Sewage treatment carbon source prepared from organic solid waste

Abstract

The invention discloses a sewage treatment carbon source manufactured by utilizing organic solid waste, and relates to the technical field of sewage treatment.The sewage treatment carbon source comprises a cross-linked complex manufactured by utilizing the organic solid waste, the cross-linked complex comprises a cross-linked carrier and multiple layers of functional media arranged on the cross-linked carrier, and the cross-linked complex sequentially comprises a fine matrix layer, a rough matrix layer and a biochar adsorption body; the cross-linking carrier is obtained by carrying out thermal cross-linking molding on waste plastics. According to the technical scheme, the fine substrate layer can be directly absorbed by bacteria, the initial carbon release speed of the added carbon source is increased, along with denitrification, microorganisms are continuously increased, and after the cross-linked complex and the fine substrate layer are degraded and consumed, the rough substrate layer is gradually exposed, so that the denitrification effect is improved. The cross-linked carrier and the rough matrix layer made of the organic solid waste can continuously supplement a carbon source and can slowly release the carbon source, and when the growth cycle of bacteria is finished, the final biochar adsorber can adsorb bacterial corpses in water, so that impurities in sewage are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and more specifically, to a sewage treatment carbon source manufactured by utilizing organic solid waste. Background Art

[0002] In recent years, with the rapid development of the national economy and the deepening of urbanization, the total amount of various organic solid wastes has been increasing. How to deal with organic solid wastes has become an important issue that needs to be solved urgently. At present, the main methods for treating organic solid wastes are landfill and incineration. Landfill is the most common method for treating organic solid wastes. However, landfill not only occupies a large amount of landfill space, but also causes secondary pollution. Although incineration can thoroughly treat organic solid wastes, incineration not only consumes a lot of energy, but also causes pollution to the atmospheric environment and waste of energy.

[0003] Organic solid waste (such as agricultural waste, food processing waste, garden waste, etc.) is gradually regarded as a potential alternative carbon source because it is rich in organic matter and carbon elements. However, there are many problems in the direct use of organic solid waste: first, its composition is complex and unstable, making it difficult to provide uniform carbon source release during sewage treatment; second, the physical form and chemical properties of organic solid waste vary greatly, resulting in low treatment efficiency in practical applications; finally, untreated organic solid waste may contain harmful substances, which will have a negative impact on the sewage treatment system.

[0004] In the prior art, organic solid waste is treated by hydrolysis to obtain carbon sources, but the hydrolysis products are difficult to meet the multiple requirements for curved carbon source release rate, adsorption performance and biodegradability in complex sewage treatment scenarios. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a carbon source for sewage treatment made from organic solid waste, aiming to solve the technical problems that the carbon source obtained from the current organic solid waste treatment has a too fast release rate, insufficient adsorption performance and insufficient biodegradability.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: A carbon source for sewage treatment made from organic solid waste, comprising a cross-linked composite made from organic solid waste, the cross-linked composite comprising a cross-linked carrier and a multi-layer functional medium arranged on the cross-linked carrier, comprising a fine matrix layer, a coarse matrix layer, and a biochar adsorbent in sequence, the cross-linked carrier being obtained by thermal cross-linking of waste plastics.

[0007] Optionally, the waste plastics are thermoplastics, and the thermoplastics include PP, PET, PBT, PBAT, PBS, PHA, and PLA.

[0008] Optionally, the fine matrix layer is made of one or more of glucose, sucrose, maltose, starch and flour.

[0009] Optionally, the coarse substrate layer is made from one or more of corn cobs, corn straw, sugarcane bagasse, rice straw, wheat straw, beet pulp, and soybean straw.

[0010] Optionally, the shape of the cross-linked complex includes sphere, column or square.

