A sludge dewatering agent and its preparation and application methods

Abstract

This application relates to a sludge dewatering agent and its preparation and application methods, including: placing a plant shell fiber material in an acidic environment according to a first ratio for stirring and mixing, and adding a salt containing ferric ions to obtain a carrier containing nano-iron oxide; domesticating a strain of bacteria, where the strain of bacteria is selected from one or more of yeast, Pseudomonas, and Bacillus; placing the carrier containing nano-iron oxide and the domesticated strain of bacteria in a culture system for cultivation to obtain a sludge dewatering agent. The solution provided by this application can use microorganisms to dewater sludge, improve the sludge dewatering efficiency without affecting the subsequent treatment of sludge, and is conducive to the resource utilization of sludge.

Description

Technical Field

[0001] The present application relates to the technical field of sludge treatment, and particularly relates to a sludge dewatering agent and a preparation and application method thereof. Background Art

[0002] Sludge is a by-product generated during the sewage treatment process. With the increasing attention to environmental issues and the improvement of environmental pollution awareness, the number and scale of sewage treatment plants have increased year by year. However, the subsequent problem is that a large amount of urban surplus sludge is inevitably generated during these sewage treatment processes, and the generation amount also shows a trend of rapid growth year by year. Since the surplus sludge is a highly plastic fluid with extremely poor compressibility, if it is directly dewatered without conditioning, the water content of the sludge cake is still above 90%, which is not conducive to the subsequent treatment, disposal and resource utilization of the sludge.

[0003] Currently, mechanical dewatering methods are mostly used to dewater sludge. Before dewatering, chemical conditioning methods are usually used to enhance the dewatering performance of sludge, such as adding quicklime, PAM, iron and aluminum salts, etc. However, these chemical agents all have certain side effects, which will affect the subsequent treatment and disposal processes of the dewatered sludge (such as anaerobic digestion, aerobic fermentation, etc.), and are not conducive to the resource utilization of the dewatered sludge. Therefore, a new sludge conditioning agent is needed to achieve efficient dewatering of sludge without affecting the subsequent treatment and disposal of the sludge. Summary of the Invention

[0004] To solve or partially solve the problems existing in the related technologies, the present application provides a sludge dewatering agent and a preparation and application method thereof, which can use microorganisms to dewater sludge, improve the sludge dewatering efficiency without changing data such as the pH value and viscosity of the sludge, and is conducive to the subsequent treatment of the sludge.

[0005] The first aspect of the present application provides a preparation method of a sludge dewatering agent, including placing a plant shell fiber material in an acidic environment according to a first ratio for stirring and mixing, and adding a salt containing trivalent iron ions to obtain a plant fiber carrier containing nano-iron oxide; domesticating a strain, and the strain is selected from one or more of yeast, pseudomonas, and bacillus; placing the carrier containing nano-iron oxide and the domesticated strain in a culture system for culturing to obtain a sludge dewatering agent.

[0006] In combination with the first aspect, in a possible implementation manner of the first aspect, it includes: grinding the plant shell fiber material and sieving it.

[0007] In combination with the first aspect, in a possible implementation manner of the first aspect, the mesh number of the sieve for sieving is 10-50 meshes.

[0008] In combination with the first aspect, in a possible implementation manner of the first aspect, the domestication, screening and cultivation of the bacterial strain are as follows: adding the bacterial strain to a first culture medium containing sludge extract, culturing the first culture medium at 20-40 °C and an oxygen content of 2-10 mg / L for 8-24 h to obtain a first bacterial strain culture medium; diluting the first bacterial strain culture medium and adding it to a second culture medium, culturing the second culture medium at 20-40 °C for 8-20 h to obtain a second bacterial strain culture medium; collecting colonies: collecting colonies from the second bacterial strain culture medium.

[0009] In combination with the first aspect, in a possible implementation manner of the first aspect, it further includes: repeating the screening and cultivation of the colonies 5-8 times to obtain the domesticated bacterial strain, and the domesticated bacterial strain is a bacterial strain capable of adapting to the environment with the sludge extract.

[0010] In combination with the first aspect, in a possible implementation manner of the first aspect, when placing the plant fiber carrier containing nano-iron oxide and the domesticated bacterial strain in a culture system for cultivation to obtain a sludge dewatering agent, it further includes: placing the carrier containing nano-iron oxide and the domesticated bacterial strain in a third culture medium according to a second ratio, culturing the third culture medium at 20-40 °C and an oxygen content of 2-10 mg / L for 12-24 h to obtain a third bacterial strain culture medium; centrifugally separating and freeze-drying the third bacterial strain culture medium to obtain the sludge dewatering agent.

