JP2019034870A - Liquid fertilizer producing system - Google Patents

Abstract

To provide a liquid fertilizer producing system capable of producing a liquid fertilizer that can be applied for fertilization to rice paddies and farmlands with an appropriate concentration and in an easy manner by processing a methane fermentation residual liquid.SOLUTION: A liquid fertilizer producing system 1 of this invention, which produces a liquid fertilizer from a methane fermentation residual liquid 2 that remains after methane is produced by fermenting organic waste, comprises: first separation means 3 that separates a first solid content by a first screen from the methane fermentation residual liquid 2; first adjustment means 4 that adjusts pH of a separate liquid 22 from which the first solid content is separated by the first separation means 3 to be acidic; condensation means 5 that evaporatively condenses a separate liquid 23 adjusted to be acidic by the first adjustment means 4; and retention means 7 that retains as the liquid fertilizer a condensed liquid 24 evaporatively condensed by the condensation means 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid fertilizer production system.

  Among biomass as energy resources, a technology is known that can recover energy at low cost from methane fermentation from wet biomass such as food processing residue, agricultural wastewater sludge, garbage, food processing residue, sewer sludge, human waste, etc. . In the process of methane fermentation, since a fermentation residue is produced, it is necessary to efficiently treat this fermentation residue. For example, a method for treating organic waste including methane fermentation of organic waste and a methane fermentation process for collecting the produced biogas and a concentration process for concentrating the fermentation residual liquid of the methane fermentation process is proposed. (For example, refer to Patent Document 1). The concentrate obtained by concentrating the methane fermentation residual liquid can be used as a fertilizer or a fertilizer raw material. However, considering the workability of fertilization to rice fields and fields, it is desirable to produce it as a liquid fertilizer that can be sprayed. Examples of important indicators for converting the methane fermentation residual liquid to liquid fertilizer include that nitrogen, phosphorus, and potassium are at appropriate concentrations, and that there is no problem when spraying liquid fertilizer.

JP 2004-298688 A

  Although the methane fermentation residual liquid contains a nitrogen component, ammonia nitrogen is easily volatilized in the alkaline state among the nitrogen components. For example, fertilization to high-density rice fields and fields other than pasture requires nitrogen, phosphorus, and potassium to have appropriate concentrations, but the pH of the methane fermentation residue is alkaline. The above method has a problem that ammonia nitrogen is volatilized during the concentration step and the concentration of the nitrogen component is lowered. Moreover, since the fermentation residual liquid contains suspended substances derived from the raw materials, there is also a problem that particles having a certain size or more are clogged in the spray nozzle during fertilization.

  The objective of this invention is providing the liquid fertilizer production | generation system which can produce | generate the liquid fertilizer which is a density | concentration suitable for the fertilization to a field or a field, and is easy to spread by processing a methane fermentation residual liquid.

  The liquid fertilizer production system according to claim 1 is a liquid fertilizer production system that produces liquid fertilizer from methane fermentation residual liquid remaining after fermenting organic waste and generating methane, and from the methane fermentation residual liquid, by a first screen A first separation means for separating the first solid content, a first adjustment means for adjusting the pH of the separation liquid from which the first solid content has been separated by the first separation means, and an acidity by the first adjustment means. And a concentrating means for evaporating and concentrating the separated liquid, and a storing means for storing the concentrated liquid evaporated and concentrated by the concentrating means as the liquid fertilizer. The liquid fertilizer production system can increase the concentration of nitrogen, phosphorus, and potassium contained in the produced concentrated liquid by concentrating the separated liquid by means of concentration, so that it can be applied to fields with high harvest density, for example. Can provide liquid fertilizer. The liquid fertilizer production system can previously remove the first solid content from the methane fermentation residual liquid by the first separation means. Thereby, when the liquid fertilizer concentrated and produced | generated by a concentrating means is sprayed on soil by spray etc. after that, it can prevent that the clogging by a 1st solid content arises in a spray nozzle. Moreover, the liquid fertilizer production | generation system can fix the ammonia component in a separated liquid by adjusting the pH of a separated liquid to acidic by a 1st adjustment means. Thereby, the nitrogen component contained in the liquid manure produced after being concentrated by the concentration means can be secured.

  The liquid fertilizer production system according to claim 2 may include second separation means for separating a second solid content from the concentrated liquid stored by the storage means by a second screen. Thereby, the liquid manure production system can remove the second solid content by the second separation means. For example, when spraying liquid fertilizer on the soil with a spray or the like, it is possible to further prevent the spray nozzle from being clogged with the second solid content. In addition, it is necessary to increase the filtration area to remove fine solids with the first screen alone, whereas when removing fine second solids with the second screen, the slit of the first screen Is rougher than the slit of the second screen. Moreover, the filtration area may be small, and the amount of the concentrated liquid after the second screen may be small and the filtration area may be small. Therefore, the second solid content finer than the first solid content can be removed, and the equipment can be downsized.

  The liquid fertilizer production system according to claim 3 may include second adjusting means for adjusting pH of the concentrated liquid evaporated and concentrated by the concentration means to 5 to 8. Thereby, since the liquid fertilizer production | generation system can neutralize a concentrate, it can prevent that an installation corrodes by components, such as a mineral acid (inorganic acid) contained in a concentrate.

  In the liquid fertilizer production system according to claim 4, the first screen may be a wedge wire screen device in which wedge wires made of a metal wire having a cross-sectional shape are arranged so as to form slits having a predetermined dimension. Thereby, the liquid manure production | generation system can isolate | separate the 1st solid content which causes the clogging of a spray nozzle efficiently. Moreover, since the liquid fertilizer production | generation system needs to process a considerable amount of water, durability of an installation is needed. Here, when a normal mesh is used as the screen, there is a possibility that the screen is damaged immediately. Therefore, the liquid manure production system can perform stable treatment continuously for a long period of time by using a wedge wire device that separates solid and liquid with a wedge wire made of a metal wire.

  In the liquid fertilizer production system according to claim 5, the concentration means may include a stirring mechanism inside. Thereby, even if it raises the preset concentration rate of an evaporative concentration apparatus, fluidity | liquidity can be maintained, without a component adhering by an internal stirring mechanism. Moreover, since solidification of methane fermentation residual liquid can be prevented by fully stirring the methane fermentation residual liquid during concentration, it can concentrate to high concentration. Furthermore, when the concentration rate of the evaporative concentration apparatus is increased and set, solid fertilizer can also be generated.

