A sludge-based biochar prepared by using brewing residual sludge and a method and application thereof

Abstract

The present application relates to sludge modification technical field, especially a kind of sludge-based biochar prepared by using brewing residual sludge and method and application, by introducing tannic acid to the mixed treatment of brewing residual sludge, under the action of ultrasonic, make the floc structure of brewing residual sludge suffer damage, release the protein and polysaccharide in floc structure, then add the above-mentioned sludge-based biochar, make full use of the characteristics of sludge-based biochar, such as large specific surface area, porous and surface N-containing functional group rich and high activity, so that protein, polysaccharide and other substances are adsorbed, then make the protein, polysaccharide and other substances with hydrophilic be solidified and separated from water in sludge, at the same time, using the high compression resistance of sludge-based biochar, promote the densification of brewing sludge floc, build into rigid skeleton structure, provide capillary flow path for brewing residual sludge dewatering, improve the dewatering performance of brewing residual sludge.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sludge modification, and particularly relates to a sludge-based biochar prepared from brewing residual sludge and a preparation method and application thereof. BACKGROUND

[0002] The Maotai-flavor liquor industry is an important industry in Guizhou Province, and with the continuous development of the liquor industry, the total industrial output value of the Maotai-flavor liquor industry in the core production area of Guizhou Province has reached more than 89.7 billion yuan. At the same time, it is proposed that by 2025, the output of Guizhou liquor will reach 600 million liters, and the total output value will reach 300 billion yuan. However, according to the existing liquor production process, it is known that: for the production of 1 t of liquor, about 60 t of water is consumed, and about 48 t of wastewater is generated, of which 1-2% of the wastewater will be converted into sludge, resulting in 200,000 tons of brewing residual sludge in Guizhou by 2025.

[0003] The brewing residual sludge floc is a space net structure formed by the adsorption and bridging of other microorganisms and organic matter on the skeleton of filamentous bacteria, and the electrostatic attraction of cations and anions. It has strong affinity with water and is difficult to dewater, resulting in a high water content of 95-99% in the brewing residual sludge. Therefore, the water content of the brewing residual sludge needs to be reduced before it is used for incineration and power generation, otherwise it will cause high energy consumption, high cost and low treatment efficiency. Moreover, the high organic matter content in the brewing residual sludge is prone to spoilage and odor, causing secondary pollution, and direct stacking treatment is not suitable. Therefore, improving the dewatering performance of the brewing residual sludge and applying incineration and power generation and similar technologies to realize the digestion and utilization of the brewing residual sludge will contribute to the development of the liquor industry.

[0004] At present, the methods for improving the dewatering performance of sludge mainly focus on physical conditioning, chemical conditioning, biological conditioning or combined conditioning of the above methods, and corresponding researches have been made. For example, patent application No. 202210922295.2 discloses a process for coupling and strengthening sludge conditioning and dewatering by using nano-ozone and sludge-based biochar. Nano-ozone and magnetic sludge-based biochar are used to couple and strengthen the dewatering performance of sludge conditioning, to destroy, modify and electrically neutralize the molecular structure of extracellular polymeric substances and new pollutants in the sludge, to strengthen the flocculation and separation effect, to build a free water release channel, to reduce the compressibility of the sludge cake, to improve the sludge conditioning and dewatering performance, and to reduce the water content of the dewatered sludge to 50%. It can be seen that this method introduces the oxidation of nano-ozone and the adsorption of sludge-based biochar to improve the dewatering performance of the sludge, resulting in a large consumption of ozone and high cost in the improvement of the dewatering performance of the sludge.

[0005] For example: Patent application number 202210766446.X discloses an iron-based sludge carbon, a preparation method and its application. The method adds complexing-chelating agent and ferrous salt to residual sludge, then adds persulfate, and filters to prepare iron-containing sludge cake, which is then dried, crushed, sieved and pyrolyzed to prepare iron-based sludge carbon. After compounding with persulfate and adding to sludge, the dewatering performance of sludge is improved. It can be seen that the main purpose of this method is to form a Fenton-like reaction in sludge combined with flocculation to improve the dewatering performance of sludge, so that the moisture content of dewatered sludge is reduced to below 79%. However, the addition of ferrous salt and persulfate not only increases the cost, but also causes secondary pollution.

