Method for treating pectin-containing wastewater and treatment plant

Abstract

The present disclosure relates to a pectin-containing wastewater treatment method and a treatment device, the method comprising: inputting first pectin wastewater into a biological conversion tank, and performing biological conversion treatment on pectin in the first pectin wastewater based on a pectin-cellulose degradation mixed bacteria to obtain second pectin wastewater containing small molecular structure pectin; wherein the pectin-cellulose degradation mixed bacteria is a mixed bacterial population capable of simultaneously degrading pectin and cellulose, and the biological conversion treatment process is used to change the pectin structure without affecting the chemical oxygen demand corresponding to the first pectin wastewater; inputting the second pectin wastewater into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment to obtain wastewater with reduced organic matter concentration after pectin decomposition and biogas; and the biogas is used for input into a power supply end or an energy storage end for recycling. In the wastewater treatment process, in-situ treatment and relatively sufficient degradation of pectin are achieved, and the treatment load and treatment efficiency are improved.

Description

Technical Field

[0001] This disclosure relates to the field of wastewater treatment technology, and in particular to a method and equipment for treating pectin-containing wastewater. Background Technology

[0002] For some companies that produce canned citrus fruits, alcohol, or perform primary coffee processing, wastewater containing pectin is generated during the production process. From an environmental protection perspective, this wastewater containing pectin needs to be treated to ensure that the effluent meets standards.

[0003] Because the wastewater contains a high amount of pectin, which causes it to become acidic and produces fruit acids after fermentation, leading to a decrease in pH, and because the organic matter concentration in pectin-containing wastewater is also high, it does not meet environmental protection requirements. Related technologies typically involve three stages for treating pectin-containing wastewater: pretreatment, main treatment, and advanced treatment. The aim is to remove pollutants such as pectin, suspended solids, and organic matter from the wastewater to ensure that the effluent quality meets standards. In the pretreatment stage, alkaline substances are often added to adjust the pH of the wastewater to neutral or slightly alkaline. Then, coagulants (such as polyaluminum chloride and iron salts) and flocculants (such as polyacrylamide) are added to promote the formation of larger flocs of pectin and other suspended particles, which are then solidified and filtered out. The remaining pectin in the wastewater is then subjected to further treatment.

[0004] In realizing the concept disclosed herein, the inventors discovered at least the following technical problems in the related technologies: In traditional treatment schemes, the pretreatment stage solidifies pectin in wastewater into larger solids through flocculation. These solids are separated in the subsequent treatment process. Therefore, the subsequent wastewater treatment stage treats the residual pectin (which is low-concentration pectin wastewater) after the main pectin solids have been removed. Although the subsequent treatment stage can treat the residual pectin, since the pectin solidified in the early stage is only separated, the separated pectin is not treated. In fact, the sludge corresponding to this separated pectin faces the problems of large accumulation, difficulty in degradation, and very low degradation efficiency (i.e., a long degradation time). Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, the embodiments of this disclosure provide a method and equipment for treating pectin-containing wastewater.

[0006] In a first aspect, embodiments of this disclosure provide a method for treating pectin-containing wastewater. The method includes: inputting a first pectin wastewater into a biological conversion tank; in the biological conversion tank, based on the introduction of pectin-cellulose degrading mixed bacteria, performing biological conversion treatment on the pectin in the first pectin wastewater to obtain a second pectin wastewater containing pectin with a small molecular structure; wherein the pectin-cellulose degrading mixed bacteria are a mixed bacterial community capable of simultaneously degrading pectin and cellulose, and the biological conversion treatment process is used to change the pectin structure without affecting the chemical oxygen demand (COD) of the first pectin wastewater; inputting the second pectin wastewater into a single-stage or multi-stage anaerobic reactor for anaerobic decomposition treatment to obtain wastewater with reduced organic matter concentration after pectin decomposition and metabolism, and biogas; the biogas is used for recycling at an energy supply end or an energy storage end.

[0007] In some embodiments, the above-mentioned pectin-cellulose degrading mixed bacteria are obtained by the following means:

[0008] *Phanerochaete chrysosporium* and *Bacillus licheniformis* were used as the main inoculum and cultured in situ in a microbial culture vessel. The culture environment of the microbial culture vessel was the same as the production environment corresponding to the first pectin wastewater. The resulting pectin-cellulose degrading mixed bacteria were continuously added to the aforementioned bioconversion tank; or...

[0009] Using *Phanerochaete chrysosporium* and *Bacillus licheniformis* as the main inoculum, the bacteria were cultured in the laboratory using the first pectin wastewater collected from the production environment as the culture environment to obtain the above-mentioned pectin-cellulose degrading mixed bacteria, which were then added to the above-mentioned bioconversion tank.

[0010] In some embodiments, an equalization tank is provided before the bioconversion tank. The first pectin wastewater is introduced into the equalization tank and its flow rate is adjusted before being discharged into the bioconversion tank. The equalization tank also contains a target chemical agent comprising multiple functional components: a first functional component for promoting microbial growth and meeting the nutritional requirements during biochemical treatment; and a second functional component for promoting pectin suspension, preventing pectin aggregation, and reducing the agglomeration of the pectin-cellulose degrading mixed bacteria during bioconversion treatment. The target chemical agent is simultaneously introduced into the bioconversion tank along with the discharge of the first pectin wastewater.

[0011] In some embodiments, the first functional component includes at least one nutrient element selected from nitrogen, phosphorus, potassium, calcium, magnesium, zinc, copper, and manganese in a liquid ionic state; the second functional component includes an amphoteric surfactant.

[0012] In some embodiments, the above-mentioned amphoteric surfactant is a sodium salt or a potassium salt of amine ether carboxylate, with the corresponding molecular formulas being: NH2-Rm -(OCH2CH2)n-COONa or NH2-R m -(OCH2CH2)n-COOK, where m ranges from 10 to 18 and n ranges from 2 to 10. The preparation method of the above amphoteric surfactant is as follows: using natural oils as raw materials, the raw materials are reacted with an aqueous solution of sodium hydroxide or potassium hydroxide to obtain the corresponding fatty acid organic soap; the above fatty acid organic soap contains a carboxyl anionic group; using a quaternization reaction, a cationic group is introduced into the above fatty acid organic soap molecule to form a primary amphoteric surfactant; a predetermined number of ethoxy functional groups are added to the anionic group of the above primary amphoteric surfactant to synthesize the above amphoteric surfactant.

[0013] In some embodiments, the method further includes one of the following: performing ultrasonic treatment after a preset time of biological conversion treatment in the biological conversion tank; or, connecting a physical conversion tank after the biological conversion tank, and introducing the second pectin wastewater obtained after treatment in the biological conversion tank into the physical conversion tank for ultrasonic treatment. Specifically, inputting the second pectin wastewater into a primary or multi-stage anaerobic reactor for anaerobic decomposition includes: ultrasonically treating the second pectin wastewater before inputting it into the primary or multi-stage anaerobic reactor for anaerobic decomposition.

[0014] In some embodiments, an aeration tank is provided after one or more anaerobic reactors; the wastewater with reduced organic matter concentration after treatment by the anaerobic reactor is further aerobically treated in the aeration tank to obtain target wastewater with further reduced organic matter concentration; wherein, the organic matter content index after treatment by the anaerobic reactor and the aeration tank is monitored; if the organic matter content index meets the preset requirements, the qualified wastewater is discharged or recycled.

[0015] In some embodiments, the first pectin wastewater is a high-concentration pectin wastewater, wherein the pectin concentration entering the bioconversion tank is 1000 mg / L to 3000 mg / L. The method further includes: feeding the fourth pectin wastewater, remaining after partial pectin solidification and filtration of the third pectin wastewater, together with the second pectin wastewater, into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment; the third pectin wastewater and the first pectin wastewater are two portions obtained after splitting the high-concentration wastewater; the fourth pectin wastewater is a low-concentration pectin wastewater, with a corresponding pectin concentration of 50 mg / L to 100 mg / L; or, the second pectin wastewater is fed into a primary anaerobic reactor for anaerobic decomposition treatment, and then mixed with the fourth pectin wastewater before being fed into a subsequent multi-stage anaerobic reactor for anaerobic decomposition treatment.