  The liquid fertilizer production system according to claim 6, wherein the condensate produced by the concentration means is collected, and the condensate collected by the collection means is biologically treated with activated sludge and filtered through a submerged membrane. It is good to provide the biological treatment means to perform. The recovery means recovers the condensate produced in the concentration means. The biological treatment means filters the condensed liquid collected by the collection means with an immersion membrane while biologically treating the condensate with activated sludge. Thereby, the liquid fertilizer production | generation system can decompose | disassemble the organic substance contained in a condensate efficiently. Moreover, since the particulate removal is performed by the immersion film and the treated water becomes transparent, the subsequent ultraviolet decomposition is efficiently performed. The term “immersion membrane” means a filtration membrane that is immersed in activated sludge. For example, a hollow fiber or a flat membrane aggregate can be used. The pore diameter of the immersion film is preferably 0.5 μm or less. By using such a submerged membrane, a sedimentation tank for completely removing the suspended matter in the condensate is not required, and the equipment can be downsized.

  The liquid fertilizer production system according to claim 7 may further include a supply unit that supplies a part of the separated liquid to the condensate that is subjected to the biological treatment by the biological treatment unit. The supply means can supply a part of the separation liquid to the condensate for biological treatment. Thereby, in biological treatment, a part of the separation liquid containing components (nitrogen, phosphorus, potassium, etc.) that are nutrients for the presence of microorganisms such as bacteria can be supplied to the condensate by the supply means. Biological treatment can be efficiently and continuously performed on the condensate in the biological treatment means.

  The liquid fertilizer production system according to claim 8, wherein the first treated water obtained by the biological treatment means is subjected to ultraviolet oxidation treatment means for performing oxidation treatment with ultraviolet rays, and second treated water obtained by the ultraviolet oxidation treatment means. You may provide the activated carbon filtration means filtered with activated carbon. The ultraviolet oxidation treatment means can oxidize the first treated water obtained by the biological treatment means with ultraviolet rays. The activated carbon filtration means can filter the second treated water obtained by the ultraviolet oxidation treatment means with activated carbon. Thereby, the liquid fertilizer production | generation system can decompose | disassemble the organic chemical substance (persistence-degradable substance) difficult to decompose | disassemble by biological treatment. Furthermore, since the liquid fertilizer production | generation system can adsorb | suck the organic substance which remains in a 2nd treated water with activated carbon, it can discharge | emit to a river. Furthermore, since it is highly processed, it can be reused as industrial water.

  The inventions of claims 1 to 8 described above can be arbitrarily combined. For example, not all or a part of claim 1 may be provided, but at least one of the configurations of other claims 2 to 8 may be provided. In particular, the configuration of claim 1 may be provided and combined with at least one of the configurations of claims 2 to 8. Further, any constituent elements of claims 1 to 8 may be extracted and combined. The applicant of the present application intends to obtain a patent right for such a configuration.

It is a flowchart of the liquid fertilizer production system 1. FIG. 5 is a flowchart of the condensate treatment unit 100. It is an external view of the wedge wire separation apparatus 301. FIG. It is a flowchart of the evaporation concentration apparatus 5. It is a table | surface which shows the process result using the liquid manure production | generation system 1. FIG.

  The liquid fertilizer production system 1 of the present invention will be described with reference to the drawings. The drawings to be referred to are used to explain technical features that can be adopted by the present invention. Each processing step, device configuration, and the like described in the drawings are merely illustrative examples, not a limitation to that.

  A liquid fertilizer production system 1 shown in FIG. 1 performs processing using a methane fermentation residual liquid produced in a methane fermentation plant as a stock solution to produce liquid fertilizer (liquid fertilizer). In addition, a methane fermentation plant means the plant which collect | recovers methane by carrying out methane fermentation of wet biomass, such as a food processing residue, agricultural settlement drainage sludge, garbage, sewer sludge, and human waste, for example.

The configuration of the liquid fertilizer production system 1 will be described with reference to FIGS. The liquid manure production system 1 includes a stock solution tank 2, a separation device 3, a filtrate solution tank 4, an acid addition device 51, an evaporation concentration device 5, a concentrate neutralization tank 6, an alkali addition device 52, a liquid manure storage tank 7, and a condensate treatment unit. 100 etc. The stock solution tank 2 stores the methane fermentation residual solution as a stock solution. The separation device 3 filters the methane fermentation residual solution supplied from the stock solution tank 2 using a wedge wire separation device 301 (see FIG. 3) described later to separate the solid content in the methane fermentation residual solution. In addition, solid content is a suspended material (SS) in a methane fermentation residual liquid, for example. The filtrate tank 4 stores the filtrate from which the solid content has been separated by the separation device 3. The acid addition device 51 adds the sulfuric acid (H ₂ SO ₄ ) to the filtrate based on the pH of the filtrate detected by the pH meter 51A, thereby changing the pH of the filtrate from alkaline or neutral to acidic. adjust. The evaporative concentration device 5 evaporates and concentrates the filtrate stored in the filtrate tank 4. The concentrated liquid neutralizing tank 6 stores the concentrated liquid evaporated and concentrated. The alkali addition device 52 neutralizes the pH of the concentrated solution by adding sodium hydroxide (NaOH) to the concentrated solution generated by the evaporation concentration device 5 based on the pH of the concentrated solution detected by the pH meter 52A. To do. The liquid manure storage tank 7 stores the neutralized concentrate as liquid fertilizer. The condensate treatment unit 100 performs biological treatment or the like in order to reuse the condensate discharged from the evaporating and concentrating device 5 as, for example, industrial water, or to conform to the discharge standard when discharged into a public water area.

