A new concept of periodically rotating biotrickling filters was developed for parallel operation of multiple bench scale biotrickling filters without the requirement for expensive equipment such as liquid recycle pumps and air flow regulation. The performance of 20 identically operated rotating biotrickling filters was reproducible with an average toluene elimination capacity of 79.4 g m−3 h−1 (s.d. = 5.7) at an empty bed residence time of 45 s and a toluene inlet gas phase concentration of 1.6 g m−3. At gas and liquid cocurrent operation, the toluene elimination capacity of rotating biotrickling filters was 20% higher than at countercurrent operation. This was probably caused by greater mass transfer limitation resulting from increased wetting of the biofilm during countercurrent operation. Performance versus load curves of rotating and of conventional biotrickling filters were comparable with non-zero order removal at toluene inlet concentrations lower than 2 g m−3. This multiple rotating biotrickling filters setup provides a new and inexpensive tool for comparative studies in biotrickling filtration for air pollution control. © 2000 Taylor & Francis Group, LLC.