[0016] Secondly, embodiments of this disclosure provide a treatment device for pectin-containing wastewater. The device includes: a biological conversion tank and one or more stages of anaerobic reactors. The biological conversion tank is used to input a first pectin wastewater, and based on the introduction of pectin-cellulose degrading mixed bacteria, the pectin in the first pectin wastewater is biologically converted to obtain a second pectin wastewater containing small-molecule pectin. The pectin-cellulose degrading mixed bacteria are a mixed bacterial community capable of simultaneously degrading pectin and cellulose. The biological conversion process is used to change the pectin structure without affecting the chemical oxygen demand (COD) of the first pectin wastewater. The second pectin wastewater is then fed into one or more stages of anaerobic reactors for anaerobic decomposition treatment, yielding wastewater with reduced organic matter concentration after pectin decomposition and metabolism, and biogas. The biogas is used for recycling at an energy supply or storage end.

[0017] In some embodiments, the above-mentioned equipment further includes at least one of the following: a microbial culture device, an equalization tank, and an aeration tank. The microbial culture device has a wastewater inlet and a microbial outlet; wherein the wastewater inlet is used to connect the first pectin wastewater as a culture environment, and *Phanerochaete chrysosporium* and *Bacillus licheniformis* are used as the main inoculum bacteria to cultivate the pectin-cellulose degrading mixed bacteria in situ within the microbial culture device; the microbial outlet is connected to the bioconversion tank, and the cultivated pectin-cellulose degrading mixed bacteria are continuously added to the bioconversion tank. The equalization tank has a wastewater inlet and a wastewater outlet; the wastewater inlet is used to introduce the first pectin wastewater into the equalization tank, and after flow regulation by the equalization tank, the first pectin wastewater is discharged to the bioconversion tank through the wastewater outlet. The aforementioned equalization tank also contains a target chemical agent, which comprises multiple functional components: a first functional component for promoting microbial growth and meeting the nutritional requirements during biochemical treatment; and a second functional component for promoting pectin suspension, preventing pectin aggregation, and reducing the clumping phenomenon of the pectin-cellulose degrading mixed bacteria during bioconversion treatment. The target chemical agent is simultaneously introduced into the bioconversion tank along with the output of the first pectin wastewater. The aforementioned aeration tank is connected to the outlet of the aforementioned primary or multi-stage anaerobic reactor to further aerobic treat the wastewater with reduced organic matter concentration after treatment by the anaerobic reactor, resulting in target wastewater with further reduced organic matter concentration.

[0018] In some embodiments, the above-mentioned biological conversion tank is integrated with an ultrasonic function, and ultrasonic treatment is performed after the biological conversion treatment in the biological conversion tank for a preset time; or, a physical conversion tank is connected after the above-mentioned biological conversion tank, and the second pectin wastewater obtained after treatment in the above-mentioned biological conversion tank enters the above-mentioned physical conversion tank for ultrasonic treatment; wherein, inputting the above-mentioned second pectin wastewater into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment includes: ultrasonically treating the above-mentioned second pectin wastewater before inputting it into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment.

[0019] In some embodiments, the primary or multi-stage anaerobic reactor is further provided with an inlet for low-concentration pectin wastewater. This inlet is used to input a fourth type of pectin wastewater, which is obtained by partially solidifying and filtering the third type of pectin wastewater. The third type of pectin wastewater and the first type of pectin wastewater are two portions obtained after the high-concentration wastewater is diverted. The fourth type of pectin wastewater is low-concentration pectin wastewater, with a pectin concentration of 50 mg / L to 100 mg / L. The fourth type of pectin wastewater is input together with the second type of pectin wastewater into the primary or multi-stage anaerobic reactor for anaerobic decomposition treatment; alternatively, the second type of pectin wastewater is input into the primary anaerobic reactor for anaerobic decomposition treatment, and then mixed with the fourth type of pectin wastewater before being input into subsequent multi-stage anaerobic reactors for anaerobic decomposition treatment.

[0020] In some embodiments, the wastewater inlet of the above-mentioned treatment equipment is used to connect to the wastewater outlet of the production equipment, the production equipment is used to produce or process one or more of canned citrus fruits, alcohol, and coffee; the energy supply end or energy storage end is used to provide energy to the above-mentioned production equipment or store energy.

[0021] The technical solutions provided in the embodiments of this disclosure have at least some or all of the following advantages:

[0022] (1) A scheme for in-situ, high-efficiency treatment of pectin in wastewater is provided. During wastewater treatment, pectin-cellulose degrading mixed bacteria introduced into a bioconversion tank first process the recalcitrant macromolecular pectin into easily degradable small molecular structure pectin. This process destroys the composition and structure of pectin without affecting the chemical oxygen demand (COD) concentration. Then, based on a single-stage or multi-stage anaerobic reactor, the dispersed small pectin molecules are further anaerobic treated to obtain wastewater with reduced organic matter concentration after pectin decomposition and metabolism, and biogas that can be input to the energy supply or storage end for recycling. Based on the complex enzyme system secreted by the pectin-cellulose degrading mixed bacteria in the liquid phase environment (such as laccase, lignin peroxidase, manganese peroxidase, pectin methyl ester), Enzymes such as pectin lyase, pectinase, pectin depolymerase, and cellulase can reduce the degree of polymerization and increase the solubility of complex organic matter such as pectin and cellulose in wastewater. Soluble pectin is then hydrolyzed into pectic acid by pectin methyl esterase, and finally hydrolyzed into galacturonic acid by polygalactase, which can be utilized by various microorganisms. Therefore, by treating recalcitrant pectin into smaller molecules based on pectin-cellulose degrading mixed bacteria in wastewater, the efficiency of subsequent anaerobic treatment can be greatly improved, increasing the treatment load to 5 times. At the same time, pectin can be treated and degraded in situ during wastewater treatment, without the need for pH adjustment, and the in-situ degradation process avoids the problems associated with sludge treatment of pectin solidified after flocculation.

[0023] (2) In some embodiments, the pectin-cellulose degrading mixed bacteria are mixed bacteria that can simultaneously degrade pectin and cellulose, obtained by in situ culture of *Phanerochaete chrysosporium* and *Bacillus licheniformis* as the main inoculum in a production environment (e.g., in wastewater containing high concentrations of pectin), and continuously added to the bioconversion tank. Since the above-mentioned in situ culture method is based on the strains obtained by culture in a pectin-containing wastewater environment, it can adapt to the wastewater treatment environment and be continuously generated and utilized in the production environment. The pectin-cellulose degrading mixed bacteria have good environmental adaptability to the wastewater to be treated. Compared with externally introduced strains, it can effectively avoid the problems of pollution caused by strain transfer or transplantation or the performance impairment or inactivation of strains in wastewater treatment due to differences in strain culture or storage environment.

[0024] (3) In some embodiments, *Phanerochaete chrysosporium* and *Bacillus licheniformis* are used as the main inoculum to culture pectin-cellulose degrading mixed bacteria in the laboratory, and then added to the bioconversion tank. In the laboratory culture method, wastewater from the production environment is collected as the culture environment for cultivation. The resulting pectin-cellulose degrading mixed bacteria have good environmental adaptability to the wastewater to be treated. Moreover, the bacteria can be cultured and preserved under suitable conditions, which helps other manufacturers to promote the large-scale use of the bacteria for wastewater treatment in suitable environments. That is, when treating wastewater in a certain environment, wastewater samples in that environment can be used as the actual culture environment for the cultivation of mixed bacteria.

[0025] (4) In some embodiments, a target chemical agent is added to the conditioning tank. This target chemical agent has a triple function: the first function is to provide nutrients for the pectin-cellulose degrading mixed bacteria added to the subsequent bioconversion tank, such as providing the nutrients required for microbial growth and enzyme production, including nitrogen, phosphorus, potassium, calcium, magnesium, zinc, copper, and manganese, promoting the growth and survival of the mixed bacteria without affecting the subsequent anaerobic treatment process. Moreover, the nutrients added at one time also have a significant effect in subsequent biochemical treatment stages (e.g., the stage of bioconversion treatment by pectin-cellulose degrading mixed bacteria, the anaerobic treatment stage of primary or multi-stage anaerobic reactors, etc.). The first benefit is that the target chemical agent can be reused; the second benefit is that it improves the suspension properties of pectin, making it less prone to sedimentation and preventing aggregation. This ensures that the pectin remains suspended in the equalization tank and subsequently enters the biological conversion tank, guaranteeing sufficient contact between the pectin and the bacteria in the pectin-cellulose degrading mixture within the biological conversion tank, thus improving the efficiency of pectin dispersion treatment. The third benefit is that the target chemical agent, flowing into the biological conversion tank with the wastewater, also reduces bioaggregation of the pectin-cellulose degrading mixture during the biological conversion process, effectively minimizing the adverse effects of bioaggregation on wastewater treatment. Therefore, based on the target chemical agent, the treatment efficiency and stability of pectin-containing wastewater can be comprehensively improved.