[0011] The present invention also proposes a method for preparing the above-mentioned carbon source for sewage treatment produced by using organic solid waste, which comprises the following steps: The organic solid waste is crushed, pyrolyzed at high temperature, cooled, and pressed into shape by adding a binder, and the carbon is activated to obtain a porous biochar core; Drying the organic solid waste and crushing it into particles to obtain a crude matrix; The waste plastic is heated to a molten state and sprayed and deposited into non-woven fabrics; The nonwoven fabric is wound around the porous biochar core, and the coarse matrix and the fine matrix are sequentially filled between the layers; The wound nonwoven fabric is placed in a mold, heated and kept warm to thermally cross-link it, and cooled to obtain a cross-linked composite.

[0012] Optionally, in the steps of crushing the organic solid waste, pyrolyzing it at high temperature, adding a binder to press and form it after cooling, and activating the carbon to obtain a porous biochar core, the pyrolysis temperature is 500-800°C.

[0013] Optionally, after the step of drying the organic solid waste and crushing it into particles to obtain a crude matrix, the step further includes: hydrolyzing the crude matrix in an acidic environment to obtain a fine matrix.

[0014] Optionally, in the step of placing the wound non-woven fabric in a mold and heating it to thermally cross-link it to obtain a cross-linked composite, the insulation temperature is 150-250°C.

[0015] Optionally, in the step of placing the wound non-woven fabric in a mold and heating it to thermally cross-link it to obtain a cross-linked composite, the heat preservation time is 5 to 30 minutes.

[0016] In the technical solution of the present invention, a cross-linked complex made of organic solid waste is used as a composite carbon source, and the manufacturing cost is low. Each layer of functional medium can work synergistically to improve the sewage treatment effect. The fine matrix layer can allow bacteria to directly absorb, which increases the initial carbon release rate of the added carbon source. As denitrification proceeds, the number of microorganisms continues to increase. After the cross-linked complex and its fine matrix layer are degraded and consumed, the coarse matrix layer is gradually exposed. The cross-linked carrier and coarse matrix layer made of organic solid waste can continuously replenish the carbon source and can be released slowly. When the bacterial growth cycle ends, the final biochar adsorbent can adsorb bacterial corpses in the water and reduce impurities in the sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained according to the structures shown in these drawings without creative work. Figure 2 It is a structural schematic diagram of the present invention; Figure 1 A schematic diagram of a process for producing a carbon source for sewage treatment using organic solid waste provided by the present invention; Figure 2 The total nitrogen in Examples 1-3 and Comparative Example 1 of the present invention over the reaction time Content change diagram.

[0018] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0019] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0020] It should be noted that, in the embodiments, those without specifying specific conditions are carried out according to normal conditions or conditions recommended by the manufacturer. Those without specifying the manufacturer of reagents or instruments used are conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, and "A and / or B" is taken as an example, including schemes A, B, or A and B that meet the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of the technical schemes is contradictory or cannot be achieved, it should be considered that the combination of such technical schemes does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work, all belong to the scope of protection of the present invention.

[0021] At present, the design of carbon source materials is mostly limited to a single structure or a simple composite form, which makes it difficult to meet the multiple requirements of carbon source release rate, adsorption performance and biodegradability in complex sewage treatment scenarios. In addition, their stability in water bodies is poor, which can easily cause waste of carbon sources and secondary pollution.

[0022] In view of this, the present invention proposes a carbon source for sewage treatment made from organic solid waste, which includes a cross-linked composite made from organic solid waste, the cross-linked composite includes a cross-linked carrier and a multi-layer functional medium arranged on the cross-linked carrier, which includes a fine matrix layer, a coarse matrix layer, and a biochar adsorbent in sequence, and the cross-linked carrier is obtained by thermal cross-linking molding of waste plastics.

