A method of reusing anaerobic digestion effluent and distiller's grains to produce ethanol

Abstract

The invention discloses a method for producing ethanol by recycling anaerobic digestion effluent and vinasse clear liquid and belongs to the technical fields of waste water treatment and ethanol fermentation industry. The method comprises the following steps: mixing and blending membrane filtrate obtained after membrane filtration of anaerobic digestion effluent, part of vinasse clear liquid, other material mixing water and crushed cereal raw materials, and performing processes of liquefying, saccharifying, fermenting and distilling to obtain ethanol, wherein the membrane filtrate accounts for30 to 90 percent of the total weight of the blending water, the vinasse clear liquid accounts for 10 to 40 percent of the total weight of the blending water, and the rest is other material mixing water; and the concentration of volatile acid of the blending water is controlled to be 100 to 1200 mg / L (based on acetic acid) by adjusting the proportion of the membrane filtrate, the vinasse clear liquid and other material mixing water or adding the acetic acid. By the method, discharge of ethanol production waste water is greatly reduced and water resources are saved; meanwhile, the problem thatthe ethanol is fermented to generate acid is effectively avoided, the alcohol yield is significantly increased, the utilization rate of the raw materials is increased by 1 to 5 percent, and the production energy consumption and cost of the ethanol are reduced.

Description

technical field [0001] The invention relates to a method for producing ethanol by reusing anaerobic digestion effluent and distiller's grain clear liquid, and belongs to the technical field of wastewater treatment and ethanol fermentation industry. Background technique [0002] Ethanol is an important industrial raw material, which is widely used in food, medicine, chemical industry and other industrial fields. It is also an important renewable biomass energy (fuel ethanol), which is highly valued by governments all over the world. [0003] Ethanol is one of the most important bulk fermentation products in my country's fermentation industry. In 2017, there were 131 ethanol production enterprises above designated size nationwide, with a total output of 8.3 million tons, ranking third in the world. In September 2017, fifteen ministries and commissions including the National Development and Reform Commission, the Energy Bureau, and the Ministry of Finance jointly issued the "I...

AI Technical Summary

Problems solved by technology

[0008] In order to reduce the discharge of wastewater and reduce the cost of wastewater treatment, part of the distiller's grains will be directly reused in the ethanol batching process during production, but studies have shown that the reuse ratio of the distiller's grains generally does not exceed 30%, otherwise the solids in the distiller's grains, Substances such as acetic acid, lactic acid and sodium salts will accumulate and poison the ethanol fermentation yeast, resulting in low raw material utilization

There are still two disadvantages in directly reusing distiller's grains as ingredients: one is that the distiller's grains contains miscellaneous bacteria, and the reuse of ingredients can easily lead to acid production by ethanol fermentation, which reduces the utilization rate of raw materials; It is necessary to add alkali or ammonia water to adjust the pH value to the optimum pH range of liquefaction enzyme, which increases the operation and cost

Taking ethanol fermentation with conventional mixing material concentration as an example, the ethanol concentration of mature fermented mash is about 11-13% (v / v) after fermentation. If the absolute concentration of ethanol is reduced by 0.1- 0.2% (v / v), it is difficult to detect in production, but for an ethanol production enterprise with an annual output of 100,000 tons, the economic loss caused by this slight impact is about 5 million yuan

Images