Preparation method of "magnetic-base" combined modified biochar and its application in processing of maotai-flavor liquor wastewater

Abstract

The application discloses a preparation method of "magnetic-base" combined modified biochar and application of the biochar in treatment of Jiangxiang Baijiu (Chinese liquor) wastewater, and belongs to the technical field of anaerobic fermentation. The modified biochar obtained by the method can effectively improve the buffering capacity of an anaerobic digestion system when treating Jiangxiang Baijiu wastewater, and improve the production and yield of methane; and the modified biochar has high magnetism and can be recycled, so that the problems of original biochar in the prior art, such as difficulty in recycling and difficulty in improving anaerobic digestion performance, can be effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of anaerobic fermentation technology, specifically relating to a method for preparing "magnetic-alkali" combined modified coconut shell biochar, and applying it to the biochemical treatment process of soy sauce-flavored liquor wastewater. Background Technology

[0002] The brewing process generates baijiu (Chinese liquor) wastewater; for every 1.0L of baijiu produced, over 15L of wastewater is generated. Baijiu wastewater mainly contains organic acids, alcohols, phenols, and other organic compounds. It has a high chemical oxygen demand (COD) and a pH of approximately 3.0-5.0. Direct discharge or inappropriate treatment can lead to environmental pollution, thus requiring an efficient, stable, and economical method for treating baijiu wastewater. Anaerobic digestion (AD), as a highly efficient energy recovery and pollutant removal technology, has been widely used in the treatment of high-concentration organic wastewater. However, for the anaerobic digestion of baijiu wastewater, the acidic environment inhibits the activity of methanogens, leading to the accumulation of volatile fatty acids (VFAs) and acidification of the anaerobic system. To improve the feasibility of using anaerobic digestion, several enhancement technologies have been developed. Commonly used AD enhancement technologies include AD substrate pretreatment, co-digestion, AD process control, and additive addition. Among these, exogenous additives are a relatively convenient method to enhance AD ​​performance.

[0003] Biochar is widely used as an additive to improve the performance of anaerobic digestion, including increasing methane production, improving system stability, shortening lag time, and increasing methane content. To enhance the application of biochar in anaerobic digestion (AD) systems, many studies have explored various methods to improve its physicochemical properties. Commonly used methods include acid, alkali, oxidation, and metal ion incorporation. Studies have found that alkali modification can improve biochar surface properties, promote microbial growth and colonization, and thus enhance the performance of the anaerobic digestion system. However, some biochar added during continuous anaerobic digestion is lost and cannot be recovered. In practical applications, continuous replenishment of biochar is necessary, which is both uneconomical and leads to the loss of microorganisms in the fermentation system. Magnetic biochar, a composite material of biochar and magnetic media, can be easily recovered by utilizing the magnetic properties of the biochar when introduced into an anaerobic digestion system. Therefore, "magnetic-alkali" combined modified biochar is a rational additive for anaerobic digestion of organic waste. Summary of the Invention

[0004] The problem to be solved by this invention is that the original biochar is not good at enhancing anaerobic digestion performance and is not easy to recycle. It provides an "alkali-magnetic" combined modified biochar material and its preparation method that can improve the efficiency of anaerobic digestion treatment of soy sauce-flavored liquor wastewater.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows: This invention provides a method for preparing "magnetic-alkali" combined modified biochar, comprising the following steps:

[0006] a. Biochar powder and KOH solid are added to pure water and magnetically stirred at room temperature to ensure full contact. Then, the mixture is filtered, dried, and ground to obtain powder.

[0007] b. Under nitrogen protection, the powder obtained in step a is placed in a tube furnace and pyrolyzed at 400°C for 1 hour, then cooled. The product is then washed and filtered until the filtrate is neutral. After drying and grinding, alkali-modified biochar is obtained.

