JP2009050800A - Apparatus and method for treating organic waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for treating organic waste in which organic waste is methane-fermented, ammonia nitrogen is removed at a stripping step to decrease bubbles due to ammonia nitrogen and the concentration of carbon dioxide in the digestion gas to be produced at a methane fermentation step is decreased to obtain high-concentration methane gas, an installation area of the whole equipment can be reduced and the cost of equipment and the operating cost can also be reduced. <P>SOLUTION: The apparatus for treating organic waste, in which the ammonia nitrogen-containing organic waste is methane-fermented, is provided with: a heat treatment unit in which the organic waste is heated and the carbonate compounds and protein in the organic waste are subjected at least partially to decarbonation treatment and protein degeneration treatment; a stripping unit for discharging/removing a part of ammonia nitrogen from the organic waste heat-treated in the heat treatment unit by a stripping operation; and a methane fermentation tank in which the organic waste, from which a part of ammonia nitrogen is removed in the stripping unit, is methane-fermented to remove organic matter and recover the digestion gas. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a processing apparatus and a processing method for methane fermentation of livestock manure, food waste, organic wastewater containing high concentration ammoniacal nitrogen, or the like.
In addition, although it is called organic waste including waste and wastewater such as livestock excreta containing the organic matter in high concentration, it may be described in terms of each.

  Conventionally, organic waste containing high concentrations of ammonia nitrogen has been denitrified by various methods to prevent eutrophication of rivers and sea areas. However, the measures for pig manure, chicken manure, cattle manure, horse manure, sheep manure, and other livestock manure are currently being delayed, and groundwater and river pollution is serious, and measures are urgently needed. It has become.

  Conventionally, as a method for treating livestock manure, solid-liquid separation of livestock manure is performed, and the separated liquid is subjected to methane fermentation to recover digestion gas containing high concentration of methane. A method for removing ammonia nitrogen, which becomes an inhibitory factor in air, by a stripping method using air or the like is disclosed (Patent Document 1).

  Further, in a method of removing ammonia from an organic wastewater / sludge having a high ammoniacal nitrogen content in an ammonia stripping process and subjecting the treated organic wastewater / sludge to methane fermentation in a methane fermentation process, it is passed through a heat exchanger at 70 to 99 ° C. Also disclosed is a method of adjusting ammonia to pH 9 to 13 by adding a strong alkaline solution composed of electrolyzed water generated by an electrolysis apparatus as a pH adjuster to organic waste water / sludge whose temperature is adjusted, and ammonia stripping. (Patent Document 2).

  Furthermore, in a method of removing ammonia from an object to be treated consisting of organic waste, organic waste water, or a mixture thereof in an ammonia removal step, and subjecting the object to be treated from which ammonia has been removed to methane fermentation in a methane fermentation step, ammonia Methane fermentation is performed in which an ammonia generation process is performed to biologically treat the object to be treated at the first stage of the removal process, ammonia is generated from nitrogen contained in the object to be treated, and methane fermentation is performed after removing ammonia with a high removal rate. A method is disclosed (Patent Document 3).

  Furthermore, the digestive liquid after the organic waste is treated with methane is solid-liquid separated, and the separated desorbed liquid and the sulfur absorbing liquid that has been desulfurized by absorbing sulfur components from the digested gas are used as biological nitrification desulfurization as a nitrification circulating liquid. There is disclosed a methane fermentation treatment apparatus that performs denitrification treatment with a nitriding means and separates the denitrification treatment liquid into solid and liquid in a precipitation tank to obtain clarified treated water (Patent Document 4).

  In the processing methods described in Patent Document 1, Patent Document 2 and Patent Document 3, ammonia is removed from organic waste by stripping or the like before the methane fermentation, so that ammonia inhibits methane fermentation. Although the problem of becoming a factor is unlikely to occur, in the treatment method described in the above-mentioned document, an operation of removing most of the ammoniacal nitrogen by a stripping process or the like is performed. However, if most of the ammonia nitrogen is removed, the amount of carbon dioxide generated in the methane fermentation increases, the proportion of carbon dioxide in the produced digestion gas increases, and the PH in the methane fermentation tank decreases. There is a problem that needs to be adjusted.

