JPH0889992A - Method for purifying water area - Google Patents

Abstract

PURPOSE: To provide a method for purifying a water area capable of treating the water contg. bottom sludge of a water area and a large amt. of nitrate in linkage and capable of reducing and removing the nitrate in water with high efficiency. CONSTITUTION: This method for purifying a water area having sludge consists of a stage 5 to separate the sludge 2, a stage for hydrogen-fermenting the separated sludge under slightly anaerobic and/or reduced pressure conditions to form hydrogen and carbon dioxide 11 and a stage 13 for introducing the formed hydrogen and carbon dioxide 7 into the water area or the water 14 contg. nitrate, converting the nitrate into gaseous nitrogen by hydrogen-assimilating bacteria to denitrify the water. Heterotrophic hydrogen producing bacteria are concentratedly cultured or a photosynthesis microorganism with a sulfide as the electron donor is concentratedly cultured in the fermentation stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying water containing sludge, such as a human waste treatment plant, a domestic human waste septic tank, livestock excrement or a water source pond contaminated by various food factory wastewater. The present invention relates to a method for comprehensively purifying water bodies, and particularly to a method for effectively removing nitrogen content in water. In addition, naturally, nitrogen derived from the above sources is present in the sludge sludge, and 80% or more of the phosphoric acid that has flowed into the water source pond is bound to metal ions and is insoluble and present in a rich concentration as inactive phosphate. are doing. The present invention relates to a method including a technique of recovering this phosphoric acid and effectively utilizing it for fertilizer and other purposes.

[0002]

2. Description of the Related Art Water is an essential substance for sustaining the life of our living beings, and the present water purification system mainly depends on the dam reservoir, and directly or indirectly takes water from the dam reservoir. Water is purified at a water purification plant to a level that meets the water quality standard value and sent to the use point. However, over the last 20 years, water source pollution has progressed due to the development of industry around dam reservoirs, the specialized and large-scale production of livestock companies, and the excessive application of fertilizers intended for large harvests in modern agriculture. Therefore, the reality of radical abatement measures is strongly demanded. The greatest pollution of dam reservoirs is abnormal growth of microorganisms such as microalgae due to nitrogen, phosphorus, and other substances originating in wastewater that are released into the environment from the above-mentioned business sites and / or businesses, that is, eutrophication of water bodies. In addition, microalgae and carcasses of zooplankton, aquatic small animals and fish that feed on them are accumulated at the bottom of the reservoir, making the reservoir fatal.

In recent years, nitrate pollution of pond water and / or groundwater has become apparent mainly due to livestock sewage and nitrogen fertilizer flowing out from field soil, and children in areas where groundwater containing nitrate at high concentrations are regularly used. Malignant anemia, or Blue Baby Syndrome, has been reported. At present, this kind of disease is common in European countries, which are dairy farming countries, but even in Japan, investigations by the Environment Agency, Ministry of Agriculture, Ministry of Health, Ministry of Construction, etc. have reached a stage where nitrate contamination of groundwater cannot be ignored. . In order to overcome such a reality, an exposure cylinder or an air diffuser was installed in a dam reservoir in the olden days, and by aerating the pond water and lake water, the surface water and the bottom water layer were reversed, and the cause of eutrophication A method to control growth has been developed and tested in several dam reservoirs, but recent information has been ineffective and in some cases heterogeneous microalgae have been reported to cause adverse effects. Even assuming that this method is effective, ignoring the existence of sludge in the reservoir is merely a temporary symptomatic treatment. At present, there is a strong worldwide demand for research and development and establishment of an integrated purification system for dam reservoirs, including treatment of sludge in the reservoir.

[0004]

[Problems to be Solved by the Invention] Since pollution of dam reservoir, which is a water intake source, has an extremely important effect on human health and maintenance of life, each research institution has a purification technology and / or purification of the water source pond. Systems research is being conducted. Among these studies, there is a study to reduce nitrates by utilizing the function of hydrogen-utilizing bacteria for the purpose of removing nitrates contained in groundwater in a concentrated manner. No consideration was given to the decomposition and disposal of mud sludge in the reservoir, and there was a problem with the comprehensive purification system for the water source pond and its countermeasures. Even if only the lake water and / or the groundwater is subject to purification, the water source pond will become infinitely contaminated and will continue as long as the sludge sludge is not treated / disposed, and it will not be a fundamental purification measure as described above. Is. INDUSTRIAL APPLICABILITY The present invention provides an innovative comprehensive purification system for a water source pond based on a completely new idea, that is, a method for connecting and treating sludge sludge in a water area and water containing a large amount of nitrate, for high-speed and high-efficiency underwater treatment. An object of the present invention is to provide a water purification method system for reducing and removing the nitrates of the above.

[0005]

[Means for Solving the Problems] The above-mentioned problem is a water source pond that reasonably combines the functions of hydrogen fermentation by a polytrophic hydrogen-producing bacterium and nitrate removal (denitrification) by an autotrophic hydrogen-assimilating bacterium. It is achieved by the comprehensive purification system. That is, the present invention, in the method for purifying a water area having sludge, a step of separating the sludge content of the water area, the separated sludge content is subjected to hydrogen fermentation under slightly anaerobic and / or reduced pressure conditions to produce hydrogen and carbon dioxide gas. Fermentation step to generate, and a denitrification step of introducing the produced hydrogen and carbon dioxide into the water or water containing other nitrates, and converting the nitrates into nitrogen gas by hydrogen-utilizing bacteria to denitrify It is what In the above, the fermentation step is a method of cultivating an allotrophic hydrogen-producing bacterium in a concentrated manner, and a culturing method in which a residence time is 5 days or less or a photosynthetic microorganism having a sulfide as an electron donor is cultivated in a concentrated manner. It should be

[0006] In this way, the sediment of the bottom sediment from which the sludge has been separated and the purified water are returned to the relevant water area,
Further, the water may be supplied directly or after further advanced treatment as water for water source. The sludge component of the present invention,
Suction pump type, graph type,
It is dredged by a conveyor method or any other suitable method, and is lifted ashore or onboard from the water area. Sediment is separated into sediment and sludge, the means of which are stirring sedimentation separation, sieving, centrifugation,
Hydrocyclone and other separations are appropriately selected depending on the separation process execution conditions. If necessary, the shipboard process and the bottom sediment separation process may be alternately provided. In the hydrogen fermentation of the separated sludge, a vessel such as a pressure tank or an existing pressure-resistant photosynthetic culture tank can be used depending on the type of the hydrogen-producing microorganism to be tested. Since this step is performed under slightly anaerobic and / or reduced pressure conditions, it is desirable to attach a vacuum pump or a gas separation membrane device. Further, since corrosive substances such as hydrogen and sulfide are stored, it is natural to select materials and take measures against corrosion.

In particular, when using a photosynthetic culture device,
Energy saving can be achieved by using a light supply system including a sunlight concentrator, an optical fiber, and a light diffusing member. Also,
In the present invention, since the sludge to be treated contains a large amount of bound phosphate, the treated water is taken out from the fermentation step to be anaerobicized, and the phosphate content liberated in free water or pore water is It can be added to the denitrification process complementarily or immobilized by a chemical treatment such as crystallization or oxidation to be utilized as a resource as a phosphorus fertilizer. The nitrate-containing water used in the denitrification process may be groundwater, industrial wastewater, or water from other water areas, but it is preferable to use water from the water area where the bottom sediment has been obtained, and again the sediment and treatment It is preferable to return the water to the water area as a water area purification method.

