed the largest to DO removal rate, reaching 67%; contribution of the middle anode and the upper cathode for DO removal was 11% and 9%, respectively. The whole DO removal rate by the bioelectrocatalytic system was up to about 90%, and the effluent DO was reduced to below 0.6 mg/L by removing 40-50% COD.