  A pipe 21 is connected between the stock solution tank 2 and the separation device 3. A pipe 22 is connected between the separation device 3 and the filtrate tank 4. A pipe 23 is connected between the filtrate tank 4 and the evaporative concentration apparatus 5. A pipe 24 is connected between the evaporation concentrator 5 and the concentrate neutralizing tank 6. A pipe 25 is connected between the concentrate neutralizing tank 6 and the liquid fertilizer storage tank 7. A pipe 26 is connected between the liquid fertilizer storage tank 7 and a facility (field or the like) to be fertilized. A pipe 27 is connected between the evaporation concentrator 5 and the condensate treatment unit 100. A piping 36 is connected to the filtrate tank 4 and the condensate treatment unit 100. A pump 31 is provided in the middle of the pipe 21. The pump 31 supplies the methane fermentation residual liquid stored in the stock solution tank 2 toward the separation device 3. A pump 32 is provided in the middle of the pipe 23. The pump 32 supplies a part of the filtrate stored in the filtrate tank 4 toward the evaporation and concentration apparatus 5. A pump 35 is provided in the middle of the pipe 36. The pump 35 supplies a part of the filtrate stored in the filtrate tank 4 toward the condensate processing unit 100.

  As shown in FIG. 2, the condensate treatment unit 100 includes a condensate tank 8, an alkali addition device 53, a biological treatment tank 9, an ultraviolet oxidation tower 10, an activated carbon tower 11, and the like. The condensate tank 8 stores the condensate generated by the evaporative concentration apparatus 5. The alkali addition device 53 neutralizes the pH of the condensate by adding sodium hydroxide (NaOH) to the condensate stored in the condensate tank 8 based on the pH of the condensate detected by the pH meter 53A. To do. The biological treatment tank 9 performs biological treatment on the neutralized condensate and performs membrane filtration. The ultraviolet oxidation tower 10 performs ultraviolet oxidation treatment on the membrane filtered water (corresponding to “first treated water” of the present invention) from the biological treatment tank 9. The activated carbon tower 11 performs activated carbon treatment on the ultraviolet treated water (corresponding to “second treated water” of the present invention) subjected to ultraviolet oxidation treatment. The final treated water that has been subjected to the activated carbon treatment is reused, for example, as industrial water.

  A pipe 28 is connected between the condensate tank 8 and the biological treatment tank 9. A pipe 29 is connected between the biological treatment tank 9 and the ultraviolet oxidation tower 10. A pipe 30 is connected between the ultraviolet oxidation tower 10 and the activated carbon tower 11. A pipe 37 is connected to the activated carbon tower 11. A pump 33 is provided in the middle of the pipe 28. The pump 33 supplies the condensate stored in the condensate tank 8 toward the biological treatment tank 9. A pump 34 is provided in the middle of the pipe 29. The pump 34 supplies the condensate biologically treated in the biological treatment tank 9 toward the ultraviolet oxidation tower 10.

  With reference to FIG. 1, the liquid manure production | generation flow by the liquid manure production | generation system 1 provided with the said structure is demonstrated. First, when the pump 31 is driven, the methane fermentation residual liquid stored in the stock solution tank 2 is pumped up and supplied to the separation device 3 through the pipe 21.

  The structure and processing of the separation device 3 will be described. The separation device 3 includes a wedge wire separation device 301 (hereinafter referred to as a separation device 301) shown in FIG. The separation device 301 includes a plurality of wedge wires 302 (only five are shown in FIG. 3), a plurality of support rods 303 (only two are shown in FIG. 3), and the like. The wedge wire 302 is a stainless steel wire having a wedge-shaped cross section, and includes a wedge-shaped pointed portion 302a, a wide surface portion 302b, and the like. The plurality of support rods 303 are arranged in parallel to each other at equal intervals. The plurality of wedge wires 302 are arranged on the plurality of support rods 303 at equal intervals in a direction orthogonal to each other, and each wedge-shaped pointed portion 302 a is spot-welded to the upper portion of the support rod 303. The wide surface portion 302b of the separation device 301 is a wide surface located on the opposite side of the wedge-shaped pointed portion 302a, and functions as a separation surface of the separation device 301 that receives the methane fermentation residual liquid.

  The wedge wire 302 of the wedge wire separation device 301 may be coated with a hydrophilic paint. As a result, the liquid film layer such as methane fermentation residual liquid flowing on the surface of the wedge wire 302 is peeled off by the hydrophilic action of the hydrophilic paint. Therefore, the surface tension of the liquid film layer is weakened, and the slit S between the wedge wires 302 can be effectively prevented from being blocked by the liquid film layer, and the solid content easily slips on the surface of the slit S due to the hydrophilic effect. Become. Therefore, the liquid is easily passed through the slit S, so that the solid content is separated. In addition, as a hydrophilic coating material, the inorganic coating material which has sodium silicate, an aluminum oxide, a titanium oxide, and water as a main component is preferable, for example.

  A slit S having a predetermined size is formed between the wedge wires 302. For example, the slit S may be smaller than the hole diameter of a spray nozzle (not shown) used when spraying liquid manure on a field or the like. For example, the slit S may be set to 0.5 mm or less, and preferably set to 0.2 mm or less. Separation device 3 can separate solid content larger than the pore diameter of the spray nozzle contained in methane fermentation residual liquid by letting methane fermentation residual liquid pass through slit S between a plurality of wedge wires 302.

  In the separation device 3, the solid content contained in the supplied methane fermentation residual liquid is separated. The solid content separated by the wedge wire 302 is recovered to the methane fermentation plant via the pipe 20. In the methane fermentation plant, the recovered solid content is used again for methane fermentation. As a result, energy resources can be effectively utilized.

  Since the separation device 3 needs to process a large amount of methane fermentation residual liquid, durability of equipment is required. By using the wedge wire separation device 301, the separation device 3 can perform a stable process continuously for a long time. The filtrate from which the solid content has been separated by the separation device 3 is supplied to the filtrate tank 4 via the pipe 22.

Next, in the filtrate tank 4, pH adjustment is performed on the supplied filtrate by the acid addition device 51. The pH of the filtrate is measured by the pH meter 51A. Since the pH of the methane fermentation residue is neutral or weakly alkaline, the pH of the filtrate supplied from the separation device 3 is also neutral or weakly alkaline. The acid addition device 51 includes an acid storage container, piping, and the like (not shown). The acid storage container stores sulfuric acid (H ₂ SO ₄ ). The pH meter 51A measures the pH of the condensate and feeds it back to the acid addition device 51. The acid addition device 51 adds H ₂ SO ₄ from the acid storage container to the condensate via a pipe so as to obtain a desired pH based on the feedback.

