CN114891623A - Skid-mounted self-powered organic waste biological treatment and mobile power system and process - Google Patents

Abstract

The invention discloses an organic waste biological treatment system, which comprises: the system comprises a pretreatment feeding module, an anaerobic biological treatment module, a solid-liquid separation module, an aerobic biological treatment module and a methane power generation module, wherein the pretreatment feeding module is used for carrying out primary treatment on organic waste biological materials; the anaerobic biological treatment module is used for receiving the organic waste biological material subjected to primary treatment from the pretreatment feeding module and preparing methane by utilizing anaerobic biological fermentation in the organic waste biological material; the solid-liquid separation module is used for separating the fermented residues into biogas residues and biogas slurry, wherein the biogas slurry flows back to the pretreatment feeding module and the anaerobic biological treatment module; the aerobic biological treatment module is used for treating the biogas residues into organic fertilizers; and the methane power generation module is used for generating power by using the methane and supplying the power to each module of the system. The invention can obtain electric energy and organic fertilizer while consuming organic waste on site.

Description

Skid-mounted self-powered organic waste biological treatment and mobile power system and process

technical field

The invention relates to the fields of waste treatment and clean energy supply, in particular to a skid-mounted self-energy organic waste biological treatment and mobile power supply system and process.

Background technique

With the rapid development of my country's economy and the continuous improvement of people's living standards, organic wastes are increasing year by year, and the production volume ranks among the top in the world. Especially in the vast rural areas and towns, a large number of organic wastes such as crop straw, organic household waste, livestock and poultry manure have not undergone harmless treatment, and are randomly discarded, stacked naked or discharged into waters, fields and ponds, polluting the ecological environment. Threats to human and animal health. From a social point of view, garbage disposal is related to the level of urban civilization, land pollution, and air pollution; from a personal point of view, it is directly related to the health status of each person's daily life.

Biological treatment technology is the use of microorganisms to degrade organic wastes and convert them into other value-added products, so as to reduce, harmless and recycle them. In my country's agricultural areas, densely populated areas, fruit and vegetable farmers markets and other areas, organic waste is relatively scattered, and it is difficult to centralize disposal site selection, land acquisition, high investment costs, and high personnel costs, and generally requires long-distance collection and transportation. The increase in treatment capacity is much lower than the increase in organic waste.

The development of the organic waste treatment industry is imperative. The existing related projects are mainly large-scale centralized treatment projects located in remote suburbs and remote areas, which are not conducive to the efficient and rapid digestion of organic waste. Long-distance transportation is not only expensive, but also easy to cause escape Drips and other contamination along the way. Therefore, there is an urgent need for technologies and equipment for the timely treatment and on-site consumption of organic waste, which complements the centralized treatment and disposal project.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the present invention provides a skid-mounted self-powered organic waste biological treatment and mobile power supply system and process, which adopts a biological method to treat organic waste, and adopts a mobile skid-mounted and functional modular design as a whole. , without external grid energy input, while solving the problem of local consumption of organic waste, electricity and organic fertilizer can be obtained.

To achieve the above object, the present invention can adopt the following technical solutions to carry out:

An organic waste biological treatment system, comprising:

a pretreatment feed module for preliminary treatment of organic waste biomass;

an anaerobic biological treatment module, which is used for receiving the pre-treated organic waste biomass from the pretreatment feed module, and utilizing the anaerobic biological fermentation therein to produce biogas;

a solid-liquid separation module for separating the residue after fermentation into biogas residue and biogas slurry, wherein the biogas slurry is returned to the pretreatment feed module and the anaerobic biological treatment module;

an aerobic biological treatment module for processing the digestate into organic fertilizer; and,

A biogas power generation module, which is used for utilizing the biogas to generate electricity and used by each module of the system.

The above-mentioned organic waste biological treatment system further includes: a photovoltaic power generation module and an electricity storage power supply module, the photovoltaic power generation module is used to generate electricity by using solar energy and is used by each module of the system, and the electricity storage module The power supply module is respectively connected with the photovoltaic power generation module and the biogas power generation module, and is used for storing the electric energy generated by the photovoltaic power generation module and the biogas power generation module for use by each module of the system.

