KR20090130276A - Anaerobic digestion system - Google Patents

Abstract

PURPOSE: An anaerobic digestion tank optimizing system is provided to optimize an anaerobic digestion apparatus and a device thereof, and to solve problems according to anaerobic digestion of mixing sludge. CONSTITUTION: An anaerobic digestion tank optimizing system includes a first sludge digestion tank(11), a second sludge digestion tank(1), a solubilization device(2), a struvite generation and separation system(3), and a heat exchanger(4). Each sludge is sprayed through an injection nozzle(101,111) installed at each digestion tank. The sludge is solubilized in the solubilization device for efficient digestion of sludge and separation of struvite. The generated struvite is send to a struvite reservoir(5).

Description

Anaerobic digestion system

The present invention is a technique for optimizing the anaerobic digestion process, the system features of the present invention is to homogenize the sludge through the internal circulation and solubilization of the sludge through the external circulation, homogeneous temperature rise through the external circulation heating in the digester, struvite It is to improve the extinguishing efficiency by accelerating the production and recovery of sewage, and in terms of operational technology, it is to apply the appropriate number of days of digestion and extinguishing system to each sludge by operating individual digesters for different sludges.

Conventional technology is a waste water sludge digestion system (PM: 10-0485639-0000) of PMC Korea, by supplying the sludge of the waste water, waste water to a plurality of digesters to agitate the upper and lower stirring blades to digest the sludge The 1st stage digester which generates and gas is formed on the output shaft with the down stir blade and outward stir blade, and the vortex control panel composed of a plurality of vertical vortex control panels with the stirring blade outer black to improve the extinguishing efficiency due to the increase of the stirring efficiency and circulate with the external heat exchanger. The two-stage digester for supplying the gas produced by stirring and supplying the gas generated by stirring to the recycling burner and storing the surplus gas forms a double top and bottom membrane at the top to form an air chamber and the outside of the upper membrane. The wire is installed in the forward direction to control the expansion of more than a certain size, and the stirred sludge in the first stage digester The wastewater sludge extinguishing system is characterized by discharging through the dehydrator and discharging the primary digestion sludge with dehydration according to the supply amount of the sludge. to be.

Organic waste treatment method using Sangwon E & C's mixed single-phase anaerobic digestion system, which is characterized by crushing before inputting the mixed organic waste into the digester, adding chemical for deodorization, and producing dry compost by using the generated digestive gas (Patent No. : 10-0374485-0000) is a pre-treatment step of crushing mixed organic wastes with a crusher and transferring them to a screw-type sorter and a cyclone separator to separate the contaminants, and hydrolyzing by chemicals to remove odors and hydrogen sulfide which are corrosive substances. The hydrolysis step of the process, the step of raising the temperature to 35-42 ℃ through a heat exchanger to maintain the temperature, the produced methane gas is supplied to the fuel, the sludge dehydrated to dry and produce a compost Severe temperature charges other than Song Young Chae, characterized by the parallel connection of patents and mesophilic and high temperature fire extinguishing Kolon Engineering Co., Ltd. developed an anaerobic digestion method of organic wastewater and wastes by a temperature-cooling process in which a high temperature anaerobic digester was internally connected to a sexual digestion (Patent No .: 10-0588166-0000), and a method of filling a digester with a hydrophilic fluidized bed microbial carrier. A high rate anaerobic digestion tank filled with a hydrophilic fluidized bed microbial carrier of Korea Co., Ltd. No. 10-0122768-0000).

      As described above, the conventional techniques have been applied such as agitation method of digester, incorporation of low temperature and high temperature digestion, incorporation of microorganism carriers, application of pressure pump for cell membrane destruction, but it is difficult to apply universally to fundamental properties of sludge. There is this.

In addition, a method and apparatus for color treatment of manure, other than the Doosan Human Resource Development Institute, and its apparatus (Patent No .: 10-0118204-0000), an apparatus and a method for pretreatment of landfill gas purification and leachate, and others (Patent No .: 10-19980061686) It is a technology that is difficult to put into practical use in view of the characteristics of sludge in actual sites such as targeting specific sludge.

In general, the solubilization technology that is commercialized is excellent in efficiency, but there is no fundamental solution to the clogging phenomenon of the pipe due to the struvite caused by phosphoric acid, which is excessively concentrated in the surplus sludge that is generated. It is an incomplete technique that causes bigger problems in the operation of sewage treatment plants by clogging of sludge pipe after solubilization.

