KR101123854B1 - Wet-dry serial parallel anaerobic digestion apparatus and method for treating organic waste - Google Patents

Abstract

PURPOSE: A high temperature wet-dry parallel anaerobic digesting apparatus for organic waste and a method for the same are provided to minimize the productivity of bio gas by accelerating the anaerobic digestion of organic waste and improving the treating capacity of the organic waste. CONSTITUTION: A high temperature wet-dry parallel anaerobic digesting apparatus includes a first screw dehydrator(11), a dry digesting bath(30), a wet digesting bath(20), and a gas storing bath(40). The first screw dehydrator dehydrates organic waste to be separated according to the concentration of solid materials. The dry digesting bath anaerobically digests organic materials of high concentration. The wet digesting bath anaerobically digests organic materials of low concentration. The gas storing bath stores bio gas generated from the digesting baths. The digesting baths are parallelly formed.

Description

WET-DRY SERIAL PARALLEL ANAEROBIC DIGESTION APPARATUS AND METHOD FOR TREATING ORGANIC WASTE}

The present invention relates to a high temperature wet-dry parallel anaerobic digestion apparatus and method for organic waste, and more particularly, to dry and compost in parallel with dry solidification and wet digestion according to solids concentration through dehydration of organic waste. In addition to increasing the rate of anaerobic digestion of organic wastes by returning the dehydrated cakes with low moisture content to the dry digester and allowing dry and wet digestion in parallel under high temperature conditions using waste heat and steam from the boilers, A high temperature wet-dry parallel anaerobic digestion apparatus and method for organic waste that can improve capacity.

In general, wastewater such as sewage, sewage, and manure that occurs in homes, livestock farms, and industrial sites contains many organic substances. Therefore, if the wastewater containing organic matter is discharged without biological and chemical oxygen demand, suspended solids content, etc., the soil or water quality will be contaminated. Accordingly, the organic matter in the wastewater is discharged to rivers and the like in a purified state through biological, physical and chemical treatments, thereby reducing environmental pollution.

However, when the organic matter in the waste water is treated by a physical method, its treatment effect is insignificant, and chemical treatment requires a lot of treatment costs along with water pollution, and recently, a biological method using microorganisms is mainly used.

One of these biological methods, anaerobic digestion, is a reaction in which anaerobic microorganisms ingest organic matter and release inorganic compounds and digestive gases (biogas). Anaerobic digestion is a traditional technique that has been established for some time, also known as methane fermentation. The main purpose of the anaerobic digestion process is to recover the energy of methane simultaneously with the disposal of organic waste.

In general, anaerobic digestion is divided into pretreatment process, anaerobic digestion process, gas collection and purification process, and solid resource recycling process. Anaerobic digestion of organic waste is divided into dry and wet depending on the state of the organic waste.

The dry anaerobic digestion process is a process for organic wastes with a total solids (TS) of 15 to 40%, using either a complete mix or a plug flow process. The dry anaerobic digestion process is structurally simpler than other processes because it is impossible to use only mechanical internal agitator due to the nature of the material, but there is no agitation, so the temperature imbalance in the scum layer and the digester due to stratification in the digester There is a problem. In addition, there is a disadvantage that the release of biogas is inhibited by the generated scum. Along with this, there is a disadvantage in that it operates in a batch type in which a new extinguishing material is input by emptying the inside of the digester.

The wet anaerobic digestion process is for organic wastes having a total solids concentration (TS) of 10% or less, and a pretreatment process for removing substances such as glass, gravel, and metals contained in organic wastes is required. If such a pretreatment process does not proceed smoothly, soils and contaminants sink in the lower part of the digester due to low TS, which acts as a factor that prevents the inflow and outflow of sludge. Accordingly, dilution water is required when the organic waste is input, which inevitably increases the volume of the digester, and inevitably generates a large amount of waste water.

The present invention has been made to solve the above problems, its purpose is to proceed in the dry and wet digestion in parallel according to the solid concentration through the dehydration process for organic waste, the low moisture content dehydration cake in the dry composting process Organic waste that can not only increase the anaerobic digestion rate of organic wastes but also improve the processing capacity of organic wastes by returning them to a dry digester and allowing high temperature dry and wet digestion to operate in parallel using waste heat and steam from the boiler. To provide a high temperature wet-dry parallel anaerobic digestion apparatus and method.

According to one aspect of the invention, the first screw dehydrator for dewatering the organic waste to separate according to the solid concentration; A dry digester for receiving anaerobic digestion by receiving a high concentration of organic material from the first screw dehydrator; A wet digester receiving anaerobic digestion by receiving a low concentration of organic matter from the first screw dehydrator; And a gas storage tank storing biogas produced from the dry digester and the wet digester. It includes, and the dry digester and wet digester configured in parallel provides a high temperature wet-dry parallel anaerobic digester characterized in that it is operated in a high temperature condition by waste heat using the biogas of the gas storage tank.

Preferably, the front of the dry digester and the wet digester is installed a mixed storage tank for receiving and storing the organic waste, by supplying waste heat or steam to the mixed storage tank to make the temperature of the internal organic waste to a high temperature condition dry dry tank and It is characterized by extinguishing in a high temperature condition by supplying the wet digester.

Preferably, an external tank is installed outside the dry digester and the wet digester, and waste heat or steam is supplied to the external tank to circulate the exterior of the dry digester and the wet digester, thereby extinguishing in a high temperature condition. It is done.

Preferably, at least one or more of limonite, iron oxide, iron sulfate, and iron hydroxide are added to the dry digester and the wet digester as a hydrogen sulfide remover to remove hydrogen sulfide generated during the digestion process.

