The US-patented BioFiltro system consists of a bio reactor composed of different filter layers, disinfection unit, and pumps. The stages at which solid and liquid waste are removed are as follow:

• The sewage or liquid industrial waste is irrigated on a bed consisting of porous strata. The upper layer contains a large number of earthworms, rotifers, and other aerobic micro organisms.
• The sewage or liquid industrial waste drains through the filter media, retaining in it the organic matter.
• The effluent organic matter is consumed by the worms, oxidizing it to carbon dioxide and water, transforming a minor part of it in body mass of earthworms and the rest in earthworm castings.
• The bacteria in the sewage or liquid industrial waste are reduced by two orders of magnitude: one by the worms and the other by the organic matter consuming micro organisms that live with the worms. The translucent liquid output can be disinfected by a UV unit or chlorine to remove any remaining coliform bacteria before being discharged.