Biodegradation of chloroform along with a mixture of VOCs (methanol, ethanol, acetone and toluene) commonly found in pharmaceutical emissions using a biotrickling filter (BTF) was evaluated. The performance of the BTF was evaluated for both steady and transient conditions, for different inlet loading rates (ILR), empty bed residence time (EBRT) and inlet chloroform concentrations. Among the VOCs studied before chloroform feeding, toluene removal was the least, under all the operating conditions. Complete removal of all pollutants was achieved up to a chloroform loading rate of 14.22 g/m(3)/h. Increase in loading rate of chloroform adversely affected the removal efficiency of toluene and declined the overall performance of BTF. The results suggest that biodegradation of VOCs is influenced by the inlet loading rate and complexity of pollutants in the inlet air stream. Results from studies on shock loading and starvation indicated that the system was highly resilient to transient operating conditions. (C) 2012 Elsevier Ltd. All rights reserved.