مشخصات پژوهش

Refinery sour water and oily wastewater streams typically contain high and highly variable organic loads, dissolved hydrocarbons, heavy metals, and polycyclic aromatic hydrocarbons. These complex and fluctuating characteristics present major challenges for conventional separation-based treatment systems, particularly under shock-loading conditions. In this study, a pilot-scale hybrid sequencing batch reactor (SBR) integrating 30% volumetric carrier media was implemented to support simultaneous suspended and attached biomass growth under real industrial operating conditions at a natural gas refinery complex in southern Iran. The system was designed to evaluate biological transformation performance without the use of physicochemical oxidation processes. The influent chemical oxygen demand (COD) varied widely between 607 and 3420 mg/l. After biomass acclimation and stabilization, sour water COD was reduced from 607 to 840 mg/l to 37–130 mg/l, achieving removal efficiencies above 80%. Even under high-strength loading conditions (up to 3420 mg/l), the reactor demonstrated strong resilience, producing effluent COD concentrations as low as 41–95 mg/l. Biochemical oxygen demand (BOD) was consistently reduced to 10–15 mg/l during stable operation. In addition to organic removal, significant attenuation of heavy metals (Cu, Pb, Ni, Cd) was observed following biological treatment, along with measurable reductions in aromatic fractions. The hybrid SBR configuration enabled simultaneous organic degradation, metal attenuation, and aromatic contaminant reduction within a single biological treatment platform. Overall, the results demonstrate the technical feasibility and operational robustness of transformation-based hybrid biofilm systems for treating high-strength refinery wastewater. The findings support their potential application for marine discharge compliance and industrial water reuse, particularly in water-stressed regions.