Design and evaluation of an open biofilter for treatment of odour from swine barns during sub-zero ambient temperatures

Biofiltration is an odour removal technology in which an odourous airstream is passed through a moist, porous filter medium prior to emission into the atmosphere. Odourous compounds are removed from the airstream by absorption and diffusion into a moist film on the surface of the filter media known as the biofilm. Odourous compounds either accumulate in the biofilm, or are digested by the resident microorganisms. The process of digestion, called bio-oxidation, occurs when microorganisms digest the gases, particulate matter, and volatile organic compounds in the presence of oxygen. Water, carbon dioxide, other non-odourous gases, biomass, and mineral salts are the end products of these reactions (Williams 1993). The result of the biofiltration process is a decrease in odour emissions.