[0008] c. Dissolve FeCl3·6H2O and FeSO4·7H2O in pure water, then add alkali-modified biochar, and magnetically stir under anaerobic conditions at room temperature until the reaction is complete. Then titrate with NaOH solution to pH 9.8-10.3 and continue magnetic stirring to ensure complete reaction. After standing, filtering, washing, drying and grinding, a solid powder is obtained.

[0009] d. Under nitrogen protection, the solid powder obtained in step c is placed in a tube furnace and pyrolyzed at 600°C for 2 hours, then cooled to obtain "magnetic-alkali" combined modified biochar.

[0010] In step a of the above preparation method, the mass-volume ratio of the biochar powder, KOH solid, and pure water is 0.9-1g:0.9-1g:10mL.

[0011] In step a of the above preparation method, the biochar powder is obtained by crushing block coconut shell biochar and passing it through a 150-mesh sieve; the magnetic stirring time is 23-24 hours.

[0012] In step b of the above preparation method, the heating rate of the tube furnace is controlled to be 10℃ / min.

[0013] In step c of the above preparation method, the mass-volume ratio of FeCl3·6H2O, FeSO4·7H2O, alkali-modified biochar, and pure water is 16-17g∶11-12g∶23-25g∶240-250mL.

[0014] In step c of the above preparation method, the anaerobic conditions are: N2 is introduced for 2-3 minutes and then sealed with a rubber stopper; the concentration of the NaOH solution is 5 mol / L.

[0015] In step c of the above preparation method, the magnetic stirring time is 30-35 min; the standing time is 11-13 h; and the product is washed with pure water 2-3 times.

[0016] In steps a, b, and c of the above preparation method, the drying process involves drying in an oven at 65°C for 23-24 hours.

[0017] In step d of the above preparation method, the heating rate of the tube furnace is controlled to be 10℃ / min.

[0018] The present invention also provides an application of the "magnetic-alkali" combined modified biochar prepared by the above preparation method in the enhanced anaerobic digestion treatment of soy sauce-flavored liquor wastewater, specifically: using soy sauce-flavored liquor wastewater as the substrate for anaerobic digestion, anaerobic granular sludge as the inoculum, and adding "magnetic-alkali" combined modified biochar to promote anaerobic digestion.

[0019] The beneficial effects of this invention are as follows: This invention provides a method for preparing "magnetic-alkali" combined modified biochar. The modified biochar obtained by this method has a relatively rough surface with a large number of irregular small particles attached, providing a favorable environment for microbial cell colonization and biofilm growth, thereby improving the microbial capacity to degrade organic matter. Therefore, it can effectively improve the buffering capacity of the anaerobic digestion system when treating soy sauce-flavored liquor wastewater, as well as increase the yield and productivity of methane. Moreover, the biochar provided by this invention has high magnetic properties, can be recycled and reused, is more economical and environmentally friendly, and can also reduce the loss of microorganisms in the fermentation system. Therefore, the "magnetic-alkali" combined modified biochar provided by this invention is expected to be efficiently applied in anaerobic fermentation systems. Attached Figure Description

[0020] Figure 1 Scanning electron microscope image of "magnetic-alkali" combined modified coconut shell biochar;

[0021] Figure 2 X-ray diffraction pattern of "magnetic-alkali" combined modified coconut shell biochar;

[0022] Figure 3 X-ray photoelectron spectra of "magnetic-alkali" co-modified coconut shell biochar;

[0023] Figure 4 The magnetic hysteresis curve of "magnetic-alkali" combined modified coconut shell biochar;

[0024] Figure 5 The methane production of simulated liquor wastewater was obtained by anaerobic digestion treatment of coconut shell biochar modified by "magnetic-alkali" combination. Detailed Implementation

[0025] The technical solution of the present invention can be implemented in the following manner.

[0026] This invention provides an "alkali-magnetic" combined modified biochar, and the method for preparing the modified biochar includes the following steps:

[0027] (1) Pulverize the blocky coconut shell biochar and pass it through a 150-mesh sieve to obtain biochar powder;

[0028] (2) Weigh 40g of biochar powder and 40g of KOH solid and add them to 400mL of pure water. Stir with a magnetic stirrer at room temperature for 1 day.