The above-mentioned organic waste biological treatment system further includes: a microbial regulation module, the microbial regulation module is respectively connected with the anaerobic biological treatment module and the aerobic biological treatment module, and is used to The anaerobic biological treatment module and the aerobic biological treatment module are put into anaerobic bacteria and aerobic bacteria.

The above-mentioned organic waste biological treatment system further includes: an intelligent control module, the intelligent control module is used to communicate and connect with each module of the system, and is used for monitoring and regulating the operation of each module of the system. state.

The organic waste biological treatment system as described above, further, the heat generated during the operation of the biogas power generation module and the aerobic biological treatment module is supplied to the pretreatment feed module and the anaerobic biological treatment module , the solid-liquid separation module and the aerobic biological treatment module.

The above-mentioned organic waste biological treatment system, further, the pretreatment feeding module includes a conveying device and a pretreatment feeding device; the anaerobic biological treatment module includes an anaerobic reactor, a stirring device and a first biogas The biogas power generation module includes a biogas purification device, a second biogas pipe and a biogas power generation device, wherein the conveying device sends the organic waste biomass to the pretreatment feeding device for preliminary treatment. The organic waste biomass is fermented in the anaerobic reactor, the stirring device is used to stir the organic waste biomass in the anaerobic reactor, and the fermented biogas enters the biogas through the first biogas pipe After the purification equipment is dehydrated and desulfurized, it is transported to the biogas power generation equipment through the second biogas pipe for power generation.

The above-mentioned organic waste biological treatment system, further, the photovoltaic power generation module has a solar heat collector plate that can be folded and unfolded; the solid-liquid separation module includes a discharging device and a solid-liquid separator, and the anaerobic The biogas residue and biogas liquid of the reactor are discharged to the solid-liquid separator through the discharge device and separated.

In the above-mentioned biological treatment system for organic waste, further, each module of the system is arranged in a skid-mounted box, and the skid-mounted box is arranged on an automobile.

A biological treatment process for organic wastes, which utilizes the above-mentioned biological treatment system for organic wastes, comprising the following steps:

Remove impurities, crush, pulverize, and de-sand the organic waste biomass, and crush it to a particle size of ≤10mm;

Biogas is generated under the action of anaerobic bacteria, and the temperature of anaerobic fermentation is controlled to be 20 to 56°C and the pH to be 6.5 to 7.8;

The residue of anaerobic fermentation is separated into biogas residue and biogas slurry, and the biogas slurry is recycled and reused. The biogas residue is made into a water content of ≤30%, an organic matter TS% of ≥45%, and a pH of 5.5 to 8.5 by adjusting the moisture content and porosity. of organic fertilizers.

In the above-mentioned biological treatment process of organic waste, further, highly active anaerobic methanogens are used in the process of anaerobic fermentation to produce biogas, and rot-promoting and nitrogen-preserving aerobic bacteria are used in the fertilizer making process.

Compared with the prior art, the present invention has the beneficial effects that: the present invention, through modular design, integrates anaerobic biological treatment, aerobic biological treatment, microbial regulation, biogas power generation, photovoltaic power generation, power storage and power supply, Internet of Things + intelligent control A number of other technologies have been organically combined and complementary technologies have been formed to form a mobile skid-mounted self-powered organic waste biological treatment and mobile power system, which can realize the timely treatment and local consumption of organic waste, and obtain clean electric energy and energy. Organic fertilizer resources do not require external energy input, and can be disposed of at any time, without the need for additional municipal facilities; and in the process of processing organic waste, it can also be used as a power source to supply power to the outside world.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following will briefly introduce the accompanying drawings that need to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

1 is a schematic diagram of a module of an organic waste biological treatment system according to an embodiment of the present invention;

2 is a top view of the equipment of the organic waste biological treatment system according to the embodiment of the present invention;

3 is a 3D front view of an organic waste biological treatment system according to an embodiment of the present invention from the perspective of a skid-mounted box;

FIG. 4 is an overall 3D view of the organic waste biological treatment system on the vehicle according to the embodiment of the present invention.

