CN102452702B - Recycling method of condensed water - Google Patents

Abstract

The invention provides a method for recycling condensed water. The condensed water is condensed water obtained after distillation or evaporation of fermentation broth and/or filtrate. It is characterized in that the method comprises: combining the condensed water with The anion exchange resin is contacted, and the conditions of the contact are such that the contents of acetate, lactate and succinate ions in the condensed water after contact are less than or equal to 20 mg/liter respectively, and the treated condensed water is used to prepare the fermentation stock solution, which can replace the existing Some fermentation stocks use water. Thus, the recycling of condensed water can be successfully realized, the total amount of water used in the fermentation process can be reduced by 30%, and the load and cost of environmental protection treatment can be greatly reduced, which is conducive to the recycling of water resources and efficient and clean production.

Description

A method for recycling condensed water

technical field

The invention relates to a method for recycling condensed water.

Background technique

The fermentation process refers to the process of using the enzymes of cultured cells to convert substrates into various useful products. It is widely used in the preparation of fuel ethanol, food, medicine and various chemical raw materials. Specifically, the fermentation process includes cell culture, substrate conversion, and the separation and purification of products after substrate conversion in industrial production. The above process needs to involve the distillation and evaporation concentration of the fermentation liquid or filtrate, etc. The condensed water obtained by the condensation of the steam generated by the concentration generally accounts for more than 60% of the total amount of fermentation water, and the condensed water generally contains HCO ₃ ^- , Inorganic anions such as CO ₃ ^2- , SO ₄ ^2- , Cl ^- , PO ₄ ^3- and cations such as Na ⁺ , Mg ²⁺ , Fe ²⁺ /Fe ³⁺ , Ca ²⁺ and organic acids such as acetic acid, lactic acid and butyl Diacid etc.

Because a large amount of condensed water produced after distillation or evaporative concentration of the fermentation broth and/or filtrate has an inhibitory effect on the enzyme activity and cell growth of the fermentation, the above-mentioned condensed water cannot be directly used to prepare the fermentation stock solution. In addition, the above-mentioned condensed water has relatively high COD and BOD values. For example, in the process of producing ethanol by fermentation, the COD value of condensed water is 4000-5000 mg/ml, and the BOD value is 300-500 mg/ml. Therefore, the current The condensed water produced during the fermentation process must be discharged after undergoing environmental anaerobic and aerobic biochemical treatment.

As mentioned above, the condensed water produced in the fermentation process cannot be recycled directly, which increases the environmental protection treatment load and cost of producers, and is not conducive to the recycling of water resources and efficient and clean production.

Contents of the invention

In order to overcome the defect that the condensed water generated in the fermentation process cannot be directly recycled, the present invention provides a condensed water reuse method.

The inventors of the present invention have found that the content of acetate, lactate and succinate ions contained in the condensed water is all high, if the concentrations of acetate, lactate and succinate ions in the condensed water are respectively reduced to a sufficiently low level, The condensed water can be reused as fermentation water without inhibiting the enzyme activity and cell growth of fermentation.

On the basis of the above findings, the present invention provides a method for recycling condensed water. The condensed water is the condensed water obtained by distilling or evaporating the fermented liquid and/or filtrate produced in the fermentation process. It is characterized in that the method comprises: contacting the condensed water with an anion exchange resin, the conditions of contacting are such that the contents of acetate, lactate and succinate ions in the contacted condensed water are respectively less than or equal to 20 mg/L, and will be combined with The condensed water after contacting the anion exchange resin is used to prepare the fermentation stock solution.

Through the method provided by the invention, the condensed water can not inhibit the enzyme activity of fermentation and the growth of cells, so that the condensed water can be successfully recycled, so the total amount of water used in the fermentation process can be reduced by more than 30%, and environmental protection can be achieved. The processing load and environmental protection processing costs are greatly reduced, which is conducive to the recycling of water resources and the efficient and clean production of producers.

