KR102139744B1 - An anaerobic sewage treatment apparatus comprising a dissolved methane recovery apparatus and anaerobic sewage treatment method - Google Patents

Abstract

In the present invention, there is no method for reducing the adverse effects of dissolved methane contained in the anaerobic reactor treatment water on global warming, explosiveness, energy balance, etc., and to solve this, a process using a biological approach and a physical approach are used. Disclosed is a dissolved methane treatment or recovery type apparatus using the used processes as a post-process of an anaerobic reactor, and sedimenting and removing solids contained in wastewater (step 1); Decomposing organic matter contained in the wastewater that has passed through step 1 into methane and carbon dioxide using anaerobic microorganisms (step 2); Recovering the dissolved methane contained in the treated water after step 2 (step 3); Includes.

Description

An anaerobic sewage treatment apparatus comprising a dissolved methane recovery apparatus and anaerobic sewage treatment method}

The present invention relates to an anaerobic sewage treatment device and an anaerobic sewage treatment method comprising a dissolved methane recovery device.

As wastewater treatment methods, an aerobic process and an anaerobic process are known. It is common to use an aerobic process called the standard activated sludge method for the treatment of municipal sewage and low-concentration wastewater. The standard activated sludge method provides a primary sedimentation basin-aerobic tank and secondary sedimentation basin, sedimentation of soil or other large floating matters affecting the pump operation in the primary sedimentation basin, and microorganisms in the aerobic tank feed organic matter in the wastewater. After decomposition or adsorption through respiration and growth, activated sludge maintained and increased in this process is precipitated in a secondary sedimentation basin by a difference in specific gravity to separate solid and liquid.

A general aerobic treatment apparatus for wastewater has a disadvantage in that it requires not only the facility cost of a blower and an air diffuser used for blowing of the aerobic reactor to supply oxygen into the aerobic reactor, but also the amount of power consumption required to operate the blower. In the case of Korea, it is known that about 40% of the total power consumption of the sewage treatment plant is consumed for ventilation.

In addition, since the general aerobic treatment device for wastewater as described above must basically be equipped with a primary sedimentation tank, an aerobic reaction tank, a secondary sedimentation tank, and a sludge transfer facility, it is economical in terms of securing an installation site, construction cost, and maintenance cost. Not only is it not high, but there is a disadvantage that there is a high risk of adversely affecting the lives of local residents due to odors emitted along with a large amount of air used in the aerobic reactor.

On the other hand, a wastewater treatment device that treats wastewater using an anaerobic process converts organic matter contained in wastewater into biogas, which is renewable energy, generates a relatively small amount of excess sludge, and does not require an aeration device required in an aerobic method. As a result, the energy saving effect is great, and the possibility of discharge of odorous substances is low because the reaction tank is sealed. In addition, since the amount of pollutant load that can be treated is high, a reaction device having a small volume can be used, and since a small amount of excess sludge is generated, the secondary sedimentation tank may be small or not, so that the site area is small.

The anaerobic process having the above advantages has not been used for urban sewage and low-concentration wastewater treatment until recently, due to the false stereotype that treatment efficiency is lower than that of aerobic process and requires a long residence time due to a slow treatment speed. It is used only for high-concentration wastewater.

Korean Patent Registration No. 10-1587764

In the anaerobic process, organic matter is converted into methane (CH ₄ ) and carbon dioxide (CO ₂ ) by absolute anaerobic bacteria (methanogen) through hydrolysis and acid fermentation. In anaerobic processes, gaseous methane exists in the effluent water in a dissolved state according to Henry's Law, and if low-concentration wastewater is treated with a short residence time, the gas generated from the solution cannot be sufficiently separated and the effluent is in an oversaturation state. Is discharged with Dissolved methane contained in the runoff water escapes into the atmosphere to achieve equilibrium when it comes into contact with air. Methane is a greenhouse gas that has a global warming potential (GWP) that is 28 to 36 times higher than that of carbon dioxide, which adversely affects global warming. Crazy. In addition, methane gas is a very explosive gas (Lower explosive limit, LEL = 5.0%), and may cause safety problems when gas is trapped in the outlet pipe.

In particular, in the case of an anaerobic process that treats low-concentration wastewater, 40% to 60% of the generated methane is discharged in the form of dissolved methane, so the recovery process is important in terms of energy independence in order to improve energy recovery efficiency.

An object of the present invention is to provide an anaerobic sewage treatment apparatus and an anaerobic sewage treatment method capable of solving the above problems.

Anaerobic sewage treatment apparatus and anaerobic sewage treatment method according to an embodiment of the present invention comprises the steps of sedimenting and removing solids contained in wastewater (step 1); Decomposing organic matter contained in the wastewater that has passed through step 1 into methane and carbon dioxide using anaerobic microorganisms (step 2); Recovering the dissolved methane contained in the treated water after step 2 (step 3); It includes an anaerobic sewage treatment method comprising a.

