| abstract |
Biofilters (3) for treating contaminated air (5) use immobilized biofilms on filter support media to biodegrade sorbed volatile organic compounds (VOCs) and biotransform inorganic oxides to sulfur (SOx) and nitrogen (NOx) to residuals such as carbon dioxide, water and various acids (HCL, H2SO4, HNO3). The buffers in the trickling liquid (9) neutralize the acid. Some preferred support materials include pelletized solids, pelletized peat, pelletized compost, pelletized activated carbon, hydrogel beads, ceramics, and straight passage media such as extruded ceramics and extruded carbon. Pelletized supports and straight passage supports permit removal of excess biomass by hydraulic or chemical cleaning and minimize pressure loss. The biofilters are characterized by low pressure drop across the bed, good contact of influent gas with the biomass, and satisfactory biomass adherence to the support. The biofilters are easily cleaned of excess biomass or are self-cleaning. |