WO2021085469A1

WO2021085469A1 - Plant processing method and plant processing system

Info

Publication number: WO2021085469A1
Application number: PCT/JP2020/040414
Authority: WO
Inventors: 戸田　龍樹; 正敏岸; 伸二郎佐藤; 岡村　和夫; 敏光小寺; 睦実関根; 藤原　正明; 明日香金田
Original assignee: 学校法人創価大学
Priority date: 2019-10-31
Filing date: 2020-10-28
Publication date: 2021-05-06
Also published as: JP7204263B2; JPWO2021085469A1

Abstract

Provided are a plant processing method and a plant processing system. A plant processing system according to this invention includes: a crushing machine 200 that crushes plants; a compressing machine 220 that compresses the crushed plants and separates the same into a fibrous solid component and a liquid component, after the crushed plants have been held in a holding device 210 that is for holding the crushed plants; a carbonizing furnace 230 that reduces the volume of the fibrous solid component and manufactures a solid fuel or the like; and a processing tank 240 that causes the liquid component to undergo methane fermentation to separate the methane gas and the digestion liquid, producing methane gas and a digestion liquid. The volume-reduced solid, the digestion liquid, and the methane gas that are produced can be utilized effectively.

Description

Plant treatment methods and plant treatment systems

The present invention relates to plant treatment, and more particularly to a plant treatment method and a plant treatment system for treating aquatic plants containing water, which are frequently damaged by mass overgrowth.

In recent years, along with the eutrophication of the inland water surface, a large amount of aquatic plants have continued to overgrow, destroying the ecosystem and causing obstacles such as hindering ship navigation, water supply and irrigation intake. For example, when water hyacinth grows in lakes and marshes, light does not reach the water and affects the photosynthesis of other aquatic plants. In addition, aquatic plants have problems such as creating an oxygen-deficient state when they rot and adversely affecting the aquatic environment. FIG. 15 shows aquatic plants (water hyacinth, water hyacinth, elodea nuttallii) that thrived in various countries around the world. As shown in FIG. 15, when aquatic plants grow excessively, sunlight does not reach the water, and as a result, photosynthesis is blocked and water pollution due to hypoxia occurs.

We are continuing to study to improve the environmental deterioration caused by the above-mentioned aquatic plants. For example, in Japanese Patent Application Laid-Open No. 59-184783 (Patent Document 1), aquatic plants are rotted and squeezed, and the juice is methane-fermented. A technique for aerobic treatment of methane fermentation residue (digestive juice) and pressed solid residue has been proposed.

However, spoilage and aerobic treatment take time and space, so it was not suitable for mass treatment of aquatic plants. That is, there is still a need for aquatic plant treatment methods and aquatic plant treatment systems for treating aquatic plants in large quantities and efficiently.

JP-A-59-184783

An object of the present invention is to solve the above-mentioned problems of the prior art.

As a result of diligent studies in view of the above-mentioned problems of the prior art, the present inventors have crushed, left and squeezed aquatic plants, processed the liquid by high-speed methane fermentation, and used the digested liquid as a valuable resource. Cultivates microalgae and vegetables, which are the raw materials for. High-speed, low-cost and high-efficiency aquatic plant treatment method and aquatic plant treatment of aquatic plants that produce solid fuel, activated carbon, building materials, compost materials, soil conditioners, etc. while rapidly treating the pressed fibrous solids by carbonization. We have completed the system.

That is, according to the present invention, it is a plant treatment method for treating a plant.
The process of crushing plants and
The process of leaving the crushed plant and
A step of squeezing the abandoned plant to separate it into a fibrous solid content and a liquid content.
The step of reducing the volume of the fibrous solid content by carbonization and
A step of methane fermentation of the liquid to produce methane gas and the digestive juice,
Plant treatment methods including.

Also, according to other aspects of the invention,
A processing system for processing plants
Means to crush plants and
Means for leaving the crushed plant and
A means for squeezing the abandoned plant to separate it into a fibrous solid content and a liquid content.
A means for reducing the volume of the fibrous solid content by carbonization and
A plant treatment system including means for producing methane gas and digestive juice by fermenting the liquid with methane and separating methane gas and digestive juice is provided.

