Carbon dioxide emission reduction system and system for preparing fuel ethanol by biological method

The utility model particularly relates to a carbon dioxide emission reduction system and a biological method fuel ethanol system, and belongs to the technical field of waste gas treatment, the carbon dioxide emission reduction system comprises: an adsorption tower for carrying out sodium hydroxide reaction adsorption on tail gas rich in carbon dioxide to obtain sodium bicarbonate; the waste gas supply pipeline is used for supplying tail gas rich in carbon dioxide to the adsorption tower, and the waste gas supply pipeline is communicated with the adsorption tower; the waste gas discharge pipeline is used for discharging the waste gas treated by the adsorption tower and is communicated with the adsorption tower; the alkali preparation tank is used for mixing sodium bicarbonate and sodium hydroxide for reaction to obtain sodium carbonate, is communicated with the adsorption tower and is used for receiving the sodium bicarbonate discharged from the adsorption tower; the sodium carbonate discharge pipeline is used