  Further, in the treatment methods described in the above-mentioned documents, no attention is paid to carbonic acid compounds and proteins in organic waste. However, as the content of carbonic acid compounds and proteins increases, ammonia nitrogen is removed by stripping operation. In the stripping process for discharging and removing the foam, foaming is vigorously induced. Therefore, the stripping process is usually performed by adding an antifoaming agent. Therefore, there is a problem that the amount of the expensive antifoaming agent used is extremely increased in the stripping process in the above-mentioned document which does not pay attention to carbonic acid compounds and proteins in organic waste.

Furthermore, it is difficult to maintain a high sludge concentration in the denitrification apparatus in the method of biological denitrification treatment for digested liquid after methane fermentation treatment described in Patent Document 4, and a sedimentation tank is provided. Therefore, there is a problem that the installation area of the entire apparatus becomes excessive.
JP 2000-263097 A JP 2001-113265 A JP 2004-024929 A JP 2006-167512 A

The present invention has been made in view of the above circumstances, and in the methane fermentation treatment of organic waste, the suppression of foaming in the removal treatment by the stripping process of ammonia nitrogen and the carbon dioxide in the digestion gas produced in the methane fermentation process. An organic waste treatment apparatus and treatment method that can reduce gas concentration, obtain high-concentration methane gas, and reduce the overall equipment installation area and equipment costs and operating costs. It was made for the purpose of providing.
In addition, the present invention has been made for the purpose of recovering various processed products discharged in the processing step as processed products that can be effectively used as fertilizer, fuel gas, and the like.

  The gist of the present invention for achieving the above object is that the present invention according to claim 1 is the organic waste processing apparatus for treating methane fermentation of organic waste containing ammoniacal nitrogen. A heat treatment device for heating the waste to decarboxylate and denature the carbonic acid compound and protein in the organic waste, respectively, and the heated organic waste heat-treated by the heat treatment device Stripping device that discharges and removes a part of ammonia nitrogen by stripping operation, and organic waste from which ammonia nitrogen part is removed by the stripping device, methane fermentation to remove organic matter and digestion gas An organic waste processing apparatus comprising a methane fermenter that collects the waste.

  The present invention according to claim 2 is a scum separation tank that separates the floating solids floating in the methane fermentation tank into three phases of a precipitation phase, an aqueous phase, and a scum phase, and the uppermost layer is separated by the scum separation tank. The organic waste according to claim 1, further comprising: a scum circulation path for circulating the scum phase to the methane fermentation tank; and a sedimentation sludge circulation path for circulating the sedimentation sludge settled and separated in the lowermost layer to the methane fermentation tank. It is a processing device.

  The present invention described in claim 3 further includes a membrane separation denitrification apparatus for denitrifying the aqueous phase separated into the intermediate layer in the scum separation tank and solid-liquid separation with a separation membrane to obtain clarified treated water. An organic waste treatment apparatus according to claim 2.

  The present invention according to claim 4 is a method for treating organic waste in which organic waste containing ammoniacal nitrogen is subjected to methane fermentation treatment, wherein the organic waste is heated in a heat treatment tank and the organic waste is treated. A heat treatment step of decarboxylation and protein denaturation treatment of at least part of the carbonic acid compound and protein in the waste, and discharging and removing the generated carbon dioxide gas, and heating organic waste heat-treated in the heat treatment step A stripping process in which a part of ammonia nitrogen is discharged and removed by a stripping operation in a stripping apparatus, and organic waste from which a part of ammonia nitrogen has been removed in the stripping process is subjected to methane fermentation to produce organic matter. It is the processing method of the organic waste characterized by including the removal of gas and the methane fermentation process which collect | recovers digestion gas.

  The present invention according to claim 5 is a scum separation step of separating the floating solid matter floating in the methane fermentation tank into three phases of a precipitation phase, an aqueous phase and a scum phase, and separation into the uppermost layer in the scum separation step A scum circulation step in which the scum phase is circulated to the methane fermentation tank, a sedimentation sludge circulation step in which the sedimentation sludge settled and separated in the lowermost layer is circulated to the methane fermentation tank, and an aqueous phase separated in the intermediate layer in the scum separation step. The organic waste treatment method according to claim 4, further comprising a membrane separation denitrification step of denitrifying and solid-liquid separation with a separation membrane to obtain clarified treated water.

