Preparation of a sludge dewatering conditioner based on microbial residue and biochar and method of application thereof

Abstract

The application discloses a kind of preparation and its application method of sludge dewatering conditioner of microbial residue based biochar, and the preparation method includes the following steps: after once crushing and screening, obtain large particle raw biomass raw material, after secondary crushing and screening, obtain small particle raw biomass raw material;Small particle raw biomass raw material is mixed with zinc chloride solution uniformly, and after standing, hydrothermal carbonization raw material is obtained, and then mixed with water to carry out hydrothermal carbonization reaction, and after centrifugal dewatering treatment, Fe 3+ Solution is mixed uniformly, and then centrifugal dewatering treatment is carried out to obtain iron-containing biochar;Iron-containing biochar is mixed with dried and dewatered large particle raw biomass raw material to obtain the final product.The application uses hydrothermal carbonization to prepare sludge dewatering conditioner of microbial residue based biochar, which can realize recycling of microbial residue;Compared with the method of preparing biochar by pyrolysis, the energy consumption is lower, and the wastewater and solid waste generated during the process can be integrated into the sludge treatment process for simultaneous treatment.

Description

Technical Field

[0001] This invention relates to the field of environmental protection equipment technology, specifically to the preparation and application method of a microbial residue-based biochar sludge dewatering conditioner. Background Technology

[0002] With the improvement of environmental protection and governance levels, sludge treatment is being carried out more and more frequently. Sludge dewatering is a crucial part of sludge treatment, as it can significantly reduce the weight of sludge, facilitating subsequent processing and disposal. However, the complex water distribution and high water binding energy in sludge make solid-liquid separation difficult, and single-stage mechanical dewatering is not ideal. To solve this problem, sludge conditioning is currently the main approach, with common methods including chemical conditioning, biological conditioning, and physical conditioning. Among these, chemical conditioning involves adding chemical reagents to the sludge to achieve deep dewatering. However, this conditioning method corrodes dewatering equipment, and the addition of chemical agents can easily cause secondary pollution, complicating the sludge disposal process. Biological conditioning involves adding microorganisms to the sludge to promote its degradation and transformation; however, the microbial conditioning process is time-consuming and requires targeted adjustments based on the sludge composition, making it relatively complex. Physical conditioning uses physical methods to break down the structure of sludge flocs, thereby removing free water and some adsorbed water from the sludge. Compared to chemical and biological conditioning methods, physical conditioning has the advantages of low pollution and convenient subsequent treatment. Using biochar as a framework is a common method in physical conditioning; adding biochar to the sludge system can create drainage channels between sludge particles, improving drainage performance.

[0003] Patent CN111437825B discloses an iron-manganese biochar catalyst and its application in sludge conditioning and dewatering. In this patent, agricultural waste is uniformly impregnated with an activator, dried, and then pyrolyzed in an inert atmosphere to obtain biochar after post-treatment. The biochar is then uniformly mixed with a Fe3+ and Mn2+ solution, separated, and the resulting solid material is further processed to obtain the iron-manganese biochar catalyst. In this patent's preparation process, the agricultural waste needs to be impregnated with an activator, dried, and pyrolyzed to obtain biochar, which is then mixed with a Fe3+ and Mn2+ solution for solid-liquid separation. This repeated drying, pyrolysis, and solid-liquid separation process is energy-intensive. Furthermore, the pyrolysis and carbonization process generates tar, volatile organic compounds, and other harmful waste gases, posing a potential pollution risk. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a biochar-based sludge dewatering conditioner, in order to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides a method for preparing and applying a biochar-based sludge dewatering conditioner.

[0006] The preparation method of the bacterial residue-based biochar sludge dewatering conditioner includes the following steps: S11, after the bacterial residue is crushed and sieved once to obtain large-particle raw biomass material, a portion of the large-particle raw biomass material is crushed and sieved a second time to obtain small-particle raw biomass material; S12, the small-particle raw biomass material obtained in step S11 is mixed evenly with zinc chloride solution and allowed to stand to obtain hydrothermal carbonization material; S13, the hydrothermal carbonization material obtained in step S12 is mixed with water and subjected to hydrothermal carbonization reaction, followed by centrifugal dewatering to obtain hydrothermal carbonization product; at the same time, the residual heat of the hydrothermal reaction is used to dry the large-particle raw biomass material; S14, the hydrothermal carbonization product is mixed evenly with Fe3+ solution and subjected to centrifugal dewatering to obtain iron-containing biochar; the iron-containing biochar is mixed with the dried and dewatered large-particle raw biomass material obtained in step S3 to obtain the final product, bacterial residue-based biochar sludge dewatering conditioner.