Detailed ways

The present invention provides a method for recycling condensed water. The condensed water is obtained by distilling or evaporating the fermented liquid and/or the filtrate produced in the fermentation process. It is characterized in that the method comprises: The condensed water is contacted with an anion exchange resin, and the conditions of contact are such that the contents of acetate, lactate and succinate ions in the contacted condensed water are respectively less than or equal to 20 mg/liter, and the condensed water after contacting with the anion exchange resin Water is used to prepare the fermentation stock solution.

According to the present invention, the fermentation process may include various processes of converting substrates into products by artificially adding enzymes and/or cells, preferably including converting starch-containing raw materials into products by artificially adding enzymes and/or bacteria species Processes, for example, the production of ethanol by fermentation from corn, wheat and tubers; the production of citric acid by fermentation from corn, wheat and tubers; the production of lysine by fermentation from corn, wheat and tubers process.

According to the present invention, the fermented liquid refers to the liquid mixture obtained after the fermentation step is completed; the filtrate refers to the liquid mixture obtained after filtering the waste tank liquid with a solids content less than or equal to 40 grams per liter; The waste tank liquid refers to the liquid mixture remaining after the fermentation broth is distilled out of the target product (such as ethanol).

According to the present invention, the concentration may include various distillation or evaporation processes for the purpose of reducing the water content in the fluid, for example, under normal pressure or reduced pressure, heating fermentation broth, filtrate, etc. to promote their evaporation , the heating method can be heat exchange between the concentrated fluid and the primary steam heated by the boiler.

According to a preferred embodiment of the present invention, the condensed water is the secondary steam condensed water obtained by evaporating the filtrate produced after the waste tank liquid in the tower kettle is press-filtered during the production of ethanol by the fermentation method.

According to the present invention, in the condensed water obtained by evaporating the filtrate produced in the fermentation process to produce ethanol, the content of acetate ions can be 200-600 mg/liter, and the content of lactate ions can be 300-700 mg/liter, The content of succinate ions may be 110-200 mg/liter.

According to the present invention, the conditions for contacting the condensed water with the anion exchange resin can include: the contact temperature can be 20-60°C, preferably 25-40°C; the weight ratio of the condensed water to the dry weight of the anion exchange resin is 1: 0.0036-0.0125 , preferably 1:0.0045-0.0075.

According to the present invention, the mode of contacting the condensed water with the anion exchange resin can be to make the condensed water pass through the anion exchange resin bed, and the conditions of the contact can also include: the volume space velocity of the condensed water can be 1.3-3 hours ⁻¹ , Preferably it is 1.6-2.3 h ^-1 .

According to the present invention, the anion exchange resin may be a strongly basic anion exchange resin and/or a weakly basic anion exchange resin.

According to the present invention, the weakly basic anion exchange resin is preferably an acrylic weakly basic anion exchange resin, a phenolic weakly basic anion exchange resin, an epoxy weakly basic anion exchange resin and a styrene weakly basic anion exchange resin. One or more of the resins.

Since the acrylic weakly basic anion exchange resin has high exchange capacity and excellent mechanical strength, it is preferred that the weakly basic anion exchange resin is an acrylic weakly basic anion exchange resin.

The inventors of the present invention have found that macroporous acrylic weakly basic anion exchange resins have higher exchange capacity and better mechanical strength than gel-type acrylic weakly basic anion exchange resins, and are more effective against acetate, lactic acid Root and succinate ions have a higher adsorption capacity, so they are more suitable for the treatment of condensed water produced in the fermentation process. Therefore, the weakly basic anion exchange resin is further preferably a macroporous acrylic acid series weakly basic anion exchange resin.

The present invention has no special limitation on the weak base group exchange capacity of the weak base anion exchange resin. In order to save material consumption, energy consumption and time in the ion exchange process, it is preferred to use a weak base with a larger weak base group exchange capacity. Anion exchange resin, specifically, it is preferred to use a macroporous acrylic acid series weakly basic anion exchange resin with a weak base group exchange capacity greater than or equal to 6.5 mmol/g dry resin, and it is further preferred that the weak base group exchange capacity is 6.5-12 mmol Mole/gram dry resin macroporous acrylic weakly basic anion exchange resin. It should be noted that the weak base group exchange capacity described in the present invention is the value measured according to the GB/T 19861-2005 standard.

