Grease biodegradation: is bioaugmentation more effective than natural populations for start-up?
Investigations were undertaken in order to compare the grease degradation rates for a natural population of acclimatised activated sludge micro-organisms with a commercial bioaugmentation product (bioadditive) under optimum conditions in laboratory-scale batch reactors. Lard was chosen as the source of grease because it contains the fatty acids more commonly found in urban wastewaters. During acclimatisation, the bioadditive reactor achieved a slightly better chemical oxygen demand (COD) removal efficiency than the activated sludge reactor. Therefore, under optimum conditions, activated sludge was able to degrade grease at nearly the same rate as a bioadditive solution. Moreover, the bioadditive and the activated sludge reactors had very similar kinetics of COD removal under different grease concentrations. It was concluded that the use of natural activated sludge micro-organisms was sufficient to acclimatise biological processes to removing grease.