[0023] In the specific implementation, the raw materials of waste plastics are thermoplastics, including PP, PET, PBT, PBAT, PBS, PHA, PLA, among which the degradable plastics can be used as a supplementary carbon source after hydrolysis; the raw materials of the fine matrix layer are selected from one or more of glucose, sucrose, maltose, starch, and flour; the raw materials of the coarse matrix layer are selected from one or more of corn cobs, corn stalks, bagasse, rice straw, wheat straw, beet residue, and soybean straw. In order to improve the adsorption effect, the shape of the cross-linked complex adopts a three-dimensional structure such as spherical, cylindrical or square, which can provide a larger contact area. In this embodiment, the shape of the cross-linked complex adopts a cylindrical structure with a column height of 5 to 50 cm and a cross-sectional diameter of 2 to 20 cm; the total thickness of the fine matrix layer is 0.5 to 5 cm; the total thickness of the coarse matrix layer is 1 to 10 cm; the porous biochar core is preferably cylindrical, and its cross-sectional diameter is 1 to 10 cm.

[0024] The present invention also proposes a method for using organic solid waste to produce a carbon source for sewage treatment, Figure 1 A flow chart of a method for producing a carbon source for sewage treatment using organic solid waste is provided, which includes the following steps.

[0025] Step S10, crushing the organic solid waste, pyrolyzing it at high temperature, adding a binder after cooling, pressing and molding, and activating the carbon to obtain a porous biochar core.

[0026] In the specific implementation, corn stalks, husks and other organic solid wastes are washed and dried, crushed and sieved by a pulverizer to obtain particles with a particle size of 0.5~2cm to improve the efficiency of the pyrolysis reaction. Then, in an anaerobic or low-oxygen environment, the crushed organic solid waste is heated to 500-800℃ for pyrolysis, and the pyrolysis product is quickly cooled to room temperature to avoid the destruction of the carbon structure due to oxidation or secondary reaction at high temperature. A binder (such as starch, lignin sulfonate, etc.) is added to the cooled carbonized material, and it is evenly dispersed by stirring and mixing, and then pressed into a cylindrical preform. The formed preform can be heated in a CO 2 Or heat to 750-1000℃ in a steam atmosphere, expand the pores by gas etching for physical activation; or use sodium hydroxide and formaldehyde modifier to activate the preform for 5-12 hours. The product is acid-washed and washed with water until neutral, and then dried to obtain a porous biochar core.

[0027] Step S20: drying the organic solid waste and crushing it into particles to obtain a crude matrix.

[0028] In the specific implementation, organic solid wastes such as corn stalks and rice husks are washed and dried, and then crushed and sieved by a pulverizer to obtain particles with a particle size of 0.5 to 5 mm.

[0029] In order to reduce manufacturing costs and avoid purchasing raw materials such as glucose, sucrose, maltose, starch, and flour, the crude matrix can also be hydrolyzed in an acidic environment to obtain a refined matrix. The specific method is: add an acidic reagent such as sulfuric acid or acetic acid to stir the hydrolysis reaction, adjust the pH of the reaction system to 3.5-4.5, control the reaction temperature at 50-80°C, and the reaction time is 4-12h. The reaction product is separated into a solid by centrifugation to obtain a liquid phase rich in organic acids, which is further concentrated to obtain a refined matrix rich in small molecular organic matter.

[0030] Step S30: heating the waste plastics to a molten state, and spraying and depositing them into a non-woven fabric.

[0031] In the specific implementation, the waste plastics are first classified by material, impurities such as metal and rubber are removed, and surface stains are cleaned; then the waste plastics are crushed into particles with a particle size of less than 5mm by a pulverizer, which is convenient for heating and melting to improve fluidity; the plastic particles are then heated to 200-300℃ by a screw extruder to form a uniform viscous melt, and the temperature needs to be controlled during the process to prevent thermal degradation; the viscous melt is sprayed and stretched through a spinneret with a high-speed airflow (about 500m / s) to form ultrafine fibers with a diameter of 1~5um, and randomly stacked into a fiber web on the surface of a moving mesh curtain or a rotating drum; the fiber web is pressed by a hot roller, and the temperature is controlled at 120~150℃ to weld the fiber intersections to obtain a non-woven fabric. Preferably, degradable petroleum-based plastics such as PBAT and bio-based plastics such as PLA can be made together with other non-degradable plastics to prevent the carrier function from failing due to the rapid degradation of degradable plastics.

