Patent ID: 7919304

Claim:
A process for the biofiltration of volatile organic compounds (VOCs) including delivering contaminated effluent gas through a biofilter, the biofilter having an inlet, outlet and a micro-organism laden filter media bed, the filter media bed having moisture retaining properties and the filter media bed being suitable for the absorption, microbial oxidation and degradation of the VOCs and the process also including delivering liquid across the filter media bed, the process comprising:— delivering contaminated effluent gas to the biofilter inlet at a biofilter throughput rate and removing the filtered air through the outlet at the same rate; recirculating the effluent gas within the biofilter whereby the rate at which gas passes through the filter media exceeds the biofilter throughput rate at the inlet and outlet, and the inlet gas being effectively diluted within the biofilter; and stimulating the liquid delivered across the filter media bed by electromagnetic radiation to favor growth of certain bacterial species while inhibiting the growth of others, thereby preventing build-up of biomass in the biofilter and increasing the dissolution properties of the recirculating liquid.