[0011] In combination with the first aspect, in a possible implementation manner of the first aspect, the first ratio of the plant shell fiber material to the acid is: 1 g: 15-30 ml, the second ratio of the carrier containing nano-iron oxide to the third culture medium is: 1 g: 8-20 mL. When the third bacterial strain culture medium is centrifugally separated, the OD of the third bacterial strain culture medium diluted 10 times 600 is 0.2-2.

[0012] The second aspect of the present application provides a sludge dewatering agent, which is prepared by using the preparation method described above.

[0013] The third aspect of the present application provides an application method of a sludge dewatering agent, and the method includes: adding the sludge dewatering agent described above to the sludge to be dewatered for dewatering to obtain the treated sludge.

[0014] In combination with the third aspect, in a possible implementation manner of the third aspect, the water content of the sludge to be dewatered is 95-99%.

[0015] The technical solution provided by the present application may include the following beneficial effects:

[0016] The sludge dewatering agent of the present application, its preparation and application method include placing a plant shell fiber material in an acidic environment according to a first ratio, stirring and mixing, and adding a salt containing ferric ions to prepare a carrier containing nano-iron oxide; domesticating a strain of bacteria, where the strain of bacteria is selected from one or more of yeast, Pseudomonas, and Bacillus; placing the carrier containing nano-iron oxide and the domesticated strain of bacteria in a culture system for cultivation to obtain a sludge dewatering agent, which can use microorganisms to dewater sludge, improve the sludge dewatering efficiency without affecting the subsequent treatment of the sludge, and is conducive to the resource utilization of the sludge.

[0017] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. Brief Description of the Drawings

[0018] By describing the exemplary embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other objects, features, and advantages of the present application will become more apparent. Among them, in the exemplary embodiments of the present application, the same reference numerals generally represent the same components.

[0019] Figure 1 is a schematic diagram of the appearance of the sludge dewatering agent shown in the embodiment of the present application;

[0020] Figure 2 is a schematic diagram of the preparation method of the sludge dewatering agent shown in the embodiment of the present application. Detailed Embodiments

[0021] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to convey the scope of the present application fully to those skilled in the art.

[0022] The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "the", and "said" used in the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0023] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0024] With the rapid development of China's economy and the acceleration of the urbanization process, the production and treatment volume of sludge in China have been increasing year by year. Sludge is characterized by a large output and high water content, and contains a large amount of toxic and harmful substances. Improper treatment will cause serious secondary pollution.

[0025] The dewatering performance of sludge is affected by various factors, mainly including: the form of sludge moisture, the size and distribution of sludge particles, surface charge, extracellular polymers, etc. Among them, due to the sludge organic floc structure formed by extracellular polymers (EPS) in sludge, it has high hydrophilicity and strong encapsulation ability, which hinders the release of bound water during the disposal and treatment of sludge. In addition, the organic matter content of sludge flocs is high and has high compressibility, which will block the pores of the filter cake in the later stage of filtration, resulting in low mechanical dewatering efficiency; and the sludge flocs are stably suspended in water in the form of colloids and are difficult to coagulate and settle. Therefore, in order to improve the sludge dewatering efficiency, a series of pretreatment measures need to be taken to condition the sludge, such as destroying the extracellular polymers of sludge and changing its surface characteristics; increasing the particle size of sludge particles to promote its destabilization, aggregation and settlement, etc.

[0026] The water content of the sludge produced by sewage treatment plants is about 99%, and its composition, structure and properties are diverse. It is difficult for traditional mechanical dewatering methods to significantly reduce the water content of sludge. Usually, various means need to be used to condition and improve the dewatering performance of sludge. At present, chemical conditioning methods are mostly used to enhance the dewatering performance of sludge, such as adding quicklime, PAM, PAC, etc. However, the addition of these chemical agents will affect the subsequent deep dewatering or other disposal of sludge. For example, the addition of quicklime will greatly increase the total amount of sludge and increase the subsequent treatment and disposal costs; the addition of PAM will make the sludge become more viscous and difficult to further dewater deeply; and the large addition of iron and aluminum salts will introduce metal elements and change the pH of the sludge, affecting subsequent anaerobic / aerobic and other treatment processes.