Preferably, the dry digester and the wet digester are characterized in that the addition of limonite or zeolite as ammonia remover to remove ammonia generated during the digestion process.

Preferably, a first centrifugal dehydrator is installed at a rear end of the wet digester, and the sludge discharged from the wet digester passes through a centrifugal dehydration process of the first centrifugal dehydrator, and the dehydrated cake having a high solidity is transferred to a third mixed storage tank. The dewatering cake of the third mixed storage tank is supplied to the drying compost tank and characterized in that it is dried.

Preferably, the rear end of the dry digester is provided with a mixer that can add a flocculant or a coagulant to the sludge discharged from the dry digester, the flocculant is a cationic inorganic polymer, the coagulant is bentonite or incinerator do.

Preferably, the second screw dehydrator is installed in the rear end of the mixer to receive the sludge discharged from the mixer for screw dehydration; A sedimentation tank installed at the rear end of the screw dehydrator to precipitate the dehydrated filtrate of the screw dehydration to separate solid-liquid; And a second centrifugal dehydrator for receiving centrifugal dehydration by receiving a dehydration cake discharged from the settling tank. Further comprising, in the settling tank is concentrated in the dehydration filtrate is separated into a supernatant and concentrated dehydration cake to reduce the moisture content of the dehydration cake, characterized in that the microorganism recovery is possible by extracting the precipitate through the filtrate precipitation.

Preferably, the dewatering cake discharged from the second screw dehydrator and the second centrifugal dehydrator is supplied to a third mixing reservoir, and the dehydration cake of the third mixing reservoir is supplied to a dry composting tank and dried.

Preferably, the dry compost tank is characterized in that the dehydration cake is supplied through a dryer to return the dehydrated cake with reduced moisture content to a dry digester.

Preferably, sewage sludge is added to maintain the solids content of the dry digester.

On the other hand, according to another aspect of the present invention, (a) a waste separation step of separating the organic waste by the solid concentration; (b) a dry digestion step of receiving dry anaerobic digestion in a dry digester by receiving the high concentration organic material separated in the waste separation step; (c) a wet digestion step of receiving anaerobic digestion in a wet digester by receiving the low concentration organic material separated in the waste separation step; And (d) a gas storage step of storing the biogas produced from the dry digestion step and the wet digestion step; It includes, the dry digestion step of step (b) and the wet digestion step of step (c) is operated in parallel, the dry digestion and wet by waste heat using the stored biogas through step (d) It provides a high temperature wet-dry parallel anaerobic digestion method characterized in that the digestion is operated at high temperature conditions.

Preferably, the front of the dry digester and the wet digester is installed a mixed storage tank for receiving and storing the organic waste, by supplying waste heat or steam to the mixed storage tank to make the temperature of the internal organic waste to a high temperature condition dry dry tank and It is characterized by extinguishing in a high temperature condition by supplying the wet digester.

Preferably, an external tank is installed outside the dry digester and the wet digester, and waste heat or steam is supplied to the external tank to circulate the exterior of the dry digester and the wet digester, thereby extinguishing in a high temperature condition. It is done.

Preferably, at least one or more of limonite, iron oxide, iron sulfate, and iron hydroxide are added to the dry digester and the wet digester as a hydrogen sulfide remover to remove hydrogen sulfide generated during the digestion process.

Preferably, the dry digester and the wet digester are characterized in that the addition of limonite or zeolite as ammonia remover to remove ammonia generated during the digestion process.

Preferably, a first centrifugal dehydrator is installed at the rear end of the wet digester, and the sludge discharged from the wet digester passes through the centrifugal dehydration process of the first centrifugal dehydrator, and the high solidity dehydration cake is transferred to the third mixed storage tank. The dewatering cake of the third mixed storage tank is supplied to a dry composting tank and characterized in that it is dried.

Preferably, the rear end of the dry digester is provided with a mixer that can add a flocculant or a coagulant to the sludge discharged from the dry digester, the flocculant is a cationic inorganic polymer, the coagulant is bentonite or incinerator do.

Preferably, the step of installing a second screw dehydrator in the rear end of the mixer and supplying sludge discharged from the mixer to screw dewatering; Installing a sedimentation tank at the rear end of the screw dehydrator and precipitating the screw dewatered filtrate to separate solid-liquid; And dewatering the dewatering cake discharged from the settling tank from a second centrifugal dehydrator; Further comprising, in the settling tank is concentrated in the dehydration filtrate is separated into a supernatant and concentrated dehydration cake to reduce the moisture content of the dehydration cake, characterized in that the microorganism recovery is possible by extracting the precipitate through the filtrate precipitation.

Preferably, the dewatering cake discharged from the second screw dehydrator and the second centrifugal dehydrator is supplied to a third mixing reservoir, and the dehydration cake of the third mixing reservoir is supplied to a dry composting tank and dried.

Preferably, the dry compost tank is characterized in that the dehydration cake is supplied through a dryer to return the dehydrated cake with reduced moisture content to a dry digester.

Preferably, sewage sludge is added to maintain the solids content of the dry digester.

According to the present invention, a dry digester and a wet digester are provided together, and the organic waste is separated according to the total solid concentration in the dehydration process to perform a parallel digestion operation in which a dry or wet digestion process is performed, and the dry digester and the wet digester Organic waste is temporarily stored by placing a mixed storage tank at the front end of the tank while supplying waste heat and steam to the mixed storage tank to make the temperature of the organic waste at a high temperature to induce dry digestion and wet digestion to allow high temperature digestion. By increasing the rate of anaerobic digestion and improving the processing capacity of organic waste, it is possible to maximize biogas production and minimize waste water generation.