[0006] For example: Patent application number 202111658803.2 discloses placing sludge in a hydrothermal reactor at a temperature of 60-160℃ and a pressure of 0.1-0.65MPa for 5-60min to break microbial cells and release intracellular water, destroy sludge flocs, and cause organic matter in sludge to dissolve and partially hydrolyze. Then tannic acid is used as a conditioner to convert bound water in sludge into interstitial water and free water, improve sludge dewatering performance, and reduce the moisture content of dewatered sludge to below 60%.

[0007] For example: Patent application number 202110559318.3 discloses preparing an iron-based biochar catalyst by impregnation-hydrothermal method, and then adding PMS, iron-based biochar catalyst and tannic acid to sludge for chemical conditioning to reduce the moisture content of dewatered sludge to 47.59%. However, this method uses catalytic oxidation-flocculation process.

[0008] For example: Patent application number 202011604521.X discloses preparing sludge-based biochar by high-temperature calcination pyrolysis of sludge, mixing sludge-based biochar with manganese and iron solutions to prepare sludge-derived biochar, and then combining with ozone to improve sludge dewatering performance. It can be seen that this method introduces Fenton-like reagent for catalytic oxidation treatment.

[0009] For example: Patent application number 202010529402.6 discloses adding cationic starch grafted condensed tannin to distilled water, gelatinizing to uniformity, obtaining cationic starch grafted condensed tannin suspension, cooling to room temperature, and adding to activated sludge to improve sludge dewatering performance.

[0010] However, the existing technology about the improvement of the dewatering performance of the residual sludge generally needs to introduce metals, heavy metals, oxidizing agents or cationic starch or pre-treat the sludge at high temperature and high pressure to promote the release of intracellular water, which is easy to cause high cost, large energy consumption and even secondary pollution of the improvement of the dewatering performance of the sludge. Moreover, whether these methods can be suitable for the treatment of the brewing residual sludge has not been reported.

[0011] Based on this, the research team is based on the current development status of the liquor industry in Zunyi, Guizhou Province, and carries out research on the improvement of the brewing residual sludge generated in the liquor brewing process, which provides a new idea for the treatment of the brewing residual sludge. SUMMARY

[0012] In order to solve the above technical problems existing in the prior art, the present application provides a sludge-based biochar prepared from brewing residual sludge and a method and application thereof.

[0013] Specifically, it is realized by the following technical solutions:

[0014] One of the purposes of the present application is to provide a method for preparing a sludge-based biochar from brewing residual sludge, which comprises the following steps:

[0015] (1) Take the brewing residual sludge and dry it at 100-110℃ to constant weight for standby use;

[0016] (2) Grind and sieve the dried brewing residual sludge of step (1) through an 80-mesh sieve to obtain a sludge powder;

[0017] (3) Place the sludge powder in a tube furnace, heat it to 500-600℃ at a heating rate of 5-10℃ / min, and keep it at constant temperature for 5-8h, and then naturally cool it.

[0018] The sludge-based biochar is prepared from the brewing residual sludge by drying-grinding-sieving-heating in a tube furnace-constant temperature treatment, so that the N in the sludge-based biochar exists in the form of pyridine type N: 398.7eV and pyridine type N: 404eV, which ensures the activity of the sludge-based biochar, and at the same time, the specific surface area of the prepared sludge-based biochar is about 99.4m 2 / g, so that it can improve the dewatering performance of the brewing residual sludge when used for the treatment of the brewing residual sludge.

[0019] Preferably, in step (1), the brewing residual sludge is dried at 105℃.

[0020] Preferably, in step (3), the sludge powder is placed in a tube furnace and heated to 500℃ at a heating rate of 10℃ / min, kept at constant temperature for 5h, and then naturally cooled.