[0027] The dewaterability of sludge after physical treatment can be improved to the greatest extent, and the moisture content is generally below 80%. However, the physical pretreatment process is complex, difficult to operate, consumes a large amount of energy during the reaction, and has a high cost. The chemical conditioning method refers to a method of using chemical conditioning agents to change the properties of sludge so as to improve the sludge dewatering performance. Because of its simple operation and stable effect, the chemical method is also the most widely used method at present. At present, the physical and chemical methods such as acid treatment, advanced oxidation technology and heat treatment, as well as the biodegradation methods such as biological leaching and enzyme treatment are relatively mature for sludge deep dewatering technology. Combining physical, chemical and biological methods to treat sludge, improving the dewatering effect of sludge through synergistic effects, or using conventional methods such as adding conditioning agents to adjust, to achieve the optimal conditions in terms of sludge dewatering performance and economy. Conventional sludge conditioning usually adds inorganic conditioning agents to change some basic characteristics of sludge. By adding flocculants or coagulants such as CaO and FeCl3, the loose structure of sludge is aggravated, a hard network skeleton is formed, and the hydrophilic phenomenon is alleviated to achieve the effect of improving the sludge dewatering performance. At the same time, when comparing the influence of oxidants on the sludge dewatering performance, it is found that hydrogen peroxide has the best effect on improving the sludge dewatering performance, and there are no by-products, which can promote the air flotation separation of solid particles in the sludge and has a good conditioning effect. However, some studies have shown that adding conventional chemical conditioning agents cannot improve the dewaterability of sludge, but only improve the sludge dewatering rate and filtration performance. The four forms of water in sludge particles are interstitial water, capillary water, surface adsorbed water and cell-bound water. Given enough time, whether or not similar conditioning agents are added, only the removable free water can be removed, and the bound water wrapped by EPS cannot be removed. A large amount of water is still locked in the sludge particles and cannot be released, and the moisture content of the final product sludge will not change, failing to achieve the purpose of deep dewatering.

[0028] Microbial flocculants are a class of metabolites produced by microorganisms or their secretions. They are obtained by microbial fermentation, extraction and refinement of bacteria, fungi and other microorganisms using microbial technology. They are water treatment agents with biodegradability, safety, high efficiency, non-toxicity and no secondary pollution. Since microbial flocculants can overcome the inherent defects of inorganic polymer and synthetic organic polymer flocculants, pollution-free discharge can be finally achieved. However, at present, problems such as long reaction time, large dosage and high price of microbial flocculants, as well as factors such as difficult selection of microorganisms, complex bacteria cultivation process and long cultivation cycle, have restricted the overall development and also affected their wide application in large-scale production and industry.

[0029] In view of the above problems, the embodiments of the present application provide a sludge dewatering agent and its preparation and application method, which can use microorganisms to dewater sludge, improve the sludge dewatering efficiency without affecting the subsequent treatment of sludge, and is conducive to the resource utilization of sludge.

[0030] The technical solutions of the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0031] As Figure 1 and Figure 2 shown, in an embodiment of the present application, a preparation method of a sludge dewatering agent includes: placing a plant shell fiber material in an acidic environment according to a first ratio for stirring and mixing, and adding a salt containing ferric ions to prepare a carrier containing nano-iron oxide; domesticating a strain of bacteria, where the strain of bacteria is selected from one or more of yeast, pseudomonas, and bacillus; placing the carrier containing nano-iron oxide and the domesticated strain of bacteria in a culture system for culturing to obtain a sludge dewatering agent.

[0032] It should be noted that Escherichia coli, yeast (Pichia pastoris), bacillus (Bacillus licheniformis), and pseudomonas (Pseudomonas fluorescens) can all be purchased from the China Industrial Microbial Culture Collection Center (abbreviated as CICC), and their respective corresponding numbers are CICC 10899, CICC 33372, CICC 20204, and CICC 23251.

[0033] Specifically, yeast is a single-celled fungus with typical heterotrophic facultative anaerobic characteristics, that is, it can survive under aerobic and anaerobic conditions; pseudomonas is an aerobic gram-negative small bacillus with flagella and a capsule, and can produce a variety of water-soluble pigments during metabolism; bacillus is a gram-positive bacterium with a rod-shaped cell and a large amount of calcium pyridine dicarboxylate covering the outer layer, and has characteristics such as high temperature resistance, rapid resuscitation, and strong enzyme secretion; the salt containing ferric ions can release Fe 3+ in the solution. For example, it can be an FeCl3 solution with a concentration of 0.02 mol / L, and the acid can be dilute hydrochloric acid with a concentration of 0.002 mol / L.