[0008]

In the present invention, the non-nutritional hydrogen-producing bacteria that inhabit wildly in ordinary soil, sludge containing organic matter such as sewage sludge, also inhabit the bottom mud sludge of the dam reservoir. Paying attention to the fact that
The first feature is that it decomposes organic substances such as biological dead bodies, fibers, proteins, carbohydrates and organic acids, which are components of sludge. In the process of this decomposition reaction, that is, in the process of metabolism of organic substances, surplus electrons generated in the cells are released to the outside of the cells as hydrogen gas together with carbon dioxide. The sludge is not limited to hydrogen-producing bacteria, but various anaerobic and / or aerobic bacteria inhabit, thus forming a so-called mixed culture system. There is a methane bacterium as an important bacterium whose existence cannot be ignored, which is directly related to the present invention, and depending on the culture conditions of the atrophic hydrogen-producing bacterium, the methane bacterium becomes the dominant species in the mixed culture system, The original intended hydrogen production may be hindered.

However, in this methane bacterium and the hydrogen-producing bacterium,
It has been confirmed that there is a considerable difference in the optimum conditions necessary for each living and growing in the natural environment, and by artificially controlling this difference in conditions, the hydrogen of interest of the present invention can be obtained. Producing bacteria can always be grown as the dominant species in a mixed culture system. The most universal way is
Utilizing the fact that the growth rate of hydrogen-producing bacteria is considerably higher than that of methane bacteria, and the volume of the hydrogen-producing bacteria culture tank is the range in which the methane bacteria are washed away, roughly, the volume of culture days is about 5 days or less. The hydrogen-producing bacterium can easily be made the dominant species (the optimum growth rate for methane is 7.8, the specific growth rate is 0.3 to 0.5 day ^-1 , and the pH for hydrogen-producing bacterium is optimum).
Specific growth rate of 5 to 15 day ⁻¹ at 5.5 to 5.8).

As a more reliable method, as described in detail in the "microanaerobic hydrogen fermentation method of organic waste" previously proposed by the present inventor (Japanese Patent Application No. 5-195329),
There is a considerable difference between the two bacteria in the redox potential suitable for growth as described below. * Methane bacterium -350 to -450 mV * Hydrogen producing bacterium -100 to -200 mV Therefore, in a continuous culture system, this redox potential is about -250.
In order to maintain a stable mV disparity at all times, it is necessary to slowly aerate the culture solution in the hydrogen-producing bacteria culture tank to maintain a slightly anaerobic atmosphere. It can be a species. It is known that normally, a concentrated organic wastewater, a methane bacterium and a hydrogen-producing bacterium (allotrophic) that spontaneously grow in an organic waste belong to the following races.

* Major methane bacteria Methanococcus Methanosarcina Methanothrix Methanobrevibacter Methananospirillum * Methanospirillum * Clostridium Enterobacter (Ruminococcus) Bifidobacterium

Further, in the slightly anaerobic hydrogen fermentation method, hydrogen equilibrium concentration increases in the liquid phase of the hydrogen fermentation tank as a result of the progress of hydrogen fermentation in preference to methane fermentation, which naturally results in closed system (sealed) fermentation. The hydrogen partial pressure in the vapor phase of the tank rises. Hydrogen fermentation of organic waste by hydrogen-producing bacteria is an absorbing ergon reaction in which the standard free energy of the biological reaction has a positive value, and the biological reaction is inherently difficult to proceed in the positive direction. Therefore, as described in the above-mentioned patent specification by the inventor himself, in order to proceed hydrogen fermentation of sludge without delay, a hydrogen fermenter may be required from -300 to -4000 mm.
Considering that the equilibrium concentration of hydrogen in the liquid phase and the hydrogen partial pressure in the gas phase are forcibly reduced by setting the reduced pressure condition of Aq and fermenting the solution in the tank under reduced pressure so that the hydrogen fermentation proceeds effectively. Preferably.

Further, in the present invention, as another method for smoothly proceeding hydrogen fermentation, the generated gas of hydrogen fermentation is separated into carbon dioxide gas and hydrogen gas by passing through a gas separation membrane, so It is also possible to adopt a method for eliminating the above-mentioned obstacle by forcibly taking out harmful hydrogen gas outside the biological reaction system. By such artificial setting, hydrogen fermentation of sludge proceeds smoothly, and sufficient hydrogen can be secured for use in the next step. A second feature of the present invention is that the mixed gas of H ₂ + CO ₂ generated as a decomposition gas from an allotrophic hydrogen-producing bacteria culture tank for decomposing sludge of sludge is groundwater and / or containing a high concentration of nitrate. Water such as lake water is introduced into a hydrogen-assimilating bacterium culture tank that is pre-filled with water, while hydrogen-assimilating bacteria isolated from the soil are inoculated and expanded under certain conditions to increase the amount of water contained in the water. It has the function of biologically reducing the existing nitrates and releasing it into the atmosphere as nitrogen gas, which is harmless to living organisms and chemically inert. If the water used here is from the water area where the bottom sediment was obtained, it is more effective for water area purification.

As the autotrophic hydrogen-utilizing bacterium, a pure strain banked by a microbial preservation organization may be used, but normally, the bacterium is wild-habited in general soil,
Since it can be easily separated from the soil, the purpose of nitrate reduction can be sufficiently achieved even if this kind of wild hydrogen-utilizing bacterium is used alone or in a mixed culture system. The main types of hydrogen-utilizing bacteria that are extremely commonly inhabiting soil are as follows. Alcaligenes de
nitrificans) Paracoccus den
itrificans) Pseudomonas de
nitrificans)

An excellent feature of the hydrogen-assimilating bacterium culture method of the present invention is that inorganic salts and / or trace elements are added to groundwater or nitrates such as lake water without using a specific culture medium for culturing the bacterium. Depends on the water it contains,
Since hydrogen and carbon dioxide gas required for the growth of hydrogen-utilizing bacteria depend on the gas generated from the hydrogen-producing bacterium culture tank, the cost can be significantly reduced and a synergistic treatment effect can be obtained. When phosphate containing water such as groundwater and / or lake water is insufficient, the amount of phosphoric acid contained in the digestive desorption solution of the hydrogen-producing bacteria culture tank and / or the digestive desorption solution is high. Phosphoric acid recovered from the syneresis may be added to the hydrogen-utilizing bacterial culture tank as needed.

[0016] The present invention is also directed to the oxidation function of sulfides of red sulfur photosynthetic bacteria, especially Chromatium, which wildly inhabit water systems such as ordinary rivers and coasts where sunlight is incident, and dark conditions. Focusing on the function of decomposing organic substances by the respiratory action in, and effectively utilizing these functions of the bacterium,
Environment of the bottom of the water source pond Sludge that decomposes and stabilizes organic substances such as carcasses, carbohydrates, proteins, fats, and organic acids, which further deteriorates the environment of the bottom of the water source pond by oxidizing and stabilizing sulfides. To make improvements, and
The third feature of this is to suppress the growth of chlorobium, which is a green sulfur photosynthetic bacterium that is a causative bacterium of blue tide.