[0007] Furthermore, in step S11, the particle size range of the large-particle raw biomass material is 20-100 mm; the particle size range of the small-particle raw biomass material is 0.5-10 mm; and the particle size range of the biochar obtained from the hydrothermal carbonization product in step 13 is 0.1-0.5 mm.

[0008] Furthermore, in step S12, the mass ratio of small-particle raw biomass material to zinc chloride is 100:(5-10); the settling time is 1-2 hours; and the concentration of the zinc chloride solution is 10-15%.

[0009] Furthermore, in step S13, the mass ratio of small-particle original biomass raw material to water in the hydrothermal carbonization raw material is 1:(3-8), the hydrothermal carbonization reaction temperature is 200-300 degrees, and the reaction time is 3-5 hours.

[0010] Furthermore, the moisture content of the large-particle raw biomass raw material is 10%-15% after drying using the residual heat from the hydrothermal reaction in step S13.

[0011] Furthermore, the Fe3+ solution in step S14 is ferric chloride, with a mass ratio of small-particle raw biomass material to ferric chloride of 100:(3-10); the concentration of the ferric chloride solution is 10%-15%.

[0012] Furthermore, the centrifugation speed for the centrifugation dehydration process in steps S13 and S14 is 3000-8000 rpm, with the centrifugation time in step S13 being 10-15 minutes and the centrifugation time in step S14 being 3-5 minutes; after drying and dehydration, the weight ratio of the large-particle raw biomass material obtained by mixing with iron-containing biochar to the small-particle raw biomass material in step 12 is (10-20):100.

[0013] The application method of the biochar dewatering conditioner based on bacterial residue includes the following steps: S21, placing the sludge in a treatment tank, adding quicklime to adjust the pH to neutral, allowing it to settle and separate into layers, and then extracting the supernatant; S22, adding the biochar dewatering conditioner based on bacterial residue to the sludge and stirring, the amount of the biochar dewatering conditioner being added is 10-50% of the dry sludge mass; allowing it to settle and separate into layers, and then extracting the supernatant; then stirring again, allowing it to settle and separate into layers, and then extracting the supernatant for subsequent dewatering treatment. The subsequent dewatering treatment can be either belt dewatering or plate and frame filter press dewatering.

[0014] This invention utilizes hydrothermal carbonization to prepare a biochar-based sludge dewatering conditioner, enabling the recycling of the bacterial residue. Compared to pyrolysis methods for biochar preparation, this process consumes less energy, and the wastewater and solid waste generated during treatment can be integrated into the sludge treatment process. Specifically, the activation effect of zinc chloride improves biochar preparation efficiency and increases its porosity, thus enhancing its dewatering effect on sludge. Simultaneously, the addition of iron ions disrupts the stability of the sludge colloidal system and promotes particle aggregation through adsorption and bridging, further improving sludge dewatering. Furthermore, mixing the dewatered and dried bacterial residue with the prepared iron-containing bacterial residue-based biochar significantly reduces the moisture content of the final product, facilitating its transportation, storage, and use. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the preparation process of the bacterial residue-based biochar sludge dewatering conditioner of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The preparation method of a microbial residue-based biochar sludge dewatering conditioner involved in this invention includes the following steps:

[0018] S11. After the mushroom residue is crushed and sieved once, large-particle raw biomass raw material is obtained. After some of the large-particle raw biomass raw material is crushed and sieved a second time, small-particle raw biomass raw material is obtained.

[0019] S12. The small-particle raw biomass material obtained in step S11 is mixed evenly with zinc chloride solution and allowed to stand to obtain hydrothermal carbonization material.

[0020] S13. The hydrothermal carbonization raw material obtained in step S12 is mixed with water and subjected to hydrothermal carbonization reaction. After centrifugation and dehydration, the hydrothermal carbonization product is obtained. At the same time, the residual heat of the hydrothermal reaction is used to dry the large-particle original biomass raw material.

[0021] S14. The hydrothermal carbonization products are combined with Fe 3+ After the solution is mixed evenly, it is centrifuged and dehydrated to obtain iron-containing biochar; the iron-containing biochar is dried and dehydrated in the same way as the one obtained in step S3 to obtain large-particle raw biomass raw material, and then mixed to obtain the final product, microbial residue-based biochar sludge dewatering conditioner.

