NOVELTY - Treating waste material comprising subjecting the waste material to increased temperature, pressure and moisture within a digester, increasing the temperature and pressure within the digester to cause the steam to reach a saturated state, rapidly reducing the pressure within the digester, removing the material from the digester, and diluting a first portion of the material with water while agitating the resulting diluted mixture.    USE - The invention is used for the treatment waste material, e.g. municipal waste material, to produce a biogas comprising carbon dioxide and methane, plus residue useful as solid fuel or compost.    ADVANTAGE - The invention further enhances the qualities of the separated biomass.    DETAILED DESCRIPTION - Treating waste material comprising subjecting the waste material to increased temperature, pressure and moisture within a digester, increasing the temperature and pressure within the digester to cause the steam to reach a saturated state, rapidly reducing the pressure within the digester, removing the material from the digester, and diluting a first portion of the material with water while agitating the resulting diluted mixture, is new. Treatment waste material, including organic and inorganic materials, with the organic materials including starches, cellulose, and other carbohydrates comprises subjecting the waste material to increased temperature, pressure and moisture within a digester by introducing steam into the digester; increasing the temperature and pressure within the digester to cause the steam to reach a saturated state within the apparatus; rapidly reducing the pressure within the apparatus to reach a pressure less than atmospheric and to cause the steam to become superheated; removing the material from the apparatus and passing the material through a screen to separate the material by size; and diluting a first portion of the material with water while agitating the resulting diluted mixture to cause cellulose fibers that became twisted and tangled during processing within the apparatus to relax and straighten out or untangle.    An INDEPENDENT CLAIM is also included for a hybrid anaerobic digester comprising a vessel having an outer wall (102); an intermediate wall (120) spaced inwardly from the outer wall and hydraulic reservoir (124) defines between the intermediate wall and the outer wall; an inner wall spaced inwardly from the intermediate wall and an attached growth media zone (122) containing growth media (123) defined between the inner wall and the intermediate wall; and a lower portion of the inner wall being permeable to provide fluid communication between an inner zone defined within the inner wall and the attached growth media zone.    DESCRIPTION OF DRAWING(S) - The figure shows illustrates the hybrid anaerobic digester.    Outer wall (102)    Intermediate wall (120)    Growth media zone (122)    Growth media (123)    Hydraulic reservoir (124)