In the process of this decomposition reaction, that is, in the process of metabolism of organic substances and oxidation of sulfides, surplus electrons generated in the cells are
It is released outside the cells as hydrogen gas together with carbon dioxide.
As described above, various anaerobic bacteria and / or aerobic bacteria live in the sludge during the process of decomposing the sludge with photosynthetic bacteria, and constitute a so-called mixed culture system. An important bacterium which is directly related to the present invention and whose presence cannot be ignored is methane bacterium, which is a dominant species against the purple sulfur photosynthetic bacterium Cromatium, which has a slow growth rate even under anaerobic conditions under sunlight irradiation. Therefore, there is a possibility that hydrogen production, which is the original purpose of the present invention, may be hindered. Although the growth rates are almost similar between the methane bacteria and the purple sulfur photosynthetic bacteria, they live in natural environments,
Moreover, it has been confirmed that there is a considerable difference in the optimum conditions necessary for growth, and by artificially controlling the difference in this living condition, the purple sulfur photosynthetic bacterium of the present invention can be mixed in a mixed culture system. Can always be propagated as a dominant species.

That is, there is a considerable disparity between the two bacteria in the optimum redox potential for growth (hereinafter abbreviated as ORP), as shown below. * Methane bacterium -350 to -450 mV * Red sulfur photosynthetic bacterium -150 to -250 mV Therefore, in a continuous culture system, in order to always maintain a stable difference of about -200 mV of this ORP, the above-mentioned patent of the present inventor. The method described in detail in the specification, that is, by slowly aerating the culture solution in the purple sulfur photosynthetic bacteria culture tank to maintain a slightly anaerobic atmosphere, the target sulfur sulfur photosynthetic bacteria is always the dominant species. Can be Further, as described above, it is preferable to reduce the pressure for extracting the generated hydrogen, and it is also possible to further perform the gas membrane separation.

In addition, according to the present invention, a large amount of inactive phosphoric acid contained in the bottom mud sludge of the dam reservoir is combined with a metal by culturing in a hydrogen-producing bacteria culture tank under anaerobic conditions. Release the inactive phosphoric acid from the metal bond,
The phosphoric acid released in the culture solution can be recovered by a chemical means and recycled as a resource. It is known that the behavior of metal (typically represented by iron) and phosphoric acid in the oxidizing or reducing atmosphere of water or bottom mud is usually due to the following reaction. Under oxidative conditions, phosphoric acid binds to the metal. Then, it becomes inactive, but under reducing conditions, it is eliminated from the metal and exists as water-soluble and active phosphoric acid.

Water system in oxidizing atmosphere, bottom mud 2Fe (OH) ₂ + H ₂ O + 1 / 2O ₂ → 2Fe (OH) ₃ ↓ Fe (OH) ₃ + PO ₄ ³ → → FePO ₄ ↓ + 3OH ^- reducing atmosphere water system, bottom mud When sulfate is present

Phosphorus is an element that is not essential to living organisms and does not have a pathway for communicating with the atmosphere in the material circulation in the global environment, and the chemical reaction as described above occurs in the water system or bottom mud (sediment). Eventually, it will be accumulated in the bottom mud such as the deep sea. Therefore, it is a preferred embodiment of the present invention to include a system in which phosphorus is mainly recovered by a chemical method from the digested liquid flowing out from the hydrogen-producing bacterium culture tank and is recycled for various purposes. The above are the means and methods for solving the problems and objects of the present invention, and by these, the total purification of the water source pond, which is the object of the present invention, is completely achieved.

[0022]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto. Example 1 FIG. 1 shows a flow process diagram when a hydrogen-producing bacterium is supplied to a fermentation process. In Fig. 1, sludge 2 accumulated at the bottom of dam reservoir 1 is lowered from a ship that can freely run on the surface of the lake to lower the sludge pumping hopper 3 at the bottom of the reservoir, and a pump 4 installed on the ship moves the surface of the lake while moving the surface of the lake. It is put into the sand remover 5. In this example, a precipitation separation method was used. It is practically difficult to separate the sludge as the bottom mud from the sediment and to pump only the sludge mainly composed of the organic matter. The sand removing device 5 can roughly separate the organic sludge and the sediment. . Moreover, you may provide the earth and sand washing process. The separated sediment can be returned to the water area or used for the purpose of land reclamation, but the so-called sludge in the upper layer of the sand remover 5 is usually
It is transferred continuously and / or batchwise to the hydrogen-producing bacteria culture tank 6A, which is the next step.

In the hydrogen-producing bacterium culture tank 6A, the following bacteria, which are very commonly inhabiting the soil, play a major role in sludge decomposition and hydrogen production, and are isolated from these soils. The single bacterium or the mixed culture system may be cultivated in an increased amount to inoculate the tank 6A in an appropriate amount, or alternatively, it may be used by being dispensed from a banking institution of a microorganism such as ATCC.
It is most easily adjusted by selective culture that naturally grows under conditions artificially prepared from the sediment. These hydrogen-producing bacteria decompose sludge (organic matter) into lower carboxylic acid, hydrogen and carbon dioxide gas. The preferable culture conditions and the specific growth rate therein are as follows. Optimum pH: 5.5-5.8 Optimum temperature: 25-30 ° C Fermentation days: 5-7 days Specific growth rate: 5-15 days- ¹

The reaction here is as follows. * (C ₆ H ₁₀ O ₅ ) _n → 4C ₆ H ₁₂ O ₆ → 3CH ₃ (CH ₂ ) ₂ COOH + 2CH ₃ COOH + 8H ₂ + 8CO ₂ (1) * 3CH ₃ (CH ₂ ) ₂ COO ⁻ + 6H ₂ O = 6CH ₃ COO ⁻ + 3H ⁺ + 6H ₂ (2) * 2CH ₃ COO ⁻ + 4H ₂ O = 10H ⁺ + 2H ₂ + 4CO ₂ (3) For the time being, the reaction of formula (1) is basically the main reaction, and due to microbial decomposition of sludge, A large amount of lower carboxylic acid (mainly butyric acid, acetic acid) contained and equimolar hydrogen and carbon dioxide gas are produced. As described above, the hydrogen-producing reaction by the hydrogen-producing bacterium is an absorption ergon reaction, and reaches a dynamic equilibrium when the lower carboxylic acid is considerably accumulated, and further hydrogen-producing reaction does not proceed.

Therefore, in the present invention, in order to improve the conversion rate of hydrogen in the organic matter as much as possible, hydrogen is forcibly removed from the biological reaction system to outside the system (vacuum fermentation), and at the same time, the tank 6 is used.
The redox potential of the solution in A is artificially set to -100 to -20.
By setting it to 0 mV, the generation of hydrogen gas is 70-
It can be increased to about 80%. The digested and desorbed liquid that has completed the hydrogen fermentation in the tank 6A is transferred to the next sludge separation / concentration tank 7 and roughly separated into treated water 8 and concentrated sludge 10, and the concentrated sludge 10 is dehydrated by a conventional means. , Converted to fertilizer or compost, and reused as a resource. On the other hand, in the so-called treated water 8 separated from the sludge, the inactive phosphorus accumulated in the sludge is concentratedly released as water-soluble phosphorus. For sludge hydrogen fermented liquor (digestion and desorption liquor) in a dam reservoir, it is usually 40 depending on the location conditions of the dam reservoir.
0 to 1000 mg / liter (nitrogen: 2000 to 350
0 mg / liter) phosphorus.

