Oilfield Wastewater Treatment via Synergistic Anodic Oxidation and Polyferric Flocculation

This report describes a method encompassing the generation of active chlorine species combined with the activity of a novel polyferric flocculation agent, which exhibits potential for the degradation of organic pollutants in oilfield wastewater. This process takes advantage of electrochemical (anodic) oxidation reactions to degrade oilfield wastewater pollutants with simultaneous generation of active chlorine species from NaCl in the electrolyte. Divalent iron ions are oxidized by active chlorine species, generating the new polyferric species. The flocculation activity of the newly-formed polyferric species demonstrates efficient reduction of the chemical oxygen demand (COD) of wastewater samples. The strong point of this process is that active chlorine species can be produced over short electrolysis times and at low voltage intensities. Overall, the novel polyferric species demonstrates better flocculation effects than traditional ferric flocculants. Specifically, it achieves 87.36% COD reduction after 50 min of electrolysis with a voltage intensity of 20 V, and after the electrolysis was stopped and ferrous ions were added to the system for 1 h, achieved results which were 3.38 times higher than the treatment of oilfield wastewater using a traditional polyferric flocculation method. The strategy described herein can effectively reduce the COD content in oilfield wastewater. (C) 2021 American Society of Civil Engineers.