[0034] In a possible implementation manner, before mixing the plant shell fiber material, the plant shell fiber material can be ground and sieved, which can increase the specific surface area of the plant shell fiber material and improve the subsequent reaction efficiency.

[0035] Specifically, the plant shell fiber material can be wood chips or coconut coir powder. Wood chips are the powders left during wood processing, mainly including sawdust and planer shavings. Wood chips are mostly in a powdery state, and their colors vary depending on the type of wood. Commonly seen colors are brown, yellow, etc. Their texture is loose, making them easy to store and transport. Wood chips are rich in natural organic substances such as cellulose and lignin. These substances are the main components of plant cell walls and have the characteristics of toughness and straightness. Coconut coir powder is made from coconut shell fibers. Coconut coir powder has the characteristic of natural degradation and is a pure natural organic matter medium. It has good hydrophobicity and air permeability, can significantly improve the soil aggregate structure, and increase the soil air permeability. At the same time, coconut coir powder has good stability, light weight, corrosion resistance, and high compatibility with other substrates. The main components of coconut coir powder are cellulose, hemicellulose, and lignin. The plant shell fiber material is inactive during the subsequent preparation reaction process but has a certain strength and can play a role as a carrier to support and provide adsorption sites for iron-based nanomaterials.

[0036] In a possible implementation manner, the plant shell fiber material can be sieved. The mesh number of the sieve for sieving is 10 - 50 meshes. After sieving, the particle size of the plant shell fiber material is 10 - 50 meshes, which can better serve as a carrier.

[0037] In a possible implementation manner, the strain is domesticated, including: screening and culturing: adding the strain to a first culture medium. The first culture medium contains sludge extract. The first culture medium is cultured at 20 - 40 °C for 8 - 24 h, and the oxygen content is 2 - 10 mg / L to obtain a first strain culture medium; diluting the first strain culture medium and adding it to a second culture medium, and culturing the second culture medium at 20 - 40 °C for 8 - 20 h to obtain a second strain culture medium; collecting colonies: collecting colonies from the second strain culture medium.

[0038] Specifically, the first culture medium can be a modified culture medium configured with a sludge environment. The composition of this culture medium can include: yeast extract powder, peptone, glucose, PIPES (piperazine - 1,4 - bis(2 - ethanesulfonic acid)), sludge extract, with a pH of 5 - 7, and sterilized at 120 - 130 °C for 20 min. Further, in one first culture medium, it can contain 2 g of yeast extract, 2 g of peptone, 2 g of glucose, 6 g of PIPES (piperazine - 1,4 - bis(2 - ethanesulfonic acid)), and 1 L of sludge extract.

[0039] Specifically, the preparation process of the sludge leaching solution can be as follows: 100 g of activated sludge is centrifugally concentrated at 8000 rpm for 10 min, and then added to 1 L of distilled water (solid-liquid ratio 1:10). It is placed on a shaker at 25°C and 200 r / min and oscillated for 24 h, and then vacuum filtered through a 0.45 μm filter paper to obtain the sludge leaching solution. Placing the sludge leaching solution in the first medium can provide an ecological environment simulating sludge, which is conducive to selecting strains that can adapt to the sludge environment.

[0040] Specifically, placing the strain in the first medium and culturing it at 20-40°C for 8-24 h can obtain the first strain medium. Then, the first strain medium can be diluted and inoculated into the second medium. For example, 20 μL of the bacterial solution diluted 10 -6 times can be inoculated into the second medium, and the second medium can be an LB solid medium; further, the LB solid medium can be composed of peptone, yeast extract powder extract, sodium chloride, and agar dissolved in 1000 mL of sterile water. For example, an LB solid medium can include 10 g of peptone, 5 g of yeast extract powder extract, 10 g of sodium chloride, and 15 g of agar dissolved in 1000 mL of sterile water, and autoclaved at 121°C for 20 min, and obtained after cooling. Dilute the first strain medium and add it to the second medium, and culture it at 20-40°C for 8-20 h to obtain the second strain medium. The microorganisms in the second strain medium can initially adapt to the sludge environment, and then select the colonies with better growth (larger bacterial masses) from the second medium and continue to inoculate them into the newly sterilized first medium.

