“…The pollutant is removed from the air by dissolution, sorption and bio-oxidation; in other words, it is dissolved into the active biofilm and adsorbed by the support, being available for biological oxidation, a process that remains dynamically (Soares 2006). Biofiltration processes can be economic and efficient due to their low operational and capital costs, together with the effective removal of the pollutant, low pressure drop and their ability to treat aid-producing contaminants (Gerrard et al 2010). In the USA, the maximum of ethanol allowed concentration is 10%, while in Europe it is only 5%.…”