The effects of wastewater temperature on treatment efficiency in an anaerobic-filter process were examined based on laboratory data on anaerobic filters treating septic-tank effluent, dairy wastewater; slaughterhouse wastewater potato-processing wastewater and whey wastewater Three anaerobic filters were operated at 5, 10 and 20 degrees C treating septic-tank effluent at different hydraulic retention times (HRTs), three anaerobic filters treating dairy wastewater were operated at 12.5, 21 and 30 degrees C at different HRTs, an anaerobic filter treating slaughterhouse wastewater was operated at 23.6, 24.3, 25, 26.6, 26.7 and 27.1 degrees C at different HRTs, an anaerobic filter treating potato-processing wastewater was operated at 2, 4, 10 and 20 degrees C and an anaerobic filter treating whey wastewater was operated at 16, 20, 26 and 30 degrees C at different HRTs. Data were analyzed for the effect of temperature using the Arrhenius equation and a relationship was developed between system temperature and first-order rate constant for each anaerobic filter system. The simple kinetic model did not fit the experimental data very well for two of the three wastewaters tested. Copyright (C) 1996 Elsevier Science Ltd.