Description of reference numerals: 1. Pretreatment feed module; 1.1, Conveying equipment; 1.2, Pretreatment feed equipment; 2, Anaerobic biological treatment module; 2.1, Anaerobic reactor; 2.2, Stirring equipment; 2.3, First Biogas pipe; 3. Biogas power generation module; 3.1, Biogas purification equipment; 3.2, Second biogas pipe; 3.3, Biogas power generation equipment; 4. Photovoltaic power generation module; (Expand); 5. Electricity storage and power supply module; 6. Solid-liquid separation module; 6.1. Discharging equipment; 6.2. Solid-liquid separator; 7. Aerobic biological treatment module; 8. Microbial regulation module; 9. Smart control module ; 10. Skid packing box; 11. Automobile.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

Example:

It should be noted that the terms "first", "second" and the like in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used may be interchanged under appropriate circumstances such that the embodiments of the invention described herein can be practiced in sequences other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to Those steps or elements that are expressly listed may instead include other steps or elements that are not expressly listed or are inherent to the process, method, product or apparatus.

Referring to FIGS. 1 to 4 , the present invention provides a skid-mounted self-powered organic waste biological treatment and mobile power supply system and process, which adopts a biological method to treat organic waste, and adopts a mobile skid-mounted and functional modular design as a whole. No external energy input is required, and electricity and organic fertilizer can be obtained while consuming organic waste on site.

Referring to Figure 1, Figure 1 shows the connection relationship between the various modules of the organic waste biological treatment system. In this example, the organic waste biological treatment system may include a pretreatment feed module 1, an anaerobic biological treatment module 2, and a biogas Power generation module 3, photovoltaic power generation module 4, power storage and power supply module 5, solid-liquid separation module 6, aerobic biological treatment module 7, microbial regulation module 8, intelligent control module 9, among which, the function of pretreatment feeding module 1 is to In the organic waste intake system, after pretreatment to meet the subsequent anaerobic treatment standards, the feed is transported to the anaerobic biological treatment module 2 for anaerobic fermentation to produce biogas; the anaerobic biological treatment module 2 has two biogas and residual outlet, the residue outlet is connected to the solid-liquid separation module 6, the solid-liquid separation module 6 has two outlets for biogas liquid and solid residue, and the biogas liquid outlet is connected to the pretreatment feed module 1 and the anaerobic biological treatment module 2, and returns to the The two modules are slurried and inoculated, and the solid slag outlet is connected to the aerobic biological treatment module 7 for aerobic fertilizer production; the biogas outlet of the anaerobic biological treatment module 2 is connected to the biogas power generation module 3, and the generated electricity is connected to the photovoltaic power generation module. 4. The generated electric energy is sent to the electricity storage and power supply module 5 for temporary storage and energy supply; the waste heat generated in the power generation process of the biogas power generation module 3 is supplied to the pretreatment feed module 1 and the anaerobic biological treatment module 2 for warming and biogas residue. The drying and aerobic biological treatment module 7 are rapidly warming up in the initial stage. The microbial control module 8 is connected to the anaerobic biological treatment module 2 and the aerobic biological treatment module 7, and actively adds microbial inoculants to the anaerobic fermentation and aerobic biological treatment and fertilizer production links respectively, and controls the anaerobic and aerobic biological treatment. residence time. The intelligent control module 9 is used to command, detect and regulate the state and operation of the entire system.