According to the present invention, the anion exchange resin can be obtained commercially. For example, the macroporous acrylic weak base can be obtained by purchasing ion exchange resins with domestic brands of D310 to D319. D in the brand represents large Pore type, the 3 in the second position means weak alkalinity, the 1 in the third position means acrylic, and the 0 to 9 in the fourth position means the sequence number used to distinguish the difference between groups and cross-linking agents.

According to a preferred embodiment of the present invention, the condensed water is the secondary steam condensed water obtained by evaporating the filtrate produced after the waste tank liquid in the tower kettle is press-filtered during the production of ethanol by fermentation method. The weakly basic anion exchange resin is a macroporous acrylic weakly basic anion exchange resin. Among them, in the process of ethanol production by fermentation method, the secondary steam condensed water produced by concentrating the filtrate in the tower tank is obtained by filtering the waste tank liquid after distillation in the tower tank to exchange heat with the primary steam heated by the boiler. , obtained by condensing the secondary vapor generated by evaporating the filtrate.

According to the present invention, the reusing method can also include activating the anion exchange resin before contacting with condensed water, and the activating method can include: soaking the commercially available resin with an acid solution for 2-6 hours at first, and then using Rinse with deionized water until the pH value is 4-6; then soak in alkaline solution for 2-8 hours and then wash the resin treated with the alkaline solution with deionized water until the pH value is 7-9.

The acid solution may be an aqueous hydrochloric acid solution, and the concentration of the acid solution may be 2-8% by weight. The alkali in the alkali solution may be sodium hydroxide and/or potassium hydroxide, and the concentration of the alkali solution may be 2-8% by weight. For every gram of dry resin, the acid solution can be used in an amount of 2-12 grams, and the alkali solution can be used in an amount of 2-12 grams.

For every gram of dry resin, the amount of deionized water used for cleaning the acid solution is 6-10 grams; the amount of deionized water used for cleaning the alkali is 16-48 grams.

According to the present invention, the activated resin can be packed into an exchange column to form an ion exchange resin bed, and the method of packing the resin into a column is well known to those skilled in the art and will not be repeated here.

According to the present invention, after the condensed water is contacted with the weakly basic anion exchange resin, the concentration of organic acid radical ions in the condensed water after being contacted with the weakly basic anion exchange resin can be detected by chromatography, if the acetate, lactate and succinate If the concentration of ions is lower than or equal to 20 mg/L, the condensed water after contact can be used to prepare the fermentation stock solution.

The fermentation stock solution is various water-containing raw material solutions for fermentation production, for example: starch slurry in the process of producing ethanol by fermentation method, starch slurry in the process of producing citric acid by fermentation method, and starch slurry in the process of producing lysine by fermentation method. Starch slurry, etc.

According to the present invention, the recycling method may also include contacting the weakly basic anion exchange resin after being contacted with condensed water with an alkaline solution for regeneration. The definition of the alkaline solution is the same as in the activation step, the mode of contacting the weakly basic anion exchange resin with the alkaline solution can be to make the alkaline solution pass through the bed of the weakly basic anion exchange resin, and the conditions of the contact can include: The temperature can be 20-60°C, the volumetric space velocity of the alkali solution can be 1.3-3 hours ^-1 , and the weight ratio of the alkali solution to the dry weight of the weakly basic anion exchange resin can be 1:0.0036-0.0125.

It should be noted that the volumes of gas and liquid in the present invention refer to volumes under standard conditions.

The content of the present invention will be specifically illustrated by the following examples, but the scope of the present invention should not be limited to the examples.

Example 1

This embodiment is used to illustrate the method for recycling condensed water provided by the present invention.