In addition, a settling tank for sedimenting and removing solids contained in wastewater; An anaerobic reactor for decomposing organic matter contained in wastewater discharged from the sedimentation tank into methane and carbon dioxide using anaerobic microorganisms; A dissolved methane recovery tank for recovering dissolved methane contained in the treated water of the anaerobic reaction tank; It includes an anaerobic sewage treatment device comprising a.

The anaerobic sewage treatment apparatus and the anaerobic sewage treatment method according to an embodiment of the present invention can reduce the adverse effects of the dissolved methane contained in the anaerobic reactor treated water on global warming through the dissolved methane treatment used as a post-process of the anaerobic reactor, and explosive, The influence on the energy balance and the like can be reduced.

In addition, it is possible to increase the energy recovery efficiency of generating methane gas, which is renewable energy from organic matter, and the generated methane gas is a heat source in the nearby area after heating and congestion of the anaerobic reaction tank and digester using power generation and waste heat using a cogeneration generator. As it can be used for supply and automobile fuel, it is possible to reduce the operating cost of the sewage treatment plant. In addition, it is possible to implement a sewage treatment plant that can sell energy.

1 is a schematic diagram of an anaerobic sewage treatment apparatus according to an embodiment of the present invention.
2 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.
3 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.
4 is an anaerobic sewage treatment apparatus according to another embodiment of the present invention.
5 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.
6 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided in order to more completely explain the present invention to those with average knowledge in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for a clearer description, and elements indicated by the same reference numerals in the drawings are the same elements. In addition, the same reference numerals are used throughout the drawings for portions having similar functions and functions. In addition, "including" a component throughout the specification means that other components may be further included, rather than excluding other components, unless otherwise specified.

Anaerobic sewage treatment method

Hereinafter, an anaerobic sewage treatment apparatus and an anaerobic sewage treatment method will be described.

1 is a schematic diagram of an anaerobic sewage treatment apparatus according to an embodiment of the present invention.

An anaerobic sewage treatment apparatus and an anaerobic sewage treatment method according to an embodiment of the present invention includes the steps of sedimenting and removing solids contained in wastewater (step 1); Decomposing organic matter contained in the wastewater that has passed through step 1 into methane and carbon dioxide using anaerobic microorganisms (step 2); Recovering the dissolved methane contained in the treated water after step 2 (step 3); Includes.

As shown in Figure 1, the anaerobic sewage treatment apparatus according to an embodiment of the present invention includes a settling tank 100, an anaerobic reaction tank 200, and a dissolved methane recovery tank 300.

In the step of sedimenting and removing solids contained in wastewater (step 1), the wastewater may be high-concentration wastewater or urban sewage and low-concentration wastewater, and the present invention is not particularly limited thereto. In step 1, solids contained in wastewater may be precipitated and removed by using the settling tank 100.

The sedimentation tank 100 removes suspended solids (SS) in the incoming urban sewage and low-concentration wastewater, and biochemical oxygen demand (BOD) or chemical oxygen demand (COD) caused by suspended solids. By removing Oxygen Demand) together, it is possible to reduce the post-treatment process load and increase processing efficiency. The sedimentation tank 100 removes suspended solids by gravity precipitation through the initial sedimentation facility, and can perform functions such as reducing the load of the biological treatment process, reducing the facility capacity of the subsequent treatment facility, and stably reducing operating costs. have. In addition, the introduced municipal sewage and low-concentration wastewater may stay for several hours to precipitate fine particles in the sewage. In the sedimentation tank 100, floating matters floating on the surface may be removed using a scraper.

The sedimentation tank 100 as described above is divided into an inlet portion, a sedimentation portion, a sludge storage portion, and an outlet portion. The inflow portion disperses the power of the lower portion, and the sediment precipitates in the precipitation portion.

At this time, the precipitated precipitate is referred to as primary sludge, and is sent to the concentration tank 500 of the sludge treatment process to be described later and undergoes a sludge treatment process, and the sewage precipitated in the settling tank 100 is an anaerobic reaction tank 200 at the outlet portion. ) And can be processed through biological treatment.

Typically, in the sedimentation tank 100, while sewage stays for about 2 to 3 hours, about 30% of the normal biological oxygen demand is removed, and about 35% of suspended matter can be removed. Sedimentation efficiency depends on the shape of the sewage network, the generation period of sewage, and the degree of crushing before sedimentation. The sedimentation tank 100 may perform a function of appropriately discharging the accumulated sludge for water quality management in order to facilitate the function of the subsequent process.

The sedimentation tank 100 may use a mechanical solids separation device such as a coagulation sedimentation tank or centrifuge using a coagulant in order to increase the removal efficiency of suspended solids and reduce the load of the anaerobic reaction tank 200 that treats soluble substances. The invention is not particularly limited.

In Step 2, the organic matter contained in the wastewater that has passed through Step 1 is decomposed into methane and carbon dioxide using anaerobic microorganisms. Step 2 may be performed using the anaerobic reactor 200.