  Here, based on the measured value of the pH meter 51A, the acid addition device 51 adds sulfuric acid to the filtrate until, for example, pH 5.0 or less. The filtrate contains nitrogen, phosphorus, and potassium, which are active ingredients as fertilizers, but nitrogen (particularly ammonia nitrogen) is volatile and easily volatile. In the present embodiment, the methane fermentation residual liquid is adjusted to be acidic in order to fix the nitrogen component in the filtrate. Thereby, it can fix in a filtrate, without volatilizing a nitrogen component.

  The pH adjuster added to the filtrate may be an acid such as hydrochloric acid, but preferably sulfuric acid. This is because sulfuric acid can be obtained at a low cost, and the possibility of corrosion of equipment is low as compared with the case where hydrochloric acid or the like is used. It is preferable that the acid addition device 51 adjusts the filtrate to an acidity of about pH 4.0. Thereby, the residual rate of nitrogen in the liquid manure produced by being concentrated by the evaporation concentrating device 5 described later can be increased to 99.9% or more. Next, the filtrate whose pH is adjusted in the filtrate tank 4 is supplied to the evaporation concentrator 5 via the pipe 23 by driving the pump 32.

  With reference to FIG. 4, the structure and process of the evaporative concentration apparatus 5 will be described. The evaporative concentration apparatus 5 includes a meter 400, a distillation still 401, a mist catcher 402, a condenser 403, a sight glass 404, a vacuum pump 405, a buffer tank 406, and a liquid feed pump 407. The meter 400 measures the amount of filtrate supplied to the distillation kettle 401. The mist catcher 402 captures water vapor generated with evaporation. The condenser 403 is liquefied by cooling the water vapor. The sight glass 404 is used to observe the outflow state of the condensate flowing out from the condenser 403. The vacuum pump 405 reduces the pressure inside the distillation pot 401. The buffer tank 406 stores the condensate that has flowed out of the condenser 403. The liquid feed pump 407 sends the condensate stored in the buffer tank 406 to the pipe 27.

  In the distillation pot 401, the filtrate is supplied into the distillation pot 401 through the supply port. Next, when steam is passed through the distillation still 401 via the steam supply port, the temperature of the still 401 increases. Along with this, the filtrate supplied into the distillation kettle 401 is heated. The heated filtrate is stirred by a scraper 415 that is a stirring mechanism. The inside of the distillation pot 401 is depressurized by a vacuum pump 405 described later. Thereby, the filtrate in the distillation pot 401 is distilled. The concentrated liquid remaining after distillation inside the still 401 is supplied from the still 401 to the concentrate neutralizing tank 6 through the pipe 24.

  On the other hand, the pressure inside the distillation pot 401 is reduced by, for example, exhausting gas by a vacuum pump via the path of the condenser 403. Then, water vapor is generated from the filtrate supplied into the distillation kettle 401. The water vapor generated in the distillation pot 101 is sucked by a vacuum pump and supplied to the condenser 403 via the mist catcher 402. The water vapor supplied to the condenser 403 is cooled by cooling water. The cooled water is stored in the buffer tank 406 as a condensate.

  Since the filtrate can be concentrated to a high concentration by the evaporative concentration device 5, the concentration of nitrogen, phosphorus, and potassium in the liquid fertilizer can be increased to such an extent that it can be sprayed on the fields. Moreover, the storage space for the concentrate can be reduced in size by evaporating and concentrating the filtrate. In addition, since the distillation kettle 401 of the evaporative concentration apparatus 5 distills while stirring the internal filtrate with the scraper 415, the fluidity can be maintained without the components in the filtrate being fixed. Moreover, since solidification of a filtrate can be prevented by fully stirring the filtrate during concentration, it can concentrate to high concentration. The concentration rate may be changed by changing the operating conditions of the evaporative concentration apparatus 5. For example, solid fertilizer may be generated by setting the concentration rate of the evaporative concentration device 5 high. Note that the evaporative concentration apparatus 5 can automatically determine the concentration rate by the initial setting. Thereby, the operation | work after setting can be made efficient by setting the optimal concentration rate.

  Next, the concentrated liquid concentrated by the evaporating and concentrating device 5 is supplied to the concentrated liquid neutralization tank 6 through the pipe 24 by driving the liquid feeding pump 407.

  The concentrated liquid neutralization tank 6 will be described. Since the filtrate adjusted to be acidic in the filtrate tank 4 is concentrated by the evaporative concentration device 5, the pH of the concentrate supplied from the pipe 24 is acidic. In the concentrated liquid neutralization tank 6, the supplied concentrated liquid is neutralized by the alkali addition device 52. The alkali adding device 52 includes an alkali storage container, piping, and the like (not shown). The alkaline storage container stores an aqueous sodium hydroxide solution (NaOH). The pH meter 52A measures the pH of the condensate and feeds it back to the alkali adding device 52. The alkali addition device 52 adds NaOH to the condensate from the alkali storage container via a pipe so as to obtain a desired pH based on the feedback.

  Here, the alkali addition apparatus 52 is good to adjust pH of a concentrate to pH 5-8 based on the measured value of pH meter 52A. Preferably, the pH is adjusted to around 5.5. Thereby, since the liquid fertilizer production | generation system 1 can neutralize a concentrate, it can prevent that an installation corrodes by components, such as a mineral acid (inorganic acid) contained in a concentrate.

  Next, the concentrated liquid neutralized in the concentrated liquid neutralization tank 6 is stored in the liquid fertilizer storage tank 7 as liquid fertilizer.

  A condensate treatment flow in the condensate treatment unit 100 will be described with reference to FIG. First, the liquid feed pump 407 is driven to pump up the condensate generated by the evaporation concentrator 5 and supply it to the condensate tank 8 via the pipe 27.

  The condensate tank 8 will be described. In the condensate tank 8, the supplied condensate is stored. The alkali adding device 53 includes an alkali storage container, piping, and the like. The alkaline storage container stores an aqueous sodium hydroxide solution (NaOH). The pH meter 53A measures the pH of the condensate and feeds it back to the alkali adding device 53. The alkali addition device 53 adds NaOH to the condensate from the alkali storage container via a pipe so as to obtain a desired pH based on the feedback.

  Here, the pH of the condensate may be adjusted to a value of pH 5-8. Thereby, when the condensate is supplied in the biological treatment tank 9 (immersion membrane type activated sludge tank) described later, an environment in which organisms such as bacteria can easily survive can be provided. In biological treatment, more efficient treatment can be performed as compared with the case where pH adjustment is not performed.

