Despite the minimal micro pollutant exposure, the synthetic wastewater sludges were able to degrade several micro pollutants present in municipal wastewater. The degradation occurred immediately after spiking (1e5 mg/L), showed no strong or systematic correlation to the sludge age, and proceeded at rates comparable to those of municipal wastewater sludges. Thus, the results from the batch experiments indicate that degradation of organic micro pollutants in biological wastewater treatment is quite insensitive to SRT increases from 25 to 80 days, and not necessarily induced by exposure to micro pollutants