The anaerobic reaction tank 200 may serve to decompose and remove organic matter in the sewage into methane and carbon dioxide by using anaerobic microorganisms in the sewage treated in the precipitation tank 100.

As such an anaerobic reactor 200, ABR (Anaerobic Baffled Reactor), AFBR (Anaerobic Fluidized Bed Reactor), AF (Anaerobic Filter), UASB (Upflow Anaerobic Sludge Blanket), AnMBR (Anaerobic Membrane Bioreactor), CSTR (Continuously Stirred Tank Reactor) , Anaerobic Expanded Granular Sludge Blanket Reactor, Anaerobic Internal Circulation Bioreactor, ASBR (Anaerobic Sequencing Batch Reactor), AFMBR (Anaerobic Fluidized Membrane Bioreactor), etc. may be used, and also, a hybrid reactor of these may be used.

Among the various anaerobic reactors 200 mentioned above, the AFBR reactor is methane that maintains a high concentration of microorganisms in the reactor by forming a fluid bed biofilm using particulate matter having a large specific surface area such as sand, mud, and activated carbon with excellent sedimentation in the reactor. It is a fermentation reactor. As a result, anaerobic microorganisms maintain high activity and can treat not only high-concentration organic wastewater but also wastewater containing low-concentration organic matter in a short residence time, enabling economic operation, and in particular, can be stable against microbial impact load.

The AFBR reactor is generally in the form of a very simple reactor consisting of an inlet, a fluid bed bed, and a gas-fluid particle separation tank. Although it varies depending on the type of wastewater, operating conditions, and culture environment conditions, in general, microorganisms attached to a media of 0.2 to 0.8 mm in diameter are maintained at a high concentration of about 40 kg/㎥, and a rapid upward flow rate of 10 to 30 m/h This applies. In this apparatus, AFBR is mainly used for decomposition of organic matter present in the treated water, but can also be used for denitrification of nitrate nitrogen.

In the process of evenly distributing the treated water through the inlet and passing through the dense fluidized bed bed, organic matter is decomposed into methane and carbon dioxide gas through an acid fermentation process. At this time, the fluid particles attached to the generated gas rise and gas- It can be separated from the gas in the fluidized particle separation tank and circulated back to the fluidized bed bed. In order for AFBR to perform a denitrification function, ammonia nitrogen present in the treated water must undergo a nitrification process in a nitrogen/phosphorus removal device 800 to be described later, and then return to the AFBR to perform a denitrification process.

In the case of using the anaerobic reaction tank 200 as described above, since the amount of excess sludge generated is very small, a separate secondary precipitation tank may not be required. Even if a separate sedimentation tank is needed, the size of the sewage treatment plant construction site can be reduced because it can be configured much smaller than the secondary sedimentation tank of the existing sewage treatment system. In addition, the generated excess sludge may be directly dehydrated or transferred to a sludge digester 600 to be described later for methane generation to be treated.

The methane gas decomposed in the anaerobic reaction tank 200 may be sent to the dissolved methane recovery tank 300. In addition, it is used as fuel for the generator 700 to be described later, and the effluent water may be sent to a stripper 400 to be described later. In the conventional sewage treatment system using an aerobic reactor, a small amount of methane gas could be generated only in the sludge digester, but when the anaerobic reactor according to the present invention is used, a large amount of methane gas can be generated in the anaerobic reactor 200. In addition, the dissolved methane recovery tank 300 and the stripper 400 to be described later can additionally recover methane gas, and the sludge digester 600 can also recover the methane gas, thereby increasing the recovery rate of renewable energy.

The anaerobic microorganism may be an absolute anaerobic microorganism or a penetrating anaerobic microorganism, and the present invention is not particularly limited thereto.

As a method of treating wastewater containing various pollutants, the principle of processing by ingesting pollutants in wastewater as a nutrient source can be used by aquatic microorganisms. Microorganisms are largely classified into anaerobic and aerobic microorganisms according to the oxygen intake method. Aerobic microorganisms use dissolved oxygen in water as an oxidizing agent to oxidize organic matter to carbon dioxide, but anaerobic microorganisms do not use external oxidizing agents such as oxygen and cause a redox reaction on their own, and as a result, produce methane from organic matter.

In a general wastewater treatment apparatus, organic matter remaining in the effluent of the primary sedimentation tank is oxidized and treated using aerobic microorganisms, and then nitrogen and phosphorus are removed if necessary. However, since the general wastewater treatment apparatus as described above uses an aerobic process that requires a large amount of oxygen, there is a disadvantage in that the amount of power consumption required for the operation of the air diffuser and blower for supplying air into the reaction tank is large.

In the case of Korea, it is known that about 40% of the total power consumption of the sewage treatment plant is consumed to supply air. In addition, in the aerobic process, there is a problem that a large amount of excess sludge is generated, resulting in a high sludge treatment cost.

