A method for producing ethanol by reusing anaerobic digestion effluent and refining tower residue

Abstract

The invention discloses a method for producing ethanol by reusing anaerobic digestion effluent and refining tower residue, and belongs to the technical field of waste water treatment and ethanol fermentation industry. In the present invention, the membrane filtrate after the anaerobic digestion effluent is filtered through the membrane, the residual liquid of the refining tower, other mixing water and the crushed grain raw material are mixed and batched, and the ratio of the batching material to water is 1: (2-3.5), and then liquefied , saccharification, fermentation, distillation and other processes to obtain ethanol, among which, the membrane filtrate accounts for 10-90% of the total ingredient water quality, the refining tower residue accounts for 1-30% of the total ingredient water quality, and other mixing water accounts for the total ingredient water quality 0-60%, by adjusting the ratio of membrane filtrate, fine tower raffinate and other mixing water, or adding acetic acid, control the volatile acid concentration of batching water at 100-1200mg / L (calculated as acetic acid). The method of the invention greatly reduces the discharge of ethanol production wastewater, saves water resources, and at the same time significantly improves the alcohol yield, increases the utilization rate of raw materials by 1-5%, and reduces the energy consumption and cost of ethanol production.

Description

technical field [0001] The invention relates to a method for producing ethanol by reusing anaerobic digestion effluent and refining tower residue, and belongs to the technical field of wastewater treatment and ethanol fermentation industry. Background technique [0002] Ethanol is a kind of 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] While the ethanol industry is developing rapidly, it is also facing very prominent practical problems. That is, the production process needs to consume a large amount of starchy raw materials and water resources, and produce a large amount of high-concentration organic wastewater (distillation waste liquid). According to statistics, at present, more than 60% of ethanol production raw materials in my country are corn, wheat, aged rice, and...

AI Technical Summary

Problems solved by technology

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 lower 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 the mature fermented mash is about 11-13% (v / v) after the end of 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

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