According to the present invention, it is possible to provide a plant treatment method and a plant treatment system that enable high-speed and high-efficiency treatment of plants.

FIG. 1 is a schematic flowchart of the aquatic plant treatment method of the present embodiment. FIG. 2 is a schematic view of the aquatic plant treatment system of the first embodiment. FIG. 3 is a graph showing weight loss, with the vertical axis representing the weight of the solid (t) and the horizontal axis representing the solid before and after treatment. FIG. 4 is a graph showing the volume reduction, where the vertical axis is the volume of the solid (m ³ ) and the horizontal axis is the solid before and after the treatment. In FIG. 5, the vertical axis represents the amount of liquid discharged from the crushed product as a ratio (%) to the water content of the crushed product, and the horizontal axis represents the crushing and squeezing conditions. FIG. 6 is a graph of methane production efficiency in which the vertical axis represents the cumulative amount of methane produced per dissolved organic carbon (mL / g-DOC) and the horizontal axis represents the operating time (days). FIG. 7 is a graph showing the total nitrogen concentration (mg-N / L) on the vertical axis and the liquid content and digestive juice on the horizontal axis. FIG. 8 is a graph in which the vertical axis represents total phosphorus concentration (mg-P / L) and the horizontal axis represents liquid content and digestive juice. The figure which showed the methane production efficiency at the time of using the neglected treatment which showed the integrated methane production amount (mL / g-DOC) on the vertical axis and the operation time (day) on the horizontal axis. The graph of the total nitrogen concentration where the vertical axis shows the total nitrogen concentration (mg-N / L) and the horizontal axis shows the leaving time. The vertical axis is the total phosphorus concentration (mg-P / L), and the horizontal axis is the graph of the total phosphorus concentration shown as the leaving time. FIG. 12 is a schematic view of the aquatic plant treatment system of the second embodiment. FIG. 13 is a diagram showing a configuration of an experimental device used for verifying the effect of the pretreatment. FIG. 14 is a graph of the dissolved organic carbon concentration in which the vertical axis represents the dissolved organic carbon concentration (mg-DOC / L) and the horizontal axis represents the operating time (days). The figure which showed the aquatic plant overgrowth state in each country of the world.

Hereinafter, the present invention will be described with reference to exemplary embodiments, but the present invention is not limited to the embodiments. FIG. 1 is a schematic flowchart of the aquatic plant treatment method of the present embodiment. The treatment of this embodiment starts from step S100, and the aquatic plants are collected in step S101. The aquatic plants to be recovered include hoteiaoi as shown in FIG. 15, wet plants, wet plants, water-extracting plants whose roots are completely below the surface of the water, and stems and leaves extending from the water to the surface of the water. Floating plants (or floating plants) that float on the surface of the water and are exposed to the air, overgrown aquatic plants such as submerged plants whose plants are completely underwater, and land such as Yoshi and Mitsuba Examples include, but are not limited to, agricultural residues and food wastes derived from plants and plant biomass.

Further, as the aquatic plant, an aquatic plant containing a large amount of water and to which the solid-liquid separation treatment can be applied without adding water or with a small amount of water is preferable, but there is no particular limitation. In addition, there are no particular restrictions on the method of collection, such as cutting and dredging by machine.

In step S102, the collected aquatic plants are crushed by a crushing means such as a crusher. The crushing means is not particularly limited, for example, mortar / pestle, mortar, food processor, tornado mill, sanitary crusher, rotary crusher, hammer crusher, wing mol, impact mill, mighty mill, roll hammer crusher, planetary mill, etc. Can be mentioned.

In step S103, after leaving the crushed aquatic plant at room temperature for a certain period of time, it is transferred to a squeezing means in step S104, a squeezing treatment is applied, and solid-liquid separation is performed in step S105. As long as the crushed aquatic plants are not dried and are left at room temperature or higher, the means of leaving is not particularly limited. The squeezing means is also not particularly limited, but any squeezing means known so far, such as a manual type, a hydraulic type, a screw type, a piston type, and a centrifugal type, can be appropriately selected according to the scale of processing. .. The fixed time can be about 6 hours or more and about 48 hours.

