Abstract
The effect of extract from activated sludge on bacterial population in activated sludge was studied especially focusing on the effect of organic loading and incubation time. A laboratory scale activated sludge reactor was operated, the extract was obtained from the sludge with ethanol as the extractant, and activated sludge was incubated with and without the addition of the extract. The incubation was performed with low (0.5kgCOD/kgMLSS·d) and high (2kgCOD/kgMLSS·d) organic loadings up to 96 hours on a microplate under aerobic condition. Samples were obtained at 24, 48 and 96 hours, and bacterial population in them were analyzed by both polymerase chain reaction (PCR) with restriction fragment length polymorphism (RFLP) and reverse transcription PCR/RFLP. Clear difference in bacterial population was observed within 24 hours of incubation even when low organic loading was applied and increase of biomass amount was thought to be only around 25%.
