A pilot study for oil refinery wastewater treatment using a fixed-film bioreactor

Abstract Biological treatment of industrial oil refinery wastewater is a well-established method for remediation of these wastes. We have designed a new bioreactor system to increase the efficiency of biological treatment systems by (1) allowing greater organic loads, (2) minimizing production of sludge waste by-products, and (3) increasing process stability and resistance to shock loading. A fixed-film bioreactor system was constructed with a highly porous polyurethane foam to incubate microorganisms at concentrations up to 8000 mg/l. The support frame of the bioreactor system was built from cylindrical plastic pall rings to form a packed bed of ‘mixed-media’. The frame support provides a high surface area-to-volume ratio (210 ft2/ft3), and reduces potential problems of plugging and channeling, distribution of air and water, and mass-transfer limitations. Performance data for fixed-film bioreactors with 8-h hydraulic retention time (HRT) demonstrated chemical oxygen demand (COD) removal rates of 85–90%, and near 100% degradation of phenol from industrial oil refinery wastewater. Furthermore, the pilot bioreactor only generated one-third of the sludge waste compared to the traditional activated sludge process.