On the other hand, a wastewater treatment device that treats wastewater using an anaerobic process converts organic matter contained in wastewater into biogas, which is renewable energy, generates a relatively small amount of excess sludge, and does not require an aeration device required in an aerobic method. As a result, the energy saving effect is great, and the possibility of discharge of odorous substances is low because the reaction tank is sealed. In addition, since the amount of contaminant load that can be treated is high, a reaction device having a small volume can be used, and since a small amount of excess sludge is generated, the secondary sedimentation pond may be small or not, so that the site area is small.

The anaerobic process having the above advantages has not been used for urban sewage and low-concentration wastewater treatment until recently due to the false stereotype that the treatment efficiency is lower than that of the aerobic process and the treatment speed is slow and requires a long residence time. It is used only for high-concentration wastewater.

However, the anaerobic process according to an embodiment of the present invention can be applied very effectively to urban sewage and low-concentration wastewater treatment, and can be operated at a short residence time such as an aerobic process.

The step of recovering the dissolved methane contained in the treated water after step 2 (step 3) may be performed in the dissolved methane recovery tank 300.

Referring to FIG. 1, in the methane recovery process according to the present embodiment, methane dissolved in the effluent discharged from the anaerobic reactor 200 may be recovered in the dissolved methane recovery tank 300.

In anaerobic processes, gaseous methane exists as dissolved in the effluent according to Henry's Law, and if low-concentration wastewater is treated at a short residence time, the gas generated from the solution cannot be sufficiently separated and the effluent is in an oversaturation state. Can be discharged with. Dissolved methane contained in the runoff water escapes into the atmosphere to achieve equilibrium when it comes into contact with air. Methane is a greenhouse gas that has a global warming potential (GWP) that is 28 to 36 times higher than that of carbon dioxide, which adversely affects global warming. It can hurt.

In addition, methane gas is a very explosive gas (Lower explosive limit, LEL = 5.0%), and may cause safety problems if the gas is trapped in the outlet pipe.

In particular, in the case of an anaerobic process that treats low-concentration wastewater, 40% to 60% of the generated methane is discharged in the form of dissolved methane, so the recovery process is very important in terms of energy independence in order to improve energy recovery efficiency.

The method of recovering the dissolved methane in step 3 may be an anaerobic sewage treatment method by oxidizing and removing the dissolved methane using methanotroph.

Dissolved methane treatment systems may include biological treatment options and physical treatment options. For biological treatment, methane is oxidized and removed using methanotroph, methane is partially oxidized and then used as an electron donor for denitrification, and PHB (polyhydroxybutyrate) that accumulates in methanetrophs. It may include a plan to recover and utilize.

As a physical treatment method, an air stripping device which is a treatment method using a concentration gradient, a method using gas sweeping using a membrane, a vacuum degassing using a pressure gradient, and a vacuum degassing membrane are applied. I can.

Methanotrophs are bacteria that oxidize methane and obtain energy, and have been known only under aerobic conditions, but recently, microorganisms that obtain energy by oxidizing methane under anaerobic conditions have also been discovered.

Methanotroph of the present invention refers to a microorganism that can use methane as a carbon source and an energy source among methylotrophs, and by absorbing methane from outside the cells, CH ₃ OH, HCHO, HCOOH and CO By sequentially changing to ₂ , ATP can be obtained by completely oxidizing methane to carbon dioxide. Methanotrophs of the present invention are not particularly limited as long as they exhibit an effect of removing methane, but may be microorganisms of the genus Methylocystis, microorganisms of the genus Methylosarcina, and microorganisms of the genus Methylocaldum.

In another embodiment of the present invention, the method of recovering dissolved methane in step 3 is one of stripping, gas sweeping using a separator, a vacuum degassing method using a pressure gradient, and a method of using a vacuum degassing separator. It may be an anaerobic sewage treatment method.

In addition, when the method of recovering the dissolved methane in step 3 is a method of using a vacuum degassing membrane, the separation membrane may be a non-porous membrane.

Stripping separates and removes gas dissolved in a liquid, and can be directly contacted by heating, pressurization, and inhalation of water vapor, inert gas, and air. Volatile components in wastewater can be dissipated by aeration. In an embodiment of the present invention, dissolved methane may be recovered using an air stripping device.

When recovering dissolved methane, it is effective to use a separation membrane, and it is possible to recover up to 98.5%. Since gas selectivity is different depending on the material of the separation membrane, it can also be applied to increase the purity of methane, and the type of filtration and the quality of the anaerobic digestion treated water affect the recovery rate. In addition, the lower the pressure on the permeate side, the better the recovery rate, but there is no influence on the temperature. The recovered methane can produce 0.16kWh/m3 of electricity, which can cover all of the electricity required for the operation of the anaerobic membrane process and the recovery and purification of the methane generated therein.

