NOVELTY - The fermenter (100) has fermenter main portion (110) which is formed with a processing space for accommodating sewage including organic waste. An underwater aerator (130) is used for providing circularly the generated gas in upper portion of main portion. A gas circulation portion (120) is connected to lower portion of main portion, to supply fresh air such that air is injected within main portion. The gas and air are sprayed on sewage, and sewage is stirred. The aerator is used for producing microbubble after stirring the sewage, such that scum floating on surface of sewage is removed.    USE - Autothermal high temperature acid fermenter of anerobic digestion system (Claimed) used for processing sewage such as food sewage and livestock excretion.    ADVANTAGE - The sewage containing high molecular weight organic material can be processed quickly and steadily. The usability of the fermenter is improved. The dwell time for processing the organic material can be reduced. Stable processing of organic waste is ensured. The organic waste can be reduced. The methane conversion process is performed to easily produce the biogas. The yield of biogas over the methane is improved. The processing water of high temperature is flowed into the anaerobic digestion tub, such that the temperature of the anaerobic digestion tub can be compensated easily. The energy generation cost can be reduced. The generation of neogenesis energy is facilitated. The economical efficiency of fermenter is improved. The operation and maintenance of the fermenter are facilitated. The impediment factor of the anaerobic digestion tub operation is reduced. The nitrogen concentration amount can be reduced.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for the anerobic digestion system.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the autothermal high temperature acid fermenter.    Autothermal high temperature acid fermenter (100)    Fermenter main portion (110)    Gas circulation portion (120)    Blower (121)    Underwater aerator (130)