Pilot study on a physical process for treating petrochemical wastewater

Petrochemical wastewater is one of the main wastewater types at petrochemical refineries and possesses high oil and suspended solid (SS) contents and exhibits high chemical oxygen demands (COD). Moreover, the petrochemical wastewater concentration fluctuates considerably. Because of their time-consuming processes, high energy and chemical consumptions, and production of volatile organic compounds (VOCs) and hazardous waste scum, traditional petrochemical sewage treatments, such as gravity sedimentation, electrochemical demulsification, and two-stage air flotation, are becoming unable to satisfy the demands for the green and efficient treatment of petrochemical sewage. Therefore, new physical processes are urgently required to replace the current traditional processes with chemical processes at the core. In this study, a new physical process was developed and sideline tested at a petrochemical refinery. After treatment with the proposed physical process, the average oil and SS contents as well as COD in the effluent dropped to 8.9 mg/L, 14.25 mg/L, and 252 mg/L, respectively, satisfying the index requirements for petrochemical wastewater entering a biochemical system. Compared with traditional processes, the proposed process reduced the costs, carbon emissions, and required floor space by 61.71%, 71.9%, and 85%, respectively, as well as the emissions of wastes, such as scum and VOCs. The proposed physical process consumes a low amount of energy, is highly efficient, does not generate any chemical pollution, and provides a new resource-based technology for treating petrochemical wastewater at petrochemical refineries in the current carbon peaking and carbon neutrality goals context.