[0021] The second purpose of the present application is to provide a sludge-based biochar prepared by the above method, which has two forms of pyridine-type N: 398.7 eV and pyridine-type N: 404 eV, improves the activity of N, and helps to improve the dewatering performance of the brewing residual sludge.

[0022] The third purpose of the present application is to provide application of the above sludge-based biochar in improving the performance of the brewing residual sludge.

[0023] The application method is to add tannic acid accounting for 0.02-0.05% of the mass of the brewing residual sludge to the brewing residual sludge, stir for 10-30 min at 100 r / min, stand for 0.5-2 h, then treat with ultrasound for 4-15 s at a frequency of 20 KHz and a sound intensity of 800-1500 W / m 2 , and then add the above sludge-based biochar accounting for 1.5-2.5% of the mass of the brewing residual sludge, stir for 30-50 min, stand for 1-3 h, and mechanically filter.

[0024] The brewing residual sludge is mixed with the introduced tannic acid, and under the action of ultrasound, the floc structure of the brewing residual sludge is destroyed, and the protein and polysaccharide in the floc structure are released. Then the above sludge-based biochar is added, and the large specific surface area, porosity, and high activity of the N-containing functional groups on the surface of the sludge-based biochar are fully utilized, so that the protein, polysaccharide, and other substances are adsorbed, and then the protein, polysaccharide, and other substances with hydrophilicity are solidified and separated from the water in the sludge. At the same time, the high compression resistance of the sludge-based biochar is utilized to promote the densification of the brewing sludge floc and build a rigid skeleton structure, to provide a capillary flow path for dewatering of the brewing residual sludge and improve the dewatering performance of the brewing residual sludge.

[0025] The fourth purpose of the present application is to provide a method for improving the performance of the brewing residual sludge, which comprises the following steps:

[0026] (1) adding tannic acid accounting for 0.02-0.05% of the mass of the brewing residual sludge to the brewing residual sludge, stirring for 10-30 min at 100 r / min, and standing for 0.5-2 h;

[0027] (2) treating the brewing residual sludge of step (1) with ultrasound for 4-15 s;

[0028] (3) adding the above sludge-based biochar accounting for 1.5-2.5% of the mass of the brewing residual sludge to the brewing residual sludge of step (2), stirring for 30-50 min, standing for 1-3 h, and mechanically filtering.

[0029] After the brewing residual sludge is added to tannic acid and stirred and static-ultrasonic treated, the obtained brewing residual sludge is treated by stirring and static- mechanical pressure filtration after adding sludge-based biochar, the water content is less than or equal to 68%, the protein content is about 367.4 mg / L, the polysaccharide is about 54 mg / L, and the Zeta potential is-17 mV, so that the performance of the brewing residual sludge is greatly improved, and the energy consumption and cost of the brewing residual sludge treatment are reduced.

[0030] The mechanical pressure filtration used in the present application includes but is not limited to plate and frame filter press filtration, belt filter press filtration and the like.

[0031] The present application uses brewing residual sludge as raw material to prepare sludge-based biochar, and uses tannic acid to pretreat the brewing residual sludge, and then adds sludge-based biochar to improve the performance of the brewing residual sludge, improve the dewatering performance of the brewing residual sludge, reduce the energy consumption and cost of the brewing residual sludge treatment, and realize the recycling of the brewing residual sludge to prepare sludge-based biochar without secondary pollution, meet the development requirement of 'waste treatment with waste', and have important environmental protection significance.

[0032] The process flow of the present application is simple and easy to operate, and can be widely promoted and implemented. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The present application is a process flow diagram.

[0034] Figure 2 The XPS characterization diagram of C in the sludge-based biochar prepared by pyrolysis in an Ar atmosphere.

[0035] Figure 3 The XPS characterization diagram of N in the sludge-based biochar prepared by pyrolysis in an Ar atmosphere.

[0036] Figure 4 The XPS characterization diagram of P in the sludge-based biochar prepared by pyrolysis in an Ar atmosphere. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be further limited in combination with the drawings and specific embodiments, but the scope of protection is not limited to the description.