[0041] In a possible implementation manner, the colony is repeatedly screened and cultured 5-8 times to obtain the domesticated strain, and the domesticated strain is a strain that can adapt to the environment with the sludge leaching solution.

[0042] Specifically, repeatedly placing the colony in the first medium and the second medium for repeated screening and culturing 5-8 times can obtain the strain that maximally adapts to the sludge environment and use it as the domesticated strain. This strain can be one or more of yeast, Pseudomonas, and Bacillus, and can adapt to the environment with the sludge leaching solution.

[0043] In a possible implementation manner, the carrier containing nano-iron oxide and the domesticated strain are placed in the third medium according to the second ratio, and the third medium is cultured at 20-40°C and an oxygen content of 2-10 mg / L for 12-24 h to obtain the third strain medium; the third strain medium is centrifuged and freeze-dried to obtain the sludge dewatering agent.

[0044] Specifically, the third culture medium can be TB medium, which can be composed of water, peptone, yeast extract, glycerol, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate. A single 1L TB medium can include 1L of water, 12g of peptone, 24g of yeast extract, 4mL of glycerol, 2.313g of potassium dihydrogen phosphate, and 12.54g of dipotassium hydrogen phosphate. Then, 100g of the carrier containing nano-iron oxide and the domesticated strain are added to 1 L of the third culture medium, and the third culture medium is placed in a constant temperature shaker at 20-40°C and shaken for 12-24h to obtain the third strain culture medium. When the OD of the third strain culture medium diluted 10 times 600 is between 0.2 and 2, the third strain culture medium is separated by a centrifuge with a centrifugal force of 500-1000 xg, and the separated solid is vacuum freeze-dried for 10-24h to obtain the sludge dewatering agent.

[0045] In a possible implementation, the first ratio of the plant shell fiber material to the reducing acid is: 1g: 15-30ml, and the second ratio of the carrier containing nano-iron oxide to the third culture medium is: 1g: 8-20 mL. When the third strain culture medium is centrifuged, the OD of the third strain culture medium diluted 10 times 600 is 0.2-2.

[0046] In another aspect of the present application, a sludge dewatering agent of the present application is prepared by the preparation method described above. Thus, the sludge dewatering agent has all the characteristics and advantages of the foregoing method, which will not be elaborated here.

[0047] It should be noted that the preparation method of the above sludge dewatering agent can refer to some or all of the steps in the foregoing preparation method, and the relevant parameters of the above sludge dewatering agent can refer to some or all of the technical features in the foregoing embodiments. For the parts not described in the embodiments of the sludge dewatering agent, reference can also be made to the foregoing embodiments and the relevant drawings, which will not be elaborated here.

[0048] In another aspect of the present application, the present application proposes an application of a sludge dewatering agent. The sludge dewatering agent can be used to dehydrate the sludge to be dehydrated, and the water content of the dehydrated sludge can be reduced to less than 55%. The water content of the sludge to be dehydrated can be 95-99%.

[0049] The application method includes: preparing the sludge dewatering agent into an aqueous solution of 0.1% - 0.5%, mixing and stirring for 20-40min. After the dewatering agent is dissolved, it is added to the sludge to be dehydrated at a volume ratio of 10% - 40%, mixed and stirred for 20-40 min, and then dehydrated using a dehydration device (such as a spiral press, a plate and frame filter press, a centrifugal dehydrator, etc.) to obtain the treated sludge.

[0050] The solutions of the present application will be described below through specific embodiments. It should be noted that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those without specific technologies or conditions noted in the embodiments, the technologies or conditions described in the literature in this field or the product specifications shall be followed. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained through commercial purchase.

[0051] Example 1

[0052] 1. Preparation of a plant fiber carrier containing nano-iron oxide:

[0053] 100 g of coconut coir was ground and passed through a 10-mesh sieve, then added to 2 L of 0.002 mol / L dilute hydrochloric acid and stirred and mixed. Subsequently, 10.8 g of FeCl3·6H2O was added, and the mixture was mixed under ultrasonic conditions of 40 kHz with an ultrasonic power of 270 W and stirred for 10 min. The mixed solution was poured into a high-pressure reactor and reacted at 98 °C for 10 days to synthesize a plant fiber carrier containing nano-iron oxide.