[0032] Step S40: Winding the non-woven fabric on the porous biochar core, and sequentially filling the coarse matrix and the fine matrix between the layers.

[0033] In specific implementation, according to the shape and size of the porous biochar core, a non-woven fabric of a certain width is wrapped, and a coarse matrix is ​​filled on the non-woven fabric. When the thickness of the coarse matrix layer reaches a predetermined value, the fine matrix is ​​filled again. When the thickness of the fine matrix layer reaches a predetermined value, the edge is heated and sealed.

[0034] Step S50, placing the wound non-woven fabric in a mold, heating and keeping it warm to thermally cross-link it, and cooling it to obtain a cross-linked composite.

[0035] In the specific implementation, the wound non-woven fabric is heated by irradiation heating and other methods, and the wound non-woven fabric is placed in the mold to prevent excessive deformation of its outer surface. The insulation temperature is set at 150~250℃, and the insulation time is set at 5~30min, so that each layer of non-woven fabric adheres to each other and undergoes thermal cross-linking reaction. The fiber structure of the non-woven fabric is reorganized to form a stable three-dimensional network structure. After cooling and forming, the fiber structure of the cross-linked composite is reorganized and its distribution is more uniform, and the mechanical properties are better, preventing the matrix between the layers of non-woven fabric from leaking prematurely. In addition, after the degradable plastic in the carrier is decomposed in the sewage, the holes formed can better allow bacteria and sewage to enter, which is conducive to the rapid treatment of sewage.

[0036] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention. Example 1

[0037] 1. Preparation of cross-linked complex The organic solid waste (corn stalk) was crushed to a particle size of 1-3 mm, pyrolyzed at 550 ° C for 2.5 hours under nitrogen protection, and porous biochar powder was obtained after cooling. The porous biochar powder and polyvinyl alcohol were mixed evenly at a weight ratio of 5:1, and pressed to form a columnar porous biochar core with a cross-sectional diameter of 3 cm and a height of 10 cm. The corn stalk was dried at 300 ° C for 10 hours, cooled and put into a crusher to crush it into particles to obtain a crude matrix. Acetic acid buffer solution was added to the crude matrix, and cellulase was added for enzymatic hydrolysis. During the enzymatic hydrolysis, the crude matrix was added in batches to obtain a fermented sugar solution, which was evaporated and concentrated to obtain a sugar-based substance, i.e., a refined matrix. The recycled PET and PBAT plastics were heated and melted into liquid state, added to the screw extruder and sprayed on the mesh curtain, cooled to form a fiber mesh non-woven fabric, and the non-woven fabric was wrapped around the porous biochar core, and a 1 cm thick fine matrix and a 2.5 cm thick coarse matrix were laid in sequence between the layers of the non-woven fabric. The wrapped non-woven fabric was placed in a mold, and the heating temperature was controlled to be 175°C and the heating time was 15 minutes, so that the organic polymer molecules of the non-woven fabric undergo a cross-linking reaction to form a three-dimensional network structure, and each layer of the non-woven fabric was fused into one, to obtain a cross-linked composite I.

[0038] 2. Structural parameters of cross-linked complexes Thickness of coarse substrate layer: 2.5 cm; thickness of fine substrate layer: 1 cm; diameter of porous biochar core: 3 cm, height: 10 cm; total volume: 1 dm³. Example 2

