Performance of a granular-bed anaerobic baffled reactor (GRABBR) treating whisky distillery wastewater

This paper reports the performance of a granular-bed anaerobic baffled reac tor (GRABBR) used in the treatment of a whisky distillery wastewater. The r esults reveal that the system was very effective in the treatment of the hi gh-strength wastewater. Its effectiveness stemmed from process stability cr eated by phase separation promoted by the reactor configuration. It combine d the advantages of baffled reactor systems and upflow anaerobic sludge bla nket (UASB) systems. Up to 80% COD (or 90% BOD) removal was observed for an organic loading of 4.75 kg COD/m(3) day. It was also found that acidogens were mostly non-granular while methanogens were granular. The GRABBR encour aged phase separation, and consequently the establishment of separate zones for granular and non-granular sludge. The system also showed very high sol ids retention with effluent suspended solids concentration of about 80 mg/l for all organic and hydraulic conditions studied. This was attributed to t he occurrence of granular methanogens in zones (or compartments) downstream of zones occupied by non-granular acidogens. (C) 2000 Elsevier Science Ltd . All rights reserved.