(1) Activation of resin and preparation of ion exchange resin bed

Soak 800 grams of macroporous acrylic series weakly basic anion-exchange dry resin (Jiangsu Su Qing Water Treatment Engineering Group Co., Ltd., resin grade D318 with 2L concentration of 4% by weight hydrochloric acid solution, weak base group exchange capacity greater than or equal to 6.5 mmoles per gram of dry resin), rinsed with deionized water to a pH between 4-6 after soaking for 4 hours. After contacting with 2L sodium hydroxide solution with a concentration of 5% by weight for 6 hours, rinse with water until the pH value of the eluent is between 7-9 to obtain an activated macroporous acrylic weakly basic anion exchange resin. With 25 grams of the activated macroporous acrylic series weakly basic anion exchange resin, it is packed into an ion exchange resin bed layer with a diameter of 2.18 centimeters and a height of 110 centimeters.

(2) Ion exchange

Make the temperature be 50 ℃ in the fermentative method production ethanol process, the secondary steam condensed water (wherein, the content of acetate ion is 450 mg/liter , the content of lactate ion is 650 mg/liter, and the content of succinate ion is 180 mg/liter) through the above-mentioned ion exchange column at a volume space velocity of 2.3 hours ^-1 , ion exchange is carried out, and the solution after exchange is collected. The concentration of acetate in the exchanged solution measured by HPLC method is 5 mg/L, the content of lactate ion is less than 0.01 mg/L, and the content of succinate ion is less than 0.01 mg/L.

(3) Preparation of fermentation stock solution and fermentation

100 g of corn ground product having an average particle diameter of 1500 microns was mixed with 220 g of the exchanged solution to obtain a starch slurry. At 50°C, mix the above-mentioned starch slurry with α-amylase (purchased by Novozymes) with 100,000 enzyme activity units to obtain a mixture, adjust the pH value of the mixture to 5, and keep it for 50 minutes to obtain an enzymatic hydrolysis product Make the temperature of the enzymatic hydrolyzate drop to 33°C, inoculate 10 ⁵ colony-forming units of Saccharomyces cerevisiae (Anqi super Saccharomyces cerevisiae high activity dry yeast, Hubei Angel Yeast Co. The mixture was cultivated at 33° C. for 65 hours. After the fermentation was finished, the alcohol content of the fermentation product measured by an alcohol meter was 14.39% by volume.

Comparative example 1

This example is used to illustrate the effect of direct reuse of condensed water without ion exchange treatment.

Preparation of fermentation stock solution and fermentation

100 g of ground corn product having an average particle diameter of 1500 μm was mixed with 220 g of the same secondary steam condensate as in Example 1 without ion exchange treatment to obtain a starch slurry. At 50°C, mix the above-mentioned starch slurry with α-amylase (purchased by Novozymes) with 100,000 enzyme activity units to obtain a mixture, adjust the pH value of the mixture to 5, and keep it for 50 minutes to obtain an enzymatic hydrolysis product Make the temperature of the enzymatic hydrolyzate drop to 33°C, inoculate 10 ⁵ colony-forming units of Saccharomyces cerevisiae (Anqi super Saccharomyces cerevisiae high activity dry yeast, Hubei Angel Yeast Co. The mixture was cultivated at 33° C. for 65 hours. After the fermentation was completed, the alcohol content of the fermentation product measured by an alcohol meter was 12.71% by volume.

Comparative example 2

This example is used to illustrate the fermentation effect of fresh deionized water.

Preparation of fermentation stock solution and fermentation

100 g of corn ground product having an average particle diameter of 1500 microns was mixed with 220 g of fresh deionized water to obtain a starch slurry. At 50°C, mix the above-mentioned starch slurry with α-amylase (purchased by Novozymes) with 100,000 enzyme activity units to obtain a mixture, adjust the pH value of the mixture to 5, and keep it for 50 minutes to obtain an enzymatic hydrolysis product Make the temperature of the enzymatic hydrolyzate drop to 33°C, inoculate 10 ⁵ colony-forming units of Saccharomyces cerevisiae (Anqi super Saccharomyces cerevisiae high activity dry yeast, Hubei Angel Yeast Co. The mixture was cultivated at 33° C. for 65 hours. After the fermentation was finished, the alcohol content of the fermentation product measured by an alcohol meter was 14.45% by volume.

