Abstract
An A/O SBR fed with acetate was operated at pH 7.0 after the inoculation of activated sludge capable of enhanced biological phosphate removal (EBPR). Glycogen-accumulating organisms (GAOs) were predominant in acetate uptake on the 19th day of operation. The operational pH was then increased to 8.2. Accordingly, the acetate uptake activity of GAOs gradually decreased as intended, whereas phosphate release activity improved. To estimate acetate uptake rate with addition of acetate more than that in the A/O SBR operation, an anaerobic batch test was conducted. Higher amounts of acetate added led to significantly high acetate uptake rates that were not consistent with phosphate release rates only when the acetate uptake activity of GAOs was relatively low in the A/O SBR operation. In other words, an acetate concentration higher than the usual influent concentration probably stimulates the acetate uptake activity of GAOs. These results suggest that a rapid increase in the acetate uptake rate of GAOs affects the sudden deterioration of EBPR.