[0026] (5) Ultrasonic treatment is performed after a preset time of biological transformation in the biological transformation tank; or, a physical transformation tank is connected after the above-mentioned biological transformation tank, and the second pectin wastewater obtained after treatment in the above-mentioned biological transformation tank enters the above-mentioned physical transformation tank for ultrasonic treatment; the above-mentioned ultrasonic treatment is used to change the pectin structure so that the molecular chains of pectin are further broken down to obtain smaller pectin molecular structures, and at the same time, it can also break up the pectin-cellulose degradation mixed bacteria that are clustered together during the biological transformation treatment, promote the full contact between pectin molecules and bacteria, thereby improving the treatment efficiency of pectin-containing wastewater. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0028] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0029] Figure 1 The diagram illustrates a process schematically of a pectin-containing wastewater treatment apparatus and corresponding treatment method according to an embodiment of the present disclosure.

[0030] Figure 2 The diagram illustrates a process schematically of a treatment apparatus and corresponding treatment method for pectin-containing wastewater according to another embodiment of the present disclosure.

[0031] Figure 3 The diagram illustrates a process schematic of a treatment apparatus and corresponding treatment method for pectin-containing wastewater according to yet another embodiment of this disclosure.

[0032] Figure 4 The illustration schematically shows a process diagram of a treatment device and method for pectin-containing wastewater that supports in-situ culture of mixed bacteria, according to an embodiment of the present disclosure. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0034] During research and development, it was discovered that the relevant technical approach for wastewater treatment involves solidifying pectin through flocculation, followed by treating the residual pectin in the wastewater after filtration. However, this approach only separates the solidified pectin; the resulting sludge faces problems such as large accumulation, difficulty in degradation, and low degradation efficiency. Subsequent treatment methods for residual pectin in the wastewater (e.g., anaerobic or aerobic treatment) are designed for low-concentration pectin wastewater. Applying these methods directly to high-concentration pectin wastewater results in extremely long treatment cycles and poor treatment outcomes.

[0035] In view of this, embodiments of the present disclosure provide a method and equipment for treating pectin-containing wastewater. During wastewater treatment, recalcitrant pectin is first dispersed into easily degradable small molecular structures. This process disrupts the pectin's structural composition without changing the corresponding COD concentration. The dispersed pectin molecules are then subjected to anaerobic treatment. Because the recalcitrant pectin is first dispersed into small molecular structures in the wastewater, the efficiency of subsequent anaerobic treatment is improved, increasing the treatment load by five times. Simultaneously, pectin is treated in situ and degraded sufficiently during wastewater treatment, eliminating the need for pH adjustment and avoiding the sludge treatment issues associated with flocculated and solidified pectin during in-situ degradation.

[0036] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0037] The first exemplary embodiment of this disclosure provides a method for treating pectin-containing wastewater.

[0038] Figure 1 The diagram illustrates a process schematically of a pectin-containing wastewater treatment apparatus and corresponding treatment method according to an embodiment of the present disclosure.

[0039] Reference Figure 1 As shown in the embodiments of this disclosure, the method for treating pectin-containing wastewater includes the following steps: S110 and S120.

[0040] In step S110, the first pectin wastewater is fed into a biological conversion tank. In the biological conversion tank, based on the added pectin-cellulose degradation mixed bacteria, the pectin in the first pectin wastewater is subjected to biological conversion treatment to obtain a second pectin wastewater containing small molecule pectin.

[0041] For example, in Figure 1 The diagram illustrates a treatment system comprising a biological conversion tank 110 and an anaerobic reactor 120. Figure 1 The diagram also uses dashed boxes to indicate the production equipment. The wastewater inlet of the aforementioned treatment equipment is used to connect to the wastewater outlet of the aforementioned production equipment, which is used to produce or process one or more of the following: canned citrus fruits, alcohol, coffee, etc.

[0042] In some embodiments, the first pectin wastewater is a high-concentration pectin wastewater, wherein the pectin concentration entering the biological conversion tank is 1000 mg / L to 3000 mg / L, including endpoint values. In one embodiment, the pectin concentration in the first pectin wastewater entering the biological conversion tank was tested to be 2000 mg / L.

[0043] In some embodiments, the operating temperature of the above-mentioned biotransformation treatment is 30°C to 45°C, including the endpoint value, for example, 35°C is used in this embodiment.

[0044] In the embodiments of this disclosure, the aforementioned pectin-cellulose degrading mixed bacteria are a mixed bacterial community capable of simultaneously degrading pectin and cellulose. These pectin-cellulose degrading mixed bacteria are obtained through in-situ culture during wastewater degradation, or through laboratory culture using wastewater from the production environment as the culture environment.

[0045] Figure 4 The diagram illustrates a process schematic of a treatment apparatus and method for pectin-containing wastewater that supports in-situ culture of mixed bacteria, according to an embodiment of the present disclosure.

[0046] For example, in some embodiments, reference Figure 4 As shown in the solid box, the above-mentioned treatment equipment also includes a microbial culture device. The above-mentioned pectin-cellulose degrading mixed bacteria are obtained by the following method: using *Phanerochaete chrysosporium* and *Bacillus licheniformis* as the main inoculum, they are cultured in situ in the microbial culture device 410. The culture environment of the microbial culture device 410 is the same as the production environment corresponding to the first pectin wastewater. The above-mentioned pectin-cellulose degrading mixed bacteria are cultured and continuously added to the above-mentioned bioconversion tank 110.

[0047] In this embodiment, *Phanerochaete chrysosporium* and *Bacillus licheniformis* are used as the main inoculum bacteria. A pectin-cellulose degrading mixed bacterium capable of simultaneously degrading pectin and cellulose is obtained through in-situ culture in a production environment (e.g., wastewater containing a high concentration of pectin). This mixed bacterium is continuously added to the bioconversion tank. Since the in-situ culture method is based on strains cultured in a pectin-containing wastewater environment, it is adaptable to the wastewater treatment environment and can be continuously generated and utilized simultaneously in the production environment. The pectin-cellulose degrading mixed bacterium exhibits good environmental adaptability to the wastewater to be treated. Compared to externally introduced strains, this method effectively avoids contamination during strain transfer or transplantation, or performance degradation or inactivation of the strain in wastewater treatment due to differences in the strain's culture or storage environment.

[0048] In other embodiments, the above-mentioned pectin-cellulose degrading mixed bacteria are obtained by: using *Phanerochaete chrysosporium* and *Bacillus licheniformis* as the main inoculum, culturing them in a laboratory using the first pectin wastewater collected from the production environment as the culture environment, and then adding the above-mentioned pectin-cellulose degrading mixed bacteria to the above-mentioned bioconversion tank.

[0049] In this embodiment, *Phanerochaete chrysosporium* and *Bacillus licheniformis* were used as the main inoculum to cultivate a pectin-cellulose degrading mixed bacteria in the laboratory, which were then added to the bioconversion tank. In the laboratory cultivation method, wastewater from the production environment was collected as the culture environment. The resulting pectin-cellulose degrading mixed bacteria showed good environmental adaptability to the wastewater to be treated. Moreover, the strain was cultured and preserved under suitable conditions, which helps other manufacturers to promote its large-scale use for wastewater treatment in suitable environments. That is, when treating wastewater in a certain environment, wastewater samples from that environment can be used as the actual culture environment for the cultivation of the mixed bacteria.

[0050] In the two embodiments described above, the differences in culture conditions (dissolved oxygen) between *Phanerochaete chrysosporium* and *Bacillus licheniformis* were utilized to set two aeration parameters, for example: one was high-frequency aeration with an aeration duration of 6 hours; the other was medium-frequency aeration with an aeration duration of 18 hours. After 5-8 days, the two microorganisms in the culture system could coexist stably, forming loose mycelial spheres with a diameter of approximately 5mm-10mm. The culture was considered complete when the number of mycelial spheres reached the preset requirement.

