Stability of Phosphorus Removal and Population of Bio-P-Bacteria under Short Term Disturbances in Sequencing Batch Reactor Activated Sludge Process

Laboratory-scale sequencing batch reactor(SBR) activated sludge processes were operated to investigate the stability of phosphorus removal capacity and population of bio-P-bacteria under short term disturbances (2 to 5 days) and to characterize the structure and dynamics of bacterial population of activated sludge for phosphorus removal. The performance on phosphorus removal deteriorated in 3 days, whereas it took more than 1 week for the recovery and the time for the recovery prolonged with the length of disturbances. The responses of phosphorus removal activity and quinone profiles suggested that the deterioration and the slow recovery were dependent not on the decrease in the activity of each bio-P-bacteria but on the decrease in their population, i.e. species succession of bacteria. The isolated strains of Acinetobacter and Pseudomonas were seen to be predominant species in the total bacterial population in the activated sludge. These strains showed high activity of phosphorus removal and low specific growth rate indicating also the slow recovery.