The treatment performance of an anaerobic hybrid reactor was investigated for different types of concentrated wastewater using a laboratory scale model reactor. Its performance was first examined using synthetic wastewater at different hydraulic retention times (0.5, 1 and 2 days) and organic loading rates (1-10 kg chemical oxygen demand (COD) m(-3) per day) over 2 years. COD removal efficiencies ranging from 77 to 90% were achieved. Baker's yeast and meat processing industry wastewater was fed to the model reactor, consecutively. HRT and OLR values were 2 days-9.0 kg COD m(-3) per day and 2 days-1.0 kg COD m(-3) per day, and about 78 and 75% COD removal efficiency was obtained for yeast and meat industry wastewater, respectively. The methane content of the biogas produced was about 58, 58, and 70% for synthetic, yeast industry and meat processing wastewater, respectively. The organic matter removal efficiency of the reactor indicated that this type of reactor is suitable for treatment of high strength effluent. (C) 2002 Elsevier Science Ltd. All rights reserved.