  The present invention described in claim 6 is the method for treating organic waste according to claim 4 or claim 5, wherein the organic waste is livestock manure.

The present invention according to claim 7 adjusts the ammonia nitrogen concentration in the organic waste from which a part of ammonia nitrogen has been removed in the stripping step to 1,000 to 2,000 mg / L. It is a processing method of the organic waste given in any 1 paragraph of Claims 6.
In addition, when the ammonia nitrogen concentration is less than 1,000 mg / L, the amount of carbon dioxide generated by methane fermentation reacts with the ammonia nitrogen in the digestive juice and is fixed as ammonium carbonate or ammonium hydrogen carbonate, Therefore, the methane concentration in the digestion gas is lowered. On the other hand, when it exceeds 2,000 mg / L, the influence of fermentation inhibition by ammonia appears.

The present invention according to claim 8 is the organic waste treatment method according to any one of claims 4 to 7, wherein the heat treatment is performed at a temperature of 60 to 85 ° C and a residence time of 3 to 20 hours. .
When the heating temperature is less than 60 ° C., decarboxylation and protein denaturation are insufficient, and the effect of reducing the amount of antifoaming agent used is low. On the other hand, when the temperature exceeds 85 ° C., foaming is induced and ammonia-based properties are reduced. Nitrogen volatilization increases. Moreover, if the residence time is less than 3 hours, decarboxylation and protein denaturation are insufficient, and the effect of reducing the amount of antifoaming agent used is low. On the other hand, if the residence time exceeds 20 hours, the amount of heat is consumed. The improvement effect of reducing the amount of antifoam used cannot be expected.

  Here, the heat treatment device is heated to a temperature of 60 to 85 ° C., preferably 70 to 80 ° C. by an appropriate heating device such as heating by indirect steam or direct steam, electric heating, etc. Since it is a carbon dioxide gas, it is released into the atmosphere, but if it generates odors, it is preferably released through an appropriate deodorizing equipment such as a biological deodorizing device. If the temperature is less than 60 ° C, protein denaturation, decarboxylation amount, etc. will be insufficient, foaming properties will be large, and there will be little effect of reducing the amount of defoaming agent used to supply to the ammonia stripping device, while the temperature is 85 ° C. If the temperature is higher than that, foaming is caused in the apparatus and the volatilization of ammonia nitrogen increases. Therefore, it is necessary to dispose a cooler. The heating residence time is 3 to 20 hours. If it is less than 3 hours, the denaturation of protein and the amount of decarboxylation will be insufficient. On the other hand, if it is longer than 20 hours, the effect on the amount of protein modification and decarboxylation will be small compared to the heat of heating.

The stripping apparatus blows heated steam from the lower part, decomposes ammonia nitrogen in the organic waste to be treated as ammonia, and fractionates it with a plurality of upper stages along with the steam, thereby purifying ammonia purity. However, it may be a device that purges ammonia with superheated air or a mixture of air and water vapor.
As an operating condition of the stripping apparatus, stripping is performed with water vapor having a pressure of 10 kPa to 20 kPa and a temperature of 100 ° C. to 105 ° C. In addition, the residence time of the organic waste to be treated is adjusted to 10 to 30 minutes, and PH is adjusted to 7.0 to 8.0.

  As the methane fermentation tank, a methane fermentation tank, a combination apparatus of an acid fermentation tank and a methane fermentation tank, an upward flow anaerobic treatment apparatus (UASB apparatus), or the like can be adopted. The recovered digestion gas can be used as fuel. In addition, although the processing temperature of methane fermentation in a methane fermentation tank is not limited, For example, it is about 35-38 degreeC in a medium temperature fermentation processing method, and is about 54-56 degreeC in a high temperature fermentation processing method. The residence time is preferably 2 days to 2 weeks.

  The membrane separation and denitrification apparatus that obtains clarified treated water by solid-liquid separation using a separation membrane after the denitrification treatment has an anaerobic denitrification tank and an aerobic nitrification tank, and circulates the nitrification liquid in the nitrification tank to the denitrification tank. A device that combines a circulating denitrification device to be treated with a membrane separation device that separates the nitrification solution with a filtration membrane is used, but the membrane separation device may be separated from the circulating denitrification device, It may be installed in the tank. In addition, as a denitrification apparatus, it is not limited to a circulation denitrification apparatus, The denitrification reaction tank (Anamox reaction tank) holding the granule sludge containing an autotrophic denitrification microorganism may be sufficient.