Referring to Fig. 2 to Fig. 3, as an optional embodiment, in some embodiments, the pretreatment feeding module 1 includes a conveying device 1.1 and a pretreatment feeding device 1.2; the anaerobic biological treatment module 2 includes an anaerobic biological treatment module 2. Reactor 2.1, stirring equipment 2.2 and first biogas pipe 2.3, biogas power generation module 3 includes biogas purification equipment 3.1, second biogas pipe 3.2 and biogas power generation equipment 3.3, wherein, conveying equipment 1.1 sends organic waste biomass to pretreatment Feeding equipment 1.2 conducts preliminary treatment, the preliminarily treated organic waste biomass is fermented in the anaerobic reactor 2.1, and the stirring device 2.2 is used to agitate the organic waste biomass in the anaerobic reactor 2.1, and the fermented biogas passes through the anaerobic reactor 2.1. A biogas pipe 2.3 enters the biogas purification equipment 3.1 after dehydration and desulfurization, and is transported to the biogas power generation equipment 3.3 through the second biogas pipe 3.2 for power generation.

The photovoltaic power generation module 4 has a foldable and unfolded solar collector plate; the solid-liquid separation module 6 includes a discharge device 6.1 and a solid-liquid separator 6.2, and the biogas residue and biogas liquid of the anaerobic reactor 2.1 are discharged to the discharge device 6.1 through the discharge device 6.1. Solid-liquid separator 6.2 and carry out separation.

Referring to FIG. 4 , FIG. 4 shows the overall 3D view of the organic waste biological treatment system on the vehicle 11 , as an optional implementation manner, in some embodiments, the various modules of the system are arranged in the skid-mounted box 10 , the skid-mounted box 10 is set on the car 11 .

In order to better understand the present invention, the system operation process in the specific embodiment is described below.

The pretreatment feeding module 1 is mainly responsible for the pretreatment and feeding of raw materials: the crop straw is taken into the system of the present invention by the conveying equipment 1.1 of the pretreatment feeding module 1, and sent to the pretreatment feeding equipment 1.2 for cutting and crushing. After being crushed to a particle size of ≤ 10 mm, the pretreatment feeding equipment 1.2 feeds it into the anaerobic reactor 2.1 of the anaerobic biological treatment module 2, which is a dry anaerobic fermentation reactor (DA) in this embodiment.

The anaerobic biological treatment module 2 is mainly responsible for the production of biogas by anaerobic fermentation: the pretreated organic waste enters the anaerobic reactor 2.1, and generates biogas (mainly composed of CH ₄ and CO ₂ ) under the action of anaerobic bacteria. The temperature of anaerobic fermentation is 20~56℃, and the pH is 6.5~7.8. During the fermentation process, the stirring equipment 2.2 will intermittently stir the feed liquid in the anaerobic reactor 2.1 to promote the contact and mass transfer between the substrate and the microorganisms. heat transfer.

The solid-liquid separation module 6 is mainly responsible for solid-liquid separation: the fermentation feed liquid in the anaerobic reactor 2.1 is extracted from the discharge equipment 6.1 at regular intervals, and sent to the solid-liquid separator 6.2 of the solid-liquid separation module 6, where the solid-liquid separation The treatment of machine 6.2 is divided into biogas residue and biogas slurry. The biogas slurry is returned to the pretreatment feeding equipment 1.2 and the anaerobic reactor 2.1, which are used for raw material sizing and microbial inoculation. The sizing concentration is TS 6%~40%. For example, the anaerobic fermentation process is dry fermentation, and the slurry concentration is TS≥15%.

The aerobic biological treatment module 7 is mainly responsible for aerobic biological treatment and fertilizer production: the biogas residue separated by the solid-liquid separator 6.2 enters the aerobic biological treatment module 7, and by adding aerobic microorganisms and adjusting parameters such as water content and porosity, and Processes such as aeration and pile turning are used to make organic fertilizers with moisture content ≤30%, organic matter TS% ≥45%, and pH 5.5-8.5.

Microbial regulation module 8 is mainly responsible for microbial regulation: in microbial regulation module 8, anaerobic methanogens with high enrichment and high activity and aerobic bacteria for promoting nitrogen and maintaining nitrogen are respectively cultivated. According to anaerobic biological treatment module 2 and aerobic biological treatment The operation of module 7 is actively added and injected with microbial inoculants to improve the efficiency of anaerobic and aerobic biological treatment, and to improve fermentation efficiency and product quality.