Discharging this high-concentration phosphorus into the water system induces eutrophication of the water system and water area at the discharge destination, and a vicious cycle continues indefinitely. Therefore, in the present invention, a phosphorus fertilizer is recovered by applying the MAP (magnesium phosphate ammonium) method and / or the HAP (hydroxyapatite) method, which is a phosphorus recovery and removal technology utilizing a chemical crystallization reaction, Used for agricultural purposes. The MAP method is
If magnesium ions, ammonium ions and phosphate ions are present in the liquid, equimolar reaction as shown below proceeds extremely stoichiometrically between these three ions in a short time, and magnesium ammonium phosphate Produces and precipitates easily. Mg ²⁺ + NH ₄ ⁺ + PO ₄ ^3- = MgNH ₄ PO ₄ ↓

In this reaction, the crystallization reaction easily proceeds even if the seed crystal does not exist in the liquid, so that the digestion / desorption liquid in which NH ₄ ⁺ and PO ₄ ^3- coexist, for example, magnesium chloride (Mg
Cl ₂ ) solution is added in an amount with a slight allowance for the stoichiometric value with respect to the phosphate ion concentration, and appropriate stirring is performed in a fluidized bed reactor under alkaline conditions to allow crystallization. The reaction produces MgNH ₄ PO ₄ crystals. The HAP method known as catalytic dephosphorization method for this method is
In the presence of seed crystals of calcium hydroxyapatite, pH adjustors (8.5) and hydroxyl ions (OH ^-) addition of calcium hydroxide for the purpose of supplying, with stirring in a reaction vessel of fluidized bed type reaction When this is done, calcium hydroxyapatite is produced on the surface of the apatite by the crystallization reaction, and HAP, which is slow-acting and residual-acting, is produced. The chemical reaction formula for producing HAP is as follows. 10Ca ²⁺ + 6PO ₄ ^3- + 2OH ^- ───Ca ₁₀ (OH) ₂ (PO ₄ ) ₆

Since the digestive desorbent usually contains bicarbonate ions, a decarboxylation step is required to make the HAP method proceed permanently, but the digestive desorbent according to the present invention contains PO ₄
^Since the ratio of ^3- / bicarbonate ion is very small, the decarboxylation step can be omitted, which not only simplifies the process but also makes it possible to manufacture phosphate fertilizer extremely economically. As a final step of the present invention, a biological treatment process of decomposing nitrate contained in groundwater and / or lake water into nitrogen gas will be described. Over the past few years, NH ₄ ⁻ originated from livestock sewage and domestic wastewater (human waste treatment plant, septic tank effluent) has been oxidized by nitrifying bacteria into NOx ⁻ in a natural ecosystem, and then enters the water system, which is becoming a problem. Taking groundwater as an example, groundwater nitrate (NO ₃
-N) Concentration is 10m based on drinking water according to a survey by public institutions
far exceeding g / l, 50-1 depending on location
It has reached 00 mg / liter.

In the present invention, the groundwater containing this nitrate 15
And / or the lake water 14 is introduced into the hydrogen-assimilating bacterium culture tank 13 by the pump 16, and a group of hydrogen-assimilating bacteria that wildly inhabit the soil in this tank 13 or a microorganism preservation organization such as ATCC. Inoculate the donated hydrogen-assimilating bacteria,
Further, hydrogen is produced from the hydrogen-producing bacterium culture tank 6A (CO ₂ + H
₂ ) By blowing the mixed gas of 11 and culturing in a continuous system and / or a batch system, the nitrate of groundwater or lake water is reduced to nitrogen gas 19 which is completely harmless to the global environment and is emitted into the atmosphere. There are various genus species of hydrogen-assimilating bacteria, but normally, the genus Alcaligenes and the genus Paracoccus have strong nitrate reducing ability,
It is advisable to utilize bacteria of this genus. The biological reduction reaction of nitrate by these bacteria is as follows. 2NO ₃ ⁻ + 5H ₂ = N ₂ + 4H ₂ O + 2OH ⁻

From the bioreaction equation of hydrogen reduction of this nitrate,
Stoichiometrically determining the amount of hydrogen required to reduce nitrate, assuming that hydrogen obtained from the sludge of the dam reservoir is used for 100% nitrate reduction, the required amount of hydrogen is 1.5 to 3. Since it is 0 times, the comprehensive purification system of the water source pond of the present invention is theoretically guaranteed. * Amount of hydrogen required for nitrate reduction 0.9 m ³ · H ₂ / kg · NO ₃ —N Excess hydrogen 12 required for the biological reduction of nitrate should be taken out from the reaction system and burned as clean energy 20. It can be used as a power source for multiple purposes. On the other hand, the surplus bacterial cells 18 grown in the hydrogen-assimilating bacterial culture tank 13 can be taken out of the reaction system and effectively used for the purpose of producing valuable materials. For example, when Alcaligenes is selected as a hydrogen-assimilating bacterium, the bacterium produces poly-β-hydroxybutyric acid (commonly known as PHB), which is a type of biodegradable biopolymer, in the microbial cells. Can be effectively used as a raw material for various products.

Experimental Example 1 From a dam reservoir sludge to Clostridium
Hydrogen production by the genus Sludge containing sediment from the dam reservoir for water intake source was selected as the substrate for hydrogen production. Since this sludge contained a considerable amount of sediment, the required amount per day was taken from the sludge stored at about 5 ° C in a large refrigerator for about 1 hour before supplying it to the hydrogen-producing bacteria culture tank. After standing still, the upper layer portion was transferred to another container by the tilting method to obtain a test sample. Table 1 shows the chemical properties of sludge which was roughly separated from the sediment.

[0032]

[Table 1] As can be understood from Table 1, the analytical values of the test sample during the experiment period vary considerably, so the period average value was used for the design calculation in the experiment and the like.

Table 2 shows the average values of the chemical properties of the test sludge.

[Table 2] *: The unit of total solids and ablation loss is kg / m ³ .

The volume of the hydrogen-producing bacterium culture tank (hereinafter abbreviated as hydrogen fermentation tank) is 5 times the actual water-filled volume (effective volume).
A liter cylindrical fermenter was set in a constant temperature water bath at 30 ° C., and medium temperature fermentation was performed for about 6 days. The experimental conditions of the hydrogen-producing bacteria culture tank are as follows. * Fermentation water temperature 30 ° C ± 1 ° C * pH during operation 5.6 to 6.0 (automatically reaches dynamic equilibrium) * Fermentation days approx. 6 days * Organic load 6.8 kg · VS / m ³ · day * Hedro's supply method In the morning and afternoon, half the amount for one day is input.

Since the hydrogen fermenter used in the examples of the present invention has an effective volume of 5 liters and is small in scale, it is technically difficult to directly apply the reduced-pressure fermentation of the present invention to the experimental apparatus of the examples. Therefore, a simplified method was used. That is, a vacuum pump is connected to a pipe made of vinyl chloride that communicates with the gas phase portion of the hydrogen fermentation tank, and the vacuum pump is operated to automatically reduce the pressure so that the entire tank is -1000 to -1500 mmAq. Controlled, vacuum fermentation was performed.
The test sludge is slowly aerated before being put into the hydrogen fermentation tank, so that the redox potential of the test sludge becomes higher than a predetermined redox potential, specifically, -50 to -100 m.
After adjusting to V, it was put into a hydrogen fermenter. An ORP sensor is installed in the hydrogen fermentation tank, and it is suitable for hydrogen-producing bacteria to grow while monitoring the ORP value.
It was operated with V as the set value.