[0051] The aforementioned bioconversion process alters the pectin structure without affecting the chemical oxygen demand (COD) of the first pectin wastewater. In some experiments, the treatment time in the bioconversion tank stage was 4–6 hours, with a pectin decomposition rate exceeding 60%.

[0052] Specifically, the aforementioned biotransformation process degrades complex macromolecules such as pectin and cellulose in high-concentration pectin wastewater into smaller molecular structures. These smaller molecular structures are more easily degraded, thus improving degradation efficiency when subsequently fed into primary or multi-stage anaerobic reactors for anaerobic decomposition. This results in a significant improvement in degradation efficiency compared to simply performing anaerobic decomposition on high-concentration pectin wastewater (see the effect comparison with Comparative Example 1 for details).

[0053] In the embodiments of this disclosure, the complex enzyme system secreted by pectin-cellulose degrading mixed bacteria in the liquid phase environment (such as laccase, lignin peroxidase, manganese peroxidase, pectin methyl esterase, pectin lyase, pectinase, pectin depolymerase, cellulase, etc.) can reduce the degree of polymerization and increase the solubility of complex organic matter such as pectin and cellulose in wastewater. The soluble pectin is then hydrolyzed into pectic acid by pectin methyl esterase, and finally hydrolyzed into galacturonic acid by polygalactase, which can be utilized by a variety of microorganisms.

[0054] Based on experimental data, the concentrations of total sugar and reducing sugar in the water sample were determined using a colorimetric method. The average degree of polymerization (DP) of the pectin-cellulose degradation products in the water sample was calculated. The average degree of polymerization (DP) reflects the size of polymer molecules; a higher average degree of polymerization indicates a larger molecular structure, and a lower average degree of polymerization indicates a smaller molecular structure. In step S110, the average degree of polymerization of pectin and cellulose in the influent sample of the bioconversion tank (first pectin wastewater, i.e., high-concentration pectin wastewater) was tested and found to be 148.3 ± 3.6. The average degree of polymerization of pectin and cellulose in the effluent sample of the bioconversion tank (second pectin wastewater) was 4.7 ± 1.0. This indicates that the bioconversion tank can effectively degrade the complex macromolecular pectin and cellulose in high-concentration pectin wastewater into smaller molecular structures, reducing the degree of polymerization and increasing the solubility of macromolecular organic matter, thereby helping to improve the degradation efficiency in the subsequent anaerobic treatment stage.

[0055] In step S120, the second pectin wastewater is fed into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment to obtain wastewater with reduced organic matter concentration after pectin decomposition and metabolism, and biogas; the biogas is then fed into an energy supply end or an energy storage end for recycling.

[0056] Chemical oxygen demand (COD) is an indicator of organic matter concentration. In step S110, the complex molecular chains of pectin and cellulose, such as cellulose, are broken down by mixed pectin-cellulose degrading bacteria to obtain smaller molecular structures. Therefore, the biotransformation process corresponding to step S110 alters the pectin structure without affecting the COD of the first pectin wastewater. Step S120 is the process of anaerobic decomposition of pectin and cellulose, which contain a large number of easily degradable small molecular structures, by anaerobic bacteria in an anaerobic reactor, promoting a reduction in organic matter concentration. This stage affects COD.

[0057] In some embodiments, refer to Figure 1 As shown, anaerobic bacteria are introduced into the anaerobic reactor described above. The anaerobic reactor can be, but is not limited to, UASB (Upflow Anaerobic Sludge Blanket) reactors, EGSB (Expansion Granular Sludge Blanket) reactors, etc., using anaerobic granular sludge in a corresponding reactor for multiple rounds of anaerobic treatment to enhance the reduction of organic matter concentration. In the anaerobic reactor, pectin and cellulose are decomposed and metabolized, undergoing acidification, acetogenesis, and methanogenesis stages.

[0058] The acidification stage refers to the phase where dissolved organic matter is converted into end products, primarily volatile fatty acids; it is also known as the fermentation stage. The vast majority of fermenting bacteria are strict anaerobes, while some facultative anaerobes exist in anaerobic environments. These facultative anaerobes can protect strict anaerobes like methanogens from oxygen damage and inhibition. The main products of this stage include volatile fatty acids, alcohols, lactic acid, carbon dioxide, hydrogen, ammonia, and hydrogen sulfide.

[0059] The acetic acidification stage is the further conversion of the products from the acidification stage into acetic acid, hydrogen, carbonic acid, etc. The anaerobic bacteria used include hydrogen-producing and acetic acid-producing bacteria.

[0060] The methanogenesis stage is the stage in which the products of the acetic acid production stage—acetic acid, hydrogen, carbonic acid, formic acid, and methanol—are converted into methane, carbon dioxide, and other substances.

[0061] In step S120, products corresponding to multiple stages, including the acidification stage, the acetic acid production stage, and the methanogenesis stage, may be present simultaneously.

[0062] Reference Figure 1 As shown, the biogas produced by the anaerobic reactor is used to be fed into the energy supply end or the energy storage end for recycling. The energy supply end or the energy storage end is connected to the production equipment used for producing or processing citrus canned goods, alcohol, coffee, etc., to provide energy for the production equipment or store energy, thus realizing the recycling of energy and improving environmental protection and energy utilization.

[0063] The embodiment including steps S110-S120 provides a scheme for in-situ, high-efficiency treatment of pectin in wastewater. During wastewater treatment, pectin-cellulose degrading mixed bacteria introduced into a bioconversion tank first process recalcitrant macromolecular pectin into easily degradable small-molecule pectin. This process disrupts the composition and structure of pectin without affecting the chemical oxygen demand (COD) concentration. Subsequently, anaerobic treatment is carried out on the dispersed small pectin molecules using a single-stage or multi-stage anaerobic reactor, resulting in wastewater with reduced organic matter concentration after pectin decomposition and metabolism, and biogas that can be input to an energy supply or storage end for recycling. The complex enzyme system secreted by the pectin-cellulose degrading mixed bacteria in the liquid phase environment (such as laccase, lignin peroxidase, and manganese peroxidase) further enhances the treatment process. Pectinase, pectin methyl esterase, pectin lyase, pectinase, pectin depolymerase, cellulase, etc., can reduce the degree of polymerization and increase the solubility of complex organic matter such as pectin and cellulose in wastewater. Soluble pectin is then hydrolyzed into pectic acid by pectin methyl esterase, and finally hydrolyzed into galacturonic acid by polygalactase, which can be utilized by a variety of microorganisms. Therefore, by treating recalcitrant pectin into a small molecular structure based on pectin-cellulose degrading mixed bacteria in wastewater, the efficiency of subsequent anaerobic treatment can be greatly improved, making the treatment load five times the original. At the same time, pectin can be treated and degraded in situ and more fully during wastewater treatment, without the need for pH adjustment. In the process of in-situ degradation, the problems associated with sludge treatment of pectin solidified after flocculation are avoided.

[0064] Figure 2 The diagram illustrates a process schematically of a treatment apparatus and corresponding treatment method for pectin-containing wastewater according to another embodiment of the present disclosure.

[0065] Based on the above embodiments, it was also found that the inherent characteristics of the pectin-cellulose degrading mixed bacteria cause them to aggregate during biotransformation, which negatively impacts the degradation of pectin, cellulose, etc. Furthermore, considering that the treatment method provided in this disclosure involves in-situ treatment of wastewater, it provides a suitable liquid environment for the growth and biotransformation of the pectin-cellulose degrading mixed bacteria. The surface tension and particle suspension levels within this liquid environment can be controlled, thus creating a better wastewater treatment environment and facilitating improved wastewater treatment efficiency through regulatory measures.

[0066] In view of this, in some other embodiments of this disclosure, the above-described processing apparatus further includes a conditioning tank. (Refer to...) Figure 2 As shown in the dashed box, an equalization tank 210 is provided before the above-mentioned biological conversion tank 110. The first pectin wastewater is introduced into the equalization tank 210 and after the flow rate is adjusted, it is output to the above-mentioned biological conversion tank 110.

[0067] The aforementioned regulating tank 210 also contains a target chemical agent, which includes multiple functional components: a first functional component for promoting microbial growth and meeting the nutritional requirements during biochemical treatment; and a second functional component for promoting pectin suspension, preventing pectin aggregation, and reducing the aggregation phenomenon of the aforementioned pectin-cellulose degrading mixed bacteria during biotransformation treatment. The target chemical agent is simultaneously introduced into the aforementioned biotransformation tank along with the output of the aforementioned first pectin wastewater.

