Continuous operation of membrane bioreactor treating toluene vapors by Burkholderia vietnamiensis G4

A laboratory-scale biofilm membrane bioreactor inoculated with Burkholderia vietnamiensis G4 was examined to treat toluene vapors in a waste gas stream. The gas feed side and nutrient solution were separated by a composite membrane consisting of a porous polyacrylonitrile (PAN) support layer coated with a very thin (0.3 μm) dense polydimethylsiloxane (PDMS) top layer. After inoculation, a biofilm developed on the dense layer. The biofilm membrane bioreactor was operated continuously at different residence times (28–2 s) and loading rates (1.2–26.7 kg m−3 d−1), with inlet toluene concentrations ranging from 0.21 to 4.1 g m−3. The overall performance of the membrane bioreactor was evaluated over a period of 165 days. Removal efficiencies ranging from 78% to 99% and elimination capacities from 4.2 to 14.4 kg m−3 d−1 were observed after start-up period depending on the mode of operation. A maximum elimination capacity of 14.4 kg m−3 d−1 was observed at a loading rate of 17.4 kg m−3 d−1. Overall, the results illustrate that biofilm membrane reactors can potentially be more effective than conventional biofilters and biotrickling filters for the treatment of air pollutants such as toluene.