Example 2

This embodiment is used to illustrate the method for recycling condensed water provided by the present invention.

(1) Activation of resin and preparation of ion exchange resin bed

Be that the hydrochloric acid solution of 4% by weight soaks 800 grams of gel-type acrylic acid series weakly basic anion exchange dry resin (Jiangsu Suqing, resin grade 313, weak base group exchange capacity greater than or equal to 5.5 mmol/g dry with 2L concentration of hydrochloric acid solution of 4% by weight) Resin), rinse with deionized water after soaking for 4 hours until the pH value is between 4-6, and then contact with 2L of sodium hydroxide solution with a concentration of 5% by weight for 6 hours, rinse with water until the pH value of the eluent between 7 and 9, the activated gel type acrylic weakly basic anion exchange resin is obtained. Use 25 grams of the above-mentioned activated gel-type acrylic series weakly basic anion-exchange resin to fill an ion-exchange resin bed layer with a diameter of 2.18 cm and a height of 106 cm.

(2) Ion exchange

In the process of producing ethanol by fermentation method, the waste tank liquid in the tower kettle is obtained by the evaporation of the filtrate produced after press filtration (wherein, the content of acetate is 514 mg/liter, and the content of lactate ion is 320 mg/liter, the content of succinate ion is 150 mg/liter) through the above-mentioned ion exchange column at a volume space velocity of 1.6 hours ^-1 , ion exchange is carried out, and the solution after exchange is collected. The concentration of acetate in the exchanged solution measured by HPLC method was 7 mg/L, the content of lactate ion was 0.1 mg/L, and the content of succinate ion was 0.1 mg/L.

(3) Preparation of fermentation stock solution and fermentation

100 g of corn ground product having an average particle diameter of 1500 microns was mixed with 220 g of the exchanged solution to obtain a starch slurry. At 50°C, mix the above-mentioned starch slurry with α-amylase (purchased by Novozymes) with 100,000 enzyme activity units to obtain a mixture, adjust the pH value of the mixture to 5, and keep it for 50 minutes to obtain an enzymatic hydrolysis product Make the temperature of the enzymatic hydrolyzate drop to 33°C, inoculate 10 ⁵ colony-forming units of Saccharomyces cerevisiae (Anqi super Saccharomyces cerevisiae high activity dry yeast, Hubei Angel Yeast Co. The mixture was cultivated at 33° C. for 65 hours. After the fermentation was finished, the alcohol content of the fermentation product measured by an alcohol meter was 14.15% by volume.

Example 3

This embodiment is used to illustrate the method for recycling condensed water provided by the present invention.

(1) Activation of resin and preparation of ion exchange resin bed

Soak 800 grams of styrene series weakly basic anion exchange dry resin (Jiangsu Suqing, D306, weak base group exchange capacity greater than or equal to 4.8 mmol/g dry resin) with the hydrochloric acid solution of 4% by weight with the concentration of 2L, After soaking for 4 hours, rinse with deionized water until the pH value is 4-6, then soak with 2L of 5% by weight sodium hydroxide solution for 6 hours, then rinse with water until the pH value of the eluent is 7-6. 9. Obtain activated styrenic weakly basic anion exchange resin. With 25 grams of the above-mentioned activated styrene series weakly basic anion exchange resin, the ion exchange resin bed layer with a diameter of 2.18 centimeters and a height of 108 centimeters was packed.

(2) Ion exchange

In the process of producing ethanol by fermentation method, the secondary steam condensed water (wherein, the content of acetate is 514 mg/liter, the content of lactate ion is 481 mg/liter, the content of succinate ion is 125 mg) / liter) through the above-mentioned ion exchange column at a volume space velocity of 1.3 hours ⁻¹ to carry out ion exchange, and collect the exchanged solution. Utilize HPLC (high performance liquid phase analyzer) method to measure the concentration of acetate in the solution after exchange is 10 mg/liter, the content of lactate ion is 0.2 mg/liter, and the content of succinate ion is 0.2 mg/liter.