In addition, it is possible to efficiently remove ammonia or hydrogen sulfide that may be generated during the high temperature operation of the digester has the effect of enabling stable operation at high temperature conditions.

In addition, by installing a settling tank after the screw dehydration step after dry fire extinguishing, there is also an effect of reducing the water content of the dewatering cake and microbial recovery through the filtrate precipitation.

In addition, the operation of the dry compost tank can reduce the operating time and ease of maintenance, and by returning the sludge from the dry compost tank to the dry digester, the amount of return dewatering cake can be reduced to enable stable operation of the dry digester. There is also an effect.

In addition, the sewage sludge is added to the dry digester to maintain the TS concentration, which is advantageous for maintaining the solid concentration of the dry digester, and the hydrogen sulfide in the sewage sludge can also control hydrogen sulfide in the digester.

1 is a schematic diagram illustrating a high temperature wet-dry parallel anaerobic digestion apparatus and method for organic waste according to the present invention.
2 to 5 is a view showing the results of experiments applying the high temperature wet-dry parallel anaerobic digestion apparatus and method of organic waste according to the present invention.

Hereinafter, an embodiment of a high temperature wet-dry parallel anaerobic digestion apparatus and method for organic waste according to the present invention will be described in more detail with reference to the accompanying drawings.

Referring to Figure 1, the high temperature wet-dry parallel anaerobic digestion apparatus of an organic waste according to an embodiment of the present invention is provided with a dry digester 30 and a wet digester 20, the organic waste is the total solid concentration in the dehydration process Parallel fire extinguishing operation is performed according to (TS, Total Solids) and undergoes a dry or wet digestion process, and puts mixed storage tanks (14, 13) in front of the dry digester (30) and the wet digester (20). While temporarily storing the organic wastes, the waste heat and steam are supplied to the mixed storage tanks 14 and 13 to make the temperature of the organic wastes at a high temperature condition, and the high temperature digestion is performed by introducing them into the dry digester 30 and the wet digester 20. Increase the rate of anaerobic digestion of organic wastes and improve the processing capacity of organic wastes to maximize biogas production and minimize wastewater generation It is possible to kill.

In more detail, the organic waste is introduced into the crushing sorter 10 and crushed, and after the screw dehydration process of the first screw dehydrator 11 is performed according to the solid concentration TS.

Here, in the first screw dehydrator 11, a low concentration organic matter (dehydration solution) having a solid concentration (TS) of less than 10% is supplied to the first mixed storage tank 13 for wet digestion, and is intermediately stored. (TS) At least 25% high concentration organic matter (solids) is fed to the second mixed reservoir 14 for dry digestion and stored intermediately.

Here, the first mixed storage tank 13 is supplied with waste heat or steam to maintain a high temperature condition (about 55 ~ 60 ℃) by the inside of the wet digestion tank 20 to receive the organic waste from the first mixed storage tank 13 Maintain the temperature at about 52 ~ 55 ℃ to allow high temperature wet extinguishing.

Alternatively, a separate external tank (not shown) may be installed outside the wet digester 20 to allow the wet digester 20 to perform high temperature wet digestion, and the waste tank may be supplied to the external tank by waste heat or steam to supply the same to the external tank. By maintaining the temperature of the water of about 55 ~ 60 ℃ and by circulating the outside of the wet digestion tank 20 to maintain the internal temperature of the wet digestion tank 20 to about 52 ~ 55 ℃ to achieve high temperature wet digestion You may.

In addition, the wet digestion tank 20 which is supplied with the low concentration organic matter from the first mixed storage tank 13 performs an acid fermentation and a methane fermentation process, that is, anaerobic wet digestion, and is collected by wet digestion of the wet digester 20. Gas (methane gas) is collected in the gas storage tank (40). The anaerobic digestion process refers to a process in which organic matter is converted to methane due to the decomposition of various microorganisms. Biogas, the final product of the anaerobic digestion process, is a methane-producing bacterium based on 70% acetic acid and 30% hydrogen. It is generated by the activity of methane gas, which is promoted by dissociation of acetic acid and hydrogen substrates attached to organic substances by internal stirring.

Here, the high temperature biogas stored in the gas storage tank 40 is introduced into the cogeneration generator. Cogeneration machines generate electricity from hot biogas. The cogeneration generator may include a hot water supplyer using waste heat generated during cogeneration. The waste heat by the cogeneration may be supplied to the first mixed storage tank 13 and the second mixed storage tank 14 to maintain the temperature of the organic waste stored therein at a high temperature condition (about 55 to 60 ° C.), Through this, the internal temperature of the dry digester 30 and the wet digester 20 is maintained at high temperature so that high temperature wet-dry parallel digestion is achieved.

In fact, in the wet digester 20, hydrogen sulfide (H ₂ S) is generated in the digestion process, and such hydrogen sulfide has a bad effect on the digestion efficiency due to competition with methane strains in the digestion furnace. Therefore, at least one remote nitro _{(Limonite, FeOOH? NH 2 O} ), iron oxide (Fe ₂ O _3), iron sulfate (F ₂ SO _4), iron hydroxide _{(Fe 2 O 3? NH 2} O) in order to remove such hydrogen sulfide one The above can be added as a hydrogen sulfide remover. Compared with iron chloride (FeCl ₂ ), limonite (FeOOH? NH ₂ O) contains about 67% of iron, so limonite is less than iron chloride to obtain the same removal rate of hydrogen sulfide generated during anaerobic digestion of organic waste. Only 1/6 supply can have a similar effect. In addition, iron oxide (Fe ₂ O ₃ ), iron sulfate (F ₂ SO ₄ ) and iron hydroxide (Fe ₂ O _{3 ~} nH ₂ O) also has a higher hydrogen control rate than iron chloride. In addition, there is an effect that can replace the trace elements required for anaerobic digestion, such as iron and magnesium, as well as contribute to the toxicity reduction effect of VFA (Volatile Fatty Acid, Volatile Organic Acid).

