TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred System: The alcohol production system has a condensed portion (12) for concentrating saccharified liquid, a distillation portion (14) for distilling mash (L4) produced by fermentation portion, and separating product into rough alcohol (L5) and distillation waste liquid (L6), and dehydration portion (15) for dehydrating rough alcohol and producing alcohol. The condensed saccharified liquid is subjected to alcoholic fermentation in fermentation portion (13). Preferred Composition: The weight ratio of water with respect to moisture weight of organic refuse is more than 1/4.Preferred Method: Enzyme (100 mg or more) is mixed with respect to moisture weight (1 kg), and saccharification is carried out at 30 degreesC or more. The organic refuse is saccharified using rotation blade or rotation drum. The produced saccharified residue (S) is separated from saccharified liquid. After recovering saccharified liquid, coarse pulverization of saccharified residue is carried out. Saccharified liquid is concentrated under normal pressure or reduced pressure in condensed portion. Nutrient used for alcoholic fermentation is concentrated by setting total saccharide concentration of saccharified liquid to 100-300 g/l. The concentration ratio of saccharified liquid is 1.5-5. The saccharified liquid is concentrated under reduced pressure or normal pressure, and pH is reduced until the value is set to two times or more before concentration of lactic acid. The proliferation of microorganism is suppressed by raising the concentration of monosaccharide in saccharide liquid. The saccharified liquid is concentrated in condensed portion and concentration of lactic acid is set to 10000 mg/l or more. The pH of saccharified liquid is adjusted by increasing concentration of lactic acid. Sterilization of concentrated saccharified liquid is avoided by reducing pH of saccharified liquid and suppressing concentration by proliferation of microorganism. Alcoholic fermentation, batch fermentation, repeating batch fermentation or continuous fermentation is carried out in fermentation portion, preferably continuous fermentation using at least one of non-aggregating yeast and cohesion yeast belonging to Saccharomyces cerevisiae which propagates and ferments at pH of 2.5-5.5, preferably cohesion yeast. Preferred Portion: The concentration of alcohol in fermentation portion is 50-150 g/l. The alcoholic fermentation is carried out at pH of 4.5 or less and 25 degreesC or more. Continuous fermentation of non-sterilized concentrated saccharified liquid is carried out by suppressing contamination by proliferation of microorganism, before propagating microorganism. The alcohol production system has a fermenter having sedimentation portion capable of performing machine stirring and gas circulation, and tower type reactor having draft tube in tower type reactor or flow portion at which sedimentation portion is provided at upper portion or later stage. The alcohol production system has fermentation portion (21) having methane fermentation tank as waste liquid processing/utilization portion (20). Biogas (G1) is produced by fermenting distillation waste liquid produced in distillation portion of methane fermentation tank, and used as at least one of energy source for condensed portion and distillation portion. Air (5-10 % of generation amount of biogas) is introduced to methane fermentation tank, and mixed with biogas, and concentration of hydrogen sulfide in mixed gas containing biogas and air is reduced. The alcohol production system has a water tank in later stage of fermenter. Mixed gas is circulated between methane fermentation tank and water tank, and hydrogen sulfide is air-oxidized to obtain sulfur. The concentration of hydrogen sulfide in mixed gas is reduced to 10 ppm or less. The alcohol production system has circulation type biological denitrification tank in later stage of methane fermentation tank, and nitrification tank in later stage of denitrification tank. Ammonium ion produced by methane fermentation is oxidized to nitrate ion by nitrification tank. Then, organic material and nitride ion remaining after methane fermentation are removed by circulating through liquids containing nitrate ion, in denitrifying tank. The treated water (L8) obtained in decoloring portion (24) is added to saccharified portion as alternative of water added to organic refuse.