Biotrickling Filters for Removal of Volatile Organic Compounds from Air in the Coating Sector

Abstract

EU environmental policy makes controlling the emissions of Volatile Organic Compounds (VOC) in waste gases necessary. Biotrickling filtration, an emergent biotreament, could be a viable technology for the coating sector. In this study, field-scale applications in two different industrial sectors are presented. A full-scale biotrickling system, including an activated carbon-smoothing prefilter, was installed at a furniture facility. Two spray booths were tested. n-Butyl acetate (20–50%) and xylenes (10–30%) were identified as the main solvents of one of the booths, while acetone (85–100%) was the main VOC coming from the other source. Due to the uneven emission pattern, the activated carbon prefilter allowed the VOC fluctuations to be buffered, increasing significantly the removal efficiency (10–20%). The second case consisted of a pilot-scale biotrickling filter tested in a plastic coating facility of the auxiliary automotive sector. In this case, emissions were quite stable, although VOC composition depends on the paint formulation used in the two robotic spray booths connected to the bioreactor. Some paints contained n-butyl acetate, butyl glycol acetate and methyl acetate in a proportion greater than 70% with a small proportion of aromatics (xylenes and ethylbenzene), while other products were mainly composed of naphtha, heavy aromatic fraction (75–100%). The systems were able to comply with legal emission limits under suitable operational conditions; with Empty Bed Residence Time (EBRT) ranging from 20 to 85 s depending on the waste gas source. The composition and pattern emissions were shown to be the crucial parameters determining the performance of the systems. Economic evaluation, including amortization and operational cost, showed a total cost of around 1.5 and 5.0 ε per year per Nm3 h-1 of air to be treated depending on the source.