[0054] 2. Preparation of domesticated strains:

[0055] 100 g of activated sludge was centrifugally concentrated at 8000 rpm for 10 min, then added to 1 L of distilled water and mixed at 25 °C and 200 r / min for 24 h, and then vacuum filtered through a filter paper with a pore size of 0.45 μm to obtain a sludge extract.

[0056] 2 g of yeast extract, 2 g of peptone, and 6 g of PIPES were taken and added to 900 mL of the sludge extract, stirred and dissolved, autoclaved at 121 °C for 20 min, and after cooling, 100 mL of a sterilized sludge extract containing 2 g of glucose was added to obtain a liquid first culture medium.

[0057] 5 g of yeast extract, 10 g of peptone, 10 g of sodium chloride, and 15 g of agar powder were taken and added to 1 L of water, stirred and dissolved, autoclaved at 121 °C for 20 min, and after cooling to 60 °C, it was dispensed into sterile petri dishes and cooled to room temperature to obtain a solid second culture medium.

[0058] Pseudomonas was added to the first culture medium, and at 35 °C and 175 r / min, the oxygen content in the culture medium was controlled at 3 mg / L (regulated by aeration or controlling the volume ratio of the culture medium in the container), and cultured for 20 h to obtain a first strain culture medium.

[0059] Take the first strain culture medium and dilute it stepwise to 10 -7Multiply it, add it to the second culture medium, incubate it at a constant temperature of 35 °C for 15 h, and use it as the second bacterial strain culture medium; select the Pseudomonas colonies with larger bacterial masses in the second bacterial strain culture medium, and repeat the culture 5 times according to the above steps to obtain the domesticated bacterial strain.

[0060] 3. Preparation of sludge dewatering agent:

[0061] Take 24 g of yeast extract, 12 g of peptone, 4 mL of glycerol, 2.313 g of potassium dihydrogen phosphate, and 12.54 g of dipotassium hydrogen phosphate, add them to 1 L of water, stir to dissolve, and autoclave at 121 °C for 20 min. After cooling to room temperature, obtain the liquid third culture medium.

[0062] Place the domesticated bacterial strain in 1 L of the third culture medium for cultivation, add 100 g of plant fiber carrier containing nano-iron oxide, and control the oxygen content in the culture medium to 5 mg / L at 35 °C and 175 r / min (adjust by aeration or controlling the volume ratio of the culture medium in the container), and cultivate for 16 h to obtain the third bacterial strain culture medium. When the OD of the third bacterial strain culture medium diluted 10 times 600 reaches 0.5, centrifuge and separate it under the conditions of 800 xg and 10 min, and obtain the sludge dewatering agent A1 after solid vacuum freeze-drying.

[0063] Example 2

[0064] 1. Preparation of plant fiber carrier containing nano-iron oxide:

[0065] The same as in Example 1.

[0066] 2. Preparation of domesticated bacterial strain:

[0067] The preparation method of the sludge leaching solution is the same as in Example 1.

[0068] Take 10 g of yeast extract and 20 g of peptone, add them to 900 mL of the sludge leaching solution, stir to dissolve, autoclave at 121 °C for 20 min, and then add 100 mL of the sterilized sludge leaching solution containing 20 g of glucose. After cooling to room temperature, obtain the liquid first culture medium.

[0069] Take 10 g of yeast extract, 20 g of peptone, and 20 g of agar powder, add them to 900 mL of water, stir to dissolve, autoclave at 121 °C for 20 min, and then add 100 mL of the sterile aqueous solution containing 20 g of glucose. After cooling to 60 °C, dispense it into sterile petri dishes, and after cooling to room temperature, obtain the solid second culture medium.

[0070] Add yeast to the first medium, and under the conditions of 30 °C and 200 r / min, control the oxygen content in the medium to be 4 mg / L (adjusted by aeration or controlling the volume ratio of the medium in the container), and culture for 18 h to obtain the first strain medium;

[0071] Take the first strain medium and dilute it by a gradient to 10 -6 times, add it to the second medium, and incubate at a constant temperature of 30 °C for 15 h to obtain the second strain medium;

[0072] Select the yeast colonies with larger bacterial masses in the second strain medium, and repeat the culture according to the above steps 5 times to obtain the domesticated strain.