As a hydrogen-producing bacterium, a hydrogen-producing bacterium group that wildly inhabits the test sludge was used without using a specific strain. Initially, about 2 liters of the test sludge was injected into the hydrogen fermenter as a seed bacterium, and the hydrogen-producing bacterium was grown by a method of gradually increasing the load from a low load. By this method,
About two weeks after the start of operation, the steady state was reached under the set organic matter loading condition. After the experiment was completed, the hydrogen-producing bacteria in the grown sludge of this experiment were identified, and it was confirmed that it was a mixed culture system of the following multiple types of hydrogen-producing bacteria. Detected hydrogen-producing bacteria Clostridium barkeri (ATCC 25849) Clostridium butyricum (ATCC 25779) Clostridium sporogenes (ATCC 7955) Clostridium thermocellum (Clostridium thermocellum)

From the results of this identification, when sludge is used as a substrate for hydrogen fermentation, a hydrogen-producing bacterium useful for sludge itself can be obtained without purchasing a pure strain from a microorganism preservation institution such as ATCC and inoculating it into a hydrogen fermentation tank. , Mainly Clostridium inhabits wildly, and hydrogen is produced without resistance by their synergism. By setting the conditions required for hydrogen fermentation, a group of hydrogen-producing bacteria that is most suitable for the substrate to be input is formed, so stable hydrogen fermentation is performed rather than artificial inoculation, and this is a natural process. It is a clever providence. As a verification experiment under the above experimental apparatus and experimental conditions, 3
The treatment results obtained for about 1 month at the end of the experiment, which was continued for a month, are shown in Table 3 (average value for period). In addition, the sample used for water quality analysis is the fermentation digestion liquid (digestion desorption liquid) with centrifugal force 1,5.
The suspension containing the bacterial cells was forcibly separated and removed by using a 00G centrifuge for 10 minutes to obtain a sample for analysis.

[0038]

[Table 3]

The results obtained by the verification experiment are summarized as follows. (1) The bottom mud sludge of the dam reservoir does not have to inoculate the hydrogen fermentation tanks with the preserved strains (pure bacteria) of the public institution. By inoculating, hydrogen fermentation proceeds smoothly without delay. (2) By fermenting sludge sludge with a wild hydrogen-producing bacterium, a numerical value of the total amount of gas generated was quantitatively approximate. (3) By slightly anaerobic and decompressing the bottom mud sludge,
Methane fermentation is suppressed and hydrogen fermentation proceeds preferentially. By adopting this fermentation method, the molar amount ratio of hydrogen and carbon dioxide gas obtained by the usual fermentation method is improved to 50%: 50%, and the generation ratio of hydrogen and carbon dioxide gas is 65 to 70%: 30 to
Improved up to 35%. This is because the hydrogen-fermentation method by slightly anaerobic / vacuum fermentation converts the absorbed ergon reaction into a substantially ergon reaction, and in the conventional method, a large amount of lower carboxylic acid such as butyric acid and acetic acid is accumulated in the fermentation broth. As a result, it is speculated that what had reached the dynamic equilibrium state progressed in the positive direction, and as a result, the hydrogen generation amount increased.

(4) The rate of decomposition of organic matter by hydrogen fermentation of sludge from bottom mud was remarkable, and the removal rate of organic matter at a period average value was as high as about 80%. This is the hydrogen-producing bacterium Clostridium (Clostridiu) that plays a major role in sludge decomposition.
m) usually produces strong enzymes such as cellulase, hemicellulase, and lysozyme, so it also decomposes biological remains that make up a considerable portion of sludge organic matter, that is, biodegradable organic matter such as cell walls and cell membranes. It is thought that this is because it is done. (5) Significant nitrogen and phosphorus are removed by hydrogen fermentation of sludge sludge, and it is reasonable to consider that this is because both elements are used for the growth of hydrogen-producing bacteria. Since this nitrogen and phosphorus naturally exist in the body of hydrogen-producing bacteria, it suggests that the surplus cells can be used as effective nitrogen and phosphorus fertilizers.

Experimental Example 2 Reduction and removal of nitrate from groundwater and lake water by hydrogen-assimilating bacteria Genus Alcaligenes, Paracoccus (Para)
Hydrogen-utilizing bacteria such as Coccus spp. or Pseudomonas spp. belong to autotrophic bacteria, in which CO ₂ is present in the liquid as a carbon source, and nitrogen sources, phosphorus sources and other inorganic substances necessary for microbial growth are present. If salts and trace elements are present, they will grow completely in a mineral nutritional environment. These bacteria are H ₂
Is used as an electron donor to reduce nitrate (NOx-N) into nitrogen gas. The present invention is most characterized by effectively utilizing this function and removing nitrate in the liquid. In this example, initially, the removal of nitrate from the dam reservoir was considered, but the concentration of nitrate nitrogen was low at 2 to 3 mg / liter even in the dam reservoir where eutrophication was extremely advanced, which was caused by hydrogen-utilizing bacteria. Since it may not be possible to accurately judge the effect of nitrate reduction, groundwater containing a large amount of nitrate, which is considered to be the source of livestock sewage, was selected as a test sample.

Table 4 shows the water quality of the groundwater used as the test sample.

[Table 4]

As can be seen from Table 4, this groundwater has a low phosphorus concentration and is insufficient for bacteria to grow. Therefore, an appropriate amount of the final treated water from the hydrogen fermentation tank of Example 1 was added to adjust the concentration of PO ₄ -P in ground water to 10 mg / liter. The hydrogen-assimilating bacterium culture tank (hereinafter abbreviated as a culture tank) used in the examples of the present invention is a cylindrical culture tank having an effective volume of 0.5 liter and naturally has a closed structure that does not directly communicate with the atmosphere. . This closed culture tank was set in a constant temperature water tank of 20 ° C. as in Example 1, and the nitrate reduction time was set in the range of 4 to 7 hours to carry out continuous experiments.

The flow sheet of the continuous experiment is shown in FIG.
First, the hydrogen-utilizing bacteria that play a major role in nitrate reduction may be obtained by using the hydrogen-utilizing bacteria of the above-mentioned pure bacteria from public institutions, but these bacteria are usually used in soil. Since it generally inhabits, soil near the point where groundwater was sampled was collected, tap water was added to this, and the mixture was stirred and allowed to stand, and the upper layer liquid that settled sediment was taken out by the gradient method, 200 ml and 24 and 300 ml of ground water were added to the culture tank 23, and the volume of the culture tank was increased to 500 ml to make the volume equal. When the operation was started, a nitrate load of ⅕ of the expected final load was applied and the loads were sequentially increased, and when the nitrate reducing function reached a steady state, a regular continuous experiment was performed. The test groundwater 24 was injected by the pump 25 so that the liquid retention time was about 4 to 6 hours (2 to 3 liters / day).

The evolved gas 28 obtained from the hydrogen fermentation tank of Experimental Example 1 was continuously blown into the culture tank 23 by a blower 29, and the gas discharged from the culture tank was passed through the circulation pipe again to the culture tank 23. It was blown into and recycled. The gas blowing rate was adjusted to about 100 to 150 ml / min. The generated gas from the culture tank reached the generated gas meter 27 via the trap 26 and measured the amount of generated gas. When collecting the treated water 30 in the culture tank, the operation of the blower 29 was temporarily stopped (about 1 hour) at the time of collection, and the amount of the upper layer liquid obtained by sedimentation and separation of the hydrogen-assimilating bacteria group was adjusted to an external amount. I took it out. Samples to be analyzed are treated water collected from the culture tank, placed in a centrifuge (3000 G, 10 minutes),
Performed on the centrifuge.