[0029] (3) The solid was obtained by vacuum filtration. The solid was placed in a 65℃ oven and dried for 1 day. The dried solid was ground with a mortar and then pyrolyzed at 400℃ for 1 hour in a tube furnace under nitrogen protection. The heating rate was 10℃ / min.

[0030] (4) After cooling, the solid product is soaked and washed with pure water multiple times until the pH value of the water obtained from washing is neutral. The solid is then dried in a 65°C oven and ground in a mortar to obtain alkali-modified biochar.

[0031] (5) Dissolve 16.89g FeCl3·6H2O and 11.88g FeSO4·7H2O in 250mL of pure water, then add 25g of alkali-modified biochar, pass N2 through for 2min, seal with a rubber stopper, and stir with a magnetic stirrer for 30min at room temperature.

[0032] (6) Titrate with 5 mol / L NaOH solution until the pH value is 9.8-10.3, then continue to stir with a magnetic stirrer for 30 min, let stand for 12 h and then filter to obtain solid;

[0033] (7) The solid obtained after washing with pure water three times was placed in an oven at 65°C to dry. After grinding, the solid was placed in a tube furnace and pyrolyzed at 600°C for 2 hours under nitrogen protection at a heating rate of 10°C / min. After cooling, “magnetic-alkali” combined modified coconut shell biochar was obtained.

[0034] The present invention also provides the application of the "magnetic-alkali" combined modified biochar described in the above scheme in the enhanced anaerobic digestion treatment of Maotai-flavor liquor wastewater. The specific method is as follows: Maotai-flavor liquor wastewater is used as the substrate for anaerobic digestion, anaerobic granular sludge is used as the inoculum, and "magnetic-alkali" combined modified biochar is added to promote anaerobic digestion.

[0035] The technical solution and effects of the present invention will be further explained below through practical examples.

[0036] Example

[0037] I. Preparation of Modified Biochar

[0038] Comparative Example 1: An alkali-modified coconut shell biochar was prepared by the following method:

[0039] 1) Crush the blocky coconut shell biochar and pass it through a 150-mesh sieve to obtain biochar powder;

[0040] 2) Weigh 40g of biochar powder and 40g of KOH solid and add them to 400mL of pure water. Stir with a magnetic stirrer at room temperature for 1 day.

[0041] 3) The solid was obtained by vacuum filtration, and the solid was dried in an oven at 65°C. The dried solid was then ground in a mortar and mortar and then pyrolyzed in a tube furnace at 400°C for 1 hour under nitrogen protection, with a heating rate of 10°C / min.

[0042] 4) After cooling, the solid product is soaked and washed repeatedly with pure water until the pH value of the washing water is neutral. The solid is then dried in a 65℃ oven to obtain alkali-modified biochar.

[0043] Example 1: A "magnetic-alkali" combined modified coconut shell biochar was prepared by the following method:

[0044] 1) Dissolve 16.89g FeCl3·6H2O and 11.88g FeSO4·7H2O in 250mL of pure water, then add 25g of alkali-modified biochar obtained in Comparative Example 1, pass N2 through for 2min, seal with a rubber stopper, and stir with a magnetic stirrer for 30min at room temperature.

[0045] 2) Titrate with 5 mol / L NaOH solution until the pH value is 9.8-10.3, then continue to stir with a magnetic stirrer for 30 min, let stand for 12 h, and then filter to obtain the solid;

[0046] 3) The solid obtained after washing with pure water three times was dried in an oven at 65℃. After grinding, the solid was placed in a tube furnace and pyrolyzed at 600℃ for 2 hours under nitrogen protection at a heating rate of 10℃ / min. After cooling, magnetic alkali modified coconut shell biochar was obtained.