[0068] Combination Figure 2 and Figure 4 The dashed box indicates that, in this embodiment of the present disclosure, the treatment device may simultaneously include an equalization tank 210 and a microbial culture device 410 for in-situ cultivation. The inlet of the microbial culture device 410 (which is the same as the wastewater interface described in the second embodiment) is connected to one outlet of the equalization tank 210 (this outlet serves as the wastewater outlet flowing to the microbial culture device; a description of the wastewater outlet is detailed in the description of the equalization tank in the second embodiment). The other outlet of the equalization tank 210 (this outlet serves as the wastewater outlet flowing to the bioconversion tank; a description of the wastewater outlet is detailed in the description of the equalization tank in the second embodiment) is connected to the inlet of the bioconversion tank 110. The pectin-cellulose degrading mixed bacteria cultivated in the microbial culture device 410 under the cultivation environment corresponding to high-concentration pectin wastewater are continuously added to the bioconversion tank 110 through a predetermined channel between the microbial culture device 410 and the bioconversion tank 110. This predetermined channel connects the microbial outlet of the microbial culture device 410 and the microbial inlet of the bioconversion tank 110. The aforementioned pectin-cellulose degrading mixed bacteria are bacterial species with a certain number of bacteria and specific morphology generated under a culture environment, which enter the bioconversion tank along with the liquid wastewater culture environment.

[0069] By adding the target chemical agent to the equalization tank, sedimentation can be prevented (including preventing pectin agglomeration and reducing bioagglomeration of mixed bacteria in the biological conversion tank during the conversion process); it can also provide nutrients for the pectin-cellulose degrading mixed bacteria added to the subsequent biological conversion tank, thereby helping to improve the treatment efficiency and stability of wastewater. Bioagglomeration affects the treatment effect of biological conversion and also the effectiveness of subsequent anaerobic (corresponding to primary or multi-stage anaerobic reactors) and anaerobic (corresponding to primary or multi-stage anaerobic reactors) + aerobic (corresponding to aeration tank) treatment processes.

[0070] Specifically, the target chemical agent added to the equalization tank has a triple function: First, it provides nutrients for the pectin-cellulose degrading mixed bacteria added to the subsequent bioconversion tank, such as nitrogen, phosphorus, potassium, calcium, magnesium, zinc, copper, and manganese, which are required for microbial growth and enzyme production. This promotes the growth and survival of the mixed bacteria without affecting the subsequent anaerobic treatment process. Moreover, the nutrients added at once can be reused in subsequent biochemical treatment stages (such as the bioconversion stage of the pectin-cellulose degrading mixed bacteria, or the anaerobic treatment stage of the primary or multi-stage anaerobic reactor). The second function is to ensure good suspension properties of pectin, making it less prone to sedimentation and preventing aggregation. This ensures that the pectin remains in suspension after entering the equalization tank and subsequently the biological conversion tank, guaranteeing sufficient contact between the pectin and the bacteria in the pectin-cellulose degrading mixed bacteria in the biological conversion tank, thus improving the treatment efficiency of pectin dispersion treatment. The third function is that the target chemical agent, after flowing into the biological conversion tank with the wastewater, can also reduce the bioaggregation phenomenon of the pectin-cellulose degrading mixed bacteria in the biological conversion tank during the biological conversion process, thereby effectively reducing the adverse effects of bioaggregation on wastewater treatment. Therefore, based on the setup of the equalization tank and the target chemical agent, the flow rate of wastewater can be controlled, allowing the wastewater to enter the biological conversion tank stably and controllably. This effectively regulates the suspension state of pectin, cellulose, and other substances in the equalization tank. Upon entering the biological conversion tank, the dispersion of the pectin-cellulose degrading mixed bacteria and the suspension state of pectin, cellulose, and other substances can also be adjusted simultaneously, promoting full contact between pectin and the bacterial strains in the pectin-cellulose degrading mixed bacteria in the biological conversion tank. This comprehensively improves the treatment efficiency and stability of pectin-containing wastewater.

[0071] In some embodiments, the first functional component includes at least one nutrient element selected from nitrogen, phosphorus, potassium, calcium, magnesium, zinc, copper, and manganese in a liquid ionic state.

[0072] The second functional component mentioned above includes an amphoteric surfactant. This amphoteric surfactant modifies the surface charge distribution and intermolecular forces of the particulate matter, providing emulsification, chelation, and dispersion functions, ensuring that the particulate matter remains suspended in the corresponding liquid phase of the wastewater.

[0073] Amphoteric surfactants are surfactants that contain both anionic and cationic hydrophilic groups within the same molecule; they can both donate and accept protons. By using a second functional component, the liquid-phase environment can be regulated, improving the efficiency of biotransformation and facilitating subsequent anaerobic and anaerobic-aerobic reactions.

[0074] In some embodiments, the above-mentioned amphoteric surfactant is a sodium salt or a potassium salt of amine ether carboxylate, with the corresponding molecular formulas being: NH2-R m-(OCH2CH2)n-COONa or NH2-R m -(OCH2CH2)n-COOK, where m ranges from 10 to 18 and n ranges from 2 to 10. To briefly explain, R represents an organic group or functional group.

[0075] The preparation method of the above-mentioned amphoteric surfactant is as follows:

[0076] Using natural oils as raw materials, the above raw materials are reacted with an aqueous solution of sodium hydroxide or potassium hydroxide to obtain the corresponding fatty acid organic soap; the above fatty acid organic soap contains carboxyl anionic groups; in some embodiments, the reaction temperature of the saponification reaction is 80℃~100℃;

[0077] By using a quaternization reaction, cationic groups are introduced into the above-mentioned fatty acid organic soap molecules to form primary amphoteric surfactants;

[0078] The aforementioned amphoteric surfactant is synthesized by attaching a predetermined number of ethoxy functional groups to the anionic group of the aforementioned primary amphoteric surfactant.

[0079] In some embodiments, the composition and mass ratio of the raw materials are: 12% sodium lauryl ether carboxylate (EO3) of C12, 8% sodium oleyl ether carboxylate (EO5) of C18, 6% sodium gluconate, 10% citric acid, 2% disodium ethylenediaminetetraacetate, and 62% water.

[0080] In some embodiments, refer to Figure 2 As shown, in step S120 above, the second pectin wastewater is fed into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment, which includes: ultrasonically treating the second pectin wastewater before feeding it into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment.

[0081] Specifically, it includes the following:

[0082] After a preset time for biotransformation treatment in biotransformation tank 110, ultrasonic treatment is performed; refer to Figure 2 The dashed double arrows corresponding to ultrasound treatment are shown; or...

[0083] A physical conversion tank 220 is connected after the aforementioned biological conversion tank 110. The second pectin wastewater obtained after treatment in the biological conversion tank 110 enters the aforementioned physical conversion tank 220 for ultrasonic treatment; see reference. Figure 2 The dashed box corresponding to the physical conversion pool is shown in the figure.

[0084] The above-mentioned ultrasonic treatment is used to change the pectin structure, thereby breaking down the molecular chains of pectin and dispersing the aggregated pectin-cellulose degradation bacteria.

[0085] In some cases, some of the pectin-cellulose degrading mixed bacteria should be physically retained in the bioconversion tank to ensure biomass and subsequent enzyme production. In this case, the physical conversion tank can be constructed as an ultrasonic function added to the bioconversion tank, that is, ultrasonic treatment is performed after the bioconversion tank has been bioconverted for a certain period of time.

[0086] In other cases, the physical conversion tank 220 can also be a separate ultrasonic treatment tank added after the biological conversion tank 110. The small molecular structure pectin, pectin-cellulose degradation mixed bacteria, target chemical agents, etc. after being treated in the biological conversion tank all flow into the ultrasonic treatment tank. In this case, the mixed bacteria obtained by in-situ growth culture can be continuously added to the biological conversion tank.

[0087] The aforementioned ultrasonic treatment can alter the pectin structure, further breaking down the pectin molecular chains to obtain smaller pectin molecules. It also disperses the clumps of pectin-cellulose degrading bacteria present during biotransformation, promoting full contact between pectin molecules and the bacteria, thereby improving the treatment efficiency of pectin-containing wastewater. In some embodiments, a power of 5W is used per ton of water, with ultrasonic treatment lasting 5 to 10 minutes.