In addition, in the wet digester 20, ammonia (NH ₃ ) is generated during the digestion process, and in order to remove such ammonia, limonite (Limonite, FeOOH? NH ₂ O) or zeolite (Zeolite) may be added as an ammonia remover. have. Due to the high concentration of free ammonia and VFA (volatile organic acids) in high temperature anaerobic digestion, wet anaerobic digestion is mostly operated at medium temperature and dry anaerobic digestion is operated only at medium temperature. Therefore, by adding limonite (Limonite, FeOOH? NH ₂ O) or zeolite (Zeolite) as ammonia remover, it is possible to operate wet-dry anaerobic digestion even at high temperature (50-55 ° C.).

And due to the anaerobic digestion process, sludge is accumulated in the wet digester 20, the sludge is subjected to a centrifugal dehydration process of the first centrifugal dehydrator 21, the high degree of dehydration cake (water content 75%) is made of 3 is transferred to the dry compost tank 36 through the mixing reservoir 35 to reduce the water content (water content 45%), and the dewatering filtrate is immediately treated wastewater.

On the other hand, the dry digester 30, the high concentration of the organic material supplied from the second mixed storage tank 14 is to perform the acid fermentation and methane fermentation process, that is, anaerobic dry digestion, collected by the dry digestion of the dry digester 30 Biogas (methane gas) is collected in the gas storage tank (40).

Here, the internal temperature of the dry digestion tank 30 receiving organic waste from the second mixed storage tank 14 is maintained by supplying waste heat to the second mixed storage tank 14 to maintain a high temperature condition (about 55 to 60 ° C.). Maintain about 52 ~ 55 ℃ to allow high temperature dry fire extinguishing.

Alternatively, a separate external tank (not shown) may be installed outside the dry digester 30 to allow the dry digester 30 to perform high temperature dry extinguishing, and the waste tank may be supplied to the external tank by waste heat or steam. By maintaining the temperature of the water of about 55 ~ 60 ℃ and by circulating the outside of the dry digester 30 to maintain the internal temperature of the corresponding dry digester 30 to about 52 ~ 55 ℃ high temperature dry digestion is made You may.

Actually, the dry digester 30 generates hydrogen sulfide (H ₂ S) in the digestion process, and this hydrogen sulfide has an adverse effect on the digestion efficiency due to competition with methane strains in the digestion furnace. Therefore, at least one remote nitro _{(Limonite, FeOOH? NH 2 O} ), iron oxide (Fe ₂ O _3), iron sulfate (F ₂ SO _4), iron hydroxide _{(Fe 2 O 3? NH 2} O) in order to remove such hydrogen sulfide one The above can be added as a hydrogen sulfide remover. Compared with iron chloride (FeCl ₂ ), limonite (FeOOH? NH ₂ O) contains about 67% of iron, so limonite is less than iron chloride to obtain the same removal rate of hydrogen sulfide generated during anaerobic digestion of organic waste. Only 1/6 supply can have a similar effect. In addition, iron oxide (Fe ₂ O ₃ ), iron sulfate (F ₂ SO ₄ ) and iron hydroxide (Fe ₂ O _{3 ~} nH ₂ O) also has a higher hydrogen control rate than iron chloride. In addition, there is an effect that can replace the trace elements required for anaerobic digestion, such as iron and magnesium, as well as contribute to the toxicity reduction effect of VFA (Volatile Fatty Acid, Volatile Organic Acid).

In addition, in the dry digester 30, ammonia (NH ₃ ) is generated during the digestion process. In order to remove such ammonia, limonite (Limonite, FeOOH? NH ₂ O) or zeolite (Zeolite) may be added as an ammonia remover. have. Due to the high concentration of free ammonia and VFA (volatile organic acids) in high temperature anaerobic digestion, wet anaerobic digestion is mostly operated at medium temperature and dry anaerobic digestion is operated only at medium temperature. Therefore, by adding limonite (Limonite, FeOOH? NH ₂ O) or zeolite (Zeolite) as ammonia remover, it is possible to operate wet-dry anaerobic digestion even at high temperature (50-55 ° C.).

The sludge discharged from the dry digester 30 is supplied to the mixer 31, and a flocculant and a coagulant may be introduced from the mixer 31. The cationic inorganic polymer can be supplied here as a flocculant, and bentonite or fly ash can be supplied as a flocculant.

The sludge passed through the mixer 31 is supplied to the second screw dehydrator 32 to undergo a dehydration process. At this time, the dehydration cake having a high solidity through the dehydration process of the second screw dehydrator 32 is supplied to the third mixing reservoir 35 to be treated as dry compost, and the dehydration filtrate having a low solidity is supplied to the settling tank 33. Will be.

That is, instead of using the screw dewatered dehydration solution after dry fire extinguishing as before, the sedimentation tank 33 is additionally installed to allow concentration.

