Interactions of resin acids with aerobic and anaerobic biomass—II. Partitioning on biosolids

Solutions of five resin acids were contacted with suspensions of non-acclimated, inactivated anaerobic and aerobic biomass to assess the contribution of partitioning on biosolids to the overall removal of resin acids in batch assays. Both types of biomass exhibited resin acid partitioning rates that were significantly greater than the rate of removal by degradation. With non-acclimated anaerobic biomass, partitioning was found to be the sole mechanism of resin acid removal. Partitioning on anaerobic biomass could not be described as a reversible adsorption process. Instead, it was found that a constant fraction of each resin acid partitioned into the biomass phase. With non-acclimated inactivated aerobic biomass, the partitioning of resin acids could be adequately described by a linear partitioning model. Dehydroabietic acid was the resin acid least strongly associated with biomass in both the anaerobic and aerobic experiments.