PILOT AND FULL-SCALE EXPERIENCE IN ANAEROBIC TREATMENT OF BREWER YEAST PROCESSING WASTE-WATER

The anaerobic expanded micro-carrier bed (MCB) process, which utilizes fine particles as expanded bed media to enhance granular sludge formation, was applied to the wastewater from a brewer's yeast processing plant. Based on the results of the pilot study, in which 97 to 99% COD removals were maintained at 13 to 24 kg COD/m3/day, a full-scale MCB plant with a total reactor volume of 985 m3 was constructed at Asahi's Koganei plant. Though not found in the pilot study, cobalt and nickel were found to be deficient in the wastewater and had to be supplemented during the start-up. However, a sufficient amount of granular sludge was cultivated so that the reactor could accept the design loading within three months of operation and achieve the average COD removal of 93.5% at 9.8 kg COD/m3/day. Thus, it was clearly demonstrated in the full-scale installation that the MCB process could provide a reliable and predictable way to cultivate granular sludge necessary for efficient anaerobic treatment.