(3) Preparation of fermentation stock solution and fermentation

100 g of corn ground product having an average particle diameter of 1500 microns was mixed with 220 g of the exchanged solution to obtain a starch slurry. At 50°C, mix the above-mentioned starch slurry with α-amylase (purchased by Novozymes) with 100,000 enzyme activity units to obtain a mixture, adjust the pH value of the mixture to 5, and keep it for 50 minutes to obtain an enzymatic hydrolysis product Make the temperature of the enzymatic hydrolyzate drop to 33°C, inoculate 10 ⁵ colony-forming units of Saccharomyces cerevisiae (Anqi super Saccharomyces cerevisiae high activity dry yeast, Hubei Angel Yeast Co. The mixture was cultured at 33° C. for 65 hours, and after the fermentation was finished, the alcohol content of the fermentation product measured by an alcohol meter was 14.05% by volume.

Example 4

This embodiment is used to illustrate the method for recycling condensed water provided by the present invention.

(1) Activation of resin and preparation of ion exchange resin bed

With the concentration of 2L, soak 800 grams of epoxy series weakly basic anion exchange dry resin (Shanghai Resin Factory, trade mark 331, mass total exchange capacity is greater than or equal to 9.0 mmol/g dry resin) with the hydrochloric acid solution of 4% by weight with the concentration of 2L, soak After 4 hours, rinse with deionized water until the pH value is between 4-6, then soak with 2L of sodium hydroxide solution with a concentration of 5% by weight for 6 hours, then rinse with water until the pH value of the eluent is between 7-9 In between, the activated epoxy-based weakly basic anion exchange resin is obtained. 25 grams of epoxy series weakly basic anion exchange resin after above-mentioned activation are packed into the ion exchange resin bed layer that diameter is 2.18 centimetres, height is 105 centimetres.

(2) Ion exchange

In the process of ethanol production by fermentation method at a temperature of 50°C, the waste tank liquid in the tower kettle is obtained by evaporating the filtrate produced after pressure filtration (wherein the content of acetate is 470 mg/liter, lactic acid The content of root ion is 375 mg/liter, and the content of succinate ion is 115 mg/liter) through the above-mentioned ion exchange column at a volume space velocity of 3 hours ⁻¹ for ion exchange, and collect the exchanged solution. Utilize HPLC (high performance liquid phase analyzer) method to measure the concentration of acetate in the solution after exchange is 15 mg/liter, the content of lactate ion is 0.8 mg/liter, and the content of succinate ion is 0.8 mg/liter.

(3) Preparation of fermentation stock solution and fermentation

100 g of corn ground product having an average particle diameter of 1500 microns was mixed with 220 g of the exchanged solution to obtain a starch slurry. At 50°C, mix the above-mentioned starch slurry with α-amylase (purchased by Novozymes) with 100,000 enzyme activity units to obtain a mixture, adjust the pH value of the mixture to 5, and keep it for 50 minutes to obtain an enzymatic hydrolysis product Make the temperature of the enzymatic hydrolyzate drop to 33°C, inoculate 10 ⁵ colony-forming units of Saccharomyces cerevisiae (Anqi super Saccharomyces cerevisiae high activity dry yeast, Hubei Angel Yeast Co. The mixture was cultivated at 33° C. for 65 hours. After the fermentation was finished, the alcohol content of the fermentation product measured by an alcohol meter was 13.98% by volume.

Example 5

This embodiment is used to illustrate the method for recycling condensed water provided by the present invention.

(1) Activation of resin and preparation of ion exchange resin bed

Soak 800 grams of strongly basic anion exchange dry resin (Jiangsu Suqing, brand D201, mass total exchange capacity greater than or equal to 3.8 mmol/g dry resin) with the hydrochloric acid solution of 4% by weight with the concentration of 2L, after soaking for 4 hours Rinse with deionized water until the pH value is between 4-6, then soak with 2L of sodium hydroxide solution with a concentration of 5% by weight for 6 hours, rinse with water until the pH value of the eluent is between 7-9, The activated strong basic anion exchange resin is obtained. It is 2.18 centimetres, and the ion exchange resin bed layer that height is 115 centimeters is filled with 25 grams of strongly basic anion exchange resins after above-mentioned activation.