  Next, when the pump 33 is driven, the pH-adjusted condensate is pumped up and supplied to the biological treatment tank 9 via the pipe 28.

  In order to decompose organic substances efficiently and at low cost, it is important to first decompose the biodegradable organic substances in a biodegradation reaction. The biological treatment tank 9 performs biological treatment for decomposing organic matter on the pH-adjusted condensate.

  The structure and process of the biological treatment tank 9 will be described. The biological treatment tank 9 includes an immersion membrane unit 9C and the like. The biological treatment tank 9 is connected to the downstream side of the condensate tank 8 via a pipe 28. The biological treatment tank 9 includes a diffuser tube 9A, an air pump 9B, and the like. The air diffuser is provided at the bottom of the biological treatment tank 9. The air diffuser discharges air supplied from the air pump and stirs the inside of the biological treatment tank 9. The submerged membrane unit 9 </ b> C is provided in the biological treatment tank 9. The membrane filtered water filtered by the submerged membrane unit 9C is sent to the ultraviolet oxidation tower 10 by the pump 34 through the pipe 29.

  In addition, the biological treatment tank 9 performs biological treatment by the submerged membrane activated sludge method. The biological treatment tank 9 holds a high concentration of activated sludge, and a high concentration of microorganisms is held in proportion thereto. Thereby, biodegradation reaction is accelerated | stimulated and organic substance is decomposed | disassembled highly. Subsequently, the waste water sufficiently decomposed by the biodegradation reaction is filtered through the submerged membrane unit 9C.

  The immersion membrane of the immersion membrane unit 9C separates activated sludge and solid content (suspended substance) generated in the biological treatment tank 9 from the condensed liquid. As the immersion membrane, an aggregate of hollow fibers or flat membranes having ultrafine pore diameters is used. The pore diameter of the immersion film may be 0.5 μm or less, and preferably the pore diameter is 0.1 μm to 0.4 μm. By using such an immersion film, a sedimentation tank for removing the solid content in the condensate is not necessary, and the equipment can be downsized.

  Here, the condensate treatment unit 100 can supply a part of the filtrate in the filtrate tank 4 as a nutrient to the condensate whose pH has been adjusted via the pipe 36 by driving the pump 35. . Most of nitrogen, phosphorus, potassium, and the like contained in the filtrate are contained in the concentrate by the evaporating and concentrating device 5. Therefore, in the condensate produced by the evaporative concentration apparatus 5, nitrogen, phosphorus, and potassium are trace amounts. Here, since nitrogen, phosphorus, and potassium are nutrient sources for organisms such as bacteria in the biological treatment tank 9 described later, a decrease in these components causes deterioration in the efficiency of biological treatment. Therefore, it is desirable that the biological treatment tank 9 contains nitrogen, phosphorus, potassium, etc. to such an extent that the organism can survive. The condensate treatment unit 100 can supply a part of the filtrate containing components (nitrogen, phosphorus, potassium), which are nutrients for the presence of microorganisms such as bacteria, to the condensate via the pipe 36. Therefore, the biological treatment can be efficiently and continuously performed on the condensate in the biological treatment tank 9.

  Next, when the pump 34 is driven, the membrane filtered water biologically treated by the biological treatment tank 9 is pumped up and supplied to the ultraviolet oxidation tower 10 via the pipe 29.

  An oxidation process in the ultraviolet oxidation tower 10 will be described. The ultraviolet oxidation tower 10 includes a UV lamp and the like. The ultraviolet oxidation tower 10 decomposes organic chemical substances (hardly decomposable substances) that are difficult to be decomposed by biological treatment contained in the membrane filtered water. As a pretreatment for this, organic matter is decomposed by performing chemical oxidation on the membrane filtered water biologically treated in the biological treatment tank 9. Specifically, in the biological treatment tank 9, while the membrane filtered water after the treatment in the submerged membrane unit 9C is sucked by the pump 34, an oxidant is added via the oxidant supply pipe, and UV oxidation is performed. Supplied to the tower 10. Examples of the oxidizing agent include ozone, hydrogen peroxide, and sodium hypochlorite. About the addition method of an oxidizing agent, it changes with kinds of oxidizing agent. Next, the UV lamp irradiates the membrane filtered water to which the oxidizing agent is added with ultraviolet rays (UV). Thereby, it is possible to decompose organic chemical substances (persistently decomposable substances) that are difficult to be decomposed by biological treatment. Next, the ultraviolet-treated water subjected to the oxidation treatment and ultraviolet treatment by the ultraviolet oxidation tower 10 is pumped up and supplied to the activated carbon tower 11 through the pipe 30.

  The activated carbon tower 11 will be described. The activated carbon tower 11 includes activated carbon inside. Activated carbon filters the ultraviolet-treated water into final treated water (such as industrial water). The final treated water is a clear treated water. The pipe 30 and the pipe 37 are connected to the activated carbon tower 11. The pipe 30 flows the ultraviolet-treated water into the activated carbon tower 11. The activated carbon tower 11 can adsorb organic substances remaining in the ultraviolet-treated water with activated carbon. The pipe 37 flows out the final treated water to a plant or the like. Since the final treated water thus obtained satisfies the discharge standard for rivers and the like, it can be discharged into rivers and the like. Furthermore, since it is highly processed, it can be reused as industrial water for the plant.

Next, in order to confirm the effect of the liquid manure production system 1, a test in the liquid manure production system 1 will be described. The processing conditions are as follows. In this experiment, the water quality at each treatment stage when the liquid fertilizer production system 1 was operated under the following treatment conditions was examined. The water quality in each treatment stage is the quality of the stock solution (methane fermentation residual liquid), filtrate, concentrate, condensate, membrane filtrate, and final treated water. The water quality analysis items are pH, BOD, COD, SS, ammoniacal nitrogen (NH ₄ -N), total nitrogen component (total N), phosphorus, and potassium. The liquid fertilizer production system 1 was evaluated by evaluating these items.