[0038] As shown in Figure 1 some embodiments, a method for preparing sludge-based biochar from brewing residual sludge includes the following steps:

[0039] (1) The brewing residual sludge is dried at 100-110 DEG C, for example, 100 DEG C, 101 DEG C, 102 DEG C, 103 DEG C, 104 DEG C, 105 DEG C, 106 DEG C, 107 DEG C, 108 DEG C, 109 DEG C, etc., to constant weight for standby;

[0040] (2) The dried brewing residual sludge of step (1) is ground and passed through an 80-mesh sieve to obtain a sludge powder;

[0041] (3) The sludge powder is placed in a tube furnace and heated to 500-600°C, for example, 500°C, 520°C, 550°C, 570°C, 590°C, 600°C, etc., at a heating rate of 5-10°C / min, for example, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, etc., and held at temperature for 5-8h, for example, 5h, 5.5h, 6h, 7h, 8h, etc., and then naturally cooled.

[0042] As shown in Figure 1 , in some embodiments, the above-mentioned sludge-based biochar is applied in the performance improvement of brewing residual sludge.

[0043] In some embodiments, the method of application is to add 0.02-0.05% of tannic acid, for example, 0.02%, 0.03%, 0.04%, 0.05%, etc., to the brewing residual sludge based on the mass of the brewing residual sludge, stir at 100 r / min for 10-30 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, etc., stand for 0.5-2h, for example, 0.5h, 0.8h, 1h, 1.3h, 1.7h, or 2h, etc., then ultrasonic treat for 4-15s, for example, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, etc., at a frequency of 20KHz and a sound intensity of 800-1500W / m 2 , for example, 800W / m 2 , 900W / m 2 , 1000W / m 2 , 1100W / m 2 , 1200W / m 2 , 1300W / m 2 , 1400W / m 2 , 1500W / m 2 , etc., then add 1.5-2.5% of the above-mentioned sludge-based biochar, for example, 1.5%, 2%, 2.5%, etc., to the brewing residual sludge based on the mass of the brewing residual sludge, stir for 30-50 min, for example, 30 min, 35 min, 40 min, 47 min, 50 min, etc., stand for 1-3h, for example, 1h, 2h, 3h, etc., and mechanically filter press.

[0044] In some embodiments, the mechanical filter press is a plate-and-frame filter press or a belt filter press.

[0045] As shown in Figure 1As shown, in some embodiments, the method for improving the performance of brewing residual sludge, including using brewing residual sludge as raw material, drying-grinding-sieving-calcining-cooling to prepare sludge-based biochar; to brewing residual sludge, 0.02-0.05% of the mass of brewing residual sludge tannic acid is added, stirring treatment 10-30min, static 0.5-2h, using ultrasonic treatment 4-15s; 1.5-2.5% of the mass of brewing residual sludge sludge-based biochar is added, stirring 30-50min, static 1-3h, mechanical pressure filtration, ready.

[0046] In order to better illustrate the technical effects of the technical scheme of the present application, the research team carried out the following experimental study.

[0047] Test 1: Preparation of sludge-based biochar from brewing residual sludge

[0048] The brewing residual sludge was taken from a brewery in Zunyi, Guizhou, and the physicochemical properties of the brewing residual sludge were detected as shown in Table 1:

[0049] Table 1 Physicochemical properties of brewing residual sludge

[0050] pH Moisture content (%) Protein (mg / L) Polysaccharide (mg / L) Zeta potential (mV) Brewery residual sludge 6.2 98.2 43 7 -35

[0051] The brewing residual sludge in Table 1 was placed in an oven at 105℃ until the weight was constant, ground, and sieved through an 80-mesh sieve. Then it was placed in a tube furnace filled with argon, and heated at a rate of 10℃ / min to 600℃ for 5h to obtain sludge-based biochar. The heavy metals in the sludge-based biochar prepared from brewing residual sludge were detected by ICP-MS, and the results are shown in Table 2.