[0088] Figure 3 The diagram illustrates a process schematic of a treatment apparatus and corresponding treatment method for pectin-containing wastewater according to yet another embodiment of this disclosure.

[0089] In some embodiments of this disclosure, the above-described treatment apparatus further includes an aeration tank. (See also...) Figure 3 As shown in the dashed box, an aeration tank 310 is set after the primary or multi-stage anaerobic reactor 120; the wastewater with reduced organic matter concentration after being treated by the anaerobic reactor 120 is further aerobically treated by the aeration tank 310 to obtain the target wastewater with further reduced organic matter concentration.

[0090] The method involves monitoring the organic matter content after treatment in the anaerobic reactor and aeration tank, using indicators such as COD and BOD (biochemical oxygen demand, the amount of oxygen consumed by microorganisms in wastewater to oxidize and decompose organic matter under specific conditions). If the organic matter content meets preset requirements, the treated wastewater is discharged or recycled. Generally, the treatment method provided in this embodiment allows for the direct discharge or recycling of treated wastewater that meets standards.

[0091] In some special application scenarios, after the anaerobic reactor or after the aerobic treatment process of anaerobic reactor + aeration tank, some post-treatment processes can be added (such as disinfection and sterilization, addition of special purpose substances, or specific treatment for use as laboratory experimental water, production water, etc.) to meet the specific needs of subsequent water recycling (such as for drinking water, irrigation water, etc.).

[0092] In some embodiments of this disclosure, processing paths compatible with existing production lines are also provided. (See also...) Figure 3 As shown in the dashed box and dashed arrow, the above method also includes: feeding the fourth pectin wastewater, which is the residue after partial pectin solidification and filtration of the third pectin wastewater, together with the second pectin wastewater, into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment.

[0093] The aforementioned third pectin wastewater and the aforementioned first pectin wastewater are two parts obtained after the high-concentration wastewater is diverted; the aforementioned fourth pectin wastewater is low-concentration pectin wastewater, with a corresponding pectin concentration of 50 mg / L to 100 mg / L.

[0094] Alternatively, in other embodiments, the above method further includes: feeding the second pectin wastewater into a primary anaerobic reactor for anaerobic decomposition treatment, and then mixing it with the fourth pectin wastewater before feeding it into a subsequent multi-stage anaerobic reactor for anaerobic decomposition treatment.

[0095] By setting an inlet in the anaerobic reactor 120 for introducing low-concentration pectin wastewater, it can be compatible with existing production lines. The existing production lines involve partially solidifying and filtering high-concentration pectin wastewater and then treating the remaining pectin in the wastewater. By setting the aforementioned inlet, the remaining low-concentration pectin wastewater (i.e., the fourth type of pectin wastewater) can be anaerobically treated simultaneously with the second type of pectin wastewater obtained after biological conversion treatment, or they can be anaerobically decomposed sequentially in the anaerobic reactor. This achieves compatibility between the new process provided in this case and the existing process, and the production lines can be merged. Only modifications need to be made to the existing equipment, without the need to set up two separate production lines, thus saving on the operation and modification costs of the treatment equipment.

[0096] The process for solidifying pectin can be any known or improved process. As an example, by adding coagulants (such as polyaluminum chloride, iron salts, etc.) and flocculants (such as polyacrylamide, etc.), pectin and other suspended particles are encouraged to form larger flocs and solidify, which facilitates subsequent separation. Then, through coagulation flotation, microbubbles are generated, causing the flocs to combine with the bubbles and float to the water surface. Subsequently, a scraping mechanism is used for solid-liquid separation, and the solidified pectin is filtered out to obtain the remaining low-concentration pectin wastewater.

[0097] The processing steps and corresponding reaction devices in the various embodiments described above can be combined with each other or extended into new embodiments, which will not be elaborated here.

[0098] To illustrate the beneficial effects of this case, the following comparative analysis of effects was conducted.

[0099] Based on the treatment scheme of biological conversion treatment + anaerobic treatment provided in the embodiments of this disclosure, in the laboratory pilot stage, 5 liters of high-concentration pectin wastewater with a pectin concentration of 2600mg / L to 3000mg / L was fed into a biological conversion tank and an anaerobic reactor with a treatment capacity of 10 liters for reaction treatment. The retention time was 2 days, which reduced the COD concentration of the wastewater by more than 80%.

[0100] In the pilot-scale stage, 100 cubic meters of high-concentration pectin wastewater with a pectin concentration of 2000 mg / L to 3000 mg / L was fed into a biological conversion tank and an anaerobic reactor with a treatment capacity of 200 cubic meters for reaction treatment. The retention time was 2 days, which reduced the COD concentration of the wastewater by more than 80%.

[0101] During the large-scale production stage, 1000 cubic meters of high-concentration pectin wastewater with a pectin concentration of 2000 mg / L to 3000 mg / L is fed into a biological conversion tank and an anaerobic reactor with a treatment capacity of 2000 cubic meters for reaction treatment. The retention time is 2 days, which reduces the COD concentration of the wastewater by more than 80%.

[0102] The biotransformation + ultrasonic + anaerobic treatment scheme provided in this embodiment can further improve the treatment efficiency compared to the biotransformation + anaerobic treatment scheme.

[0103] In the laboratory pilot phase, 5 liters of high-concentration pectin wastewater with a pectin concentration of 2600 mg / L to 3000 mg / L was fed into a biological conversion tank to be converted into easily degradable small molecular structures. After further ultrasonic treatment, it was fed into an anaerobic reactor with a treatment capacity of 5 liters for reaction treatment, with a retention time of 1 day, which reduced the COD concentration of the wastewater by more than 80%.

[0104] In the pilot-scale stage, 100 cubic meters of high-concentration pectin wastewater with a pectin concentration of 2000 mg / L to 3000 mg / L was fed into a biological conversion tank to be converted into easily degradable small molecular structures. After further ultrasonic treatment, it was fed into an anaerobic reactor with a treatment capacity of 100 cubic meters for reaction treatment, with a retention time of 1 day, which reduced the COD concentration of the wastewater by more than 80%.

[0105] During the large-scale production stage, 1000 cubic meters of high-concentration pectin wastewater with a pectin concentration of 2000 mg / L to 3000 mg / L is fed into a biological conversion tank to be converted into easily degradable small molecular structures. After further ultrasonic treatment, it is fed into an anaerobic reactor with a treatment capacity of 1000 cubic meters for reaction treatment, with a retention time of 1 day, which reduces the COD concentration of the wastewater by more than 80%.

[0106] Comparative Example 1

[0107] The treatment process adopted is as follows: 5 liters of high-concentration pectin wastewater with a pectin concentration of 2600mg / L to 3000mg / L are fed into a 25-liter anaerobic reactor for reaction treatment. The retention time is 5 days or even longer to achieve the final treatment effect of reducing the COD concentration of the wastewater by more than 80%.

[0108] Therefore, compared with Comparative Example 1, the solution provided in this disclosure embodiment, compared with the solution based on anaerobic process for treating high concentrations of pectin in wastewater (without filtration), has the advantage of setting up a biological conversion tank, which decomposes pectin, cellulose and other substances into easily degradable small molecular structures based on pectin-cellulose degradation mixed bacteria, resulting in a treatment load of 5 times that of the original and faster treatment time in the subsequent anaerobic treatment.

[0109] Comparative Example 2

[0110] The treatment process adopted is as follows: for high-concentration pectin wastewater with the same flow rate and concentration, solidified pectin is obtained by flocculation filtration. The treatment time for solidified pectin is 20 days or more; the treatment time for the remaining low-concentration pectin wastewater is about 2 days; the total time obtained is 22 days or more.

[0111] Based on the comparison of the treatment time of the above-mentioned comparative example with the treatment time of the pectin-containing wastewater provided in this application, it can be seen that this application provides a solution for in-situ, high-efficiency treatment of pectin in wastewater, which can greatly improve the wastewater treatment efficiency, while increasing the treatment load of anaerobic treatment to 5 times the original, thus improving the wastewater degradation efficiency; it achieves in-situ treatment and relatively complete degradation during wastewater treatment, without the need for pH adjustment, and avoids the related problems of sludge treatment for pectin solidified after flocculation during the in-situ degradation process.

