Patents

This invention relates to a biological filter for the purification of waste gases emanating from tanneries that contain compounds such  as ammonia, hydrogen sulfide and volatile organic compounds such as, benzene, toluene and xylene by passage through a porous bio-active solid media. The media comprises a combination of natural and synthetic materials containing micro-organisms which convert  the contaminant compounds to oxidised products, thereby effecting the desired purification. Biofilter system configured in the innovation is capable of  achieving higher removal rates of odour causing compounds in tannery with lower Empty Bed Residence Time (EBRT) than  conventional biofilter systems. The design of the system is very novel in the sense that contaminated air and nutrient or water dosage  is in co-current fashion so that normal moisture content required for the biofilter is always maintained even at the bottom part of  the filter.