The dehydration filtrate generated in the second screw dehydrator 32 is precipitated filtrate in the settling tank (33). After dry extinguishing, the sludge is solid-liquid separated and the filtrate is precipitated to recover microorganisms. As described above, the dehydration filtrate that occurs during the screw dehydration process of the second screw dehydrator 32 after the flocculant is added includes solids containing microorganisms (about 5% of TS basis), and the cohesive force of the dehydration filtrate. Since it exists, sedimentation is high. Therefore, to prevent the loss of microorganisms contained in the solid is to use the settling tank 33. In other words, by concentrating the dehydration filtrate (about TS 2 ~ 4%) in the settling tank (33) to the supernatant (about TS 0.2%) and concentrated sludge (about TS 8 ~ 10%) to reduce the moisture content of the dehydration cake and the filtrate By sediment extraction through precipitation, microorganisms can be recovered.

The supernatant with low solidity through the settling tank 33 is directly treated with wastewater, and the dewatering cake is supplied to the second centrifugal dehydrator 34. The dewatering cake is subjected to the centrifugal dehydration process of the second centrifugal dehydrator 34, and the dehydrated cake having a high solidity (about 65% water content) is supplied to the third mixed storage tank 35, and the dehydrated filtrate having a low solidity is directly wastewater. Will be processed.

On the other hand, the dehydration cake of the third mixing reservoir (35) in which the screw dehydrator (32) or the centrifugal dehydrator (21, 34) stores the dehydration cake is supplied to the drying compost tank (36) to be dried. When aerobic composting of a dehydrated cake occurs, a large amount of odor is generated due to the air input for the site and operation for the composting process, or an auxiliary material is needed. In order to solve this problem, if the dehydration cake is processed through the dryer of the drying compost tank 36, the operation time is shortened and maintenance is easy. For example, if anaerobic digestion of 100 tonnes of food waste is required per day, the amount of side-use is 5 tonnes / day. However, if the dehydrated cake is used for dry composting, there is no need to add such side-uses.

In addition, such a dry compost tank 36 can be returned to the dehydration cake of less than 45% water content to maintain the solid content of the dry digester (30). In order to maintain the TS concentration of the dry digester 30, in the past, centrifugal dehydration cake (water content 65%) was used, but in the present invention, sludge (water content less than 45%) from the dry digester 36 to the dry digester 30 ), The amount of the return dewatering cake is reduced by 40%.

100 tons / day (based on fresh food, based on TS 18%, VS 80%) When operating a dry digester for food waste, the TS inside the dry digester will be maintained by returning the dehydrated cake. When dehydrated cake (water content 65%) is returned after dehydration of digested sludge in the conventional manner, 55 ton / day dewatered cake should be returned, but only 33 ton / day should be returned in the dry compost tank (45% water content). Therefore, compared with the conventional conveying method, the inflow of organic wastes is increased by 22 tons / day, and the stability of the dry digester operation can be improved.

And the dewatering cake of the dry composting tank 36 which is not conveyed or composted can be condensed in the condenser 37 and treated with wastewater.

Meanwhile, in the present invention, sewage sludge may be added to maintain the solid content of the dry digester 30. Such sewage sludge is introduced into the second mixed storage tank 14 to be supplied to the dry digester 30, and to maintain the solid concentration of the dry digester by injecting sewage sludge having a TS of about 25 to 28% to the dry digester 30. Advantageously, the hydrogen sulfide control of the digester is also enabled by the iron salt component contained in the sewage sludge. In this case, the amount of sewage sludge added is preferably 2 to 15% of the amount of organic waste introduced.

Experimental Example 1

Existing digestive systems have been developed that combine dry anaerobic digestion and wet anaerobic digestion. However, this prior art is composed of a dry digester and a wet digester in series is different from the parallel configuration of the present application. Here, it is to demonstrate the superiority of the wet-dry parallel anaerobic digestion method by comparing the biogas generation efficiency of the conventional dry-wet serial anaerobic digestion method and the wet-dry parallel anaerobic digestion method of the present invention.

Specific experimental conditions for comparing the biogas generation efficiency of the wet-dry parallel anaerobic digester and the dry-wet serial anaerobic digester are as follows.

Four 20 L digesters were configured in wet-dry parallel and dry-wet series, respectively. Organic waste was used as food waste, and after analyzing the collected food waste after screw dehydration, TS was analyzed, and about 18% TS of collected food waste, about 24% food TS after screw dehydration, About 10%.

The results of comparing the biogas production of the wet-dry parallel digester and the dry-wet serial digester through 20 weeks of culturing and experiments are shown in FIG. 2 (the experimental results of the wet-dry parallel digester according to the present invention) and FIG. Dry-wet serial digester according to the experimental results). Digester operating conditions were maintained at medium temperature (33 ~ 35 ℃) and HRT 30 days. However, the dry-wet tandem anaerobic digester was operated with 25 days of dry digester HRT and 5 days of wet digester as a characteristic of the serial system to maintain the total HRT at 30 days.

Referring to the experimental results of FIGS. 2 and 3, the anaerobic digester biogas generation in the wet-dry parallel method was observed to be 1.6 times higher in the food waste experiment.

The reason for this was that the total HRT was maintained at 30 days for both anaerobic digesters with the same volume, while the wet-dry parallel digester was efficiently processed, resulting in an approximately 20% increase in the amount of incoming food waste compared to the dry-wet tandem. As a result, biogas production was relatively high. In addition, in the dry-wet tandem method, after 18 days of anaerobic digestion of food of TS 18%, the amount of organic gas flowing into wet digestion was less than 4%, and the amount of biogas generated by wet digestion was drastically reduced. In other words, dry-wet tandem digestion was not suitable for maximizing biogas generation due to organic waste treatment.

As a result of these experiments, it was concluded that the anaerobic digestion of high concentration organic waste can maximize the biogas production by appropriately using the wet-dry parallel method.

