Biogenic substrate benefits activated sludge in acclimation to a xenobiotic

Activated sludge that originated from a biogenic fed-batch reactor under steady-state was re-cultivated with the same biogenic substrates to test the changes in the sludge's performance in acclimation and degradation of a xenobiotic. Re-cultivations with varying biogenic concentrations were conducted at time points ranging from 16 d before to 4 d after the acclimation reactions. Biogenic re-cultivation energizes sludge cells thereby benefiting the re-cultivated biomass by shortening its acclimation lag time. Lag time increases on both sides of the re-cultivation time where lag has been shortened the most: (1) in short re-cultivation times before and after acclimation reactions, high concentrations of new or unfinished biogenic substrates cause diauxic growth that delays acclimation; (2) in long re-cultivation times, the re-cultivated biomass loses its energy-rich advantage. Both these lag lengthening situations have their worst cases in which acclimation lag times become longer than that of the original sludge, thus counterbalancing the benefits.