Advanced oxidation/air flotation collaborative treatment of high-sulfur oilfield produced water

Considering the inherent limitations of conventional technologies for treating produced water (PW) from high-sulfur oilfields—such as low efficiency, elevated operational costs, and the risk of secondary pollution—this study proposes a novel, integrated multi-stage synergistic treatment strategy encompassing chemical desulfurization, vacuum degassing, corrugated plate settling, dual-stage air flotation, triple-stage hybrid coarse filtration, and dual-stage membrane-based fine filtration. This system employs selective desulfurizing agents for targeted sulfur removal and synergistically combines vacuum degassing with corrugated plate settling units to markedly improve desulfurization efficiency. The hierarchical purification architecture, comprising dual-stage air flotation and a three-tier filtration sequence—including both coarse and membrane filtration—effectively alleviates clogging challenges prevalent in traditional treatment processes. Following the optimization of critical process parameters through grey relational analysis, the treated effluent achieved a transmittance (TR) of 97.4 %, an oil content (OC) of 4.08 mg/L, and S²⁻ concentration (SC) of 0.97 mg/L, thereby fully complying with the SY/T 5329–2022 reinjection water quality standards. In comparison with conventional methodologies, the proposed approach reduced operational expenditures by 0.74 USD/m³ and enhanced the sulfur removal efficiency to 99.2 %, offering a high-performance, cost-effective, and environmentally sustainable integrated solution for the remediation of produced water from high-sulfur oilfields. • Novel process optimization tailored for sulfur-containing wastewater treatment. • Multi-level synergistic process enabling efficient and targeted desulfurization. • Application of grey relational analysis to identify key influencing factors. • Development of an efficient process integration strategy. • Operating cost reduction of 0.74 USD/m³ achieved.