Experimental Example 2

Next, by comparing the biogas generation efficiency of the wet-dry digestion method at a medium temperature and the wet-dry digestion method at a high temperature, it is to demonstrate the superiority of the wet-dry digestion method at a high temperature.

Table 1 below compares the advantages and disadvantages of mesophilic and high temperature digestion in anaerobic digestion.

division Moderate temperature digestion High temperature fire extinguishing Temperature 35 ℃ ± 3 ℃ 55 ℃ ± 2 ℃ Advantages -High quality biogas production
High process stability
Low ammonia toxicity
Low energy consumption -High gas generation
-Fast digestion
-Low digester capacity Disadvantages Low gas generation
Low reaction rate
-Low pathogen killing rate -Easy to progress ammonia by protein and amino acid
-High concentration of free ammonia, low resistance to nitrogen
High energy requirements Application case -Most domestic digesters -No cases of domestic application

Similar to Experiment 1, specific experimental conditions for comparing the biogas generation efficiency of the medium temperature wet-dry anaerobic digester and the high temperature wet-dry anaerobic digester are as follows.

Four 20 L volume digesters were composed of medium temperature wet-dry digesters and high temperature wet-dry digesters, respectively. Organic waste was used as food waste, and the collected food waste was subjected to screw dehydration, and then food was supplied as a dry digester and food waste was supplied as a wet digester.

The results of comparing the biogas production of the medium temperature wet-dry digester and the high temperature wet-dry digester through 20 weeks of cultivation and experiment are shown in FIG. 4 (the experimental results of the medium temperature wet-dry parallel digester according to the prior art) and FIG. Experimental results of the high temperature wet-dry parallel digester according to the invention). Other operating conditions are the same as in Experimental Example 1. However, in order to maintain the conditions of the medium temperature (33 ~ 35 ℃) and high temperature (52 ~ 56 ℃) by installing a heat heater outside the anaerobic digester proceeded by adjusting the temperature through the external circulation of the digester of the heated water.

4 and 5, it can be seen that anaerobic digestion of food waste is promoted compared to the medium temperature wet-dry digester during operation of the high temperature wet-dry digester, thereby increasing the biogas production by about 35% or more. However, ammonia and hydrogen sulfide are generated at a relatively high concentration in proportion to the high biogas production amount, so it is necessary to take countermeasures.

[Experimental Example 3]

Next, a method of additionally installing a sedimentation tank after the screw dehydration step after high temperature dry fire extinguishing, which is one of the characteristics of the present invention, will be described for reducing the moisture content of the dewatering cake.

In the present invention, by using the cohesive force of the dehydration filtrate generated in the second screw dehydrator 32, TS (2-4%) in the sedimentation tank 33 to concentrate the supernatant (TS 0.2% or less) and concentrated sludge (TS 8 ~ 10) Concentration to reduce the moisture content of the dehydrated cake. And microorganisms can be recovered through the filtrate precipitation.

Comparing the existing method and the method of adding the sedimentation tank according to the present invention with respect to the dehydration cake generated in the high temperature dry digester 30, the following Table 2 (the existing method without the settling tank) and Table 3 (addition of the settling tank) Method of the present invention).

division Screw dehydrator filtrate Centrifugal Dehydrator Filtrate TS 40,000 mg / L 12,000mg / L

division Screw dehydrator filtrate After concentration Supernatant concentrate TS 40,000 mg / L 1,970 mg / L 87,200 mg / L

The result of Table 3 is the result of arranging the settling tank.In the conventional method of Table 2, the concentration of the filtrate is 12,000mg / L when the screw dewatering filtrate of TS 40,000 mg / L is centrifuged after dry digestion. Concentrated and concentrated after precipitation, the concentration of the concentrate is 87,000mg / L to recover the high concentration of microorganisms, it is effective to increase the TS content of the dewatered sludge.

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

10: shred sorter 11: first screw dehydrator
13: 1st mixing reservoir 14: 2nd mixing reservoir
20: wet digester 21: first centrifugal dehydrator
30: dry digester 31: mixer
32: second screw dehydrator 33: sedimentation tank
34: 2nd centrifugal dehydrator 35: 3rd mixing reservoir
36: dry compost 37: condenser
40: gas storage tank

Claims (22)

