A novel rotating biological contactor (RBC) with biodrum was designed to remove hydrocarbons in wastewater from industrial discharges, and its performance was investigated. The biodrum, a cylindrical mesh drum, filled with random packing of polyurethane foam cubes retaining petroleum-degrading achlorophyllous micro-alga Prototheca zopfii cells, was approximately 40% submergence in the culture. The amount of algal cells, immobilized in the 10-mm-cube pieces, was greater than in pieces of smaller pore size under the experimental conditions studied. A mixture of n-alkanes (C-14, C-15 and C-16) was used as a model oil, and the influent hydrocarbons were removed by immobilized cells in the biodrum. The single-stage RBC system was operated at 25 degrees C and at pH 7.0 in a batch mode. The removal rate for n-alkanes in the RBC with biodrum system was significantly increased as compared to those in the RBC system with polycarbonate biodisk. (c) 2005 Elsevier Ltd. All rights reserved.