The recovery of dissolved methane using a separation membrane is advantageous in that the cost is low and high concentration of methane can be produced with minimal upgrade. Separators used for the recovery of dissolved methane can be largely classified into non-porous and porous. Pore wetting occurs due to organic matter, which reduces the efficiency of the porous membrane, so the non-porous membrane is used for raw water with high organic matter such as UASB treated water, and the porous membrane may be suitable for raw water with good water quality such as AnMBR treated water. have. The shape of the separator may be a hollow fiber membrane capable of processing a large flow rate due to a large surface area of the separator per unit volume. There are two types of filtration of the hollow fiber membrane: lumen-side flow and shell-side flow. Lumen-side flow has the advantage of having a large treatment capacity, but is not suitable for raw water with a large amount of solids, and shell-side flow can be applied even when the solids concentration is high.

The material of the non-porous separator may be at least one of poly-dimethylsiloxane (PDMS), polyisoprene (PI), polyocte-namer (PO), and polyurethane (PU). Since the permeability of gas is different depending on the polymer and PDMS has higher permeability than other materials, it is very effective in recovering dissolved gas. Since carbon dioxide has a very high permeability compared to methane and can be easily removed through a separation membrane, it can be used to increase the purity of methane.

The diffusion of gas through the separation membrane may occur due to a pressure difference between the inlet side and the permeate side, and a pressure gradient on both sides may be formed by reducing the pressure on the permeate side to a sweep gas or vacuum.

If the recovery of dissolved methane by the separation membrane is not configured as a separate process, a circulation pipe is installed in the anaerobic tank, and a separation membrane capable of recovering dissolved methane is installed in this pipe to perform in situ degassing. As a result, it is possible to obtain a high methane concentration of about 94%, and the pH of the reaction tank may increase, thereby increasing the stability of the anaerobic digestion process. In addition, since dissolved hydrogen is removed, conditions suitable for the decomposition of intermediate products in the anaerobic digestion process such as alcohol or fatty acids are formed, so that the reaction takes place well, and the gas adsorbed on the microorganisms is dissolved, thereby improving the precipitation of microorganisms .

In the present embodiment, in the case of the degassing membrane, the membrane is a non-porous membrane, and when the anaerobic process of the front end includes the membrane and the effluent water is membrane permeate, a porous membrane may be applied.

In the anaerobic sewage treatment method according to another embodiment of the present invention, when the method of recovering dissolved methane in step 3 is a vacuum degassing method using a pressure gradient, and the discharged water discharged through step 2 is permeate to a separation membrane, The method of recovering dissolved methane in step 3 may include increasing a mass transfer rate by spraying the discharged water of step 2.

When the vacuum degassing method is applied to the water permeated to the separation membrane, the treated water does not contain particles, so the treatment time is increased by increasing the mass transfer rate by spraying the treated water with a nozzle in the vacuum degassing tank. You can shorten it. When the anaerobic process treated water is permeate to the separation membrane, the flow method of the separation membrane may be a lumen side or a shell side.

In the case of device configuration using a pressure gradient, a water trap is installed at the suction front of the vacuum pump that induces the pressure gradient to remove water vapor that flows with the gas, thereby maintaining the efficiency of the pump and maintaining the quality of the recovered gas. have.

In the anaerobic sewage treatment apparatus according to another embodiment of the present invention, after step 3, methane dissolved in the effluent discharged through step 3 is additionally recovered, the DO concentration of the effluent is increased, and the biological It may further include reducing the reactivity. Hereinafter, it will be described based on FIG. 2.

2 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.

As shown in Figure 2, the anaerobic sewage treatment apparatus according to another embodiment of the present invention may include a settling tank 100, an anaerobic reaction tank 200, a dissolved methane recovery tank 300, and a stripper 400.

Since the sedimentation tank 100, the anaerobic reaction tank 200, and the dissolved methane recovery tank 300 have the same configuration and operation as those of the anaerobic sewage treatment apparatus according to an embodiment of the present invention described above, detailed descriptions are omitted here. , Hereinafter, the stripper 400 will be described.

The stripper 400 additionally recovers methane dissolved in the effluent flowing out of the anaerobic reactor 200, increases the concentration of dissolved oxygen (DO) in the effluent, and reduces the biological reactivity of the effluent Can be installed as.

The stripper 400 may use an existing device, and may aerate for a short time using air. Since the air generated here contains methane, when supplied to the generator 700, the heat amount of the recovered methane can be used as a heat source.

The anaerobic sewage treatment apparatus according to another embodiment of the present invention according to claim 1, wherein after the step 2, methane dissolved in the effluent discharged through the step 2 is additionally recovered, and the DO concentration of the effluent is Increasing, and may further include reducing the biological reactivity of the effluent. It will be described below based on FIG. 3.

3 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.

Referring to FIG. 3, the stripper 400 has the same configuration and function as described above, and additionally recovers methane dissolved in the effluent flowing out of the anaerobic reactor 200 before step 3 of recovering dissolved methane, and , Increase the concentration of dissolved oxygen (DO) in the effluent, and reduce the biological reactivity of the effluent.