[0047] Figure 1 This is a scanning electron microscope image of the modified coconut shell biochar in this embodiment; Figure 2 This is the X-ray diffraction pattern of the modified coconut shell biochar in this embodiment; Figure 3 This is the X-ray photoelectron spectrum of the modified coconut shell biochar in this embodiment; Figure 4 The figure shows the hysteresis curve of the modified coconut shell biochar in this embodiment. As can be seen from the figure, the surface of the "magnetic-alkali" combined modified biochar prepared in this embodiment is relatively rough and has a large number of irregular small particles attached. The modified biochar has high magnetic properties, which is beneficial for recycling.

[0048] Comparative Example 2: An acid-modified coconut shell biochar was prepared by the following method:

[0049] 1) Crush the blocky coconut shell biochar and pass it through a 150-mesh sieve to obtain biochar powder;

[0050] 2) Weigh 40g of coconut shell charcoal powder and mix it with 200mL of 66% HNO3 solution. Use ultrasound to suspend the mixture for 1h, and then stir it with a magnetic stirrer at room temperature for 12h.

[0051] 3) The solid was obtained by vacuum filtration and washed with pure water until the pH of the waste liquid obtained by vacuum filtration was neutral. The obtained solid was dried in an oven at 65°C and then ground to obtain acid-modified coconut shell biochar.

[0052] Comparative Example 3: A type of "magnetic-acid" co-modified coconut shell biochar was prepared by the following method:

[0053] 1) Dissolve 16.89g FeCl3·6H2O and 11.88g FeSO4·7H2O in 250ml of pure water, then add 25g of acid-modified biochar obtained in Example 3, pass N2 through for 2min, seal with a rubber stopper, and stir with a magnetic stirrer for 30min at room temperature.

[0054] 2) Titrate with 5 mol / L NaOH solution until the pH value is 9.8-10.3, then continue to stir with a magnetic stirrer for 30 min, let stand for 12 h, and then filter to obtain the solid;

[0055] 3) The solid obtained after washing with pure water three times was dried in an oven at 65°C. After grinding, the solid was placed in a tube furnace and pyrolyzed at 600°C for 2 hours under nitrogen protection at a heating rate of 10°C / min. After cooling, magnetic acid modified coconut shell biochar was obtained.

[0056] Comparative Example 4: A magnetic coconut shell biochar was prepared by the following method:

[0057] 1) Crush the blocky coconut shell biochar and pass it through a 150-mesh sieve to obtain biochar powder;

[0058] 2) Dissolve 16.89g FeCl3·6H2O and 11.88g FeSO4·7H2O in 250mL of pure water, then add 25g of biochar powder, pass N2 through for 2min, seal with a rubber stopper, and stir with a magnetic stirrer for 30min at room temperature.

[0059] 3) Titrate with 5 mol / L NaOH solution until the pH value is 9.8-10.3, then continue to stir with a magnetic stirrer for 30 min, let stand for 12 h, and then filter to obtain the solid;

[0060] 4) The solid obtained after washing with pure water three times was dried in an oven at 65°C. After grinding, the solid was placed in a tube furnace and pyrolyzed at 600°C for 2 hours under nitrogen protection at a heating rate of 10°C / min. After cooling, magnetic coconut shell biochar was obtained.

[0061] II. Application of Modified Biochar in Anaerobic Digestion Treatment of Soy Sauce-Flavored Baijiu Wastewater

[0062] A 500mL blue-mouth bottle was used as the reaction flask for anaerobic digestion. The modified biochar prepared in Example 1 and Comparative Examples 1-4 was used to enhance the anaerobic digestion of soy sauce-flavored liquor wastewater. The specific method is as follows:

[0063] (1) Add 100 mL of anaerobic granular sludge and 200 mL of simulated sauce-flavored liquor wastewater to a blue-mouthed bottle. The final total solids concentration (TS) in the system is 4.33%. Add the original biochar and the modified biochar prepared in Example 1 and Comparative Examples 1-4 at a ratio of 10 g / L.