delete A first screw dehydrator for dewatering the organic waste and separating the organic waste according to the solid concentration;
A dry digester for receiving anaerobic digestion by receiving a high concentration of organic material from the first screw dehydrator;
A wet digester receiving anaerobic digestion by receiving a low concentration of organic matter from the first screw dehydrator; And
A gas storage tank storing biogas produced from the dry digester and the wet digester; Including;
The dry digester and the wet digester configured in parallel are operated at high temperature by waste heat using biogas of the gas storage tank.
At the front end of the dry digester and wet digester, a mixed storage tank for receiving and storing organic waste is installed.
A high temperature wet-dry parallel anaerobic digestion apparatus characterized by extinguishing in a high temperature condition by supplying waste heat or steam to the mixed storage tank to the temperature of the internal organic waste to a high temperature condition and supplying it to a dry digester and a wet digester.
A first screw dehydrator for dewatering the organic waste and separating the organic waste according to the solid concentration;
A dry digester for receiving anaerobic digestion by receiving a high concentration of organic material from the first screw dehydrator;
A wet digester receiving anaerobic digestion by receiving a low concentration of organic matter from the first screw dehydrator; And
A gas storage tank storing biogas produced from the dry digester and the wet digester; Including;
The dry digester and the wet digester configured in parallel are operated at high temperature by waste heat using biogas of the gas storage tank.
Install an external tank on the outside of the dry digester and wet digester,
A high temperature wet-dry parallel anaerobic digestion apparatus characterized by extinguishing in a high temperature condition by supplying waste heat or steam to the outer tank to circulate the outside of the dry digester and the wet digester.
A first screw dehydrator for dewatering the organic waste and separating the organic waste according to the solid concentration;
A dry digester for receiving anaerobic digestion by receiving a high concentration of organic material from the first screw dehydrator;
A wet digester receiving anaerobic digestion by receiving a low concentration of organic matter from the first screw dehydrator; And
A gas storage tank storing biogas produced from the dry digester and the wet digester; Including;
The dry digester and the wet digester configured in parallel are operated at high temperature by waste heat using biogas of the gas storage tank.
High temperature wet-dry parallel anaerobic digestion apparatus, characterized in that the dry digester and the wet digester inject at least one or more of limonite, iron oxide, iron sulfate, iron hydroxide as a hydrogen sulfide remover to remove hydrogen sulfide generated during the digestion process.
A first screw dehydrator for dewatering the organic waste and separating the organic waste according to the solid concentration;
A dry digester for receiving anaerobic digestion by receiving a high concentration of organic material from the first screw dehydrator;
A wet digester receiving anaerobic digestion by receiving a low concentration of organic matter from the first screw dehydrator; And
A gas storage tank storing biogas produced from the dry digester and the wet digester; Including;
The dry digester and the wet digester configured in parallel are operated at high temperature by waste heat using biogas of the gas storage tank.
High temperature wet-dry parallel anaerobic digester characterized in that the dry digester and the wet digester is added as ammonia remover limonite or zeolite to remove ammonia generated during the digestion process.
A first screw dehydrator for dewatering the organic waste and separating the organic waste according to the solid concentration;
A dry digester for receiving anaerobic digestion by receiving a high concentration of organic material from the first screw dehydrator;
A wet digester receiving anaerobic digestion by receiving a low concentration of organic matter from the first screw dehydrator; And
A gas storage tank storing biogas produced from the dry digester and the wet digester; Including;
The dry digester and the wet digester configured in parallel are operated at high temperature by waste heat using biogas of the gas storage tank.
The first end of the wet digester is installed with a first centrifugal dehydrator,
The sludge discharged from the wet digester goes through the centrifugal dehydration process of the first centrifugal dehydrator, and the dehydrated cake having a high solidity is transferred to the third mixed storage tank, and the dewatered cake of the third mixed storage tank is supplied to the dry compost tank and dried. High temperature wet-dry parallel anaerobic digester.
A first screw dehydrator for dewatering the organic waste and separating the organic waste according to the solid concentration;
A dry digester for receiving anaerobic digestion by receiving a high concentration of organic material from the first screw dehydrator;
A wet digester receiving anaerobic digestion by receiving a low concentration of organic matter from the first screw dehydrator; And
A gas storage tank storing biogas produced from the dry digester and the wet digester; Including;
The dry digester and the wet digester configured in parallel are operated at high temperature by waste heat using biogas of the gas storage tank.
The rear end of the dry digester is provided with a mixer that can add a flocculant or a coagulant to the sludge discharged from the dry digester,
Wherein said flocculant is a cationic inorganic polymer, and said flocculant is bentonite or incineration ash.
The method of claim 7, wherein
A second screw dehydrator installed at a rear end of the mixer and configured to receive and dehydrate the sludge discharged from the mixer;
A sedimentation tank installed at the rear end of the screw dehydrator to precipitate the dehydrated filtrate of the screw dehydration to separate solid-liquid; And
A second centrifugal dehydrator for receiving centrifugal dehydration by receiving a dehydration cake discharged from the settling tank; More,
In the settling tank, the dehydrated filtrate is concentrated to separate the supernatant and the concentrated dehydrated cake to reduce the water content of the dehydrated cake, and the precipitate is extracted through the filtrate precipitation to recover the microorganisms. Device.
The method of claim 8,
The dewatering cake discharged from the second screw dehydrator and the second centrifugal dehydrator is supplied to a third mixing reservoir, and the dehydration cake of the third mixing reservoir is supplied to a dry compost tank and dried to be treated. Anaerobic digestive system.
The method according to claim 6 or 9,
The dry compost tank is a high temperature wet-dry parallel anaerobic digestion apparatus, characterized in that for processing the supplied dehydration cake through a dryer to return the dehydrated cake with reduced moisture content to a dry digester.
delete delete (a) a waste separation step of dewatering the organic waste and separating it according to the solid concentration;
(b) a dry digestion step of receiving dry anaerobic digestion in a dry digester by receiving the high concentration organic material separated in the waste separation step;
(c) a wet digestion step of receiving anaerobic digestion in a wet digester by receiving the low concentration organic material separated in the waste separation step; And
(d) a gas storage step of storing the biogas produced from the dry digestion step and the wet digestion step; Including;
