BACKGROUND: Evaluation of the biodegradation interactions between styrene and acetone, two typical paint solvents and vapor phase pollutants differing in water solubility and biodegradability, was conducted both in a trickle bed reactor (TBR) and a biofilter (BF). The loading rate experiments were performed by increasing the acetone concentration in the inlet air while keeping the styrene concentration and loading rate constant. RESULTS: At acetone loading rates (OLAC) between 25 and 35 gc m-3 h-1, the BF featured greater steady state performance characteristics for styrene degradation. At OLAC between 35 and 48 gc m-3 h-1, a decline of removal efficiency (RE) was observed for both pollutants, due to the system's overloading with acetone. Increasing OLAC above 52-55 gc m-3 h-1 in both reactors resulted in drifts of RE and EC over time to much lower values. A step-drop of acetone loading rate back to OLAC of 3 gc m-3 h-1 (gc denotes grams of carbon) resulted in lag periods lasting for several hours. CONCLUSIONS: Two important issues inherent for acetone biofiltration, e.g., from paint booths or polystyrene production, were identified: (1) poor performance at high loadings of this aggressive solvent and (2) acetone back-stripping into the air following periods of high overloading. Copyright (c) 2012 Society of Chemical Industry