Prior to this experiment in a continuous activated sludge reactor, the biomass from domestic
wastewater was acclimated to the substrate of interest (Kraft effluent), for 39 days to permit the growth
of the microorganisms which can use the Kraft E1 effluent as a carbon source. Acclimation is widely
used to maximize the removal efficiency of specific compounds that are difficult to biodegrade. The
steady-state condition was verified when the average of the consecutive measurements for COD
parameter showed a standard deviation less than 5%.