[0022] In step S11, the particle size range of the large-particle raw biomass material is 20-100 mm; the particle size range of the small-particle raw biomass material is 0.5-10 mm. The particle size of the small-particle raw biomass material is mainly used to control the particle size range of the biochar obtained from the hydrothermal carbonization product in step S13. The particle size range of the biochar obtained from the hydrothermal carbonization product in step S13 is 0.1-0.5 mm, preferably 0.1-0.2 mm. If the biochar particle size is too large, it easily floats on the sludge surface and cannot be evenly mixed with the sludge, affecting its conditioning effect. If the biochar particle size is too small, it cannot play a role in building a framework and improving sludge dewatering.

[0023] In step S12, the mass ratio of small-particle raw biomass material to zinc chloride is 100:(5-10); the settling time is 1-2 hours; and the concentration of the zinc chloride solution is 10-15%.

[0024] In step S13, the mass ratio of small-particle original biomass raw material to water in the hydrothermal carbonization raw material is 1:(3-8), the hydrothermal carbonization reaction temperature is 200-300 degrees, and the reaction time is 3-5 hours.

[0025] The utilization of waste heat from the hydrothermal reaction in step S13 is standard knowledge in the field. The moisture content of the large-particle raw biomass feedstock after drying is 10%-15%, and the drying method is also standard knowledge in the field.

[0026] Fe in step S14 3+ The solution is ferric chloride, with a mass ratio of small-particle raw biomass material to ferric chloride of 100:(3-10); the concentration of the ferric chloride solution is 10%-15%.

[0027] The centrifugal dehydration process in steps S13 and S14 is standard practice in the field, with a centrifugation speed of 3000-8000 rpm. The centrifugation time in step S13 is 10-15 minutes, and the centrifugation time in step S14 is 3-5 minutes.

[0028] After drying and dehydration, the large-particle raw biomass material obtained by mixing with iron-containing biochar is in a weight ratio of (10-20):100 with the small-particle raw biomass material in step 12. This material is used to adsorb Fe in steps S13 and S14. 3+ The water remaining after the solution is added.

[0029] This invention also provides a method for applying a microbial residue-based biochar sludge dewatering conditioner, comprising the following steps:

[0030] S21. Place the sludge into the treatment tank, add quicklime to adjust the pH value to neutral, let it stand and separate into layers, and then extract the supernatant.

[0031] S22. Add the biochar dewatering conditioner based on bacterial residue to the sludge and stir. The amount of the biochar dewatering conditioner added is 10-50% of the dry sludge mass. After settling and stratification, extract the supernatant. Then, stir again, let it settle and stratify, extract the supernatant, and then proceed with subsequent dewatering treatment. The subsequent dewatering treatment can be either belt dewatering or plate and frame filter press dewatering.

[0032] Based on the above-described invention, the following embodiments and comparative experiments were conducted. In these experiments, sludge specific resistance (SRF) was used as a characterization index of the conditioning effect. Sludge specific resistance (SRF) is one of the most important indicators reflecting the filtration characteristics of sludge. It refers to the resistance of sludge per unit dry weight of filter cake per unit filtration area under a certain pressure. The higher the sludge specific resistance, the lower the sludge dewatering efficiency and the worse the effect of the conditioning agent. The method and apparatus for measuring sludge specific resistance are standard knowledge in the field. The initial sludge specific resistance was: 3.4 × 10⁻⁶. 12 m / kg.

[0033] The preparation parameters of the conditioner in Example 1 are as follows: the particle size range of the large-particle raw biomass is 20 mm; the particle size range of the small-particle raw biomass is 0.2 mm; the mass ratio of the small-particle raw biomass to zinc chloride is 100:10, the concentration of the zinc chloride solution is 10%, and the settling time is 1 h; the mass ratio of the small-particle raw biomass to water in the hydrothermal carbonization raw material is 1:6; the hydrothermal carbonization reaction temperature is 240 degrees Celsius, and the reaction time is 4 h; the moisture content of the large-particle raw biomass after drying is 10%; the Fe3+ solution is ferric chloride, the mass ratio of the small-particle raw biomass to ferric chloride is 100:5, and the concentration of the ferric chloride solution is 10%. The centrifugation speed in steps S13 and S14 is 3000-8000 rpm, the centrifugation time in step S13 is 10 minutes, and the centrifugation time in step S14 is 5 minutes. The mass ratio of the small-particle raw biomass to the large-particle raw biomass obtained after drying and dehydration is 100:20.

[0034] The specific steps of the application method are as follows: Take 500g of sludge and place it in the treatment tank. Add quicklime to adjust the pH value to 7.0 neutral. After standing and separating the layers, extract the supernatant. Add the bacterial residue-based biochar sludge dewatering conditioner to the sludge and stir. The amount of bacterial residue-based biochar sludge dewatering conditioner added is 30% of the dry sludge mass.