After squeezing, the aquatic plants are separated into fibrous solids and liquids. Since the fibrous solid content is a carbonic component mainly composed of cellulose, the fibrous solid content is recovered in step S106, transferred to a carbonization means for applying the volume reduction treatment, and hypoxic or oxygen-blocked in step S107. Carbonize under the conditions. The carbonization means used for the carbonization treatment is not particularly limited, and an electric furnace, a heating furnace using fossil fuel, wood, or the like, or a charcoal kiln can be used. The volume reduction treatment for the fibrous solid content is the most beneficial treatment for carbonization, but depending on the plant, volume reduction treatment such as drying, incineration, pressing, and molding is also possible.

After the carbonization treatment in step S107, the fixed amount is recovered as carbide in step S108. Carbides can be used, for example, as solid fuels, activated carbon raw materials, building materials, compost materials, soil conditioners and the like. Further, the liquid content recovered by the solid-liquid separation treatment in step S105 is treated with an organic substance by recovering the liquid content in step S109 and then fermenting the liquid content with methane in step S110.

Methanogenesis can be performed by using a flora that allows methanogenesis, specifically Methanomicrobia, such as archaea that synthesize methane under anaerobic conditions, such as Methanogen. , Methanogens, Methanomicrobia, Archaea belonging to Methanogens, and bacteria involved in hydrolysis or acidity, or flora. The temperature of methane fermentation can be appropriately set in the range of 20 ° C. to 60 ° C.

Further, although the means and equipment for performing methane fermentation are not particularly limited, in the exemplary embodiment, the liquid content is contained in a high-speed methane fermentation tank such as an upward flow anaerobic sludge tank (UASB) containing a bacterial flora. It was found that methane fermentation can be efficiently stabilized by supplying methane fermentation.

When another anaerobic sludge tank is used, it may take several tens of days to complete the methane fermentation in the past, but in the present embodiment, the methane fermentation is completed in about 2 to 5 days, which is efficient. It has been found that typical methane fermentation is possible.

The methane gas generated in the methane fermentation in step S110 is recovered in step S112 and can be used as a heat source for methane fermentation, and can also be used as electric power by generating electricity. In addition, the liquid after methane fermentation is used as digestive liquid. If it is necessary to separate the methane bacteria in step S111, appropriate solid-liquid separation such as filtration is applied and the digested juice is recovered in step S111. As shown in step S114, the use of the digestive juice can include, for example, chlorella, euglena, spirulina, microalgae, a medium for other high-value-added microorganisms, liquid fertilizer, and the like, but is not particularly limited.

When the recovery of carbides, the recovery of high-value-added microorganisms and liquid products, and the recovery of methane gas are completed, the series of treatments is completed. The process of FIG. 1 can be a continuous process or a batch process. According to this embodiment, the treatment of aquatic plants can be efficiently achieved with the minimum amount of carbon released.

FIG. 2 shows a schematic diagram of the aquatic plant treatment system of the first embodiment. The aquatic plant treatment system shown in FIG. 2 includes a crusher 200 as a crushing means, a leaving device 210 as a leaving means, a squeezing machine 220 as a squeezing means, and a carbonizing furnace 230 as a carbonizing means. In FIG. 2, valves, pumps and other means used for processing are omitted. The collected plants are put into the crusher 200 and crushed by a cutter member or the like arranged inside. Since the size of the crushed material affects the efficiency of the subsequent squeezing step, the crushing of aquatic plants can be optimized in advance including the crushing time and crushing conditions according to the characteristics of the crushing means to be used.