The anaerobic sewage treatment apparatus according to another embodiment of the present invention further includes the steps of concentrating the sludge precipitated in step 1 and heating and stirring the concentrated sludge to decompose the organic matter of the sludge into by-products and methane gas. can do. Hereinafter, it will be described based on FIG. 4.

4 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.

As shown in Figure 4, the anaerobic sewage treatment apparatus according to another embodiment of the present invention is a settling tank 100, an anaerobic reaction tank 200, a dissolved methane recovery tank 300, a concentration tank 500, a sludge digester 600 ), a generator 700 may be provided.

The step of concentrating the sludge precipitated in step 1 may be performed in the concentration tank 500.

The concentration tank 500 may solid-liquid separating the primary sludge generated and settled in the settling tank 100 to increase the concentration and reduce the volume of the sludge. At this time, the sludge can be concentrated by a precipitation method by gravity.

Since the primary sludge is an inevitable by-product from the sewage treatment process, the sewage treatment plant should reduce such sludge to a minimum, and the concentration tank 500 may function to reduce moisture from 97% to 99.2%. At this time, since the sludge concentration situation has a great influence on the overall effect of the sludge treatment facility, the separated liquid also affects the sewage treatment facility, so sufficient management is required. For high concentration concentration of primary sludge, a mechanical thickener can also be used.

The sludge concentrated in the thickening tank 500 may be sent to the sludge digester 600.

The step of heating and stirring the concentrated sludge to decompose the organic matter of the sludge into by-products and methane gas may be performed in the sludge digester 600.

The sludge digester 600 chemically treats the concentrated sludge, and by heating and stirring the sludge in a sealed tank, organic matter of the sludge is decomposed to generate methane gas and by-products.

The sludge digester 600 may be composed of an aerobic digester or an anaerobic digester that treats sludge by decomposing organic matter by the action of microorganisms. In this case, the aerobic digester has advantages in that it is easy to operate, has almost no odor, and has a low biological oxygen demand and a low concentration of suspended substances in the treated water.

In addition, the anaerobic digester has advantages in that it does not require a power facility and can perform continuous treatment in a small-scale case, is easy to maintain, can obtain useful methane gas, and can kill pathogens or parasitic eggs. Methane gas generated in the anaerobic digester may be used as its own fuel (generator 700) to help recycle resources.

Since the sludge digester 600 mainly uses an anaerobic digestion method, which is a method of treating sludge by blocking oxygen, it may play a role of minimizing and stabilizing secondary pollution after reducing the content of organic matter.

The anaerobic digestion of sludge through such an anaerobic digester has the advantage of not only reducing sludge, but also improving the dehydration of sludge, making sludge safe for hygiene, and using the generated digestion gas as fuel.

The sludge in the sludge digester 600 may be sent to a dewatering tank (not shown) to reduce the water content and then incinerated, dried and recycled, or buried. In general, the sludge generated as a result of sewage treatment has a large volume and high moisture content, so it is almost impossible to dispose of it as it is. Therefore, by using a sludge dewatering facility such as a pressurized filter that combines filtration and compression, it can be dewatered into a cake with a water content of less than 80% to reduce the sludge capacity, making it easy to carry out, transport and dispose of.

In another embodiment of the present invention, in the case of using methane trophic bacteria to remove dissolved methane in step 3, methane trophic bacteria oxidizing the dissolved methane are used for denitrification of the effluent discharged through step 3. Can be used as a donor. Hereinafter, it will be described based on FIG. 5.

5 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.

As a method of removing nitrogen (N), a phenomenon in which nitrogen gas is converted into nitrogen gas by nitrifiers in an aerobic state and denitrifiers in an oxygen-free state can be used in the natural nitrogen cycle. Phosphorus (P) can be removed by releasing phosphorus in the microbial cells to the outside of the body in an anoxic state, and by excessive intake of phosphorus in an aerobic state. At this time, when non-aeration for denitrification and dephosphorization, microorganisms require organic substances (electron donors) in the process of metabolism. Therefore, it is preferable that the ratio of organic matter/nitrogen in the inflow wastewater is high, and when the ratio of organic matter/nitrogen is low, nitrogen and phosphorus treatment is possible only when external organic matter is injected.

Referring to FIG. 5, a nitrogen/phosphorus removal device 800 is connected to the dissolved methane recovery tank 300 to oxidize the dissolved methane, and the methane nutrient bacteria (methanotroph) are used for denitrification of the effluent discharged through step 3. Can be used as a donor.

