NOVELTY - A biochemical system (100) for processing organic waste material to a biomass product, comprises a rotatable drum (105), sloped relative to the horizontal, and including a feed end (115) and a discharge end (120), breaker bars extending inwardly from an interior surface of drum, and an aerotolerant anaerobic bacteria; and an air system configured to blow air into the discharge end of the drum. The air system includes an air scrubber to remove volatile organic compounds from air discharged from feed end of drum; and a blower to recirculate air from air scrubber to discharge end of drum.    USE - For processing organic waste material to a biomass product (claimed), which is useful as compost.    ADVANTAGE - The aerotolerant anaerobic bacteria within the rotating drum promotes the fermentation of the waste material, while the tumbling of the waste material due to the rotation of the drum mechanically shears the waste material. The system (biomixer) employs a combination of mechanical shearing and biological activity in a controlled environment to produce biomasses suitable for anaerobic digestion and other purposes. Air carrying volatile organic compounds released by the fermentation process can be collected from the drum and scrubbed to recover the volatile organic compounds. The cleansed air can then be recirculated back into the drum. The waste material can be screened prior to fermentation in the drum to remove a fraction of the smallest particles. The biomass produced by the drum can also be screened.    DETAILED DESCRIPTION - A biochemical system (100) for processing organic waste material to a biomass product, comprises a rotatable drum (105), sloped relative to the horizontal, and including a feed end (115) and a discharge end (120), breaker bars extending inwardly from an interior surface of the drum, and an aerotolerant anaerobic bacteria; and an air system configured to blow air into the discharge end of the drum. The air system includes an air scrubber configured to remove volatile organic compounds from air discharged from the feed end of the drum; and a blower configured to recirculate air from the air scrubber to the discharge end of the drum. The air scrubber is a water scrubber having water with a basic pH. The system further comprises loading equipment configured to load the waste material into the drum; a receiving building and a biomass processing building; and a trommel configured to receive the biomass product from the discharge end of the drum. An INDEPENDENT CLAIM is included for processing organic waste material to a biomass product, involving fermenting a biodegradable fraction of the waste material with an aerotolerant anaerobic bacteria in a rotating drum; and controlling the environment within the rotating drum, including maintaining the oxygen content of the air within the drum below the ambient oxygen concentration, maintaining an acidic pH of the waste material within the drum proximate to its discharge end, and maintaining a moisture content of the waste material within the drum in the range of 40-60%.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of biomixer.    biomixer (100)    rotatable drum (105)    feed end of drum (115)    discharge end of drum (120)    air injector (130)    air collection device. (135)