  In the present invention according to claim 1, at least a part of the carbonic acid compound and protein in the organic waste that causes foaming in the heat treatment device is decarboxylated and protein-denatured, respectively, so that the ammonia stripping device is obtained. Since it supplies, the usage-amount of the antifoamer which suppresses foaming can be reduced. In addition, because ammonia nitrogen, which is an inhibitory factor in methane fermentation, is reduced to a concentration that does not affect methane fermentation and supplied to the methane fermentation tank using a stripping device, efficient fermentation treatment is possible and some ammonia The amount of carbon dioxide generated in methane fermentation can be suppressed by reducing the amount of carbon dioxide in the methane fermentation, and the proportion of carbon dioxide in the produced digestion gas can be kept low, and the PH in the methane fermentation tank is also maintained at a suitable value. be able to. Note that the present invention described in claim 4 has the same effect.

  In addition, in the present invention described in claim 2, in addition to the effects of the present invention described in claim 1, the floating solid matter that has floated in the methane fermentation tank is converted into a three-phase structure including a precipitation phase, an aqueous phase, and a scum phase. Since the scum phase separated and separated into the uppermost layer and the settled sludge separated and separated into the lowermost layer are circulated to the methane fermentation tank, there is a need to worry about sludge flowing into the treated water due to sludge floating in the methane fermentation tank. In addition, the sludge concentration in the methane fermentation tank can be maintained high.

Furthermore, in the present invention described in claim 3, in addition to the effect of the present invention described in claim 2, the aqueous phase separated into the intermediate layer in the scum separation tank is denitrified and solid-liquid separated by a separation membrane. By obtaining the clarified treated water, the clarified treated water can be directly discharged to a river or the like, and the installation area of the apparatus can be greatly reduced by using a separation membrane for solid-liquid separation.
Note that the present invention described in claim 5 has the same effect.

Moreover, also in this invention of Claims 6-8, there can exist the effect of this invention in any one of the said Claims 4-5.
Furthermore, in the present invention described in claim 7, the concentration of methane in the digestion gas can be increased and fermentation inhibition by ammonia can be prevented. In the present invention described in claim 8, Can suppress foaming and volatilization of ammonia, sufficiently perform decarboxylation and protein denaturation, and can greatly reduce the amount of antifoaming agent used in the ammonia stripping step.

The present invention will be specifically described below.
FIG. 1 is a system diagram of an organic waste processing apparatus according to an embodiment of the present invention.

  FIG. 1 shows a processing apparatus for livestock excreta as organic waste, and the main apparatus configuration is an adjustment tank 1 for adjusting the supply amount of organic waste, heat treatment for decarboxylation and protein denaturation processing. Tank 2, stripping device 3 for discharging and removing a part of ammonia nitrogen, methane fermentation tank 4 for methane fermentation, scum separation tank 5 for separating three phases of floating solids floating in the methane fermentation tank, scum separation tank 5 And a membrane separation denitrification device 10 comprising a separation membrane device 7 for solid-liquid separation with a separation membrane to obtain clarified treated water.

Hereinafter, these configurations will be described in detail.
In order to adjust the supply amount of the separation liquid, the adjustment tank 1 supplies liquid organic waste (hereinafter referred to as “separation liquid”) obtained by removing contaminants from livestock manure with the screen 11 to a subsequent processing step. It is a storage tank that stores, and PH adjustment is performed if necessary. In addition, it may replace with the screen 11 and may be another solid-liquid separation apparatus, and the dephosphorization apparatus which removes phosphorus from a separation liquid may be arrange | positioned in the back | latter stage of the adjustment tank 1. FIG. As the dephosphorization apparatus, it is preferable to use a crystallization dephosphorization apparatus for dephosphorization by bringing magnesium, calcium, phosphorus and crystal species in livestock manure into contact with each other and precipitating a calcium phosphate compound or the like.