[0112] Based on the same technical concept, a second exemplary embodiment of this disclosure provides a treatment apparatus for pectin-containing wastewater.

[0113] Combination Figures 1-4 As shown, the above-mentioned treatment equipment includes: a biological conversion tank 110 and a single-stage or multi-stage anaerobic reactor 120.

[0114] The aforementioned biological conversion tank 110 is used to input the first pectin wastewater. Based on the added pectin-cellulose degrading mixed bacteria, the pectin in the first pectin wastewater is subjected to biological conversion treatment to obtain a second pectin wastewater containing pectin with a small molecular structure. The aforementioned pectin-cellulose degrading mixed bacteria are a mixed bacterial community that can simultaneously degrade pectin and cellulose. The aforementioned biological conversion treatment process is used to change the pectin structure without affecting the chemical oxygen demand corresponding to the first pectin wastewater.

[0115] The aforementioned second pectin wastewater is fed into a primary or multi-stage anaerobic reactor 120 for anaerobic decomposition treatment, yielding wastewater with reduced organic matter concentration after pectin decomposition and metabolism, and biogas; the biogas is then fed into an energy supply or storage facility for recycling.

[0116] In some embodiments, refer to Figure 1 As shown in the dashed box, the wastewater inlet of the above-mentioned treatment equipment is used to connect to the wastewater discharge outlet of the production equipment, and the above-mentioned production equipment is used to produce or process one or more of canned citrus fruits, alcohol, and coffee; the above-mentioned energy supply end or energy storage end is used to provide energy to the above-mentioned production equipment or store energy.

[0117] In some embodiments, combined with Figures 1-4 As shown, the above-mentioned treatment equipment also includes at least one of the following: a microbial culture device 410, an equalization tank 210, and an aeration tank 310.

[0118] The above-mentioned microbial culture device 410 has a wastewater inlet and a microbial outlet.

[0119] The aforementioned wastewater inlet is used to connect the first pectin wastewater as a culture environment, and Phanerochaete chrysosporium and Bacillus licheniformis are used as the main inoculum to obtain the aforementioned pectin-cellulose degradation mixed bacteria in situ culture within the aforementioned bacterial culture vessel.

[0120] The aforementioned microbial outlet is connected to the aforementioned bioconversion tank 110, and the cultured pectin-cellulose degrading mixed bacteria are continuously added to the bioconversion tank. In some embodiments, the pectin-cellulose degrading mixed bacteria are continuously added to the bioconversion tank 110 via a preset channel between the microbial culture device 410 and the bioconversion tank 110. This preset channel connects the microbial outlet of the microbial culture device 410 and the microbial inlet of the bioconversion tank 110. The aforementioned pectin-cellulose degrading mixed bacteria are microbial strains with a certain number of bacteria and specific morphology generated under a culture environment, which enter the bioconversion tank along with the liquid wastewater culture environment.

[0121] The aforementioned equalization tank 210 has a wastewater inlet and a wastewater outlet. The wastewater inlet is used to introduce the aforementioned first pectin wastewater into the aforementioned equalization tank. After the flow rate is regulated by the aforementioned equalization tank, the aforementioned first pectin wastewater is discharged to the aforementioned biological conversion tank 110 through the aforementioned wastewater outlet.

[0122] The aforementioned regulating tank 210 also contains a target chemical agent, which includes multiple functional components: a first functional component for promoting microbial growth and meeting the nutritional requirements during biochemical treatment; and a second functional component for promoting pectin suspension, preventing pectin aggregation, and reducing the agglomeration of the aforementioned pectin-cellulose degrading mixed bacteria during biotransformation treatment. The target chemical agent is simultaneously introduced into the aforementioned biotransformation tank 110 along with the output of the aforementioned first pectin wastewater.

[0123] Based on the setup of the equalization tank and the target chemical agent, the flow rate of wastewater can be controlled, allowing the wastewater to enter the biological conversion tank stably and controllably. This effectively regulates the suspended state of pectin in the wastewater and promotes the dispersion of pectin-cellulose degradation mixed bacteria in the biological conversion tank, thereby comprehensively improving the treatment efficiency and stability of pectin-containing wastewater.

[0124] The aeration tank 310 is connected to the outlet of the primary or multi-stage anaerobic reactor 120 to continue aerobic treatment of the wastewater with reduced organic matter concentration after treatment by the anaerobic reactor, so as to obtain the target wastewater with further reduced organic matter concentration.

[0125] In some embodiments, refer to Figure 2 and Figure 3 As shown, the second pectin wastewater is fed into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment, including: ultrasonically treating the second pectin wastewater before feeding it into the primary or multi-stage anaerobic reactor for anaerobic decomposition treatment. The biological conversion tank 110 integrates ultrasonic functionality, performing ultrasonic treatment after a preset time of biological conversion in the biological conversion tank; or, a physical conversion tank 220 is connected after the biological conversion tank 110, and the second pectin wastewater obtained after treatment in the biological conversion tank enters the physical conversion tank for ultrasonic treatment. The ultrasonic treatment is used to alter the pectin structure, breaking down the pectin molecular chains and dispersing the aggregated pectin-cellulose degrading mixed bacteria.

[0126] The aforementioned ultrasonic treatment can alter the pectin structure, further breaking down the pectin molecular chains to obtain smaller pectin molecular structures. It can also break up the clumps of pectin-cellulose degrading bacteria during biotransformation, promoting full contact between pectin molecules and bacteria, thereby improving the treatment efficiency of pectin-containing wastewater.

[0127] In some embodiments, refer to Figure 3As shown, the primary or multi-stage anaerobic reactor 120 is also equipped with an inlet for low-concentration pectin wastewater. This inlet is used to input fourth pectin wastewater, which is obtained after partially solidifying and filtering the third pectin wastewater. The third and first pectin wastewaters are two portions obtained after the high-concentration wastewater is diverted. The fourth pectin wastewater is low-concentration pectin wastewater, with a pectin concentration of 50 mg / L to 100 mg / L. The fourth pectin wastewater is input together with the second pectin wastewater into the primary or multi-stage anaerobic reactor for anaerobic decomposition treatment; alternatively, the second pectin wastewater is input into the primary anaerobic reactor for anaerobic decomposition treatment, and then mixed with the fourth pectin wastewater before being input into subsequent multi-stage anaerobic reactors for anaerobic decomposition treatment.

[0128] By setting an inlet in the anaerobic reactor 120 for introducing low-concentration pectin wastewater, it can be compatible with existing production lines. The existing production lines involve partially solidifying and filtering high-concentration pectin wastewater and then treating the remaining pectin in the wastewater. By setting the aforementioned inlet, the remaining low-concentration pectin wastewater (i.e., the fourth type of pectin wastewater) can be anaerobically treated simultaneously with the second type of pectin wastewater obtained after biological conversion treatment, or they can be anaerobically decomposed sequentially in the anaerobic reactor. This achieves compatibility between the new process provided in this case and the existing process, and the production lines can be merged. Only modifications need to be made to the existing equipment, without the need to set up two separate production lines, thus saving on the operation and modification costs of the treatment equipment.

[0129] Other details of this embodiment can be found in the relevant description of the first embodiment, and will not be repeated here.