The nitrogen/phosphorus removal device 800 may be installed in order to adjust the concentration of nitrogen and phosphorus in the effluent water discharged after the final treatment based on the quality of the effluent water. In urban sewage and low-concentration wastewater, nutrients including nitrogen and phosphorus as well as organic substances are present. Nutrients are inorganic elements necessary for the growth and proliferation of microorganisms that cause decomposition of organic matter, and among these, nitrogen compounds and phosphates are elements that must be continuously supplied for the formation of biological cells and energy metabolism. However, when nutrients such as nitrogen (N) or phosphorus (P) are increased, the balance of the ecosystem is destroyed, causing eutrophication. Sources of nitrogen that cause eutrophication include domestic sewage, factory wastewater, and agricultural wastewater. Household sewage contains proteins, peptides, amino acids and urea as organic nitrogen compounds, and a small amount of ammonia as inorganic nitrogen compounds. The organic nitrogen compound form or nitrogen is oxidized to nitrite or nitrate by the action of microorganisms in water, consuming oxygen in water. Nitrite or ammonia has a fatal effect on fish.

The main source of phosphorus (P) is synthetic detergent, which accounts for 30-40% of phosphorus flowing into the aquatic ecosystem. Phosphate is used as a builder of synthetic detergents, and together with surfactants, it has a synergistic effect on the cleaning action and accounts for a large part of synthetic detergents. As the usage of synthetic detergents increases day by day, the proportion of phosphate in sewage is gradually increasing.

When such nitrogen (N) or phosphorus (P) accumulates in the reservoir, eutrophication occurs. Eutrophication is a phenomenon that begins to occur when nitrogen or phosphorus components are introduced into water bodies such as reservoirs, as microorganisms that feed on these nitrogen or phosphorus are overproduced. Therefore, in order to fundamentally prevent eutrophication, nutrients in sewage and wastewater must be removed before entering water bodies such as rivers.

In this embodiment, by further providing a nitrogen/phosphorus removal device 800 that removes nitrogen (N) or phosphorus (P) contained in the effluent that is finally discharged by decomposing organic substances in wastewater, the concentration of nitrogen or phosphorus is reduced. It can be adjusted according to the effluent water quality standards.

The anaerobic sewage treatment method according to another embodiment of the present invention may recover polyhydroxybutyrate (PHB) accumulated in methanotroph obtained by oxidizing the dissolved methane. Hereinafter, it will be described based on FIG. 6.

6 is a schematic diagram of an anaerobic sewage treatment apparatus according to another embodiment of the present invention.

In general, if the wastewater treatment focuses on the removal of organic matter and operates only up to the secondary treatment, the activated sludge process, nitrogen and phosphorus dissolved in sewage and wastewater may be discharged into rivers or introduced into lakes and reservoirs without being treated. have. In this case, problems such as eutrophication due to the introduction of nutrients (nitrogen/phosphorus) into the lake may occur.

In this embodiment, the methane nutrient bacteria recovery tank 900 is additionally coupled to the anaerobic treatment device to recover the polyhydroxybutyrate (PHB) accumulated in the methanotroph obtained by oxidizing the dissolved methane.

PHB, one of the PHAs, is commercially known as a very useful biopolymer, and can be variously used as an asymmetric carbon source, biodegradable/thermoplastic material, drug delivery matrix, and bone replacement matrix for the organic synthesis of antibiotics.

The methane nutrient bacteria can biosynthesize PHB in a carbon source-rich environment and store it in the body. PHB can be separated from the methane trophic bacteria by chemical treatment of the methane trophic bacteria containing the PHB in the body. For example, PHB can be separated by treating the methanotrophs with sodium hypochlorite. The method of recovering PHB from the methane trophic bacteria may be a conventional method and is not particularly limited.

Anaerobic sewage treatment method according to an embodiment of the present invention, after the step of recovering dissolved methane, methane nutrient to recover PHB (polyhydroxybutyrate) accumulated in methane trophic bacteria (methanotroph) that oxidized dissolved methane. It can be recovered in the bacteria recovery tank 900.

The method of recovering the methane nutrient bacteria in the methane nutrient bacteria recovery tank 900 may be carried out by a gravity precipitation method or a centrifugation method, and the present invention is not particularly limited thereto.

Anaerobic sewage treatment system

An anaerobic sewage treatment apparatus according to an embodiment of the present invention includes a settling tank for sedimenting and removing solids contained in wastewater; An anaerobic reactor for decomposing organic matter contained in wastewater discharged from the sedimentation tank into methane and carbon dioxide using anaerobic microorganisms; A dissolved methane recovery tank for recovering dissolved methane contained in the treated water of the anaerobic reaction tank; Includes.

An anaerobic sewage treatment apparatus according to another embodiment of the present invention includes a settling tank for sedimenting and removing solids contained in wastewater; An anaerobic reactor for decomposing organic matter contained in wastewater discharged from the sedimentation tank into methane and carbon dioxide using anaerobic microorganisms; A dissolved methane recovery tank for recovering dissolved methane contained in the treated water of the anaerobic reaction tank; It includes a stripper that additionally recovers methane dissolved in the effluent discharged from the anaerobic reactor, increases the concentration of dissolved oxygen (DO) in the effluent, and reduces the biological reactivity of the effluent.