After the crushing step, the crushed material is transferred to the leaving device 210, charged into the squeezing machine 220, and solid-liquid separation is performed. In the standing and squeezing, the elution amount of the component is increased by repeating squeezing twice after leaving for 12 hours. However, the method of leaving is not limited as long as the crushed material does not dry and is at room temperature or above room temperature. Further, the squeezing machine is not limited to a pressurizing mechanism or method such as a manual type, a mechanical type, or a hydraulic type as long as it can pressurize the crushed material and squeeze out the water contained in the crushed material. By squeezing, the crushed material is separated into a fibrous solid content containing carbon and a liquid content.

The fibrous solid content is put into the carbonization furnace 230 and carbonized as an exemplary volume reduction treatment. Depending on the state of the carbide, a crushing means for further crushing the carbide and a means for recovering the carbide may be provided. The carbonization furnace 230 can be an electric furnace, a gas furnace, a simple carbonization furnace, etc., and is heated to a maximum temperature of 350 to 900 ° C. at a heating rate of 5 to 10 ° C./min and held for 1 to 4 hours. Carbonize. After that, it is naturally cooled. Further, in a specific embodiment, since the carbonization furnace is heated, methane gas produced by methane fermentation can be directly used. Further, when bioelectric power generation is performed using the generated methane gas, the electric furnace can be heated by the generated electric power. By using the methane gas produced by methane fermentation for heating the carbonization furnace, low carbonization treatment becomes possible.

The aquatic plant treatment system further includes a high-speed methane fermentation treatment tank 240 and a separation means such as a solid-liquid separation device 250 in a preferred embodiment. The high-speed methane fermentation treatment tank 240 is filled with an anaerobic flora containing methanogens, and liquids are supplied from the lower part, and the liquids are sequentially transported upward. The liquid component may be circulated using an appropriate discharge port and return port of the high-speed methane fermentation treatment tank 240, or the flow rate of one pass can be controlled so as to secure a predetermined treatment time. Further, the methane gas produced by methane fermentation is sent as produced methane to the biogas refining unit 270 composed of hydrogen sulfide treatment means and the like, and is processed for power generation, heating, drying, storage or subsequent use. To.

Further, the digested juice after the treatment is periodically or continuously discharged from the high-speed methane fermentation treatment tank 240, preferably after passing through a solid-liquid separator 250 for separating methanogens and the like, and then the digestive juice. Is stored in the digestive juice storage tank 260. The digestive juice in the digestive juice storage tank 260 is provided as a liquid product such as a medium for microalgae and a liquid fertilizer after pH adjustment and other appropriate treatments.

As described above, according to the aquatic plant treatment method and the aquatic plant treatment apparatus of the present embodiment, it is possible to efficiently produce an environmentally beneficial product from aquatic plants containing a large amount of water while satisfying the requirements for low carbon emission. Is possible.

Hereinafter, the present invention will be described with reference to specific examples.

(Examination of squeezing efficiency)
By crushing and squeezing aquatic plants, liquids containing highly degradable dissolved organic matter and fibrous solids containing cell walls with low degradability are separated. In Example 1, it was demonstrated how much the volume of aquatic plants is reduced by the aquatic plant treatment of this embodiment. The experimental conditions are as follows.

Substrate: Water hyacinth (Eichhornia crassipes)
Crushing conditions: No crushing, 0.5 cm, 3.0 cm
Squeezing pressure: 20MPa, 40MPa (squeezing pressure is changed and squeezing treatment is performed twice)
Carbonization temperature: 800 ° C
Carbonization time: 2 hours

FIG. 3 shows the result as a graph. In the graph of FIG. 3, the vertical axis represents the weight (t) of the solid, and the horizontal axis represents the solid before and after the treatment, indicating the weight loss. As shown in FIG. 3, when the weight of water hyacinth after cutting is 100 tons, the weight of the fibrous solid content after crushing and pressing is reduced to 33 tons. Further, it is observed that the weight is reduced to about 1.5 tons after carbonization, and according to this embodiment, the aquatic plants are crushed / pressed or carbonized in a short time to effectively reduce the volume. It was shown to be possible.

