A mesophilic digestion of brewery wastewater in an unheated anaerobic filter

An anaerobic filter (5•8 m3) operated at ambient temperature was used to treat brewery wastewater. The hydraulic retention time was maintained at a constant value (10 h) throughout the trial. The start-up period, to achieve fully stabilized conditions, was 6 months. At an applied loading rate of about 8 kg COD/m3 d, the mean COD removal was 96% and the mean gas production was 7•1 m3/d. The methane content of the biogas was higher than is normally found. During the steady state regime it was 80–95%. The results show that, when the ambient temperature is high, an anaerobic filter can operate in the mesophilic range and be used to treat brewery wastewater successfully.