Liquid–Liquid Continuous Extraction and Fractional Distillation for the Removal of Organic Compounds from the Wastewater of the Oil Industry

This is the first study to carry out a laboratory-scale assay to assess the potentiality of continuous liquid–liquid extraction with dichloromethane (CLLEDCM) and high-power fractional distillation (HPFD) as a treatment to decontaminate the wastewater generated by the petroleum industry (WW). The analytical parameters of treated wastewater (TWW) evidenced a remarkable quality improvement compared to the original WW. CLLEDCM–HPFD yielded 92.4%–98.5% of the WW mass as more environmentally friendly water. Compared to the original values determined in the WW, total petroleum hydrocarbon (TPH) decreased by 95.0%–100.0%, and the chemical oxygen demand (COD) decreased by 90.5%–99.9%. Taking into account the yield of the treated water, the amount of pollutant removed, and the risks of each process, the order of the potentiality of these treatments, from highest to lowest, was HPFD > CLLEDCM–HPFD > CLLEDCM. CLLEDCM treatment alone produced TWW with poorer quality, and the CLLEDCM–HPFD sequence involved the greatest consumption of time and energy (0.390–0.905 kWh/kg). CLLEDCM-only was the least effective treatment because the TWW obtained failed to comply with the regulations of oil-producing countries.