The culture conditions (treatment conditions) of hydrogen-assimilating bacteria in the culture tank are summarized as follows. * Culturing temperature: 20 ° C ± 1 ° C * Groundwater supply rate: Approximately 2 to 3 liters / day (phosphorus is strengthened with hydrogen fermented water) * Dwelling time: Approximately 4 to 6 hours (continuous treatment method) * Nitrogen load by nitrate : Approximately 0.21 kg / m ³ · day * Load on bacterial cells: Approximately 0.15 kg / kg · day * Supply gas: H ₂ 65% + CO ₂ 35% (gas generated from hydrogen fermenter) * pH: 7. 3 to 7.8 * Cell concentration: Approximately 1,500 mg / liter

The results obtained by the above verification experiments are summarized as follows. (1) The groundwater of Table 4 containing nitrate nitrogen of about 30 to 40 mg / liter is used as the inoculum of the hydrogen-utilizing bacteria group that wildly inhabits the soil, and the gas generated from the hydrogen fermentation tank (H ₂
By supplying + CO ₂ ), about 0.15 kg / k
Under the nitrogen loading condition of g · day (residence time is about 4 hours), the nitrate of the above concentration can be almost completely removed. Since there was still a margin under this load condition, the nitrogen removal rate at the culture water temperature of 20 ° C is estimated to be 0.2 kg / kg · day or more. (2) In this treatment experiment, inorganic components were not corrected at all, except that the phosphorus concentration of groundwater was strengthened by the hydrogen-fermented final treated water. Therefore, it is considered that the denitrification rate will be further improved if the components are sufficiently corrected. However, in reality, it will process a huge amount of groundwater, so
The experimental fact that complete nitrate removal was achieved without compensating components is a valuable finding.

(3) Further, in this verification experiment, a continuous treatment experiment using a group of hydrogen-assimilating bacteria living in normal soil was used without using pure bacteria obtained from public institutions such as ATCC. However, nitrate in groundwater was completely removed under the nitrogen loading conditions. The hydrogen-assimilating bacteria that became the dominant species in this mixed culture system were the following bacteria. Major hydrogen-utilizing bacteria detected: Alcaligenes eutrop
hus) Alcaligenes de
nitrificans) Usually, the genus Paracoccus, a hydrogen-utilizing bacterium commonly found in soil, was also found, but it was not the dominant species.

(4) The total amount of gas generated from the culture tank is 15
0 to 200 ml / day, the gas components were nitrogen gas, hydrogen gas and carbon dioxide gas, of which nitrogen gas was about 75 to 1
It was 10 ml / day, and a value close to the stoichiometric value was obtained for nitrogen gas. (5) The characteristic feature of the present invention is that the sludge sludge from the dam reservoir is used as a substrate, and the synergistic action of hydrogen-producing bacteria and hydrogen-assimilating bacteria causes the sludge to inhabit the sludge and soil without the use of specific pure bacteria. It was demonstrated that it is possible to almost completely remove high-concentration nitrates even with the use of wild bacteria. It was also confirmed that the amount of hydrogen obtained from the hydrogen fermenter reaches about three times the required amount when the lake water in a general dam reservoir is targeted.

Example 2 An example of the case where a photosynthetic microorganism having a sulfide as an electron donor is supplied to two types of fermentation will be described with reference to FIG. In FIG.
The sludge 2 accumulated at the bottom of the dam reservoir 1 can be moved freely on the lake surface, or the dredger can be used to lower the sludge pumping hopper 3 to the bottom of the reservoir and move the liquid level to move it above the ground with the pump 4 installed on the ship. It is put into the sand remover 5. It is practically difficult to separate the sludge as bottom mud from the bottom of the lake and to pump only the sludge mainly composed of organic matter, and the sand removing device 5 separates the organic sludge and the sediment largely. The separated sediment is used for landfilling, etc., but the so-called sludge in the upper layer of the sand removing device 5 is usually a continuous and / or batch next step, which is a red sulfur photosynthetic bacterial culture tank. 6B (hereinafter abbreviated as hydrogen fermentation tank)
Be transferred to.

In the sludge of the water source pond, sulfate ions and various metal ions originating from various sewage flowing into the water source pond chemically react with each other in the water source pond to form a sulfate, which is deposited on the bottom of the lake and sludge. When it reaches the reduction zone, various metal sulfides and / or hydrogen sulfides are present in a high concentration. So-called sulfides in this sludge and sunlight, which is weakly incident on the bottom of the lake, cause red sulfur photosynthetic bacteria to inhabit the sludge, and hydrogen fermentation is carried out in the environment of the bottom mud, although weakly. Therefore, the solar energy collected by the solar light concentrator using the Fresnel lens floated on the lake surface in the hydrogen fermenter 6B and / or the solar light concentrator 21 installed on land is transmitted to the solar energy such as an optical fiber. By introducing into the hydrogen fermenter 6B with the cable 22 and culturing under specific load conditions and temperature conditions, the red sulfur photosynthetic bacterium Chromatium proliferates vigorously, and decomposition of organic matter by respiration and hydrogen production in the growth process are performed. .

Red sulfur photosynthetic bacterium Chromatium
The biological reaction equations for organic matter production and hydrogen production by (tium) are as follows. Red sulfur photosynthetic bacteria ・ ・ ・ Electron donor Sulfide Photosynthesis 6CO ₂ + 12H ₂ S = C ₆ H ₁₂ O ₆ + 12S + 6H ₂ O Hydrogen production C ₆ H ₁₂ O ₆ + 6H ₂ O = 12H ₂ + 6CO ₂ + 680kcal Hydrogen fermenter For 6B, for example, a pure strain of purple sulfur photosynthetic bacterium may be purchased from a microorganism preservation institution such as ATCC, and may be inoculated with an increased amount of culture, but the sludge is inoculated with a wild bacterium that naturally grows, It is also possible to carry out expansion culture in a hydrogen fermenter.

In reality, the red sulfur photosynthetic bacterium Chromatium is often mixed with the hydrogen-producing microalga Oscillatoria in a natural environment. It is known that not only the hydrogen production of algae itself is added, but also the photosynthetic bacteria utilize other organic acids secondarily produced by algae for other nutrition, and the growth rate is significantly accelerated. There is. Microalgae Oscillatoria ・ ・ ・ ・ ・ Electron donor Water Photosynthesis 6CO ₂ + 12H ₂ O = C ₆ H ₁₂ O ₆ + 6O ₂ + 6H ₂ O Hydrogen production 2H ₂ O = 2H ₂ + O ₂

Oscillatoria described above
Microalgae of the genus Anabaena produce fungi, organic matter, and hydrogen using carbon dioxide as a carbon source in the presence of light energy, but about 30% of fixed carbon dioxide is polysaccharides, acetic acid, or glycol. It is released as a lower fatty acid such as an acid to the outside of the bacterium, and the red sulfur photosynthetic bacteria further decompose organic matter and produce hydrogen by using these organic matter as a nutrient source. As hydrogen production _{CH 3 COOH + 2H 2 O =} 2CO 2 + 4H 2 hydrogen production from glycolic acid _{CH 2 (OH) COOH + H} 2 O + 2H 2 or more from acetic acid, inoculated with a pure strain obtained from the outside to the hydrogen fermenter 6B It is more rational to inoculate a mixed culture system of wild red sulfur photosynthetic bacteria and microalgae, and it is superior from the viewpoint of organic matter decomposition and hydrogen production.

Further, the solar light concentrating device 21 described above floats on the surface of a lake having a vast surface area and restricts the amount of sunlight incident on the water source pond, whereby the growth of algae that cause eutrophication can be significantly achieved. Since it can be controlled, it is better to use this type of solar concentrator if the location of the source pond allows. The digested and desorbed liquid that has completed the hydrogen fermentation in the tank 6B is transferred to the next sludge separation and concentration tank 7, where the treated water 8 and the concentrated sludge 1
The sludge 10 is roughly separated into 0 and dehydrated by conventional means, then converted into fertilizer or compost and reused as a resource. The following phosphorus recovery and nitrate denitrification methods, treatment of excess sludge, utilization of excess hydrogen gas, etc. are the same as in Example 1.