Therefore, the inventor of the present invention, as a result of research efforts to solve the above problems, the present invention as a method for improving the treatment efficiency by having a system suitable for each sludge based on the separate fire extinguishing method to enable the appropriate operation for the individual sludge. Was completed.

Accordingly, an object of the present invention is to provide an apparatus and an application method for optimizing the system and the problems caused by anaerobic digestion of mixed sludge which is a conventional treatment method as described above.

The present invention is to reduce the extinguishing efficiency caused by the mixed sludge treatment by digesting the excess sludge and fresh sludge and short digestion days in the raw sludge extinguishing process in the current technology that is closed to the struvite in the entire pipe Maximizing the throughput of the log and extinguishing the excess sludge in the process of extinguishing the longest extinguishing efficiency to achieve maximum extinguishing efficiency, and also characterized by water content reduction by eliminating the struvite scale. In addition, the present invention is to the sludge is sprayed in a circular manner from the bottom to solve the problem of reducing the capacity of the digester by the lower sludge precipitation in the digester.

Through the present invention, it is possible to reduce waste generation and discharge water quality by improving digestion efficiency and thermal efficiency in the existing anaerobic digestion process and solving the waste air problem by eliminating the by-product struvite, reducing sludge and reintroducing the phosphorus process by the return water. Improvements will reduce the cost of treating environmental pollution.

The present invention can be divided into operation method and facility system as follows.

The first operation method is composed of organic materials that are low in organic components but easy to biodegrade in primary fresh sludge, and have high overall density due to soil components in sewage, etc., and decomposition rate in secondary surplus sludge. It is composed of very slow aerobic microorganism, metabolite EPS (Extra-cellular polymeric substance) and microbial carcass, which makes it difficult to anaerobic digestion, and has high aerobic content such as food, manure and leachate waste liquid It is characterized by extinguishing each sludge separately by supplying other sludge which is very fast to each digester.

The reason for the separate digestion is about 15 days for the first digestion of sludge, about 10 days for other sludges such as food, and about 30 days for the second sludge, so that each sludge is mixed to anaerobic digestion. When applying the process, there is a problem that certain sludges are first decomposed according to the selectivity of anaerobic microorganisms, so that other sludges are not decomposed. In order to decompose all sludges, anaerobic microorganisms of each dominant species must be circulated and cultured. There is a drawback to more than 40 days. However, when digesting them individually, dominant species suitable for the characteristics of each sludge grow in each digester, and only the microorganisms that meet specific sludge do not grow mutually by anaerobic microorganisms. It is a possible technique, and the product after decomposition of each individual sludge is also different, so the technical invention for optimizing the post-stage process is the first. It is possible to maximize digestion efficiency and increase throughput of raw sludge through separate digestion, and to operate efficient anaerobic digestion process without problems of struvite production, and to manage mixed sludge through digestion of surplus sludge. Improved efficiency of downstream sludge dewatering process by solving the problem of lowering dehydration efficiency, increasing the amount of digestion gas generated by increasing the extinguishing efficiency, and applying the efficient and economical struvite generation and separation process. Water pollution problem can be solved.

The primary sludge is the biggest problem when the digester volume decreases due to soil components, and in the case of the secondary sludge, the decomposed products are ammonia (NH ₃ ), phosphoric acid (PO ₄ ) and metal ions (Mg, etc.). The waste gas problem in the sludge conveying pipe is the biggest problem due to the generation of the true bite.In the case of other sludges, there is a big difference in the proper treatment method for individual sludges such as low pH and high conductivity for food, and high TN and TP concentration for manure. If you do, there is a problem that must be installed in each digester complement the installation for all problems that may occur in the total sludge.

Generally, the concentration of ammonia, phosphorus, alkalinity, Ca and Mg in the primary sludge of the primary sedimentation tank is very high but the pH is low to suppress the generation of struvite, and the organic matter in the sludge is less than 65%. Its high natural sedimentation properties allow good sedimentation efficiency in the primary sedimentation tank, and soil minerals in the sludge precipitate in the sewage tanks, thus reducing the effective digester capacity. The technology of the present patent is a way to spray the sludge from the bottom to the bottom can be solved by the supply method to solve the lower sludge sedimentation in the digester.