―Processing conditions―
・ Amount of stock solution: 500 L / h × 20 h / d = 10,000 L / d
Separation device 3: slit S = 0.2 mm, wedge wire 302 subjected to hydrophilic treatment. Evaporation concentration device 5: evaporation capacity 500 kg H ₂ O / h
Concentration rate: approx. 5 times ・ Biological treatment tank 9: Capacity of biological treatment tank (aeration tank capacity) 6m ³
Immersion membrane activated sludge method
Membrane filtration area 60m ²
-UV oxidation tower 10: UV lamp 300W x 1
Dimension φ400 × 1800H
Capacity 200L
-Activated carbon tower 11: Upward flow liquid method
Dimension φ300 × 2400H

With reference to FIG. 5, the results of processing performed based on the above processing conditions will be described. The pH of the stock solution was 8.4, BOD was 5500 (mg / L), COD was 7800 (mg / L), and SS was 12000 (mg / L). The pH of the filtrate is 8.4, BOD is 3000 (mg / L), COD is 6000 (mg / L), SS is 5500 (mg / L), NH ₄ -N is 1500 (mg / L), all N Was 2100 (mg / L), phosphorus was 100 (mg / L), and potassium was 1800 (mg / L). The pH of the concentrated solution (after neutralization) is 6.8, BOD is 12000 (mg / L), COD is 28000 (mg / L), SS is 27000 (mg / L), NH ₄ -N is 7500 (mg / L). L), total N was 11000 (mg / L), phosphorus was 500 (mg / L), and potassium was 9000 (mg / L). The pH of the condensate (after neutralization) is 7.0, BOD is 800 (mg / L), COD is 500 (mg / L), SS is <1 (mg / L), NH ₄ -N is 1.5 (Mg / L), total N was 3 (mg / L), phosphorus was <1 (mg / L), and potassium was <1 (mg / L). The pH of the membrane filtered water is 6.6, BOD is 20 (mg / L), COD is 35 (mg / L), SS is <1 (mg / L), NH ₄ -N is 0.5 (mg / L) ), Total N was 5 (mg / L) and phosphorus was 1.5 (mg / L). The pH of the final treated water is 7.1, BOD is 1.5 (mg / L), COD is 2.0 (mg / L), SS is <1 (mg / L), NH ₄ -N is 0.3 (Mg / L), total N was 2.4 (mg / L), and phosphorus was 1.2 (mg / L).

  Consider the water quality of the filtrate. The SS of the stock solution was 12000 (mg / L), but the SS of the filtrate was 5500 (mg / L), which was reduced to about ½. Thereby, it turned out that the solid content more than the predetermined magnitude | size contained in the methane fermentation residual liquid was removed favorably by the separator 3.

Examine the water quality of the concentrate (after neutralization). NH ₄ -N in the filtrate was 1500 (mg / L), but NH ₄ -N in the concentrated liquid was 7500 (mg / L), which could be concentrated to about 5 times. The total N of the filtrate was 2100 (mg / L), but the total N in the concentrate was 11000 (mg / L), which could be concentrated to about 5 times. The phosphorus in the filtrate was 100 (mg / L), but the phosphorus in the concentrate was 500 (mg / L), which could be concentrated up to about 5 times. The potassium of the filtrate was 1800 (mg / L), but the potassium of the concentrate was 9000 (mg / L), which could be concentrated to about 5 times. As described above, it was found that the concentration of nitrogen, phosphorus, and potassium in the concentrated solution was about 5 times that of the filtrate (set concentration rate in this experiment) by the evaporative concentration device 5. In addition, as described above, by adjusting the pH of the filtrate to acidic by the acid addition device 51 before concentrating the filtrate, the volatilization of ammonia nitrogen and all nitrogen components is suppressed, and the filtrate is concentrated well. I found out that Therefore, it was proved that the concentrated liquid produced by the liquid fertilizer production system 1 can be used as liquid fertilizer that can be sprayed on land such as fields with high harvest density.

  Examine the water quality of the condensate (after neutralization). Since the condensate was neutralized in the condensate tank 8 as described above, the pH was 7.0. The BOD of the filtrate was 3000 (mg / L), but the BOD of the condensate was 800 (mg / L), which was reduced to about 1/4. The COD of the filtrate was 6000 (mg / L), but the COD of the condensate was 500 (mg / L), which was reduced to about 1/12. Further processing is performed in the biological treatment tank 9, the ultraviolet oxidation tower 10, and the activated carbon tower 11 so that the BOD and COD values of these condensates satisfy the water discharge standard.

The concentrations of NH ₄ —N, total N, phosphorus and potassium in the condensate are 1.5 (mg / L), 3 (mg / L), <1 (mg / L), and <1 (mg / L), respectively. L). This means that most of nitrogen, phosphorus, and potassium contained in the filtrate before evaporation and concentration by the evaporation and concentration apparatus 5 remain in the concentrate and are concentrated.

  Consider the water quality of membrane filtration water. The pH of the membrane filtered water is 6.6. The BOD of the condensate was 800 (mg / L), but the BOD of the membrane filtrate was 20 (mg / L), which was reduced to about 1/40. The COD of the condensate was 500 (mg / L), but the COD of membrane filtrate was 35 (mg / L), which was reduced to about 1/14. From this, it was found that BOD and COD were greatly reduced by biological treatment and membrane filtration in the biological treatment tank 9. In order to reuse as industrial water, it is desirable to further reduce BOD and COD. Therefore, in the liquid fertilizer production system 1, the membrane filtered water is further subjected to the ultraviolet oxidation treatment by the ultraviolet oxidation tower 10, and the activated carbon tower 11 adsorbs organic matter in the ultraviolet treatment water.

  Consider the quality of the final treated water. The pH of the final treated water was 7.1. The BOD of the membrane filtrate was 20 (mg / L), but the BOD of the final treated water was 1.5, which was reduced to about 1/14. The COD of membrane filtered water was 35 (mg / L), but the COD of final treated water was 2.0 (mg / L), which was reduced to about 1/17. Thereby, BOD and COD could be further reduced by the ultraviolet oxidation treatment in the ultraviolet oxidation tower 10 and the adsorption in the activated carbon tower 11. Therefore, in the liquid fertilizer production | generation system 1, it was demonstrated by processing the condensate produced | generated with the evaporative concentration apparatus 5 by the condensate process part 100 that the final treated water reusable as industrial water can be obtained.