The dry digestion step of step (b) and the wet digestion step of step (c) are operated in parallel, wherein the dry digestion and wet digestion are performed at high temperature by waste heat using the stored biogas through step (d). Operates in,
At the front end of the dry digester and wet digester, a mixed storage tank for receiving and storing organic waste is installed.
A high temperature wet-dry parallel anaerobic digestion method characterized by extinguishing in a high temperature condition by supplying waste heat or steam to the mixed storage tank to the temperature of the internal organic waste to a high temperature condition and supplying it to a dry digester and a wet digester.
(a) a waste separation step of dewatering the organic waste and separating it according to the solid concentration;
(b) a dry digestion step of receiving dry anaerobic digestion in a dry digester by receiving the high concentration organic material separated in the waste separation step;
(c) a wet digestion step of receiving anaerobic digestion in a wet digester by receiving the low concentration organic material separated in the waste separation step; And
(d) a gas storage step of storing the biogas produced from the dry digestion step and the wet digestion step; Including;
The dry digestion step of step (b) and the wet digestion step of step (c) are operated in parallel, wherein the dry digestion and wet digestion are performed at high temperature by waste heat using the stored biogas through step (d). Operates in,
Install an external tank on the outside of the dry digester and wet digester,
High temperature wet-dry parallel anaerobic digestion method characterized in that the extinguishing is carried out at high temperature conditions by supplying waste heat or steam to the outer tank to circulate the outside of the dry digester and the wet digester.
(a) a waste separation step of dewatering the organic waste and separating it according to the solid concentration;
(b) a dry digestion step of receiving dry anaerobic digestion in a dry digester by receiving the high concentration organic material separated in the waste separation step;
(c) a wet digestion step of receiving anaerobic digestion in a wet digester by receiving the low concentration organic material separated in the waste separation step; And
(d) a gas storage step of storing the biogas produced from the dry digestion step and the wet digestion step; Including;
The dry digestion step of step (b) and the wet digestion step of step (c) are operated in parallel, wherein the dry digestion and wet digestion are performed at high temperature by waste heat using the stored biogas through step (d). Operates in,
High temperature wet-dry parallel anaerobic digestion method for the dry digester and the wet digester, at least one or more of limonite, iron oxide, iron sulfate, iron hydroxide as a hydrogen sulfide remover to remove hydrogen sulfide generated during the digestion process.
(a) a waste separation step of dewatering the organic waste and separating it according to the solid concentration;
(b) a dry digestion step of receiving dry anaerobic digestion in a dry digester by receiving the high concentration organic material separated in the waste separation step;
(c) a wet digestion step of receiving anaerobic digestion in a wet digester by receiving the low concentration organic material separated in the waste separation step; And
(d) a gas storage step of storing the biogas produced from the dry digestion step and the wet digestion step; Including;
The dry digestion step of step (b) and the wet digestion step of step (c) are operated in parallel, wherein the dry digestion and wet digestion are performed at high temperature by waste heat using the stored biogas through step (d). Operates in,
High temperature wet-dry parallel anaerobic digestion method characterized in that the dry digester and the wet digester is added as ammonia remover limonite or zeolite to remove the ammonia generated during the digestion process.
(a) a waste separation step of dewatering the organic waste and separating it according to the solid concentration;
(b) a dry digestion step of receiving dry anaerobic digestion in a dry digester by receiving the high concentration organic material separated in the waste separation step;
(c) a wet digestion step of receiving anaerobic digestion in a wet digester by receiving the low concentration organic material separated in the waste separation step; And
(d) a gas storage step of storing the biogas produced from the dry digestion step and the wet digestion step; Including;
The dry digestion step of step (b) and the wet digestion step of step (c) are operated in parallel, wherein the dry digestion and wet digestion are performed at high temperature by waste heat using the stored biogas through step (d). Operates in,
The first end of the wet digester is installed with a first centrifugal dehydrator,
The sludge discharged from the wet digester goes through the centrifugal dehydration process of the first centrifugal dehydrator, and the dehydrated cake having high solidity is transferred to the third mixed storage tank, and the dewatered cake of the third mixed storage tank is supplied to the dry compost tank and dried. High temperature wet-dry parallel anaerobic digestion.
(a) a waste separation step of dewatering the organic waste and separating it according to the solid concentration;
(b) a dry digestion step of receiving dry anaerobic digestion in a dry digester by receiving the high concentration organic material separated in the waste separation step;
(c) a wet digestion step of receiving anaerobic digestion in a wet digester by receiving the low concentration organic material separated in the waste separation step; And
(d) a gas storage step of storing the biogas produced from the dry digestion step and the wet digestion step; Including;
The dry digestion step of step (b) and the wet digestion step of step (c) are operated in parallel, wherein the dry digestion and wet digestion are performed at high temperature by waste heat using the stored biogas through step (d). Operates in,
In the rear end of the dry digester is installed a mixer that can add a flocculant or a coagulant to the sludge discharged from the dry digester,
Wherein said flocculant is a cationic inorganic polymer and said flocculant is bentonite or incineration ash.
19. The method of claim 18,
Installing a second screw dehydrator at the rear end of the mixer and supplying sludge discharged from the mixer to dewater the screw;
Installing a sedimentation tank at the rear end of the screw dehydrator and precipitating the screw dewatered filtrate to separate solid-liquid; And
Centrifugal dehydration of the dewatering cake discharged from the settling tank by being supplied from a second centrifugal dehydrator; More,
In the settling tank, the dehydrated filtrate is concentrated to separate the supernatant and the concentrated dehydrated cake to reduce the water content of the dehydrated cake, and the precipitate is extracted through the filtrate precipitation to recover the microorganisms. Way.
The method of claim 19,
The dewatering cake discharged from the second screw dehydrator and the second centrifugal dehydrator is supplied to a third mixing reservoir, and the dehydration cake of the third mixing reservoir is supplied to a dry compost tank and dried to be treated. Anaerobic Digestion Method.
The method of claim 17 or 20,
The dry compost tank is a high temperature wet-dry parallel anaerobic digestion method characterized in that the dehydration cake is supplied through a dryer to return the dehydrated cake with reduced moisture content to a dry digester.
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