[0052] Table 2 Heavy metal detection in sludge-based biochar

[0053]

[0054] From Table 2, it can be seen that the heavy metal content in the sludge-based biochar obtained by the present application is very low, and all comes from the brewing residual sludge itself, without causing secondary pollution due to the addition of new heavy metal components.

[0055] The C, N, and P in the prepared sludge-based biochar were characterized by XPS, as shown in Figure 2 and Figure 3 and Figure 4 The results show that the N in the sludge-based biochar prepared from brewing residual sludge by drying-grinding-sieving-calcining in an argon atmosphere exists in the form of pyridine-type N: 398.7eV and pyridine-type N: 404eV, making the N-containing functional groups in the sludge-based biochar have good activity, which helps to promote the hydrophilic adsorption of proteins and polysaccharides and improve the compression resistance.

[0056] The sludge-based biochar prepared by drying-grinding-sieving-argon atmosphere calcination was detected by BET, and the results showed that the sludge-based biochar prepared by drying-grinding-sieving-argon atmosphere calcination was a porous structure, had a large specific surface area, and the specific surface area was about 99.4m 2 / g.

[0057] Test 2: Tannic acid-sludge-based biochar synergistically improves the performance of the remaining sludge in the wine-making process

[0058] Example 1

[0059] Take 1000g of the remaining sludge in the wine-making process described in test 1, add 0.4g of tannic acid, stir at 100r / min for 20min, then stand for 1h, then treat under ultrasonic waves with a frequency of 20kHz and an acoustic intensity of 1000w / m 2 for 5s to obtain tannic acid-ultrasonic synergistically treated remaining sludge in the wine-making process.

[0060] Example 2

[0061] Take 1000g of the remaining sludge in the wine-making process described in test 1, treat under ultrasonic waves with a frequency of 20kHz and an acoustic intensity of 1000w / m 2 for 5s, then add 20g of the sludge-based biochar prepared in test 1, stir at 100r / min for 30min, then stand for 1h to obtain ultrasonic-sludge-based biochar synergistically treated remaining sludge in the wine-making process.

[0062] Example 3

[0063] On the basis of example 1, add 20g of the sludge-based biochar prepared in test 1 to the remaining sludge treated by ultrasonic waves for 5s, stir at 100r / min for 30min, then stand for 1h to obtain the modified remaining sludge.

[0064] Example 4

[0065] On the basis of example 2, add 0.4g of tannic acid to the remaining sludge treated by the sludge-based biochar, stir at 100r / min for 20min, then stand for 1h to obtain the modified remaining sludge.

[0066] Example 5

[0067] Take 1000g of the remaining sludge in the wine-making process in test 1, add 0.5g of tannic acid, stir at 100r / min for 30min, then stand for 1h, then treat under ultrasonic waves with a frequency of 20kHz and an acoustic intensity of 1000w / m 2 for 5s, then add 15g of the sludge-based biochar prepared in test 1, stir at 100r / min for 20min, then stand for 1h to obtain the modified remaining sludge.

[0068] Example 6

[0069] Take 1000g of brewery residual sludge in Test 1, add 0.3g of tannic acid, stir at 100r / min for 20min, then stand for 1h, then treat under ultrasound at a frequency of 20kHz and a sound intensity of 1000w / m 2 for 10s, then add 16g of sludge-based biochar prepared in Test 1, stir at 100r / min for 20min, stand for 1h, to obtain the modified residual sludge.

[0070] The treated residual sludge of Example 1-Example 6 is subjected to pressure filtration treatment using a plate and frame filter press, and the moisture content, protein, polysaccharide and Zeta potential of the pressure-filtered residual sludge are detected, and the results are shown in Table 3.

