a biofilter for use in treating contaminated gasses is provided with a container having a layer of particulate rubber , which serves as a filter media . one preferred source of the rubber particulate is recycled tires . smaller containers may be provided with apertures in their bottom walls and a cover for the top of the container , so that the containers can be incorporated within municipal sewage systems as manhole covers . another embodiment floats the layer of rubber particulate on a layer of water or sludge . various systems are provided for the delivery of gaseous , liquid or solid waste to the container . the rubber particulate provides a platform for the growth and maintenance of a microbial ecosystem that substantially treats the contaminated gases emanating from the waste .