Therefore, since the production of the strut bite and the solubilization system are not necessary for the digestion of the primary sludge, it is possible to reduce the initial installation cost, achieve high efficiency, and efficiently manage the facility when operating the digester for each sludge. It is an operational feature.

Unlike the sludge mixing method, which is a fire extinguishing method, it is possible to separate and digest the primary sludge (hereinafter referred to as primary sludge) of the first initial sedimentation tank and the surplus sludge (hereinafter referred to as secondary sludge) of the activated sludge generated in the secondary sedimentation tank or the final sedimentation tank. It features.

In FIG. 1, the sludge is separated and introduced into the primary sludge digester 11 and the secondary sludge digester 1, and each sludge is injected from the lower part through the injection nozzles 101 and 111 installed in the lower part of each digester. .

Secondary sludge, which is excess sludge, is made from the solubilization device 2 for sludge solubilization for the efficient digestion of the sludge and separation of the struvite generated during external circulation. In the struvite generation and separation system (3), dismantling and generation of struvite are continuously performed through high-speed stirring, and both externally circulated sludge and initial inflow sludge are continuously homogenized through the heat exchanger through the heat exchange device (4). One warming is done.

At this time, the generated struvite is continuously circulated and grown in the digester, separated from the external circulation system, and sent to the struvite storage tank 5.

As such, the external circulation of the secondary sludge consists of a digester (1)-solubilizer (2)-struvite generation and separation system (3)-heat exchanger (4).

Further, the biogas degassing inside the sludge is promoted through the internal circulation 6 of the injection method.

The dewatered sludge is transferred to the storage tank 7.

Fresh sludge primary sludge does not require a solubilizer and a struvite generation and separation system as described above, so only the heat exchanger 14 is needed.

In general, the digestive system has a characteristic of heterogeneous digestion according to the digester status by mixing and digesting primary and secondary sludges with different characteristics, but the patented technology causes predominance of each sludge of anaerobic microorganisms through a separate digestion method for each sludge. It is characterized by minimizing the reduction of extinguishing efficiency due to sludge fluctuation.

In addition, the conventional sludge input method is introduced into the upper part, and the soil component of the high specific gravity in the digester is deposited at the lower part, which causes the digester volume to be reduced. May cause stirring effects through a homogeneous circulation in the interior.

In addition, in order to improve the concentration reduction and heterogeneous temperature gradient in the digester, which is a problem of the direct heating method, the extinguishing efficiency due to the homogeneous temperature rising effect through the sludge dissolving through the high speed stirring in the external circulation system and the heat exchange in the circulation system. It is composed of a device that can improve the waste pores of the sludge pipe due to the struvite can be generated during the digestion process.

In the case of secondary sludge in the secondary sedimentation tank, the concentration of Ca, Mg and K is high, but the production is suppressed in the same way due to the low ammonia, phosphorus and pH. However, after the digestion process, the nitrogen component is changed to ammonia form, so that the pH is increased, and as the microorganisms are decomposed in the secondary sludge, struvite is formed as the phosphoric acid, which is over-concentrated in the microorganisms, is discharged. In general, there are many technical developments and patents for generating struvite to remove nitrogen and recover phosphorus, but in the part of actual operation, problems due to the vacancy of the pipelines cause problems of separation or suppression after generation. It is a more important technical factor.

Struvite is a salt having the formula NH ₄ MgPO ₄ · 6H ₂ O or Struvite- (K) [KMgPO ₄ · 6H ₂ O], which is usually in the form of high dissolved dissolved orthophosphates, free or salt ammonia (NH ₄₎ and magnesium (Mg) can be generated in the region of the pump, a valve, such as during and fitting the pipe of a material that occurs after an anaerobic digestion step of the co-existence, and the main factor of the generation is NH _4, Mg and chemically condition The concentration of PO ₄ -P, rapid turbulence, pressure change, strong rotational force such as centrifugal force, and other pHs are caused by physical conditions, and the produced struvite has very low solubility in water and various derivatives. As a result of the high nitrogen and phosphorus in the recovery, it can be used as a fertilizer or precipitate in the pipeline as shown in the picture below, which is a big problem in the operation of the treatment plant.

2 is a photograph of a state in which a pipe is closed by Struvite.

