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 mu m) 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 (28-2s) 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. (c) 2007 Elsevier B.V. All rights reserved.