REACTIVATION CHARACTERISTICS OF PRESERVED ANAEROBIC GRANULAR SLUDGES

Re-activation characteristics of anaerobic granular sludges starved fo r 10 months were studied. Specific biomass activities were monitored a nd both scanning and transmission electron microscopies were used to i nvestigate the microbial and the morphological changes in granular slu dges during storage. In order to investigate the re-activating capabil ity of granular sludges starved for 10 months, the recovery of microbi al activity was observed in a reactor re-feeding test as well as in a serum bottle test (SET). Specific biomass activity tests indicated tha t the room temperature was preferred to the refrigerated conditions in maintaining the methanogenic activity. The specific biomass activity after IO months of storage decreased by more than 30% of the initial. The re-activating test showed that granular sludge was quickly re-acti vated by re-feeding the substrate. With 10 months old granular sludge a 11.2 kg COD/m(3).day loading rate was achieved within 12 days after the onset of refeeding. The overall performance of the reactor with gr anular sludges stored at room temperature was more stable than that at 4 degrees C.