  The heat treatment tank 2 decarboxylates at least a part of the carbonic acid compound and the protein in the separated liquid by heat-treating the separated liquid with the steam heater 2a while stirring with the stirrer 2b at a predetermined temperature and residence time. And a treatment tank for protein denaturation treatment, and the heat-treated liquid (hereinafter referred to as “decarboxylation liquid”) is supplied to the subsequent stripping apparatus 3 via the heat exchanger 12.

  The stripping device 3 is a tray-type distillation tower that discharges and removes a part of ammonia nitrogen in the decarbonation liquid. The decarbonation liquid subjected to heat treatment is supplied from the middle stage of the tower, and steam is directly blown into the bottom of the tower. Then, the ammonia content in the organic waste rises accompanied by the rising steam, is fractionated and concentrated by the shelf, is discharged as an ammonia-containing vapor from the top of the tower, is introduced into the ammonia storage tank 14 through the condenser 13, Stored as concentrated ammonia water. In addition, a deammonia liquid (hereinafter referred to as “deammonia liquid”) is extracted from the bottom of the tower, and heat-exchanged with the decarbonation liquid supplied to the stripping device 3 by the heat exchanger 12 to be adjusted to a suitable temperature. Then, it is configured to be supplied to the subsequent methane fermentation tank 4.

  The methane fermentation tank 4 is an apparatus for recovering digestion gas containing methane that is used as a fuel by subjecting the deammonification liquid supplied from the stripping apparatus 3 to methane fermentation by the action of methane-producing bacteria. Specifically, the methane fermentation apparatus 4 communicates with a fermentation tank 4a that contains a deammonification liquid that is a methane treatment liquid, a draft tube 4b that is disposed vertically in the center of the fermentation tank, and a draft tube 4b. The fermenter 4a has a sealed structure covered with the head tank 4c.

  The scum separation tank 5 is a sedimentation separation tank that separates floating solids that have floated in the methane fermentation tank into three phases: a precipitation phase, an aqueous phase, and a scum phase. It is circulated and used for maintaining the sludge concentration in the methane fermentation tank 4, and the remainder is supplied to the dehydrator 9 for processing.

  The membrane separation denitrification apparatus 10 is a combination of a circulation denitrification apparatus 6 that circulates and processes the nitrification liquid in the nitrification tank 6b to the denitrification tank 6a and a membrane separation apparatus 7 that separates the nitrification liquid with a filtration membrane. The aqueous phase separated into the intermediate layer in the scum separation tank 5 is denitrified and solid-liquid separated by a separation membrane to obtain clarified treated water.

Next, a processing method for processing livestock excreta based on the system diagram of the livestock excrement processing apparatus according to the present invention shown in FIG. 1 will be described.
First, livestock manure is supplied to the screen 11 to remove impurities from the livestock manure. The separated impurities can be composted by a composting apparatus (not shown) as an organic solid content processing apparatus together with the dewatered sludge by the dehydrator 9 described later, and can be used effectively.

  The separation liquid separated by the screen 11 is supplied to and stored in the adjustment tank 1, is appropriately adjusted to the supply amount, and is supplied to the heat treatment tank 2. The separation liquid supplied to the heat treatment tank 2 is heated to a temperature of 60 to 85 ° C., preferably 70 to 80 ° C. by a steam heater 2a while being stirred by a stirrer 2b, and the residence time is processed for 3 to 20 hours. The Since the generated gas is mainly carbon dioxide gas, it is released to the atmosphere, and in the case of generating odor, it is released through an appropriate deodorizing equipment such as a biological deodorizing device. Further, when there is a risk of volatilization of ammonia, a cooler is arranged and condensed and refluxed.

  The decarboxylation solution heated for the predetermined time is supplied to the subsequent stripping device 3 through the heat exchanger 12, and an antifoaming agent is added by an antifoaming agent supply device (not shown). In the decarboxylation solution, since at least a part of the carbonic acid compound and the protein is decarboxylated and protein-denatured, respectively, it is possible to add a defoamer amount that is extremely smaller than before.