[0064] (2) After N2 is introduced to reach the anaerobic conditions, the mixture is sealed with a rubber stopper and placed in a 35°C incubator. The mixture is manually shaken once a day. Anaerobic digestion is carried out for a total of 20 days. Each group of experiments is repeated 3 times.

[0065] (3) During anaerobic digestion, the biogas production was monitored daily using a pressure gauge, and gaseous products were collected. The methane content was detected using a gas chromatograph; and liquid samples were collected on days 1, 3, 5, 7, 10, 14, 18, and 20 to detect changes in pH, chemical oxygen demand (COD), and volatile fatty acids (VFAs).

[0066] In step (1), the simulated chemical oxygen demand (COD) of the soy sauce-flavored liquor wastewater is 18000 mg / L, resulting in a COD of 12000 mg / L in the reaction system. The specific formula of the simulated soy sauce-flavored liquor wastewater is as follows: 1.17 g / L butyric acid, 1.09 g / L valeric acid, 1.38 g / L hexanoic acid, 0.61 g / L ethanol, 0.773 g / L phenol, and 0.51 g / L p-cresol.

[0067] The methane production of simulated liquor wastewater treated by anaerobic digestion of modified biochar is as follows: Figure 5 As shown in Table 1, where CK is the blank sample, BC is the original biochar, KBC is the alkali-modified biochar, NBC is the acid-modified biochar, MBC is the magnetically modified biochar, KMBC is the "magnetic-alkali" combined modified biochar, and NMBC is the "magnetic-acid" combined modified biochar.

[0068] Table 1 Measurement Results

[0069]

[0070]

Claims

1. The application of a "magnetic-alkali" combined modified biochar in the treatment of soy sauce-flavored liquor wastewater, characterized in that: The preparation method of the "magnetic-alkali" combined modified biochar includes the following steps: a. After crushing the blocky coconut shell biochar, pass it through a 150-mesh sieve to obtain biochar powder. Add the biochar powder and KOH solid to pure water and stir magnetically at room temperature to ensure full contact. Then, after filtration, drying, and grinding, obtain the powder. The mass-to-volume ratio of the biochar powder, KOH solid, and pure water is 0.9-1 g: 0.9-1 g: 10 mL; b. Under nitrogen protection, the powder obtained in step a is placed in a tube furnace and pyrolyzed at 400°C for 1 hour, then cooled. The product is then washed and filtered until the filtrate is neutral. After drying and grinding, alkali-modified biochar is obtained. c. Dissolve FeCl3·6H2O and FeSO4·7H2O in pure water, then add alkali-modified biochar, and magnetically stir under anaerobic conditions at room temperature until the reaction is complete. Then titrate with NaOH solution to pH 9.8-10.3 and continue magnetic stirring to ensure complete reaction. After standing, filtering, washing, drying and grinding, a solid powder is obtained. The mass-to-volume ratio of FeCl3·6H2O, FeSO4·7H2O, alkali-modified biochar, and pure water is 16-17g: 11-12g: 23-25g: 240-250mL; d. Under nitrogen protection, the solid powder obtained in step c is placed in a tube furnace and pyrolyzed at 600°C for 2 hours, then cooled to obtain "magnetic-alkali" combined modified biochar; The application uses soy sauce-flavored liquor wastewater as the substrate for anaerobic digestion, anaerobic granular sludge as the inoculum, and adds "magnetic-alkali" combined modified biochar to promote anaerobic digestion.

2. The application according to claim 1, characterized in that: In step b, the heating rate of the tube furnace is controlled at 10℃ / min.

3. The application according to claim 1, characterized in that: In step c, the anaerobic conditions are: N2 is introduced for 2-3 minutes and then sealed with a rubber stopper; the concentration of the NaOH solution is 5 mol / L.

4. The application according to claim 1, characterized in that: In steps a, b, and c, the drying process involves drying in an oven at 65°C for one day.

5. The application according to claim 1, characterized in that: In step d, the heating rate of the tube furnace is controlled to be 10℃ / min.

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