FIG. 4 shows a graph of the volume loss of the solid, corresponding to the graph of weight loss in FIG. In the graph of FIG. 4, the vertical axis is the volume of the solid (m ³ ), and the horizontal axis is the solid before and after the treatment, indicating the volume reduction. As shown in FIG. 4, when the volume of water hyacinth after cutting is 100 m ³ , the fibrous solid content after crushing and pressing is ^{reduced to about 8.5 m 3} , and the volume of water hyacinth after carbonization is further reduced. that volume to 0.4 m ³ of less than 2% decrease was observed against. From this, it was shown that the volume can be significantly reduced.

(Examination of juice squeezing rate)
As Example 2, the size and squeezing pressure of the crushed product prepared under the conditions of Example 1 were changed, and the squeezing condition dependence of the squeezed amount, that is, the squeezing efficiency dependence was examined. The result is shown in FIG. FIG. 5 is a graph showing the amount of liquid discharged from the crushed material on the vertical axis as a ratio (%) to the water content of water hyacinth, and the horizontal axis as crushing and squeezing conditions. As shown in FIG. 5, it was confirmed that the smaller the crushing size than the larger one, the better the squeezing efficiency, and the higher the squeezing pressure, the better the squeezing efficiency.

(Compressed methane fermentation process)
Under the following conditions, methane fermentation was carried out using the liquid obtained by pressing water hyacinth, and the methane fermentation rate was examined. The experimental conditions are as follows.

Substrate: Water hyacinth (Eichhornia crassipes) crushing / pressing liquid Crushing: 0.5 cm
Squeezing pressure: 50 MPa
Reaction tank: A 500 mL medium bottle (effective volume 300 mL) in which a high-speed methane fermentation tank is simulated.
Seed sludge: Medium-temperature anaerobic digested sludge distributed by the Northern Sludge Recycling Center, Environmental Creation Bureau, Yokohama City, Kanagawa Prefecture Substrate input conditions: Seed sludge: Substrate = 2g-VS: 1g-DOC
Temperature: 37 ± 1 ° C
Stirring: 100 rpm

FIG. 6 shows the amount of methane produced by methane fermentation as a graph. In the graph of FIG. 6, the vertical axis represents the integrated methane production amount (mL / g-DOC), and the horizontal axis represents the operating time (days). As shown in FIG. 6, by methane fermentation of the liquid in a treatment tank simulating a high-speed methane fermentation treatment tank, methane production is substantially completed in about 4 to 5 days, and high-speed methane fermentation treatment is performed. It was shown that it can be done. Therefore, in the present embodiment, it has been found that the residence period of the liquid in the high-speed methane fermentation treatment tank 240 can be reduced to about several days.

(Nutrient preservation of liquid and digestive juice)
The liquid contains nitrogen and phosphorus, which have a fertilizer effect and are possessed by water hyacinth. Since digestive juice is produced by methane fermentation of the liquid content, whether or not the amounts of nitrogen and phosphorus components, which are the active components, are preserved in the digestive liquid, the total nitrogen concentration and total phosphorus in the liquid content and digestive juice It was examined by quantitative analysis of the concentration. The analysis conditions are as follows.

The total nitrogen concentration was measured by the total method (industrial wastewater test method JIS K 0102 45.2), and the total phosphorus concentration was measured by the potassium perioxosulfate decomposition method (factory wastewater test method JIS K 0102 46.3.1).

FIG. 7 shows the analysis result of the total nitrogen concentration. FIG. 7 is a graph showing the total nitrogen concentration (mg-N / L) on the vertical axis and the liquid content and digestive juice on the horizontal axis. Note that FIG. 7 shows the confidence limit (95%) for the total nitrogen concentration. As shown in FIG. 7, it was confirmed that the total nitrogen concentration did not change substantially before and after the methane fermentation.

FIG. 8 shows the analysis result of the total phosphorus concentration. FIG. 8 is a graph in which the vertical axis represents total phosphorus concentration (mg-P / L) and the horizontal axis represents liquid content and digestive juice. Note that FIG. 8 shows the confidence limit (95%) for the total phosphorus concentration. As shown in FIG. 8, it was confirmed that the total phosphorus concentration did not substantially change before and after the methane fermentation.