  The decarboxylation solution supplied to the stripping apparatus 3 is supplied with the decarboxylation solution heated from the middle stage of the tower, and steam is blown directly into the bottom of the tower, so that the ammonia content in the organic waste rises to steam. It rises along with it, is fractionally concentrated by a shelf, is discharged as an ammonia-containing vapor from the top of the tower, is introduced into an ammonia storage tank 14 via a condenser 13, and is stored as concentrated ammonia water. In the stripping process, the stripping process is performed with water vapor having a pressure of 10 kPa to 20 kPa and a temperature of 100 ° C. to 105 ° C. Moreover, the residence time of the decarboxylation liquid to process is adjusted to 10-30 minutes. The ammoniacal nitrogen concentration after stripping is adjusted to 1,000 to 2,000 mg / L. Here, when the ammoniacal nitrogen concentration is less than 1,000 mg / L, the amount of carbon dioxide generated by methane fermentation reacts with the ammoniacal nitrogen in the digestive juice and is fixed as ammonium carbonate or ammonium bicarbonate. Therefore, the methane concentration in the digestion gas is lowered. On the other hand, when it exceeds 2,000 mg / L, the influence of fermentation inhibition by ammonia appears. Furthermore, PH is maintained at 7.5 to 8.5. Outside the PH range, the effect of PH inhibition in methane fermentation appears.

  The deammonia solution that has been subjected to deammonia treatment by the stripping device 3 is extracted from the bottom of the column, and heat-exchanged with the decarbonation solution supplied to the stripping device 3 by the heat exchanger 12 to be adjusted to an appropriate temperature, followed by To the methane fermentation tank 4.

The deammonia solution supplied to the methane fermentation tank 4 is produced by a medium temperature fermentation treatment method at 35 to 38 ° C in the fermentation tank 4a, but may be a high temperature fermentation treatment method at about 54 to 56 ° C. Moreover, PH in methane fermentation treatment is maintained at 8.0 to 8.5, and is operated at a volumetric load CODcr (chemical oxygen demand measured using potassium dichromate) 20 to 25 kg / m ³ / d. Is done. The generated digested gas stays in the gas reservoir formed at the upper part of the fermenter 4a to increase the internal pressure, and communicates with the draft tube 4b to push up the digested liquid to the head tank 4c disposed at the upper part.

Digestion gas staying in the gas reservoir formed in the upper part of the fermenter 4 a is discharged from the digestion gas discharge pipe at that pressure, supplied to the desulfurization tower 8 through the seal pot 15, and mixed in the digestion gas by the desulfurization tower 8. Hydrogen sulfide to be removed is removed and stored in the gas holder 16. Digestion gas stored in the gas holder 16 is appropriately used as heated fuel or the like. The generated digestion gas is decomposed in the heat treatment tank 2 to remove carbonates such as ammonium carbonate and ammonium hydrogen carbonate in the separated liquid and removed as carbon dioxide gas. Since it reacts with the residual ammoniacal nitrogen and is fixed as carbonate, the methane concentration can be kept high, and the value as a fuel for fuel cells and the like is also increased.

  The digested liquid that rises and stays in the head tank 4c floats on the liquid surface to form a scum layer, but the floated solids are extracted from the extraction pipe and supplied to the scum separation tank 5, It is separated into three phases: precipitation phase, aqueous phase and scum phase. A part of the scum phase separated into the uppermost layer of the scum separation tank 5 and a portion of the settled sludge settled and separated into the lowermost layer is circulated to the methane fermentation tank 4 to maintain the sludge concentration in the methane fermentation tank. Therefore, there is no need to worry about the sludge flowing into the treated water due to the sludge floating in the methane fermentation tank 4 as in the prior art, and the sludge concentration in the methane fermentation tank can be kept high. In addition, the solid content concentration in the methane fermentation tank 4 is adjusted to be 4 wt% to 15 wt%.

  The aqueous phase separated in the middle stage in the scum separation tank 5 is supplied to the denitrification tank 6a of the denitrification apparatus 6 in the membrane separation denitrification apparatus 10 and maintained anaerobic, and the aerobic nitrification tank 6b disposed in the subsequent stage. Biological denitrification treatment is performed by circulating between them. A part of the nitrification liquid denitrified by the denitrification apparatus 6 is supplied to the membrane separation apparatus 7, solid-liquid separated by the separation membrane, and the separation liquid that has permeated the separation membrane is discharged out of the system as clarified treated water. . Further, the concentrated liquid obtained on the non-permeating side of the separation membrane is circulated to the denitrification tank 6a and used as a carbon source for biological denitrification reaction.