(2) Ion exchange

In the process of ethanol production by fermentation method at a temperature of 50°C, the waste tank liquid in the tower kettle is obtained by evaporating the filtrate produced after pressure filtration (wherein the content of acetate is 470 mg/liter, lactic acid The content of root ion is 380 mg/liter, and the content of succinate ion is 117 mg/liter) through the above-mentioned ion exchange column with a volume space velocity of 1.7 hours ^-1 , ion exchange is carried out, and the solution after exchange is collected. The concentration of acetate in the exchanged solution measured by HPLC method was 18 mg/L, the content of lactate ion was 2 mg/L, and the content of succinate ion was 2 mg/L.

(3) Preparation of fermentation stock solution and fermentation

100 g of corn ground product having an average particle diameter of 1500 microns was mixed with 220 g of the exchanged solution to obtain a starch slurry. At 50°C, mix the above-mentioned starch slurry with α-amylase (purchased by Novozymes) with 100,000 enzyme activity units to obtain a mixture, adjust the pH value of the mixture to 5, and keep it for 50 minutes to obtain an enzymatic hydrolysis product Make the temperature of the enzymatic hydrolyzate drop to 33°C, inoculate 10 ⁵ colony-forming units of Saccharomyces cerevisiae (Anqi super Saccharomyces cerevisiae high activity dry yeast, Hubei Angel Yeast Co. The mixture was cultivated at 33° C. for 65 hours. After the fermentation was finished, the alcohol content of the fermentation product measured by an alcohol meter was 13.82% by volume.

The results of Examples 1-5 and Comparative Examples 1-2 show that using the condensed water recycling method provided by the present invention can make the fermentation stoste prepared with the condensed water after contacting with the anion exchange resin and the fresh deionized water prepared The fermented liquid obtained a similar fermentation effect, and was obviously better than the condensed water not in contact with the anion exchange resin.

Claims (7)

1. A method for recycling condensed water, the condensed water is the condensed water obtained after distillation and evaporation concentration of the fermented liquid and/or filtrate, it is characterized in that the method comprises: exchanging the condensed water with anions Resin contact, the conditions of contact make the content of acetate, lactate and succinate ions in the condensed water after contacting less than or equal to 20 mg/liter respectively, and the condensed water after contacting with anion exchange resin is used to prepare the fermentation stock solution, Wherein, the anion exchange resin is an acrylic weakly basic anion exchange resin. 2. The recycling method according to claim 1, wherein the condensed water is condensed water obtained by evaporating the filtrate produced in the process of producing ethanol by fermentation. 3. The recycling method according to claim 1 or 2, wherein the conditions for contacting the condensed water with the anion exchange resin include: the contact temperature is 20-60°C, and the weight ratio of the condensed water to the dry weight of the anion exchange resin is 1 : 0.0036-0.0125. 4. The recycling method according to claim 3, wherein the conditions for contacting the condensed water with the anion exchange resin include: the contact temperature is 25-40°C, and the weight ratio of the condensed water to the dry weight of the anion exchange resin is 1:0.0045- 0.0075. 5. recycling method according to claim 3, wherein, the mode that condensed water is contacted with anion-exchange resin is to make condensed water pass through anion-exchange resin bed, the condition of described contact also comprises that the volume space velocity of condensed water is 1.3-3 hours ^-1 . 6 . The recycling method according to claim 5 , wherein the volumetric space velocity of the condensed water is 1.6-2.3 h ⁻¹ . 7. recycling method according to claim 1, wherein, described acrylic acid series weakly basic anion exchange resin is macroporous type acrylic series weakly basic anion exchange resin, and this macroporous type acrylic series weakly basic anion exchange resin The weak base group exchange capacity is greater than or equal to 6.5 mmol/g dry resin.