Interactions of resin acids with aerobic and anaerobic biomass .1. Degradation by non-acclimated inocula

The fate and effects of resin acids in anaerobic and aerobic biological treatment systems were compared under batch reactor test conditions. With a non-acclimated anaerobic biomass inoculum, no degradation of resin acids was observed under anaerobic conditions after exposure times of up to 24 d. Inhibition of methanogenic activity of the anaerobic consortium was noted at initial resin acid/biomass ratios exceeding 0.0031 mg resin acids/mg VSS. Inhibited methanogenic populations were capable of acclimation to high concentrations of resin acids after 7-13 d of exposure. Under aerobic batch conditions with a non-acclimated activated sludge inoculum, high initial resin acid concentrations were reduced to detection limits in 2-3 d. The highest specific removal rate of 109 mg resin acids/g VSS d measured in this study with non-acclimated aerobic biomass, was much higher than comparable values reported by others for acclimated aerobic biomass. The time required for removal appeared to be independent of the batch reactor biomass concentration. No evidence was found to suggest that high concentrations of resin acids resulted in inhibition under aerobic conditions.