  Further, a part of the denitrification sludge is extracted from the denitrification tank 6a, supplied to the dehydrator 9 together with a part of the settled sludge in the scum separation tank 5, and dehydrated and composted by a composting device or the like. Can be used. The liquid separated by the dehydrator 9 is circulated to the denitrification tank 6a and processed again.

  By configuring the livestock manure processing device in this way and processing livestock manure, methane fermentation of livestock manure can be performed efficiently, and the livestock manure that is the waste can be removed by the nearby farmhouse of the discharge source, etc. It can be recovered as many effective processed materials such as livestock feed, fertilizer and fuel gas that can be used, and discharge as waste can be minimized.

Test Example A test example in which pig manure was treated is described below. In addition, the screen exit liquid property (hereinafter referred to as “stock solution”) of the treated swine manure is as follows.
CODcr (chemical oxygen demand measured using potassium dichromate) = 41,000 mg / L, TN (total nitrogen) = 4,100 mg / L, NH ₄ —N (ammonia nitrogen) = 2 , 900 mg / L, SS (floating matter) = 18,000 mg / L, PH = 8.2

1. Change in the amount of antifoam added by treatment in the heat treatment tank (defoamer added in which the effect is recognized)
As the antifoaming agent, a silicone-based antifoaming agent (manufactured by Shin-Etsu Chemical Co., Ltd., KM-73) is used <Influence of temperature>
Defoamer addition amount in the stock solution: 400-450 mg / L
Temperature 60 ° C., 20 hours, heat treatment: 100 to 150 mg / L
Temperature 70 ° C., 20 hours, heat treatment: 100 to 150 mg / L
Temperature 80 ° C., 20 hours, heat treatment: 40-50 mg / L
<Influence of heating time>
Defoamer addition amount in the stock solution: 3,000 mg / L
Temperature 80 ° C., 1 hour, heat treatment: 600 mg / L
Temperature 80 ° C., 5 hours, heat treatment: 400 mg / L
Temperature 80 ° C., 20 hours, heat treatment: 200 mg / L
From the results, it was found that the amount of antifoaming agent used can be greatly reduced by heat treatment.

2. Effect of deammonification on methane fermentation Ammonia was removed by a stripping device, supplied to a methane fermentation tank, and the treatment performance was examined by medium temperature fermentation at a temperature of 35 ° C. As a result, when ammoniacal nitrogen exceeded 2,000 mg / L, the CODcr removal rate decreased to 40% or less, and 1,000 to 2,000 mg / L of organic acid in the methane fermentation tank accumulated.
From the above results, it was found that the influence of fermentation inhibition by ammonia appears as the amount of ammoniacal nitrogen increases.

Example 1
An embodiment in which pig manure at the screen exit is treated according to the present invention will be described.
Stock solution CODcr: 45,000 mg / L, BOD: 24,000 mg / L, VTS [Loss on ignition (reduction rate when evaporation residue is ignited at 600 ° C.)]: 18,000 mg / L, T _{-N: 5,000mg / L, NH 4} -N: 4,200mg / L, SS: 15,000mg / L, PH: 8.2
The stock solution was heat-treated in a heat treatment tank at a temperature of 80 ° C. for 20 hours, CO ₂ removal rate: 50%, PH: 8.6 to 8.9, NH ₄ —N: 2,600 to 3,800 mg / L was supplied to the stripping device, deammoniated with the stripping device, and supplied to the methane fermenter as ammonia nitrogen amount: 1,300 to 1,800 mg / L, PH: 7.5 to 8.0. .
As a result of processing in a methane fermenter at a temperature of 35 ° C., a pH of 8.2 to 8.5, a volumetric load CODcr of 20 kg / m ³ / d, and a VTS of 7 kg / m ³ / d, the amount of methane generated: 500 Nm ³ was -CH ₄ / T- entrance VTS. Further, the gas _{composition, CH 4: 80~88vol%, CO} 2: was 20~12vol%.
In the conventional method without heat treatment or deammonia treatment, the volume load VTS was 2.5 to ³ kg / m ³ / d, and the amount of methane generated was 350 Nm ³ —CH ₄ / T-inlet VTS. Further, the gas _{composition, CH 4: 60vol%, CO} 2: was 40 vol%.
From the above results, it was found that a very high concentration of methane gas can be produced and recovered in a large amount in the present invention in which the amount of ammoniacal nitrogen is left at about 1,000 to 2,000 mg / L and methane fermentation treatment is performed. Thus, the high methane concentration is due to the fact that the carbonate in the stock solution is removed as carbon dioxide in the heat treatment tank, and the carbon dioxide generated during methane fermentation reacts with the residual ammoniacal nitrogen to produce carbonic acid. It is thought to be due to a synergistic effect fixed as a salt.