The patented technology degass the supersaturated carbon dioxide in the digester-producing gas due to the pressure drop in the recycling system, thereby increasing the pH in the digestion sludge to facilitate the production of struvite, and the struvite can be formed through multi-speed agitation. By minimizing the resistance of the diaphragm present to form a struvite in the circulation system to maximize the waste phenomena caused by the strutbite in the pipe after the fire extinguishing process.

In addition, the efficiency of anaerobic digestion process is maximized through the solubilization of sludge through the circulation system, and the struvite generated at this time is systematically separated and removed from the lower circulation to remove the struvite from the bottom, thereby improving digestion efficiency and The simultaneous removal of phosphorus is characterized in that it is possible to solve the clogging phenomenon such as sludge pipe and desorption pipe.

In the heating for anaerobic digestion, the heating should be warmed to 35 ℃ for medium temperature digestion and 55 ℃ for high temperature digestion, but in this case partial warming, partial killing of microorganisms and sludge dilution by steam In order to solve the problem of heat loss and heat transfer to the inside, which is a problem of the method of sending hot water to the jacket and the method of sending steam, the heat is uniformly transferred to the sludge in the entire digester through an external heat exchange system. When sludge is introduced into the digester on the basis of low temperature, the sludge is introduced at low temperature and the temperature of the inlet is lowered, resulting in a problem that the temperature of the entire digester becomes uneven, so the sludge is heated through the heat exchange system from the inflow stage. While the sludge is not introduced, the internal circulation sheath The system is characterized in that the sludge is continuously heated and circulated through the heat exchange system.

By heating the inflow sludge, it solves the problem of deactivation of anaerobic microorganism caused by the low sludge introduced into the digester, and by heating the circulating sludge when the sludge is not introduced, the limited application of heat loss and heating medium to the whole sludge by heating Any type of heat medium (steam, heat medium or hot water) is possible.

The purpose of the continuous heating and circulation was invented to prevent the degradation of digester efficiency due to the problem of sedimentation of soil components in the lower specific gravity in the digester and the problem of digester temperature unevenness due to intermittent and irregular sludge inflow.

Therefore, the present patent system can solve the problems of the existing fire extinguishing process as follows.

Old way problem This patent technology Sludge mixture (primary, secondary, food, etc.) Due to the heterogeneous digestion of individual sludges, it is inhomogeneously degraded to reduce the extinguishing efficiency and treatment efficiency due to the sludge change during the subsequent dehydration process. Separate digestion by individual sludge enables maximum installation cost and treatment efficiency by operating according to each sludge and necessary system configuration Simple solubilization Dissolved T-P increases due to secondary sludge solubilization, resulting in the formation of struvite, resulting in the closure of sludge pipes Integrated system that solves the additional problem of solubilization by equipping with solubilization + strubit generation and separation system Digester volume reduction Sludge is supplied from the upper part and homogenized through stirring, but the volume is reduced by precipitation of the lower specific gravity soil component without actual homogenization. Sewage sludge injection method enables stable treatment by homogeneous concentration distribution and externalization through homogenization without volume reduction in digester Degassing system As there is no separate degassing system, problems such as flotation and pH rise due to residual biogas It facilitates the degassing of the biogas in the sludge through the internal circulation and injection method in the digester. External circulation heat exchange system Direct and indirect heating method of digester As inflow sludge is heated in indirect heating method, stable operation is possible without temperature change after inflow of digester.

1 is a schematic diagram of an anaerobic digester optimization system of the present invention.

Figure 2 is a photograph showing the pore state in the pipe by the struvite.

           * Description of the symbols for the main parts of the drawings *

1,11: digester

2: solubilizer

3: struvite generation and separation system

4,14: heat exchanger

5: struvite reservoir

6: internal circulation

7,17: sludge storage tank

Claims (3)

The digester 11 for primary sludge (fresh sludge) and the digester 1 for secondary sludge (surplus sludge) are separated and digested, and a solubilizing device (2) is provided in the digester (1) for secondary sludge (surplus sludge). And anaerobic digestion system, characterized in that the struvite generation and separation system (3) is installed. The anaerobic digestion system according to claim 1, wherein a sludge injection device (101.111) is installed under the digester (1, 11). The anaerobic digestion system according to claim 1, wherein the sludge is warmed through a heat exchanger (4, 14) in an external circulation.

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