According to the results of Example 4 above, the digestive juice after methane fermentation contains a sufficient amount of fertilizer components for plants, and zooplankton that grows by digesting the plant itself, chlorella, phytoplankton or phytoplankton. It was confirmed that it can be provided as fertilizer or culture solution.

(Methane fermentation treatment and elution nutrients of squeezing after performing pretreatment for leaving)
After leaving the water hyacinth to stand under the following conditions, methane fermentation was carried out using the liquid obtained by pressing, and the methane fermentation rate was examined. In addition, the eluted nutrients of the liquid were analyzed, and the nutrient recovery was examined. The experimental conditions are as follows.

Substrate: Water hyacinth (Eichhornia crassipes) crushing / pressing liquid Crushing: 0.5 cm
Squeezing pressure: 50 MPa
Standing time: 0 hours, 12 hours, 24 hours, and 12 hours, then squeezing and then leaving the fiber solids again for 12 hours Reaction tank: 500 mL medium bottle (effective volume 300 mL) in which a high-speed methane fermentation tank was simulated. )
Seed sludge: Medium-temperature anaerobic digested sludge distributed by the Northern Sludge Recycling Center, Environmental Creation Bureau, Yokohama City, Kanagawa Prefecture Substrate input conditions: Seed sludge: Substrate = 2g-VS: 1g-DOC
Temperature: 37 ± 1 ° C
Stirring: 100 rpm

FIG. 9 shows a graph showing the amount of methane produced by methane fermentation when the neglected treatment is added to the process. In the graph of FIG. 9, the vertical axis represents the integrated methane production amount (mL / g-DOC), and the horizontal axis represents the operating time (days). As shown in FIG. 9, it was shown that a higher amount of methane production can be obtained by methane fermentation of the liquid content obtained by pressing after the standing treatment. Therefore, it was found that in the present embodiment, it is possible to increase the amount of methane produced in the high-speed methane fermentation treatment tank 240.

(Nutrient elution of liquid after squeezing by pretreatment for leaving)
The liquid contains nitrogen and phosphorus, which have a fertilizer effect and are possessed by water hyacinth. It was examined by quantitative analysis of the total nitrogen concentration and total phosphorus concentration of the liquid. The analysis conditions are as follows.

FIG. 10 shows the analysis result of the total nitrogen concentration. FIG. 10 is a graph of total nitrogen concentration in which the vertical axis represents the total nitrogen concentration (mg—N / L) and the horizontal axis represents the standing time. As shown in FIG. 10, it was confirmed that the total nitrogen concentration to be eluted increased by performing the leaving treatment. Further, it was confirmed that the elution amount was significantly increased by repeating the standing for 12 hours and the pressing twice (12h → 12h in FIG. 10). Therefore, it can be seen that the total nitrogen concentration in the digestive juice can be increased and the amount of microalgae recovered can be increased by performing the pretreatment for leaving.

FIG. 11 shows the analysis result of the total phosphorus concentration. FIG. 11 is a graph in which the vertical axis represents the total phosphorus concentration (mg-P / L) and the horizontal axis represents the standing time. As shown in FIG. 11, it was confirmed that the total phosphorus concentration to be eluted increased by performing the leaving treatment. Furthermore, it was confirmed that the elution amount was significantly increased by repeating the leaving and pressing for 12 hours twice (12h → 12h in FIG. 11). Therefore, it can be seen that the total phosphorus concentration in the digestive juice can be increased and the amount of microalgae recovered can be increased by performing the pretreatment for leaving.

As shown in Examples 5 and 6, by carrying out the pretreatment before squeezing, the amount of recovered methane produced during methane fermentation is increased, and the fertilizer component in the digestive juice after methane fermentation is increased. An increase in the yield of microalgae and vegetables can be confirmed.

The liquid (squeezed liquid) containing highly decomposable soluble organic matter obtained by crushing and squeezing may be sent to the high-speed methane fermentation treatment tank 240 and treated as it is, but pretreatment of the squeezed liquid is carried out. It was found that it is expected that the operation efficiency will be improved. Therefore, pretreatment such as pH adjustment can be carried out.