  Moreover, as a result of supplying and processing the digested liquid after the said methane fermentation process to a membrane separation denitrification apparatus, clarified treated water is BOD (biochemical oxygen demand): 10-20 mg / L, TN: 50- 120 mg / L could be maintained.

  INDUSTRIAL APPLICABILITY According to the present invention, it is useful for the treatment of livestock manure such as cattle, pigs, chickens, horses and sheep, food waste, or organic waste such as organic wastewater containing a high concentration of ammonia nitrogen.

It is a systematic diagram of the processing device of organic waste (livestock manure) concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Adjustment tank 2: Heat processing tank 3: Stripping apparatus 4: Methane fermentation tank 5: Scum separation tank 6: Denitrification apparatus 6a: Denitrification tank 6b: Nitrification tank 9: Membrane separation denitrification apparatus

Claims (8)

In the organic waste treatment equipment for methane fermentation of organic waste containing ammonia nitrogen,
A heat treatment apparatus that heats the organic waste and decarboxylates and protein-denatures at least part of the carbonic acid compound and the protein in the organic waste, and
A stripping device that discharges and removes a part of the ammoniacal nitrogen by a stripping operation from the heated organic waste heat-treated by the heat treatment device;
A methane fermentation tank for removing organic matter and recovering digestion gas from organic waste from which ammonia nitrogen has been partially removed by the stripping device,
And an organic waste processing apparatus. A scum separation tank for separating the floating solids floating in the methane fermentation tank into three phases of a precipitation phase, an aqueous phase and a scum phase;
A scum circulation path for circulating the scum phase floated and separated in the uppermost layer in the scum separation tank to the methane fermentation tank, and a settling sludge circulation path for circulating the settled sludge settled and separated in the lowermost layer to the methane fermentation tank,
The organic waste processing apparatus according to claim 1, further comprising: A membrane separation and denitrification device for obtaining a clarified treated water by denitrifying the aqueous phase separated into an intermediate layer in the scum separation tank and performing solid-liquid separation with a separation membrane;
The organic waste processing apparatus according to claim 2, further comprising: In the organic waste processing method of fermenting methane fermentation of organic waste containing ammonia nitrogen,
A heating treatment step of heating the organic waste in a heat treatment tank to decarboxylate and denature each of the carbonic acid compound and protein in the organic waste, and discharge and remove the generated carbon dioxide; ,
A stripping step of discharging and removing a part of the ammoniacal nitrogen by a stripping operation in a stripping apparatus from the heated organic waste heat-treated in the heat treatment step;
Organic waste from which a part of ammonia nitrogen has been removed in the stripping process is subjected to methane fermentation to remove organic substances and collect digestion gas,
And a method for treating organic waste. A scum separation step of separating the floating solids floating in the methane fermentation step into three phases of a precipitation phase, an aqueous phase and a scum phase;
A scum circulation step for circulating the scum phase separated in the uppermost layer in the scum separation step to the methane fermentation tank, and a settling sludge circulation step for circulating the settled sludge settled and separated in the lowermost layer to the methane fermentation tank;
A membrane separation denitrification step in which the aqueous phase separated into the intermediate layer in the scum separation step is denitrified and subjected to solid-liquid separation in a separation membrane to obtain clarified treated water;
The organic waste processing method according to claim 4, further comprising:   The method for treating organic waste according to claim 4 or 5, wherein the organic waste is livestock manure. The ammonia nitrogen concentration in the organic waste from which a part of the ammonia nitrogen has been removed in the stripping step is adjusted to 1,000 to 2,000 mg / L. A method for treating organic waste as described in 1. above.
  The organic waste treatment method according to any one of claims 4 to 7, wherein in the heat treatment step, the heat treatment is performed at a temperature of 60 to 85 ° C and a residence time of 3 to 20 hours.

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