[0035] To facilitate the statistical analysis of changes in sludge specific resistance, the supernatant after the first stirring and settling was not removed, and a second stirring was not performed in this embodiment. Only the sludge specific resistance after the first stirring was measured.

[0036]

[0037] The above comparison shows that the conditioner involved in this application can effectively improve the sludge dewatering effect. Zinc chloride mainly affects the dewatering effect by influencing the morphology of biochar. The effect of iron ions on the dewatering effect can also be seen by comparing Comparative Example 1 and Example 1.

[0038] It should be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "joining," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

Claims

1. A method for preparing a biochar-based sludge dewatering conditioner, characterized in that, The process includes the following steps: S11, after the fungal residue is crushed and sieved once, large-particle raw biomass raw material is obtained, and after a second crushing and sieving of some of the large-particle raw biomass raw material, small-particle raw biomass raw material is obtained. S12. The small-particle raw biomass material obtained in step S11 is mixed evenly with zinc chloride solution and allowed to stand to obtain hydrothermal carbonization material. S13. The hydrothermal carbonization raw material obtained in step S12 is mixed with water and subjected to hydrothermal carbonization reaction. After centrifugation and dehydration, the hydrothermal carbonization product is obtained. At the same time, the residual heat of the hydrothermal reaction is used to dry the large-particle original biomass raw material. S14. The hydrothermal carbonization products are combined with Fe 3+ After the solution is mixed evenly, it is centrifuged and dehydrated to obtain iron-containing biochar; the iron-containing biochar is dried and dehydrated in the same way as the one obtained in step S13 to obtain large-particle raw biomass material, and then mixed to obtain the final product, microbial residue-based biochar sludge dewatering conditioner. The particle size range of the large-particle raw biomass raw material in step S11 is 20-100 mm; the particle size range of the small-particle raw biomass raw material is 0.5-10 mm; and the particle size range of the biochar obtained from the hydrothermal carbonization product in step 13 is 0.1-0.5 mm.

2. The preparation method of the microbial residue-based biochar sludge dewatering conditioner according to claim 1, characterized in that, In step S12, the mass ratio of small-particle raw biomass material to zinc chloride is 100:(5-10); the standing time is 1-2 hours; and the concentration of the zinc chloride solution is 10-15%.

3. The preparation method of the microbial residue-based biochar sludge dewatering conditioner according to claim 1, characterized in that, In step S13, the mass ratio of small-particle original biomass raw material to water in the hydrothermal carbonization raw material is 1:(3-8), the hydrothermal carbonization reaction temperature is 200-300 degrees, and the reaction time is 3-5 hours.

4. The preparation method of the microbial residue-based biochar sludge dewatering conditioner according to claim 1, characterized in that, After drying using the residual heat from the hydrothermal reaction in step S13, the moisture content of the large-particle raw biomass material is 10%-15%.

5. The preparation method of the microbial residue-based biochar sludge dewatering conditioner according to claim 1, characterized in that, Fe in step S14 3+ The solution is ferric chloride, with a mass ratio of small-particle raw biomass material to ferric chloride of 100:(3-10); the concentration of the ferric chloride solution is 10%-15%.

6. The preparation method of the microbial residue-based biochar sludge dewatering conditioner according to claim 1, characterized in that, The centrifugation speed for centrifugation dehydration in steps S13 and S14 is 3000-8000 rpm, with the centrifugation time in step S13 being 10-15 minutes and the centrifugation time in step S14 being 3-5 minutes. After drying and dehydration, the large-particle raw biomass material obtained by mixing with iron-containing biochar has a weight ratio of (10-20):100 with the small-particle raw biomass material in step 12.

7. A method for applying the biochar-based sludge dewatering conditioner according to any one of claims 1-6, characterized in that, The process includes the following steps: S21, placing the sludge into the treatment tank, adding quicklime to adjust the pH to neutral, allowing it to settle and separate into layers, and then extracting the supernatant; S22, adding the bacterial residue-based biochar sludge dewatering conditioner to the sludge and stirring it, with the amount of bacterial residue-based biochar sludge dewatering conditioner added being 10-50% of the dry sludge mass; allowing it to settle and separate into layers, and then extracting the supernatant; then stirring it a second time, allowing it to settle and separate into layers, and then extracting the supernatant for subsequent dewatering treatment, which can be either belt dewatering or plate and frame filter press dewatering.

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