[0073] 3. Preparation of sludge dewatering agent:

[0074] Take 10 g of yeast extract and 20 g of peptone, add them to 900 mL of water, stir and dissolve, sterilize under high pressure at 121 °C for 20 min, and then add 100 mL of a sterile aqueous solution containing 20 g of glucose. After cooling to room temperature, obtain the liquid third medium.

[0075] Place the domesticated strain in 1 L of the third medium for culture, add 100 g of a plant fiber carrier containing nano-iron oxide, and under the conditions of 30 °C and 200 r / min, control the oxygen content in the medium to be 7 mg / L (adjusted by aeration or controlling the volume ratio of the medium in the container), and culture for 18 h to obtain the third strain medium. When the OD of the third strain medium diluted 10 times 600 reaches 0.8, centrifuge and separate under the conditions of 800 xg and 10 min, and obtain sludge dewatering agent A2 after solid vacuum freeze-drying.

[0076] Example 3

[0077] 1. Preparation of plant fiber carrier containing nano-iron oxide:

[0078] The same as Example 1.

[0079] 2. Preparation of domesticated strain:

[0080] The preparation method of the domesticated strain is basically the same as that in Example 1, except that Bacillus is added to the first medium, and both the first strain medium and the second strain medium are media inoculated with Bacillus.

[0081] 3. Preparation of sludge dewatering agent:

[0082] Take 24 g of yeast extract, 12 g of peptone, 4 mL of glycerol, 2.313 g of potassium dihydrogen phosphate, and 12.54 g of dipotassium hydrogen phosphate. Add them to 900 mL of water, stir to dissolve, autoclave at 121 °C for 20 min, and then add 100 mL of a sterile aqueous solution containing 10 g of glucose. After cooling to room temperature, a liquid third culture medium is obtained.

[0083] Place the domesticated strain in 1 L of the third culture medium for cultivation. Add 100 g of a plant fiber carrier containing nano-iron oxide. Under the conditions of 35 °C and 175 r / min, control the oxygen content in the culture medium to 5 mg / L (adjusted by aeration or controlling the volume ratio of the culture medium in the container), and cultivate for 14 h to obtain a third strain culture medium. When the OD of the third strain culture medium diluted 10 times 600 reaches 0.8, centrifuge and separate at 800 xg for 10 min, and obtain sludge dewatering agent A3 after solid vacuum freeze-drying.

[0084] Example 4

[0085] The plant fiber carrier containing nano-iron oxide, the domesticated strain, and the sludge dewatering agent provided in this example have basically the same preparation method as in Example 1. The difference is that in the preparation of the plant fiber carrier containing nano-iron oxide, coconut coir is replaced with sawdust, and after grinding, it is sieved through a 20-mesh sieve to obtain sludge dewatering agent A4.

[0086] Comparative Example 1

[0087] The plant fiber carrier containing nano-iron oxide, the domesticated strain, and the sludge dewatering agent provided in this example have basically the same preparation method as in Example 1. The difference is that in the preparation of the plant fiber carrier containing nano-iron oxide, 10.8 g of FeCl3·6H2O is replaced with 9.64 g of AlCl3·6H2O to obtain sludge dewatering agent B1.

[0088] Comparative Example 2

[0089] The plant fiber carrier containing nano-iron oxide, the domesticated strain, and the sludge dewatering agent provided in this example have basically the same preparation method as in Example 1. The difference is that the selected strain is replaced from Pseudomonas to Escherichia coli to obtain sludge dewatering agent B2.

[0090] Comparative Example 3

[0091] The plant fiber carrier containing nano-iron oxide, the domesticated strain, and the sludge dewatering agent provided in this embodiment have basically the same preparation method as that of Embodiment 1, except that the sludge extract is not used to domestically cultivate Pseudomonas. During the preparation process of the domesticated strain, the sludge extract is replaced with an equal amount of sterile water to obtain the sludge dewatering agent B3.

[0092] Testing method:

[0093] Using the sludge dewatering agents prepared in each example and comparative example, a small plate and frame machine is used to dehydrate the sludge. The initial moisture content is 94.7%. The dewatering agents used in the factory are polyaluminum chloride (PAC) and polyacrylamide (PAM). The specific treatment effects are shown in Table 1.

[0094] Table 1

[0095]

[0096] It can be seen from the examples and comparative examples that the sludge dewatering agent provided in this application has good dewatering effect, and the dewatered sludge after conditioning can still be quickly dehydrated during the subsequent stacking process. The moisture content can be reduced by about 10% after one week, which can save a large amount of costs for the subsequent treatment of sludge.

