Patent ID: 7314190

Claim:
Method for biological decomposition of waste which contains organic matter, where said method comprises the steps of pre-treatment of said waste, and subsequent biological decomposition of the pre-treated waste in a decomposition reactor in the presence of anaerobic bacteria, wherein said pre-treatment step comprises fragmentation, homogenisation, and slurrying of said waste into a liquid to bring said waste in a pumpable condition in a pre-treatment apparatus, which is a multi-ring double action impact mill, which comprises a housing equipped with a feed opening and a discharge opening, a first rotor disposed inside the housing, which rotor is equipped with blades having impact surfaces, and which blades form at least one or more rings that are coaxial with the said rotor, and a stator disposed inside the housing coaxially with the first rotor, or a second rotor rotating in an opposite direction, and which said stator or said second rotor are equipped with blades having impact surfaces, these blades of said stator or said second rotor forming at least one or more rings fitted coaxially with said stator or said second rotor, and which rings are disposed so as to be staggered in relation to the ring or rings of the first rotor, whereby the waste is fed through the feed opening of the pre-treatment apparatus into the hub of the rings formed by the blades, from where the waste is moved by the effect of a rotor or rotors to the ring formed by the outermost blades, and further to the discharge opening.