An anaerobic sewage treatment apparatus according to another embodiment of the present invention includes a settling tank for sedimenting and removing solids contained in wastewater; An anaerobic reactor for decomposing organic matter contained in wastewater discharged from the sedimentation tank into methane and carbon dioxide using anaerobic microorganisms; A stripper 400 that additionally recovers methane dissolved in the effluent discharged from the anaerobic reactor 200, increases the concentration of dissolved oxygen (DO) of the effluent, and reduces the biological reactivity of the effluent; A dissolved methane recovery tank for recovering dissolved methane contained in the treated water of the anaerobic reaction tank; Includes.

An anaerobic sewage treatment apparatus according to another embodiment of the present invention includes a settling tank for sedimenting and removing solids contained in wastewater; An anaerobic reactor for decomposing organic matter contained in wastewater discharged from the sedimentation tank into methane and carbon dioxide using anaerobic microorganisms; A dissolved methane recovery tank for recovering dissolved methane contained in the treated water of the anaerobic reaction tank; A thickening tank for solid-liquid separating the primary sludge generated and settled in the settling tank to increase the concentration and reduce the volume of the sludge; A sludge digester for chemically treating the concentrated sludge; Includes a generator.

An anaerobic sewage treatment apparatus according to another embodiment of the present invention includes a settling tank for sedimenting and removing solids contained in wastewater; An anaerobic reactor for decomposing organic matter contained in wastewater discharged from the sedimentation tank into methane and carbon dioxide using anaerobic microorganisms; A dissolved methane recovery tank for recovering dissolved methane contained in the treated water of the anaerobic reaction tank; And a nitrogen/phosphorus removal device.

An anaerobic sewage treatment apparatus according to another embodiment of the present invention includes a settling tank for sedimenting and removing solids contained in wastewater; An anaerobic reactor for decomposing organic matter contained in wastewater discharged from the sedimentation tank into methane and carbon dioxide using anaerobic microorganisms; A dissolved methane recovery tank for recovering dissolved methane contained in the treated water of the anaerobic reaction tank; And a methane nutrient bacteria recovery tank.

The contents of the sedimentation tank, reaction tank, dissolved methane recovery tank, concentration tank, sludge digester, stripper nitrogen/phosphorus removal device, and methane nutrient bacteria recovery tank are the same as those described above, and the description will be omitted.

The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited by the appended claims. Therefore, various types of substitutions, modifications and changes will be possible by those of ordinary skill in the art within the scope not departing from the technical spirit of the present invention described in the claims, and this also belongs to the scope of the present invention. something to do.

100: settling tank
200: anaerobic reactor
300: dissolved methane recovery tank
400: stripper
500: thickening tank
600: sludge digester
700: generator
800: nitrogen/phosphorus removal device
900: Methanotrophic bacteria recovery tank

Claims (11)

delete delete delete delete A settling tank for sedimenting and removing solids contained in wastewater;
An anaerobic membrane bioreactor for decomposing organic matter contained in the wastewater discharged from the sedimentation tank into methane and carbon dioxide using anaerobic microorganisms;
A dissolved methane recovery tank including a circulation pipe installed in the anaerobic membrane bioreactor and a degassing separation membrane installed in the circulation pipe, the dissolved methane recovery tank for recovering dissolved methane contained in the treated water of the anaerobic membrane bioreactor;
A stripper that additionally recovers methane dissolved in the effluent discharged from the anaerobic membrane bioreactor, increases the concentration of dissolved oxygen (DO) in the effluent, and reduces the biological reactivity of the effluent;
And
A nitrogen/phosphorus removal device for removing nitrogen and phosphorus in the effluent water discharged from the stripper;
As an anaerobic sewage treatment method using an anaerobic sewage treatment device comprising a,
Precipitating and removing solids contained in wastewater in a settling tank (Step 1);
In the anaerobic membrane bioreactor, the organic matter contained in the wastewater that has undergone step 1 is decomposed into methane and carbon dioxide using anaerobic microorganisms to obtain treated water containing dissolved methane (step 2);
In a dissolved methane treatment tank including a circulation pipe installed in the anaerobic membrane bioreactor and a degassing separation membrane installed in the circulation pipe, the treated water obtained in step 2 is permeated through the degassing separation membrane to perform in situ degassing. Treating the dissolved methane contained in the treated water obtained in step 2 by removing hydrogen and carbon dioxide dissolved in the treated water and recovering methane having a concentration of 94% (step 3);
In the stripper, further recovering the dissolved methane in the treated water that has passed through step 3, increasing the DO concentration of the effluent, and reducing the biological reactivity of the effluent (step 4);
Removing nitrogen and phosphorus in the effluent passed through step 4 in a nitrogen/phosphorus removal device (step 5);
Including,
Anaerobic sewage treatment method, characterized in that the permeation form in the degassing membrane of step 3 is a lumen-side flow.
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