The biogas power generation module 3 , the biogas power generation module 3 and the electricity storage and power supply module 5 are jointly responsible for generating, storing and supplying electricity: the energy converted by the system of the present invention is electric energy, which comes from the biogas power generation module 3 and the photovoltaic power generation module 4 . The biogas produced by the anaerobic reactor 2.1 is passed through the first biogas pipe 2.3 to the biogas purification equipment 3.1 of the biogas power generation module 3 for dehydration, desulfurization and purification, and the purified biogas is passed through the second biogas pipe 3.2 to the biogas power generation equipment 3.3 for power generation; photovoltaic The power generation module 4 is integrated on both sides and the top of the skid-mounted box 10 in this embodiment, and is in a folded state during the non-operation period of the system (see the solar collector (folding) 4.1), and is in an unfolded state during the system operation (see the solar collector Panel (expanded) 4.2), the solar energy is converted into electric energy through the solar heat collector plate, which is connected in parallel with the biogas power generation module 3, and the generated electric energy is temporarily stored in the electricity storage and power supply module 5 to form the energy supply source of the whole system; the electricity storage and power supply module 5 The electric energy of biogas power generation and photovoltaic power generation is temporarily stored, and is respectively supplied to the electrical equipment and external power supply of the system of the present invention, and the temporary power supply demand of local residents outside the system is met to form a portable power supply.

The present invention makes full use of the waste heat. Specifically, the biogas power generation equipment 3.3 and the aerobic biological treatment module 7 of the biogas power generation module 3 of the system of the present invention generate heat during operation, and the heat is collected by the heat exchanger and used for pretreatment into Feed equipment 1.2, temperature increase of anaerobic reactor 2.1 and solid-liquid separator 6.2 drying of solid-liquid separation biogas residue and rapid heating of the initial stage of aerobic biological treatment module 7.

The intelligent control module 9 is mainly responsible for the intelligent control of the system: based on the Internet of Things + and navigation, the intelligent control module 9 automatically plans the processing route and time of the scattered organic waste in the system, and displays the biological treatment module through technologies such as sensors and digital signal transmission. , status and data of power generation, storage, power supply and other modules, and make early warning and operation adjustment instructions according to digital model operations, and intelligently control the stable operation of each module.

The modules and equipment of the system are integrated in the skid-mounted box 10 , which is set on the car 11 , and is driven by the car 11 to the organic waste disposal site for harmless and resource-based treatment.

By applying the skid-mounted zero-energy-consumption organic waste biological treatment and mobile power system of this embodiment, and operating according to the above process, the automatic disposal and resource utilization of organic solid waste generated by small-scale decentralized urban and rural areas, markets, and enterprises can be realized, Obtain clean energy and resources while eliminating environmental pollution.

Meanwhile, the present invention also provides a process for biological treatment of organic wastes, which utilizes the above-mentioned biological treatment system for organic wastes, which comprises the following steps:

Remove impurities, crush, pulverize, and de-sand the organic waste biomass, and crush it to a particle size of ≤10mm;

Biogas is generated under the action of anaerobic bacteria, and the temperature of anaerobic fermentation is controlled to be 20 to 56°C and the pH to be 6.5 to 7.8;

The residue of anaerobic fermentation is separated into biogas residue and biogas slurry, and the biogas slurry is recycled and reused. The biogas residue is made into a water content of ≤30%, an organic matter TS% of ≥45%, and a pH of 5.5 to 8.5 by adjusting the moisture content and porosity. of organic fertilizers.

