Abstract: In an apparatus and process described, an organic fraction of solid waste is separated from light contaminants such as plastics and heavy contaminants such as grit. The organic fraction is subsequently processed by anaerobic digestion, which converts volatile solids to gas. In a first stage of the process, the waste is processed through a separator such as a vertical mill, which removes light fraction contamination, reduces organics particle size and dilutes the waste to thereby produce a slurry. In a second stage of the process, the slurry passes through a grit removal system, which removes heavy and settleable material, for example by way of a hydrocyclone. The light and heavy fraction contaminants are not carried through to the digestion process. The particle size of the organics is also reduced to facilitate digestion and the slurry has a dry solids concentration suitable for anaerobic digestion.

Abstract: In an apparatus and process described, an organic fraction of solid waste is separated from light contaminants such as plastics and heavy contaminants such as grit. The organic fraction is subsequently processed by anaerobic digestion, which converts volatile solids to gas. In a first stage of the process, the waste is processed through a separator such as a vertical mill, which removes light fraction contamination, reduces organics particle size and dilutes the waste to thereby produce a slurry. In a second stage of the process, the slurry passes through a grit removal system, which removes heavy and settleable material, for example by way of a hydrocyclone. The light and heavy fraction contaminants are not carried through to the digestion process. The particle size of the organics is also reduced to facilitate digestion and the slurry has a dry solids concentration suitable for anaerobic digestion.