  As explained above, the liquid fertilizer production system 1 of the present embodiment produces liquid fertilizer from methane fermentation residual liquid remaining after fermenting organic waste and producing methane. The liquid fertilizer production system 1 includes a separation device 3 that separates the solid content from the methane fermentation residual liquid by the wedge wire separation device 301, and an acid addition device that adjusts the pH of the separated liquid separated by the separation device 3 to be acidic. 51, an evaporation concentration device 5 for evaporating and concentrating the separation liquid adjusted to acidity by the acid addition device 51, and a liquid manure storage tank 7 for storing the concentrated solution evaporated and concentrated by the evaporation concentration device 5 as liquid manure. Thereby, since the liquid fertilizer production | generation system 1 can increase the density | concentration of nitrogen, phosphorus, and potassium contained in the produced | generated concentrated liquid by concentrating a separated liquid with the evaporative concentration apparatus 5, for example, a high harvest density is high. It can provide liquid fertilizer that can be applied to fields. The liquid fertilizer production system 1 can remove solids from the methane fermentation residual liquid in advance by the separation device 3. Thereby, when the liquid fertilizer concentrated and produced | generated by the evaporative concentration apparatus 5 is spread | dispersed on soil by spray etc. after that, it can prevent that the clogging by solid content arises in a spray nozzle. Moreover, the liquid fertilizer production | generation system 1 can fix the ammonia component in a separated liquid by adjusting the pH of a separated liquid to acidity with the acid addition apparatus 51. FIG. Thereby, the nitrogen component contained in the liquid fertilizer concentrated and produced | generated by the evaporative concentration apparatus 5 after that can be ensured.

  The liquid fertilizer production system 1 includes an alkali addition device 52 that adjusts the pH of the concentrated solution evaporated and concentrated by the evaporation and concentration device 5 to 5 to 8. Thereby, since the liquid fertilizer production | generation system 1 can neutralize a concentrate, it can prevent that an installation corrodes with components, such as a mineral acid (inorganic acid) contained in a concentrate.

  The separation device 3 is a wedge wire separation device 301 in which wedge wires made of metal wires having a cross-sectional shape are arranged so as to form slits having a predetermined size. Thereby, the liquid fertilizer production | generation system 1 can perform the isolation | separation of solid content causing the clogging of a spray nozzle efficiently. Moreover, since the liquid fertilizer production | generation system 1 needs to process a considerable amount of water, durability of an installation is needed. Here, when a normal mesh is used as the separating device 3, there is a possibility that the separating device 3 is damaged immediately. Therefore, the liquid fertilizer production | generation system 1 can perform the stable process continuously for a long period of time by using the wedge wire separation apparatus 301 which carries out solid-liquid separation with the wedge wire which consists of metal wires.

  The evaporative concentration apparatus 5 includes a scraper 415. Thereby, even if it raises the setting concentration rate of the evaporation concentration apparatus 5, a fluidity | liquidity can be maintained, without a component adhering by an internal stirring mechanism. Moreover, since solidification of methane fermentation residual liquid can be prevented by fully stirring the methane fermentation residual liquid during concentration, it can concentrate to high concentration. Furthermore, when the concentration rate of the evaporative concentration apparatus 5 is increased and set, solid fertilizer can also be generated.

  The liquid fertilizer production system 1 includes a condensate tank 8 that collects the condensate produced in the evaporative concentrator 5, and the condensate collected in the condensate tank 8 is biologically treated with activated sludge and filtered through an immersion membrane. And a biological treatment tank 9 to be performed. The condensate tank 8 collects the condensate generated in the evaporative concentration device 5. The biological treatment tank 9 filters the condensate collected by the condensate tank 8 with an activated membrane while performing biological treatment with activated sludge. Thereby, the liquid fertilizer production | generation system 1 can decompose | disassemble the organic substance contained in a condensed liquid efficiently. Moreover, since the particulate removal is performed by the immersion film and the treated water becomes transparent, the subsequent ultraviolet decomposition is efficiently performed. The term “immersion membrane” means a filtration membrane that is immersed in activated sludge. For example, a hollow fiber or a flat membrane aggregate can be used. The pore diameter of the immersion film is preferably 0.5 μm or less. By using such a submerged membrane, a sedimentation tank for completely removing the suspended matter in the condensate is not required, and the equipment can be downsized.

  The liquid fertilizer production system 1 includes a pump 35 and a pipe 36 that supply a part of the separated liquid to the condensate subjected to the biological treatment in the biological treatment tank 9. The pump 35 and the pipe 36 can supply a part of the separated liquid to the condensate subjected to biological treatment by the biological treatment tank 9. Thereby, in biological treatment, a part of the separation liquid containing components (nitrogen, phosphorus, potassium, etc.) that are nutrients for the presence of microorganisms such as bacteria can be supplied to the condensate by the pump 35 and the pipe 36. Therefore, the biological treatment can be efficiently and continuously performed on the condensate in the biological treatment tank 9.

  The liquid fertilizer production system 1 includes an ultraviolet oxidation tower 10 that oxidizes membrane filtered water obtained by the biological treatment tank 9 with ultraviolet rays, and an activated carbon tower 11 that filters the ultraviolet treated water obtained by the ultraviolet oxidation tower 10 with activated carbon. With. The ultraviolet oxidation tower 10 can oxidize the membrane filtrate obtained by the biological treatment tank 9 with ultraviolet rays. The activated carbon tower 11 can filter the ultraviolet treated water obtained by the ultraviolet oxidation tower 10 with activated carbon. Thereby, the liquid fertilizer production | generation system 1 can decompose | disassemble the organic chemical substance (persistence-degradable substance) difficult to decompose | disassemble by biological treatment. Furthermore, since the liquid fertilizer production | generation system 1 can adsorb | suck the organic substance which remains in ultraviolet-treated water with activated carbon, it can discharge | emit to a river. Furthermore, since it is highly processed, it can be reused as industrial water.

  In the above description, the separation device 3 is an example of the “first separation means” in the present invention. The acid addition device 51 is an example of the “first adjusting means” in the present invention. The evaporative concentration apparatus 5 is an example of the “concentration means” in the present invention. The liquid fertilizer storage tank 7 is an example of the “storage unit” in the present invention. The alkali adding device 52 is an example of the “second adjusting means” in the present invention. The scraper 415 is an example of the “stirring mechanism” in the present invention. The condensate tank 8 is an example of the “recovery means” in the present invention. The biological treatment tank 9 is an example of the “biological treatment means” in the present invention. The pump 35 and the pipe 36 are an example of the “supplying unit” in the present invention. The ultraviolet oxidation tower 10 is an example of the “ultraviolet oxidation means” in the present invention. The activated carbon tower 11 is an example of the “activated carbon filtering means” in the present invention.

