Abstract: An improved digester apparatus converts wet carbonaceous biomass materials to biogas in a digestion unit operating at a controlled temperature and having a concentrator component and a pressure swing component each containing anaerobic bacteria. The apparatus conveys slurried aqueous biomass from a biomass source to the concentrator component and removes the biogas from the concentrator component and conveys concentrated aqueous biomass from the concentrator component to the pressure swing component and conveys digested aqueous biomass from the pressure swing component to the concentrator component. The apparatus removes waste solids from the pressure swing component and a pressure swing pump controls the pressure within the pressure swing component in a cycle comprising a sub-atmospheric first pressure phase and a second pressure phase at or above atmospheric pressure.

Abstract: An improved digester apparatus for converting wet carbonaceous biomass materials to biogas comprises a digestion unit operating at a controlled temperature and having a concentrator component and a pressure swing component each containing anaerobic bacteria; means for conveying slurried aqueous biomass from a biomass source to the concentrator component and for removing the biogas from the concentrator component; means for conveying concentrated aqueous biomass from the concentrator component to the pressure swing component and for conveying digested aqueous biomass from the pressure swing component to the concentrator component; means for removing waste solids from the pressure swing component; and a pressure swing pump for controlling the pressure within the pressure swing component in a cycle comprising a sub-atmospheric first pressure phase and a second pressure phase at or above atmospheric pressure.

Abstract: Anaerobic digestion of organic material, particularly biological sludge, such as sewage sludge, is carried out in a closed system having a first digestion tank and a second concentration and partial digestion tank. The concentrated and partially digested sludge is fed to the first tank where it is maintained under vacuum such that an active zone of organic material undergoing digestion is detained therein for a long period of time. The digested sludge is withdrawn against the vacuum and has approximately 80 to 90% of the organic solids therein mineralized; thus simplifying dewatering and ultimate disposal of the sludge. Pathogens including viruses are also removed from the digested sludge. Denitrification takes place in the vacuum digester tank and gas consisting essentially of nitrogen is removed. Return sludge from the vacuum digester and influent sludge is fed into the second or concentrator tank to facilitate reseeding with anaerobic organisms.

Abstract: Anaerobic digestion of organic material, particularly biological sludge, such as sewage sludge, is carried out in a closed system having a first digestion tank and a second concentration and partial digestion tank. The concentrated and partially digested sludge is fed to the first tank where it is maintained under vacuum such that an active zone of organic material undergoing digestion is detained therein for a long period of time. The digested sludge is withdrawn against the vacuum and has approximately 80 to 90% of the organic solids therein mineralized; thus simplifying dewatering and ultimate disposal of the sludge. Pathogens including viruses are also removed from the digested sludge. Denitrification takes place in the vacuum digester tank and gas consisting essentially of nitrogen is removed. Return sludge from the vacuum digester and influent sludge is fed into the second or concentrator tank to facilitate reseeding with anaerobic organisms.

Abstract: Anaerobic digestion of organic material, particularly biological sludge, such as sewage sludge, is carried out in a closed system having a first digestion tank and a second concentration and partial digestion tank. The concentrated and partially digested sludge is fed to the first tank where it is maintained under vacuum such that an active zone of organic material undergoing digestion is detained therein for a long period of time. The digested sludge is withdrawn against the vacuum and has approximately 80 to 90% of the organic solids therein mineralized; thus simplifying dewatering and ultimate disposal of the sludge. Pathogens including viruses are also removed from the digested sludge. Denitrification takes place in the vacuum digester tank and gas consisting essentially of nitrogen is removed. Return sludge from the vacuum digester and influent sludge is fed into the second or concentrator tank to facilitate reseeding with anaerobic organisms.