Further, highly active anaerobic methanogens are used in the process of producing biogas by anaerobic fermentation, and rot-promoting and nitrogen-retaining aerobic bacteria are used in the fertilizer making process.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and the purpose thereof is to enable those of ordinary skill in the art to understand the content of the present invention and implement them accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the essence of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A biological treatment system for organic waste, comprising:

the pretreatment feeding module is used for carrying out primary treatment on the organic waste biological material;

the anaerobic biological treatment module is used for receiving the organic waste biological material subjected to primary treatment from the pretreatment feeding module and preparing methane by utilizing anaerobic biological fermentation in the organic waste biological material;

the solid-liquid separation module is used for separating the fermented residues into biogas residues and biogas slurry, wherein the biogas slurry flows back to the pretreatment feeding module and the anaerobic biological treatment module;

the aerobic biological treatment module is used for treating the biogas residues into organic fertilizers; and the number of the first and second groups,

and the methane power generation module is used for generating power by utilizing the methane and supplying the power to each module of the system.

2. The organic waste biological treatment system of claim 1, further comprising: the system comprises a photovoltaic power generation module and an electricity storage and supply module, wherein the photovoltaic power generation module is used for generating electricity by utilizing solar energy and supplying electricity to each module of the system, and the electricity storage and supply module is respectively connected with the photovoltaic power generation module and the methane power generation module and is used for storing electric energy generated by the photovoltaic power generation module and the methane power generation module so as to supply electricity to each module of the system.

3. The organic waste biological treatment system of claim 1, further comprising: the microorganism regulation and control module is respectively connected with the anaerobic organism treatment module and the aerobic organism treatment module and is used for feeding anaerobic bacteria and aerobic bacteria into the anaerobic organism treatment module and the aerobic organism treatment module.

4. The organic waste biological treatment system of claim 1, further comprising: and the intelligent control module is used for being in communication connection with each module of the system and used for monitoring and controlling the state of each module of the system.

5. The organic waste biological treatment system of claim 2, wherein heat generated in operation of the biogas power generation module and the aerobic biological treatment module is supplied to the pretreatment feed module, the anaerobic biological treatment module, the solid-liquid separation module, and the aerobic biological treatment module.

6. The organic waste biological treatment system of claim 1, wherein the pretreatment feed module comprises a conveyor apparatus and a pretreatment feed apparatus; the anaerobic biological treatment module comprises an anaerobic reactor, a stirring device and a first biogas pipe, the biogas power generation module comprises a biogas purification device, a second biogas pipe and a biogas power generation device, wherein the conveying device conveys organic waste raw materials to the pretreatment feeding device for preliminary treatment, the organic waste raw materials subjected to preliminary treatment are fermented in the anaerobic reactor, the stirring device is used for stirring the organic waste raw materials in the anaerobic reactor, and fermented biogas enters the biogas purification device through the first biogas pipe, is dehydrated and desulfurized and then is conveyed to the biogas power generation device through the second biogas pipe for power generation.

7. The organic waste biological treatment system of claim 6, wherein the photovoltaic power generation module has a solar collector panel that can fold and unfold; the solid-liquid separation module comprises a discharge device and a solid-liquid separator, and biogas residues and biogas slurry of the anaerobic reactor are discharged to the solid-liquid separator through the discharge device and separated.

8. The organic waste biological treatment system of claim 1, wherein the individual modules of the system are disposed within a skid case disposed on a vehicle.

9. A biological treatment process for organic waste using the biological treatment system for organic waste according to any one of claims 1 to 8, comprising:

removing impurities from the organic waste raw material, crushing, and removing sand until the particle size is less than or equal to 10 mm;

generating biogas under the action of anaerobic bacteria, controlling the temperature of anaerobic fermentation to be 20-56 ℃ and the pH value to be 6.5-7.8;

and separating residues of anaerobic fermentation into biogas residues and biogas slurry, refluxing the biogas slurry for reuse, and adjusting the water content and the porosity of the biogas residues to prepare an organic fertilizer with the water content of less than or equal to 30%, the TS% of organic matters of more than or equal to 45% and the pH of 5.5-8.5.

10. The biological treatment process for organic waste according to claim 1, wherein high-activity anaerobic methanogens are used in the process of producing biogas by anaerobic fermentation, and decay-promoting nitrogen-retaining aerobic bacteria are used in the process of producing fertilizer.

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