[0097] It can be seen from Example 1 and Comparative Example 1 that after loading nano-iron oxide on the surface of the plant shell fiber material, the amount of microorganisms that can be adsorbed on the material surface can be significantly increased, and the conditioning performance of the agent on the sludge dewatering performance can be improved.

[0098] It can be seen from Example 1, Example 2, Example 3 and Comparative Example 2 that the sludge dewatering agent in Example 1 contains Pseudomonas, the sludge dewatering agent in Example 2 contains Saccharomyces cerevisiae, the sludge dewatering agent in Example 3 contains Bacillus, and the sludge dewatering agent in Comparative Example 2 contains Escherichia coli. After dehydrating the sludge with the sludge dewatering agent containing Saccharomyces cerevisiae, Bacillus or Pseudomonas, the moisture content of the sludge is about 50%, while after dehydrating the sludge with the sludge dewatering agent containing Escherichia coli, the moisture content of the sludge is 85.7%. Therefore, the sludge dewatering agent contains one or more of Saccharomyces cerevisiae, Pseudomonas, and Bacillus, which can better dehydrate the sludge.

[0099] It can be seen from Example 1 and Comparative Example 3 that in Example 1, the microorganisms are cultured and domesticated, and then the sludge dewatering agent is prepared. In Comparative Example 3, the microorganisms are not cultured and domesticated. The sludge dewatering agent in Example 1 has a better dewatering effect than that in Comparative Example 3. Therefore, by culturing and domesticating the microorganisms during the preparation of the sludge dewatering agent, the activity of the microbial agent in the sludge dewatering process can be improved, and its conditioning effect can be strengthened.

[0100] The technical features of the above-described embodiments may be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0101] The embodiments of the present application have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A preparation method of a sludge dewatering agent, characterized in that The plant shell fiber material is placed in an acidic environment and stirred and mixed in a first ratio, and a salt containing ferric ions is added to obtain a plant fiber carrier containing nano iron oxide; The strain is domesticated, and the strain is selected from one or more of yeast, pseudomonas, and bacillus; The plant fiber carrier containing nano iron oxide and the domesticated strain are placed in a culture system for cultivation to obtain a sludge dewatering agent; The domestication of the strain includes: Screening culture: The strain is added to a first culture medium containing sludge extract, and the first culture medium is cultured at 20-40 °C and an oxygen content of 2-10 mg / L for 8-24 h to obtain a first strain culture medium; The first strain culture medium is diluted and added to a second culture medium, and the second culture medium is cultured at 20-40 °C for 8-20 h to obtain a second strain culture medium; Collect colonies: Collect colonies from the second strain culture medium; The placing of the plant fiber carrier containing nano iron oxide and the domesticated strain in a culture system for cultivation to obtain a sludge dewatering agent further includes: The carrier containing nano iron oxide and the domesticated strain are placed in a third culture medium in a second ratio, and the third culture medium is cultured at 20-40 °C and an oxygen content of 2-10 mg / L for 12-24 h to obtain a third strain culture medium; The third strain culture medium is centrifuged and freeze-dried to obtain the sludge dewatering agent.

2. The preparation method according to claim 1, characterized in that, Including: The plant shell fiber material is ground and sieved.

3. The preparation method according to claim 2, wherein Including: The mesh number of the sieve for sieving is 10-50 meshes.

4. The preparation method according to claim 1, wherein Further including: The colonies are repeatedly screened and cultured 5-8 times to obtain the domesticated strain, and the domesticated strain is a strain capable of adapting to an environment with the sludge extract.

5. The preparation method according to claim 1, wherein The first ratio of the plant shell fiber material to the acid is: 1 g: 15 - 30 ml, the second ratio of the carrier containing nano iron oxide to the third culture medium is: 1 g: 8 - 20 mL. When centrifuging the third strain culture medium, the OD of the third strain culture medium diluted 10 times is 600 0.2 - 2.

6. A sludge dewatering agent, characterized in that, Prepared by using the preparation method according to any one of claims 1 to 5.

7. An application method of a sludge dewatering agent, characterized in that, The method includes: adding the sludge dewatering agent according to claim 6 to the sludge to be dewatered for dewatering to obtain the treated sludge.

8. The method according to claim 7, characterized in that, The water content of the sludge to be dewatered is 95-99%.

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