[0039] 1. Preparation of cross-linked complex The organic solid waste (corn stalk) was crushed to a particle size of 1-3 mm, and pyrolyzed at 650 ° C for 2.5 hours under nitrogen protection. After cooling, a columnar porous biochar powder with a cross-sectional diameter of 3 cm and a height of 10 cm was obtained. The porous biochar powder and polyvinyl alcohol were mixed evenly at a weight ratio of 5:1 and pressed to form a porous biochar core. The corn stalk was dried at 300 ° C for 10 hours, and after cooling, it was put into a crusher and crushed into particles to obtain a crude matrix. Acetic acid buffer solution was added to the crude matrix, and cellulase was added for enzymatic hydrolysis. During the enzymatic hydrolysis, the crude matrix was added in batches to obtain a fermented sugar solution, which was evaporated and concentrated to obtain a sugar-based substance, that is, a fine matrix. The recovered PET and PBAT plastics were heated and melted into a liquid state, added to a screw extruder and sprayed on a mesh curtain, cooled to form a fiber mesh non-woven fabric, and the non-woven fabric was wrapped around the porous biochar core, and a 1 cm thick fine matrix and a 2.5 cm thick crude matrix were laid in sequence between the layers of the non-woven fabric. The wound nonwoven fabric is placed in a mold, and the heating temperature is controlled to be 200°C and the heating time is 15 minutes, so that a cross-linking reaction occurs between the organic polymer molecules of the nonwoven fabric to form a three-dimensional network structure, and each layer of the nonwoven fabric is fused into one to obtain a cross-linked composite II.

[0040] 2. Structural parameters of cross-linked complexes Thickness of coarse substrate layer: 2.5 cm; thickness of fine substrate layer: 1 cm; diameter of porous biochar core: 3 cm, height: 10 cm; total volume: 1 dm³. Example 3

[0041] 1. Preparation of cross-linked complex The organic solid waste (corn stalk) was crushed to a particle size of 1-3 mm, pyrolyzed at 750 ° C for 2.5 hours under nitrogen protection, and porous biochar powder was obtained after cooling. The porous biochar powder and polyvinyl alcohol were mixed evenly at a weight ratio of 5:1, and pressed to form a columnar porous biochar core with a cross-sectional diameter of 3 cm and a height of 10 cm. The corn stalk was dried at 300 ° C for 10 hours, cooled and put into a crusher to crush it into particles to obtain a crude matrix. Acetic acid buffer solution was added to the crude matrix, and cellulase was added for enzymatic hydrolysis. During the enzymatic hydrolysis, the crude matrix was added in batches to obtain a fermented sugar solution, which was evaporated and concentrated to obtain a sugar-based substance, i.e., a refined matrix. The recycled PET and PBAT plastics were heated and melted into liquid, added to the screw extruder and sprayed on the mesh curtain, cooled to form a fiber mesh non-woven fabric, and the non-woven fabric was wrapped around the porous biochar core, and a 1 cm thick fine matrix and a 2.5 cm thick coarse matrix were laid in sequence between the layers of the non-woven fabric. The wrapped non-woven fabric was placed in a mold, and the heating temperature was controlled to be 225°C and the heating time was 15 minutes, so that a cross-linking reaction occurred between the organic polymer molecules of the non-woven fabric to form a three-dimensional network structure, and each layer of the non-woven fabric was fused into one, to obtain a cross-linked composite III.

[0042] 2. Structural parameters of cross-linked complexes Thickness of coarse substrate layer: 2.5 cm; thickness of fine substrate layer: 1 cm; diameter of porous biochar core: 3 cm, height: 10 cm; total volume: 1 dm³. Comparative Example 1

[0043] 1. Preparation of traditional composite carbon sources Acetic acid, sodium acetate and glucose were respectively prepared in a volume ratio of 2:1:3 to prepare a traditional composite carbon source. Performance Testing

[0044] (1) Denitrification rate test The activated sludge in the anoxic tank was taken as the sludge sample, and the sewage sample was introduced into the four test tanks. The cross-linked complex prepared in Examples 1-3 was cut into five parts, and evenly laid on the bottom of the corresponding test tanks. 1L of the traditional composite carbon source prepared in Comparative Example 1 was injected into the test tank, and each test tank was mixed evenly and then subjected to denitrification treatment. The denitrification rate was tested under the following carbon sources. Among them, the volume of the anoxic tank sludge sample added was 10L, and the total experimental volume after the sewage sample and the carbon source were added was 100L.