  In addition, this invention is not limited to said embodiment, A various deformation | transformation is possible. In the liquid fertilizer production system 1 of the above embodiment, the solid content is separated by the separation device 3 before the evaporation concentration by the evaporation concentration device 5, but may be performed after the evaporation concentration by the evaporation concentration device 5, for example. In that case, the separation device 3 before evaporation and concentration may be omitted. After evaporating and concentrating by the evaporating and concentrating device 5, by separating the solid content by the separating device 3, not only the solid content originally contained in the methane fermentation residual liquid but also the solid content of the concentrated solution generated at the time of evaporating and concentrating Can be separated. Further, in the evaporation concentration process, the liquidity may change and aggregates may be generated. Therefore, by processing the concentrated liquid that can be used as liquid fertilizer with the separation device 3, the solid content that causes clogging of the spray nozzle can be reliably removed.

  In addition, the liquid fertilizer production system 1 uses the separation device 3 that separates the solid content in the methane fermentation residual liquid before the evaporative concentration by the evaporative concentration device 5 as a “pre-stage separation device”, and after the evaporative concentration, May be provided as a “second-stage separator”. In this case, for example, the slit S of the front separator is set to be rough (for example, 0.5 mm or less), and the slit S of the rear separator is finer (for example, 0.2 mm or less) than the slit S of the front separator. It is good to.

  Here, if the slit S is set finely in order to remove fine solids, the filtration resistance increases. When the filtration area is the same, the filtration rate is slower than when the slit S is rough. In the case of the pre-stage separator alone, it is necessary to increase the filtration area in order to remove fine solids. On the other hand, when the solid content is removed by the downstream separator, the slit S of the upstream separator may be rougher than the slit S of the downstream separator. Thereby, since the filtration area of a front | former stage separator can be set small, size reduction of an installation can be performed. Furthermore, the post-separation device after producing the concentrate has a small filtration area because the amount of the target concentrate is small. Thereby, size reduction of a back | latter stage separation apparatus can be performed. Therefore, in the liquid fertilizer production system, fine solids can be removed by the subsequent separation apparatus, and the equipment can be downsized. The latter-stage separation device is an example of the “second separation means” in the present invention.

  The separation device 3 of the above embodiment uses the wedge wire separation device 301, but the method for separating the solid content may be a separation method other than this, or a general screen device. Moreover, the method of isolate | separating solid content with a wire mesh etc. may be used. Further, the wedge wire 302 of the above embodiment may not be provided with a hydrophilic paint.

  Although the acid addition apparatus 51 added sulfuric acid as an additive, an acid other than sulfuric acid may be added. Although the alkali adding devices 52 and 53 use NaOH as an additive, an alkali other than NaOH may be added. The alkali adding device 52 may be omitted depending on the properties of the soil.

  The condensate treatment unit 100 of the above embodiment includes the ultraviolet oxidation tower 10 and the activated carbon tower 11 after the biological treatment tank 9, but these may be omitted. The BOD and COD of the treated water become a constant level due to the biological treatment in the biological treatment tank 9, so if the discharge destination standard is gentle, the membrane filtered water filtered in the biological treatment tank 9 can be discharged as it is. it can.

  The evaporative concentration apparatus 5 of the above embodiment concentrates the separation liquid in the distillation kettle 401 by introducing the steam into the distillation kettle 401 and depressurizing the separation liquid with the scraper 415 while stirring. A general concentrating device for concentrating with may be used.

  The liquid fertilizer storage tank 7 of the above embodiment may be omitted. In this case, the concentrated liquid neutralization tank 6 functions as the “reserving means” of the present invention.

  The condensate treatment unit 100 of the above embodiment may be omitted as long as the condensed water can be discharged as it is. Moreover, you may abbreviate | omit the pump 35 and the piping 36 of the said embodiment.

DESCRIPTION OF SYMBOLS 1 Liquid fertilizer production system 2 Stock solution tank 3 Separation device 4 Filtrate tank 5 Evaporation concentration device 6 Concentration neutralization tank 7 Liquid fertilizer storage tank 8 Condensate tank 9 Biological treatment tank 10 Ultraviolet oxidation tower 11 Activated carbon tower 415 Scraper

Claims (8)

A liquid fertilizer production system for producing liquid fertilizer from methane fermentation residual liquid remaining after fermenting organic waste to produce methane,
A first separation means for separating a first solid content from the methane fermentation residual liquid by a first screen;
First adjusting means for adjusting the pH of the separation liquid from which the first solid content has been separated by the first separating means to acidity;
A concentration means for evaporating and concentrating the separation liquid adjusted to be acidic by the first adjustment means;
A liquid fertilizer production system comprising: a storage unit that stores the concentrated solution evaporated and concentrated by the concentration unit as the liquid fertilizer. The liquid fertilizer production system according to claim 1, further comprising second separation means for separating a second solid content from the concentrated liquid stored by the storage means using a second screen. The liquid fertilizer production system according to claim 1 or 2, further comprising second adjusting means for adjusting the pH of the concentrated solution evaporated and concentrated by the concentration means to 5-8. The said 1st screen is a wedge wire screen apparatus which arranged the wedge wire which consists of a metal wire with a cross-sectional shape so that the slit of a predetermined dimension may be formed. Liquid fertilizer generation system. The liquid fertilizer production system according to any one of claims 1 to 4, wherein the concentration means includes a stirring mechanism inside. Recovery means for recovering the condensate produced in the concentration means;
The liquid fertilizer production according to any one of claims 1 to 5, further comprising biological treatment means for performing biological treatment with activated sludge while filtering the condensed liquid collected by the collection means, and filtering with a submerged membrane. system. The liquid fertilizer production system according to claim 6, further comprising a supply unit that supplies a part of the separated liquid to the condensate subjected to the biological treatment by the biological treatment unit. UV oxidation treatment means for performing oxidation treatment with ultraviolet rays on the first treated water obtained by the biological treatment means;
The liquid fertilizer production system according to claim 6 or 7, further comprising activated carbon filtration means for filtering the second treated water obtained by the ultraviolet oxidation treatment means with activated carbon.

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