[0071] Table 3 Effect of different treatment methods of brewery residual sludge on sludge performance

[0072]

[0073]

[0074] From the data in Table 3, it can be seen that the technology of simply using tannic acid + ultrasound treatment of residual sludge can release the protein and polysaccharide components in the residual sludge to some extent, thereby improving the dewatering performance of the brewery sludge, but the release degree of protein and polysaccharide components is not ideal, resulting in insufficient destruction of the flocculent structure, causing a large amount of free water and intracellular water to be "locked" in the sludge; the technology of using ultrasound + sludge-based biochar alone to treat residual sludge is difficult to cause the flocculent structure to be largely destroyed, resulting in insufficient release of protein and polysaccharide, causing a large amount of free water and intracellular water to be "locked" in the sludge, resulting in poor dewatering performance of the sludge; using tannic acid-ultrasound-specific sludge-based biochar addition treatment, the tannic acid assists the ultrasound to remove the flocculent structure in the residual sludge, causing the flocculent structure to be largely destroyed, and then using specific sludge-based biochar to introduce and absorb protein, polysaccharide and other components, reducing the affinity adsorption ability of protein and polysaccharide and water, and providing a skeleton structure to form a pressure filtration capillary water flow channel, thereby improving the dewatering performance of the sludge; using the specific sludge-based biochar-ultrasound-tannic acid treatment process, the tannic acid cannot cause a large degree of damage to the flocculent structure of the residual sludge, causing the specific sludge-based biochar to be pre-added to be affected by the subsequent ultrasound-tannic acid, resulting in the desorption of the absorbed protein and polysaccharide components, and even causing the structure of the specific sludge-based biochar to be affected by the ultrasound, resulting in an unsatisfactory improvement effect on the dewatering performance of the residual sludge.

[0075] Test 3: Morphology study before and after treatment of brewery residual sludge

[0076] The brewing residual sludge in test 1 and the brewing residual sludge after being treated by the treatment method in example 3 are compared by scanning electron microscopy, and it can be seen that the appearance and morphology of the brewing residual sludge before and after treatment have great changes, and before treatment, the flocculation structure is relatively smooth and dense, and there are few holes; after treatment, the flocculation surface is rough and uneven, and there are a large number of holes and cracks. It shows that the pores and cracks appear between the flocculation in the treated residual sludge, which can create favorable conditions for the release of bound water.

[0077] The present application creates other matters not fully understood by referring to the prior art or common knowledge well known by those skilled in the art, and is realized by conventional technical means.

[0078] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for improving the performance of brewing waste sludge, characterized in that, Includes the following steps: (1) Add 0.02-0.05% of tannic acid by weight of brewing waste sludge to the brewing waste sludge, stir at 100r / min for 10-30min, and let stand for 0.5-2h; (2) The brewing residue sludge from step (1) is treated with ultrasound at a frequency of 20KHz and a sound intensity of 800-1500W / m² for 4-15s; (3) Add 1.5-2.5% of the weight of the brewing waste sludge to the brewing waste sludge in step (2), stir for 30-50 minutes, let stand for 1-3 hours, and then mechanically filter to obtain the product; The method for preparing sludge-based biochar includes the following steps: S1: Dry the remaining sludge from brewing at 100-110℃ to constant weight for later use; S2: Grind the remaining brewing sludge dried in step S1 and pass it through an 80-mesh sieve to obtain sludge powder; S3: Place the sludge powder in a tube furnace and heat it to 500-600℃ at a heating rate of 5-10℃ / min. Maintain the temperature for 5-8 hours and allow it to cool naturally to obtain the final product.

2. The method for improving the performance of brewing waste sludge as described in claim 1, characterized in that, In step S1, the remaining sludge from brewing is dried at 105°C.

3. The method for improving the performance of brewing waste sludge as described in claim 1, characterized in that, In step S3, the sludge powder is placed in a tubular furnace and heated to 600°C at a heating rate of 10°C / min for 5 hours and then naturally cooled.

4. The method for improving the performance of brewing waste sludge as described in claim 1, characterized in that, The specific surface area of ​​the sludge-based biochar is 99.4 m². 2 / g.

5. The brewing waste sludge obtained by the method according to any one of claims 1-4, characterized in that, The resulting brewing waste sludge has a moisture content of ≤68%, a protein content of 367.4 mg / L, a polysaccharide content of 54 mg / L, and a zeta potential of -17 mV.

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