Removal of ethyl acetate, n-hexane and toluene from waste air in a membrane bioreactor under continuous and intermittent feeding conditions

摘要

European Union environmental policy has focused on abatement of volatile organic compounds (VOCs) from industrial emissions, and new European VOC emission limits have been established. This study analyzes the performance of a composite membrane bioreactor treating air stream contaminated with ethyl acetate, n-hexane and toluene under continuous and intermittent feeding conditions. RESULTS: The system was operated under continuous feeding conditions: removal efficiencies (REs) higher than 99% were obtained for inlet loads up to 200 g m ~(-3) h ~(-1) and empty bed residence times (EBRTs) as short as 15 s for ethyl acetate. A maximum elimination capacity of 75 g m ~(-3) h ~(-1) (RE ～66%) at an EBRT of 60 s was obtained for toluene. The system was unable to degrade n-hexane when a 1:1:1 ethyl acetate:n-hexane:toluene was supplied. Intermittent feeding with pollutants supplied for 16 h day ~(-1), 5 days week ~(-1), did not significantly affect the system performance. CO _2 production recovered within 1-2 h and 12 h after night and a weekend closures, respectively. CONCLUSIONS: The membrane bioreactor has been shown to be effective for controlling air emissions and this study illustrated the capacity of the system to handle intermittent feeding conditions that are common in industrial practices.