Experimental Example 3 Hydrogen production from the dam reservoir sludge by the genus Clomatium The sludge containing sediment obtained from the dam reservoir for clean water intake was selected as a substrate for hydrogen production. Since this sludge contained a considerable amount of sediment, take out the required amount per day from the sludge stored in a large refrigerator at 5 ° C and leave it for about 1 hour before supplying it to the hydrogen fermentation tank. After that, the upper layer portion was transferred to another container by the tilting method to prepare a test sample. Table 5 shows the chemical properties (average value during the experimental period) of sludge obtained by roughly separating this sediment content.

[0057]

[Table 5]

The volume of the hydrogen fermenter is a cylindrical fermenter with an actual water-filled volume (effective volume) of 5 liters, which is installed in a constant temperature water bath of 30 ° C., and sludge is fed so that the number of fermentation days is 6 days. Was injected. Experimental conditions for red sulfur photosynthetic bacteria group culture (average value in steady state for 5 months)
Is as follows. * Fermentation temperature: 30 ° C. ± 1 ° C. * pH dynamic equilibrium value during operation: 7.8 * Fermentation days: 6 days * organic load: 7.5kg · / m ³ · day * cell concentration at steady state: 4,500 mg / liter (including suspended matter) * Cell load: 1.7 kg / kg-day * Sulfide cell load: 0.25 kg / kg-day * Sludge supply method 1 each in the morning and afternoon Input half the amount for the day

Since the hydrogen fermenter used in the examples of the present invention has an effective volume of 5 liters and is small in scale, it is technically difficult to directly apply the reduced-pressure fermentation of the present invention to the experimental apparatus of the examples. Therefore, the simplified method was used. That is,
Connect the vacuum pump to the vinyl chloride pipe that communicates with the gas phase part of the hydrogen fermentation tank, and operate the vacuum pump,
The reduced pressure was automatically controlled so that all the tanks were substantially -1000 to -1500 mmAq, and the reduced pressure fermentation was performed. The test sludge was slowly aerated before being put into the hydrogen fermentation tank, and the ORP of the test sludge was adjusted to be higher than a predetermined ORP, specifically, adjusted to -100 to -150 mV. Then it was put into a hydrogen fermenter. An ORP sensor was installed in the hydrogen fermenter, and while operating the ORP value, the hydrogen-producing bacterium (red sulfur photosynthetic bacterium group) was operated with a set value of -200 mV suitable for growing.

The hydrogen fermenter was initially inoculated with 1 liter of the sludge to be tested and 1 liter of sludge in the open channel near the laboratory as inoculum, and the load was gradually increased from the low load to acclimate the hydrogen-producing bacteria. The cells were allowed to grow, and by this method, a steady state was reached under the set sulfide loading condition about one month after the start of operation. After the experiment was completed, red sulfur photosynthetic bacteria were identified in the grown sludge of this experiment, and as a result, it was confirmed to be a mixed culture system of the strains shown below. Detected red sulfur photosynthetic bacterium Clomatium vinosum (ATCC 1
7899) Clomatium buderi (ATCC 2558
3) In addition, about 1.5 months after the start of cultivation, a kind of cyanobacteria, Oscillatoria sp., Was found, and a symbiotic system was constructed in the culture tank. Was not specifically identified.

As the light energy required for the photosynthesis of the red sulfur photosynthetic bacteria and the symbiotic cyanobacteria, the experimental conditions cannot be determined and the data cannot be analyzed if the sun rays are directly used. Using a xenon lamp that is relatively close to, ultraviolet rays and infrared rays were cut as much as possible by a filter, and only visible light was introduced into the hydrogen fermentation tank by an optical fiber. The light amount was adjusted so that the light energy intensity was in the range of approximately 60 to 65 W / m ² . In addition, the light irradiation has a daily irradiation time (bright condition) of 10
The time and dark conditions were controlled to be 14 hours. The verification experiment under the above experimental apparatus and experimental conditions continued for 3 months after the operation reached a steady state, and the treatment results obtained during the approximately 1 month at the end of the experiment are shown in Table 6 (period average value). . The sample used for water quality analysis was digested and desorbed liquid with centrifugal force of 150.
The suspension containing the bacterial cells was forcibly separated and removed by applying a 0 G centrifuge to obtain a sample for analysis.

[0062]

[Table 6]

The results obtained by the verification experiment are summarized as follows. (1) The sludge in the dam reservoir can be hydrogenated by inoculating reddish sulfur photosynthetic bacteria that wildly inhabit the sludge or normal ditches, without using the preserved strains of public institutions. Fermentation proceeds without delay. (2) The hydrogen gas generation amount obtained in this verification experiment is considerably larger than the stoichiometric value roughly calculated from the biochemical reaction formula. Although the reason for this is not clear, as described in the detailed description of the invention, the organic matter produced by these species, which is produced by the expression of Oscillatoria sp. It is thought that the hydrogen production amount and the hydrogen production amount of cyanobacteria themselves are added.

(3) By slightly anaerobic / vacuum-fermenting the sludge in the water source pond, the growth of methane bacteria was suppressed and the hydrogen fermentation proceeded preferentially. By adopting this fermentation method, the molar ratio of hydrogen and carbon dioxide gas obtained by the normal fermentation method is improved to 50%: 50%, and the generation ratio of hydrogen and carbon dioxide gas is improved to about 70% and 30%. It was Hydrogen fermentation using sulfide as an electron donor with Chromatium is an absorbing ergon reaction in which the standard free energy value is positive, but it is substantially converted to an ergon reaction by slightly anaerobic and vacuum fermentation, and the positive direction It is considered that hydrogen production increased due to the progress of biological reactions. (4) By hydrogen fermentation of sludge, considerable nitrogen and phosphorus are removed, and it is reasonable to consider that this is because both elements were utilized for the growth of purple sulfur photosynthetic bacteria and cyanobacteria. Since the nitrogen and phosphorus naturally exist in the proliferating cells, the surplus cells can be used as effective nitrogen fertilizer and phosphorus fertilizer.

Experimental Example 4 Reduction and removal of nitrate from groundwater and lake water by hydrogen-assimilating bacteria An experiment similar to Experimental Example 2 was carried out using the treated gas (CO ₂ +
H ₂ ) gave similar results.

Experimental Example 5 Recovery of Phosphorus from Hydrogen Fermentation-treated Water of Sludge In the sludge of the dam reservoir, microalgae which had grown by feeding phosphorus, nitrogen, phosphorus and sulfide as nutrients in the past,
A large amount of phosphorus derived from zooplankton and other small animals is accumulated as inactive phosphorus. The present invention is a novel comprehensive purification system for a water source pond, which is one of the features of recovering and utilizing valuable phosphorus resources sleeping indefinitely without being used for this bottom mud. When the sludge sludge is treated by hydrogen fermentation under the reducing conditions of the first step of the present invention, the inert phosphorus that was strongly bound to the metal ion in the sludge is released from the binding with the metal ion, and the water-soluble Leaches into the fermentation digestive juice as phosphorus. In the hydrogen fermentation of the present invention, for example, as shown in Table 6, a high concentration of phosphorus (PO ₄ −
P) was included.