FIG. 12 shows a schematic diagram of the aquatic plant treatment system of the second embodiment. The aquatic plant treatment system shown in FIG. 12 has almost the same configuration as the system shown in FIG. 2, but the pH is adjusted as an example of a pretreatment device between the press 220 and the high-speed methane fermentation treatment tank 240. Device 280 has been added. The crusher 200, the leaving device 210, the squeezing machine 220, the carbonization furnace 230, the high-speed methane fermentation treatment tank 240, the solid-liquid separation device 250, the digestive juice storage tank 260, and the biogas purification unit 270 have already been described. Is omitted.

The pH adjuster 280 accepts the liquid that is discharged from the upper part of the high-speed methane fermentation treatment tank 240 and circulates, and the liquid that is supplied from the squeezer 220 after merging, and receives the pH of calcium hydroxide or the like. A regulator is used to adjust the pH of the liquid supplied to the high speed methane fermentation treatment tank 240. The pH of the liquid is adjusted to, for example, 6 to 8, preferably 6.5 to 7.5.

The pH adjusting device 280 includes, for example, a liquid storage tank for storing liquid, a container for storing a pH adjusting liquid such as an aqueous solution of calcium hydroxide, a pH measuring device for measuring pH in the liquid storage tank, and pH. It includes a regulating valve that adjusts the amount of pH adjusting liquid supplied from the container based on the pH measured by the measuring instrument. The pH adjusting device 280 may include a stirrer for stirring the inside of the liquid content storage tank. The pH adjusting device 280 is not limited to this configuration as long as the pH of the liquid can be adjusted. Here, pH adjustment is given as an example of the pretreatment of the liquid component, but the pretreatment may be solubilization, heat treatment, addition of a trace amount of metal, or the like, and is not limited to pH adjustment.

Hereinafter, the effect of the pretreatment will be described by way of examples.

(Effect of pretreatment)
As shown in FIG. 13, the liquid content obtained by squeezing hotiaoi under the following conditions is pH-adjusted, and the pH-adjusted liquid content is a bacterium that enables methane fermentation with a pump 300 such as a Perista pump (registered trademark). Pretreatment from the dissolved organic carbon (DOC) concentration of the substrate and wastewater discharged from the reaction tank 310 when sent to the reaction tank 310 filled with the carrier 320 on which the flora is fixed and set to each hydraulic residence time (HRT). The effect of was examined. The hydraulic residence time is the average time from the inflow of the liquid into the reaction tank 310 to the outflow. The crushing, squeezing pressure, and seed sludge were the same as in the examples shown in FIG. The biogas generated by methane fermentation was discharged from the top of the reaction tank 310, and the waste water was discharged by overflow. The experimental conditions are as follows.

Substrate: Water hyacinth (Eichhornia crassipes) crushing / pressing solution Temperature: 37 ± 1 ° C
pH adjustment: Ca (OH) ₂
Reaction tank: Effective volume 6.5 m ³
Hydraulic dwell time (HRT):
Operating period (days) 0-12: 5 days 12-44: 4 days 44-77: 3 days 77-120: 2 days The pH was adjusted to 6.5-7.5.

FIG. 14 is a graph showing the DOC concentration. The DOC concentration is the DOC concentration contained in the substrate before pH adjustment and the waste water discharged from the reaction tank 310, using the combustion catalytic oxidation method by TOC-L CPH / CPN (manufactured by Shimadzu Corporation) every two days. Measured. FIG. 14 is a graph of the DOC concentration in which the vertical axis represents the DOC concentration (mg-DOC / L) and the horizontal axis represents the operation period (days). During the operation period of 0 to 12 days, the hydraulic residence time was set to 5 days, the amount of the pH-adjusted treatment liquid supplied into the reaction vessel 310 was reduced, and after the 12th day, the above number of days was increased. The experiment was conducted by shortening the hydraulic residence time by one day and increasing the supply amount of the treatment liquid each time.

