A Promising Device Based on Step Stage Theory for Highly Effective Treatment of Oil Field Wastewater

This study proposed a solar thermal electrochemical photo (STEP) theory-based integrated device for highly efficient oilfield-produced wastewater (OPW) purification, combining photothermal and electric technologies. The major oil fields in China reaching the mid-to-late stage of high-water content extraction have substantially increased the amount of OPW, the complex composition of which makes degradation challenging. This research aimed to improve OPW treatment efficiency and reduce energy consumption and mining costs via innovative processes and integrated experimental devices. A solar five-field demulsification model was developed by combining filtration, distillation, condensation, and other processes using the solar STEP theory and incorporating the photocatalytic oxidation, thermal effect, electro-oxidation, air flotation, and flocculation derived from solar energy. The model enables the utilization of photocatalysts to harness solar power.and get the full spectrum energy hierarchical conversion utilization. The results showed that petroleum hydrocarbon removal was positively correlated with the environmental temperature and voltage. The device significantly improved the petroleum hydrocarbon removal rate at an optimized temperature and voltage. At 100°C and 3 V, the petroleum hydrocarbon removal rate reached 93%, confirming the efficiency and feasibility of the device in improving OPW treatment efficacy and environmental protection.