The existing phosphorus recovery technology includes MAP method and HAP.
Although there are methods and the like, as described above, both technologies are the same kind of technology from the viewpoint of the technology applying the chemical crystallization reaction, although there are differences in the chemicals used and the conditions. Therefore, in Experimental Example 5, the treatment experiment was limited to the phosphorus recovery experiment to which the MAP method was applied. Since the fermented digestive juice contains not only PO ₄ -P but also a large amount of NH ₄ -N at the same time,
When a magnesium chloride (MgCl ₂ ) solution as a magnesium source is injected into this fermentation digestive liquid, the phosphoric acid in the liquid reacts extremely stoichiometrically, and magnesium ammonium phosphate (MgNH ₄ PO ₄ ·. 6H
₂ O) is produced and this material precipitates very rapidly.

In Experimental Example 5, first, the fermented digested liquid (centrifuged water) was diluted 5 times with the lake water in the dam reservoir, and the diluted digested liquid was placed in a 1-liter beaker. PO of this diluted fermentation digestive juice
_4- P is 120 to 130 mg / liter, NH ₄ -N is 230 to 240 mg / liter, and pH is 7.8 to 7.9.
Met. Add alkali to this solution to adjust the pH to 8.5.
After adjusting so as to be in the range of 8.8, Mg / P≈1.
A solution of magnesium chloride was added so that the mixture became 5, and the mixture was gently stirred for about 1 hour, then the product was forcibly separated by centrifugal force and returned to the beaker. Next, again add the 5-fold diluted fermentation digestion solution to the beaker, perform the same operation as before, and repeat this operation about 5 times a day for about 5 to 7 days, and crystals of magnesium ammonium phosphate will undergo crystallization reaction. Gradually grow and become granular,
After 10 days, it will be easily separated by gravity precipitation. This reaction has the same mechanism as the catalytic dephosphorization method by the HAP method, and the crystal is about 1.0 at the final stage of the experiment.
Grew to ~ 1.5 mm.

When the treatment experiment reached a steady state, the removal rate of phosphoric acid (PO ₄ -P) reached a high efficiency of about 95%, and about 10 mg / liter of phosphoric acid remained in the treated water. There wasn't. This granulated product was very similar in physical properties to the granular crystals obtained by the catalytic dephosphorization method, and moisture was easily released when left standing naturally, and handling was extremely easy. Further, since this reaction is carried out in a strict stoichiometric manner, NH ₄ -N naturally remained in the separated liquid to a considerable extent. In conclusion, water-soluble phosphorus in fermentation digestive juice can be recovered extremely effectively and economically as phosphate fertilizer and nitrogen fertilizer by applying MAP method and / or HAP method. .

[0070]

As described above in detail, the present invention is an innovative invention based on a concept and a concept completely different from the prior art, and has the following effects. (1) Utilizing sludge accumulated at the bottom of dam reservoirs as an effective resource as a method of fundamentally purifying dam reservoirs that have reached their limits from the viewpoint of eutrophication in recent years By doing so, comprehensive purification of the water source pond can be achieved. In other words, infinitely existing sludge is supplied as a substrate for hydrogen-producing bacteria and purple sulfur photosynthetic bacteria, and hydrogen fermentation is performed to stabilize and decompose sludge (organic matter in bottom mud) and to produce a large amount of hydrogen. it can. Generated in the process of hydrogen production (H ₂ + CO ₂ )
Is a causative agent of pernicious anemia (mainly blue infant syndrome) by supplying hydrogen gas as a nutrient source and electron donor to groundwater and / or lake water containing a large amount of nitrate, and culturing hydrogen-utilizing bacteria. Not only can nitrate be completely removed, but it will also contribute significantly to the prevention of eutrophication in the water source pond.

(2) In order to completely prevent or eliminate eutrophication in closed water areas and stagnant water areas, even if only nitrogen and phosphorus in the water system are removed as targets, they have a high eutrophication potential. Eutrophication of water bodies will continue indefinitely unless the sludge sludge is treated and disposed of. The present invention is a comprehensive purification system for water source ponds that gives an accurate answer to this fact. Sludge is not evaluated as organic waste but as a valuable resource, and hydrogen-producing bacteria, purple sulfur photosynthetic bacteria, and hydrogen resources are evaluated. It is an innovative technology for regenerating a water source pond by synergistic action with oxidative bacteria. (3) Most of the final metabolic gas released from both microbial reaction systems into the atmosphere is nitrogen gas, which is harmless to the global environment,
It does not pollute the global environment.

(4) Dam reservoirs are at the same level as natural lakes, or are often located in highlands and mountainous areas, and have a large surface area. Therefore,
In the integrated purification system for water source ponds of the present invention, the red sulfur photosynthetic bacteria or blue-green algae that play a leading role in the hydrogen fermentation process of the first step are relatively easy to obtain the energy from the natural sunlight necessary for photosynthesis. In particular, if a floating solar concentrator is installed on the lake surface of the reservoir, the irradiation amount of solar energy required by the algae that cause eutrophication into the reservoir can be considerably limited, reducing eutrophication. It will be a help to you and you will win both.

(5) The fermentation digestion liquid from the culture tank (hydrogen fermenter) using hydrogen-producing bacteria and purple sulfur photosynthetic bacteria,
Phosphorus resources that had been stored as inactive phosphorus in sludge were revealed as active phosphorus resources, and by applying chemical phosphorus recovery technology, this phosphorus was regenerated as phosphorus fertilizer or nitrogen fertilizer for agricultural purposes. Can be used. This phosphorus recovery step is an important step that is inseparable from the above-mentioned two-step biological reaction step, and the present invention combines these three elements to achieve an important function of comprehensive purification of water source ponds and recycling of waste. Is expressed.

[Brief description of drawings]

FIG. 1 is a flow process diagram when a hydrogen-producing bacterium is supplied to a fermentation process by the purification method of the present invention.

FIG. 2 is a partially enlarged flow sheet of a denitrification process used in the present invention.

FIG. 3 is a flow process diagram when a photosynthetic microorganism is supplied to a fermentation process by the purification method of the present invention.

[Explanation of symbols]

1: Dam reservoir, 2: Sludge of bottom mud, 3: Hopper for pumping sludge, 4, 16, 25: Pump, 5: Sand remover, 6
A: Hydrogen-producing bacteria culture tank, 6B: Photosynthetic microorganism culture tank,
7: Sludge separation and concentration tank, 8: Treated water, 9: Phosphorus recovery, 1
0: concentrated sludge, 11: H ₂ + CO ₂ , 12: H ₂ , 1
3, 23: Hydrogen-assimilating bacterial culture tank, 14: Nitrate-containing lake water, 15, 24: Nitrate-containing groundwater, 17: Denitrated salt water, 18: Excess bacterial cells, 19: Nitrogen gas, 20: Combustion, 2
1: Solar concentrator, 22: Solar energy transmission, 2
6: trap, 27: evolved gas meter, 28: H ₂ + C
O ₂ , 29: blower, 30: treated water

Claims (3)

[Claims] 1. A method for purifying a water area having sludge, a step of separating a sludge content of the water area, and a hydrogen fermentation of the separated sludge content under slightly anaerobic and / or reduced pressure conditions,
A fermentation step of producing hydrogen and carbon dioxide, and introducing the produced hydrogen and carbon dioxide into the water area or water containing other nitrates, and denitrifying by converting the nitrates into nitrogen gas by hydrogen-utilizing bacteria. A method for purifying a water body, which comprises a nitrogen process. 2. The method for purifying a water body according to claim 1, wherein the fermentation step is a concentrated culture of a heterotrophic hydrogen-producing bacterium, and a residence time is 5 days or less. 3. The method for purifying an aquatic body according to claim 1, wherein the fermentation step is a concentrated culture of a photosynthetic microorganism having a sulfide as an electron donor.