NOVELTY - Removing methane from landfill biogas streams and/or bioaerosols comprises: providing at least one container (2); introducing a biofiltering matrix inside the container; placing a supporting system (33) inside the container; placing a permeable sheet (30) on the supporting system and a cover (3) on the permeable sheet, thus creating at least one biofiltering unit (1); feeding a biogas stream containing methane into the biofiltering unit; allowing the removal of methane; controlling the formation of condensate; and discharging the purified gaseous stream from the biofiltering unit.    USE - The process is useful for removing methane from landfill biogas streams and/or bioaerosols.    ADVANTAGE - The process: has high methane removal efficiency; and minimizes or even nullifies the release of the methane contained in the biogas into the surrounding environment.    DETAILED DESCRIPTION - Removing methane from landfill biogas streams and/or bioaerosols comprises: providing at least one container (2) equipped with a ventilation bottom; introducing a biofiltering matrix inside the container, on the ventilation bottom; placing a supporting system (33) inside the container, above the biofiltering matrix; placing a permeable sheet (30) on the supporting system and a cover (3) on the permeable sheet, thus forming a double covering for the container and thus creating at least one biofiltering unit (1); feeding a biogas stream to be treated into the biofiltering unit, the stream containing methane (lower than 25 vol.%); allowing the removal of methane from landfill biogas and/or bioaerosols inside the biofiltering unit up to a methane value of 0.2-13.2 vol.%; controlling the formation of condensate that tends to form inside the double covering, and more precisely between the permeable sheet and the cover, by means of a collection and discharge system, thus assuring the optimum humidity and temperature conditions of the biofiltering unit; and allowing the purified gaseous stream to be discharged from the biofiltering unit, the purified gaseous stream containing methane (0.2-13.2 vol.%). INDEPENDENT CLAIMS are also included for:    (1) a plant for removing methane from landfill biogas streams and/or bioaerosols comprising at least one biofiltering unit (1); and    (2) a biofiltering unit for removing methane from landfill biogas streams and/or bioaerosols through the process, comprising: a container (2) equipped with an ventilation bottom and containing a biofiltering matrix; a supporting system (33) placed inside the container, above the biofiltering matrix; a permeable sheet (30) set on the supporting system; a cover (3) set, in its turn, on the permeable sheet, to form a double covering for the container; and a collection and discharge system to control the formation of condensate that tends to form inside the double covering, and more precisely between the permeable sheet and the cover, to guarantee the optimum humidity and temperature conditions of the biofiltering unit.    DESCRIPTION OF DRAWING(S) - The diagram shows a front view of the biofiltering unit.    Biofiltering unit (1)    Container (2)    Cover (3)    Permeable sheet (30)    Supporting system (33)