[0130] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0131] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for treating pectin-containing wastewater, characterized in that, include: The first pectin wastewater is fed into a biological conversion tank. In the tank, pectin-cellulose degrading mixed bacteria are introduced to bioconvert the pectin in the first pectin wastewater, resulting in a second pectin wastewater containing small-molecule pectin. The pectin-cellulose degrading mixed bacteria are a mixed bacterial community capable of simultaneously degrading both pectin and cellulose. The biological conversion process alters the pectin structure without affecting the chemical oxygen demand (COD) of the first pectin wastewater. The pectin concentration in the first pectin wastewater entering the biological conversion tank is 1000 mg / L to 3000 mg / L. The cellulose-degrading mixed bacteria were cultured in the production environment corresponding to the first pectin wastewater using *Phanerochaete chrysosporium* and *Bacillus licheniformis* as the main inoculum. An equalization tank was also provided before the bioconversion tank, into which the first pectin wastewater was introduced and its flow rate regulated before being discharged to the bioconversion tank. A target chemical agent was also added to the equalization tank, comprising a first functional component and a second functional component. The first functional component included at least one nutrient element selected from nitrogen, phosphorus, potassium, calcium, magnesium, zinc, copper, and manganese in liquid ionic form. The second functional component included an amphoteric surfactant. The second pectin wastewater is fed into a single-stage or multi-stage anaerobic reactor for anaerobic decomposition treatment to obtain wastewater with reduced organic matter concentration after pectin decomposition and metabolism, and biogas; the biogas is used to be fed into the energy supply end or energy storage end for recycling. The amphoteric surfactant is a sodium salt or a potassium salt of an amino ether carboxylate, with the corresponding molecular formulas being: NH2-R m -(OCH2CH2)n-COONa or NH2-R m -(OCH2CH2) n-COOK, where m takes values ​​from 10 to 18 and n takes values ​​from 2 to 10; The preparation method of the amphoteric surfactant is as follows: Using natural oils as raw materials, the raw materials are reacted with an aqueous solution of sodium hydroxide or potassium hydroxide to obtain the corresponding fatty acid organic soap; the fatty acid organic soap contains carboxyl anionic groups; By using a quaternization reaction, cationic groups are introduced into the fatty acid organic soap molecule to form a primary amphoteric surfactant; The amphoteric surfactant is synthesized by attaching a predetermined number of ethoxy functional groups to the anionic group of the primary amphoteric surfactant.

2. The method according to claim 1, characterized in that, The pectin-cellulose degrading mixed bacteria were obtained through the following method: Phanerochaete chrysosporium and Bacillus licheniformis were used as the main inoculum and cultured in situ in a microbial culture device. The culture environment of the microbial culture device was the same as the production environment corresponding to the first pectin wastewater. The resulting pectin-cellulose degradation mixed bacteria were then continuously added to the bioconversion tank. or, Phanerochaete chrysosporium and Bacillus licheniformis were used as the main inoculum bacteria and cultured in the laboratory using the first pectin wastewater collected from the production environment as the culture environment to obtain the pectin-cellulose degradation mixed bacteria, which were then added to the bioconversion tank.

3. The method according to claim 1, characterized in that, The first functional component is used to promote microbial growth and meet the nutritional requirements during biochemical treatment. The second functional component is used to promote pectin suspension, prevent pectin aggregation, and reduce the agglomeration of the pectin-cellulose degrading mixed bacteria during bioconversion treatment. The target chemical agent is simultaneously input into the bioconversion tank along with the output of the first pectin wastewater.

4. The method according to claim 1, characterized in that, It also includes the following: After a preset time for biotransformation treatment in the biotransformation tank, ultrasonic treatment is performed; or... A physical conversion tank is connected after the biological conversion tank. The second pectin wastewater obtained after treatment in the biological conversion tank enters the physical conversion tank for ultrasonic treatment. The process of feeding the second pectin wastewater into a primary or multi-stage anaerobic reactor for anaerobic decomposition includes: subjecting the second pectin wastewater to ultrasonic treatment before feeding it into the primary or multi-stage anaerobic reactor for anaerobic decomposition.

5. The method according to claim 1, characterized in that, An aeration tank is set up after the primary or multi-stage anaerobic reactor; The wastewater with reduced organic matter concentration after being treated in the anaerobic reactor is further treated aerobically in the aeration tank to obtain the target wastewater with further reduced organic matter concentration. Among them, the organic matter content index is monitored after treatment by the anaerobic reactor and the aeration tank respectively; If the organic matter content index meets the preset requirements, the qualified wastewater will be discharged or recycled.

6. The method according to any one of claims 1-5, characterized in that, The method further includes: The fourth pectin wastewater, after partial pectin solidification and filtration of the third pectin wastewater, is fed together with the second pectin wastewater into a single-stage or multi-stage anaerobic reactor for anaerobic decomposition treatment; the third pectin wastewater and the first pectin wastewater are two portions obtained after the high-concentration pectin wastewater is separated; the fourth pectin wastewater is a low-concentration pectin wastewater, with a corresponding pectin concentration of 50 mg / L to 100 mg / L; or... The second pectin wastewater is fed into a primary anaerobic reactor for anaerobic decomposition treatment. After treatment, it is mixed with the fourth pectin wastewater and then fed into a subsequent multi-stage anaerobic reactor for anaerobic decomposition treatment.

7. A treatment device for pectin-containing wastewater, used to perform the treatment method for pectin-containing wastewater according to claim 1, characterized in that, include: Biological conversion tank, single-stage or multi-stage anaerobic reactor, microbial culture device, equalization tank and aeration tank; The bioconversion tank is used to input the first pectin wastewater. Based on the added pectin-cellulose degrading mixed bacteria, the pectin in the first pectin wastewater is bioconverted to obtain a second pectin wastewater containing pectin with a small molecular structure. The pectin-cellulose degrading mixed bacteria are a mixed bacterial community that can simultaneously degrade pectin and cellulose. The bioconversion process is used to change the pectin structure without affecting the chemical oxygen demand of the first pectin wastewater. The second pectin wastewater is fed into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment to obtain wastewater with reduced organic matter concentration after pectin decomposition and metabolism, and biogas; the biogas is used to be fed into the energy supply end or energy storage end for recycling. The microbial culture device has a wastewater inlet and a microbial outlet; wherein, the wastewater inlet is used to connect the first pectin wastewater as a culture environment, and *Phanerochaete chrysosporium* and *Bacillus licheniformis* are used as the main inoculum to in-situ culture the pectin-cellulose degrading mixed bacteria in the microbial culture device; the microbial outlet is connected to the bioconversion tank, and the cultured pectin-cellulose degrading mixed bacteria are continuously added to the bioconversion tank; The equalization tank has a wastewater inlet and a wastewater outlet. The wastewater inlet is used to introduce the first pectin wastewater into the equalization tank. After the flow rate is regulated by the equalization tank, the first pectin wastewater is discharged to the biological conversion tank through the wastewater outlet. The equalization tank also contains a target chemical agent. The aeration tank is connected to the outlet of the primary or multi-stage anaerobic reactor and is used to further treat the wastewater with reduced organic matter concentration after treatment by the anaerobic reactor with aerobic treatment to obtain target wastewater with further reduced organic matter concentration.

8. The device according to claim 7, characterized in that, The target chemical agent comprises multiple functional components: a first functional component for promoting microbial growth and meeting the nutritional requirements during biochemical treatment; and a second functional component for promoting pectin suspension, preventing pectin aggregation, and reducing the agglomeration of the pectin-cellulose degrading mixed bacteria during bioconversion treatment; wherein the target chemical agent is simultaneously input into the bioconversion tank along with the output of the first pectin wastewater.

9. The device according to claim 7 or 8, characterized in that, The bioconversion tank integrates ultrasonic functionality, performing ultrasonic treatment after a preset duration of bioconversion processing within the tank; or... A physical conversion tank is connected after the biological conversion tank. The second pectin wastewater obtained after treatment in the biological conversion tank enters the physical conversion tank for ultrasonic treatment. The process of feeding the second pectin wastewater into a primary or multi-stage anaerobic reactor for anaerobic decomposition includes: subjecting the second pectin wastewater to ultrasonic treatment before feeding it into the primary or multi-stage anaerobic reactor for anaerobic decomposition.

10. The device according to claim 7 or 8, characterized in that, The primary or multi-stage anaerobic reactor is also equipped with an inlet for low-concentration pectin wastewater. The inlet is used to input fourth pectin wastewater, which is obtained by partially solidifying and filtering the third pectin wastewater. The third pectin wastewater and the first pectin wastewater are two parts obtained after the high-concentration pectin wastewater is separated. The fourth pectin wastewater is low-concentration pectin wastewater with a corresponding pectin concentration of 50 mg / L to 100 mg / L. The fourth pectin wastewater is fed together with the second pectin wastewater into a primary or multi-stage anaerobic reactor for anaerobic decomposition treatment; or, the second pectin wastewater is fed into a primary anaerobic reactor for anaerobic decomposition treatment, and then mixed with the fourth pectin wastewater before being fed into a subsequent multi-stage anaerobic reactor for anaerobic decomposition treatment.

11. The device according to claim 7, characterized in that, The wastewater inlet of the treatment equipment is used to connect to the wastewater outlet of the production equipment, which is used to produce or process one or more of canned citrus fruits, alcohol, and coffee; the energy supply end or energy storage end is used to provide energy to the production equipment or store energy.

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