[0045] The denitrification test results are shown in Table 1, where the total nitrogen in Examples 1-3 and Comparative Example 1 over the reaction time The content of Figure 2 shown.

[0046]

[0047] It can be seen from the above data that the cross-linked complex made from organic solid waste in this embodiment, compared with the traditional composite carbon source, has a lower denitrification rate in the early stage, but after 3 to 4 hours, the crude matrix and degradable plastic can be used as a supplementary carbon source, and the denitrification rate is already comparable to the traditional composite carbon source, and can be slowly released without the need for additional carbon sources. When the growth cycle of denitrifying bacteria ends, the porous biochar core that is finally exposed can also adsorb bacterial corpses in the water and reduce impurities in sewage. In addition, the cross-linked complex in this scheme is made from organic solid waste, has low cost, and also achieves solid waste treatment.

[0048] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A carbon source for sewage treatment produced using organic solid waste, characterized in that: It includes a cross-linked composite made from organic solid waste, the cross-linked composite includes a cross-linked carrier and a multi-layer functional medium arranged on the cross-linked carrier, which includes a fine matrix layer, a coarse matrix layer, and a biochar adsorbent in sequence, and the cross-linked carrier is obtained by thermal cross-linking of waste plastics.

2. The carbon source for sewage treatment produced by using organic solid waste as claimed in claim 1, characterized in that: The waste plastics are thermoplastic plastics, and the thermoplastic plastics include PP, PET, PBT, PBAT, PBS, PHA, and PLA.

3. The carbon source for sewage treatment produced by using organic solid waste as claimed in claim 1, characterized in that: The fine matrix layer is made of one or more of glucose, sucrose, maltose, starch and flour.

4. The carbon source for sewage treatment produced by using organic solid waste as claimed in claim 1, characterized in that: The crude matrix layer is made of one or more of corn cobs, corn stalks, sugarcane bagasse, rice stalks, wheat stalks, beet pulp, and soybean stalks.

5. The carbon source for sewage treatment produced by using organic solid waste as claimed in claim 1, characterized in that: The shape of the cross-linked complex includes sphere, column or square.

6. A method for producing a carbon source for sewage treatment using organic solid waste as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: The organic solid waste is crushed, pyrolyzed at high temperature, cooled, and pressed into shape by adding a binder, and the carbon is activated to obtain a porous biochar core; Drying the organic solid waste and crushing it into particles to obtain a crude matrix; The waste plastic is heated to a molten state and sprayed and deposited into non-woven fabrics; The nonwoven fabric is wound around the porous biochar core, and the coarse matrix and the fine matrix are sequentially filled between the layers; The wound nonwoven fabric is placed in a mold, heated and kept warm to thermally cross-link it, and cooled to obtain a cross-linked composite.

7. The method for producing a carbon source for sewage treatment using organic solid waste according to any one of claim 6, characterized in that: In the steps of crushing the organic solid waste, pyrolyzing at high temperature, adding a binder to press and form after cooling, and activating the carbon to obtain a porous biochar core, the pyrolysis temperature is 500-800°C.

8. The method for producing a carbon source for sewage treatment using organic solid waste according to any one of claim 6, characterized in that: After the step of drying the organic solid waste and crushing it into particles to obtain a crude matrix, the method further includes: hydrolyzing the crude matrix in an acidic environment to obtain a fine matrix.

9. The method for producing a carbon source for sewage treatment using organic solid waste according to any one of claim 6, characterized in that: In the step of placing the wound nonwoven fabric in a mold and heating it to thermally crosslink it to obtain a crosslinked composite, the insulation temperature is 150-250°C.

10. The method for producing a carbon source for sewage treatment using organic solid waste according to any one of claim 6, characterized in that: In the step of placing the wound non-woven fabric in a mold and heating it to thermally cross-link it to obtain a cross-linked composite, the heat preservation time is 5 to 30 minutes.

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