An oil-in-water emulsion was separated by bed coalsecence using polyurethane foam chips as the filter media in a steady-state regime, including gravity settling. A study was made of the effect of working conditions such as fluid velocity, bed length, and influent oil content on the effluent oil concentration and separation efficiency. Model emulsions were prepared by mixing the vacuum fraction of naphthenic-base oil and water to obtain a mean droplet diameter of about 20 mu m. All experiments were carried out at a constant temperature of 20 degrees C. The range of the influent oil concentration was from 500 to 2000 mg L-1, the range of the fluid velocity from 10 to 45 m h(-1), and the range of the bed length from 3 to 15 cm. The obtained effluent oil concentration was from 3.12 to 138 mg L-1, and the separation efficiency was 82.0-99.8%. Empirical equations were derived describing the coalescence efficiency and effluent concentration as a function of bed length, influent concentration, and fluid velocity.