As a result of the experiment, even if the hydraulic residence time was set to 2 days, the DOC concentration could be reduced by 90% or more to complete the methane production, and the residence time of the liquid in the reaction vessel 310 was set to 2 days. It turned out that it can be reduced to.

As described above, according to the present embodiment, aquatic plants are crushed, left to stand, and squeezed, and the liquid content is subjected to high-speed methane fermentation treatment to recover biogas, and the digestive juice is used as a raw material for valuable resources. High-speed, low-cost, and highly efficient aquatic plant treatment methods and aquatic plants capable of producing solid fuels, building materials, etc. while culturing certain microalgae and rapidly treating pressed fibrous solid residues by carbonization. A plant processing system can be provided. Further, by carrying out pretreatment such as pH adjustment, the hydraulic residence time can be reduced to 2 days, and the operating efficiency can be improved.

The numerical provisions used in the present embodiment should be understood as median, average, and representative values including a certain range, and the numerical values disclosed in the present disclosure exceed the numerical values by 20%. It should also be understood to define a numerical range that is 20% below the numerical value.

Although the present invention has been described with embodiments so far, the present invention is not limited to the embodiments, and other embodiments, additions, changes, deletions, etc. can be conceived by those skilled in the art. It is included in the scope of the present invention as long as the action / effect of the present invention is exhibited in any of the embodiments.

200 ... Crusher 210 ... Leaving device 220 ... Squeezer 230 ... Carbonization furnace 240 ... High-speed methane fermentation processing tank 250 ... Solid-liquid separation device 260 ... Digestive liquid storage tank 270 ... Biogas purification 280 ... pH adjustment device 300 ... Pump 310 ... Reaction tank 320 ... Carrier

Claims

It is a plant treatment method for treating plants,
The process of crushing plants and
The process of leaving the crushed plant and
A step of squeezing the abandoned plant to separate it into a fibrous solid content and a liquid content.
The step of reducing the volume of the fibrous solid content by carbonization and
A step of methane fermentation of the liquid to produce methane gas and digestive juice,
Plant treatment methods including.
The plant treatment method according to claim 1, wherein in the crushing step, a step of controlling the degree of crushing, leaving time and pressing is included.
The plant treatment method according to claim 1 or 2, further comprising a step of pretreating the separated liquid component after the separation step and before the production step.
The plant treatment method according to claim 3, further comprising a step of adjusting the pH of the liquid component to 6 to 8 in the pretreatment step.
The plant treatment method according to any one of claims 1 to 4, wherein the methane fermentation has a hydraulic retention period in the fermenter within 8 days.
The plant treatment method according to any one of claims 1 to 5, wherein the carbonization is applied at a maximum temperature of 350 to 900 ° C. and a holding time of 1 to 4 hours.
The plant treatment method according to any one of claims 1 to 6, wherein the plant is an aquatic plant.
An aquatic plant treatment system for treating plants,
A processing system for processing plants
Means to crush plants and
Means for leaving the crushed plant and
A means for squeezing the abandoned plant to separate it into a fibrous solid content and a liquid content.
A means for reducing the volume of the fibrous solid content by carbonization and
A plant treatment system comprising means for producing methane gas and digestive juice by fermenting the liquid with methane and separating methane gas and digestive juice.
The plant treatment system according to claim 8, wherein the crushing means controls the degree of crushing, the leaving time, and the squeezing pressure.
The plant treatment system according to claim 8 or 9, which comprises means for pretreating the liquid content separated by the separating means.
The plant treatment system according to claim 10, wherein the pretreatment means adjusts the pH of the liquid to 6 to 8.
The plant treatment system according to any one of claims 8 to 11, wherein the methane fermentation is applied to the hydraulic retention period in the fermenter within 8 days.
The plant treatment system according to any one of claims 8 to 12, wherein the carbonization is applied at a maximum temperature of 350 to 900 ° C. and a holding time of 1 to 4 hours.
The plant treatment system according to any one of claims 8 to 13, wherein the plant is an aquatic plant.