JP5414056B2 - Water treatment apparatus and water treatment method - Google Patents

Description

  The present invention relates to a water treatment apparatus and a water treatment method.

  When rearing livestock (eg fish, shellfish, crustaceans, amphibians, etc.) in a closed-circulation breeding aquarium, suspended suspended matter (SS) derived from the excrement and residual food of the livestock, ammonia nitrogen It is necessary to perform water treatment by an appropriate method so that the water quality is not deteriorated by others.

  As a method of removing (denitrifying) ammonia nitrogen and nitrate nitrogen (nitrate ions) contained in the breeding water in the breeding tank, for example, a nitrification tank and a denitrification tank are provided in parallel in the circulation line for circulating the breeding water In addition to oxidizing (nitrifying) ammonia nitrogen and nitrite nitrogen to nitrate nitrogen by the action of nitrifying bacteria (autotrophic bacteria) in the nitrification tank, and by the action of denitrifying bacteria (heterotrophic bacteria) in the denitrification tank A breeding water treatment apparatus (see Patent Document 1) that reduces (denitrifies) nitrite nitrogen or nitrate nitrogen to nitrogen is known.

JP 2000-126794 A

  In order to maintain the performance of the breeding water treatment device, it is necessary to backwash the nitrification tank etc. at an appropriate timing to remove the organic matter trapped in the nitrification tank etc. Therefore, there is a risk that the cost for treating contaminated water accompanying backwashing will increase.

  The above problem is not limited to the purification of breeding water, but water containing nitrogen compounds such as factory wastewater, sewage, sewage, groundwater and manure (hereinafter referred to as “treated water”) is nitrified and denitrified. This is a common problem when purifying.

  From such a viewpoint, an object of the present invention is to provide a water treatment apparatus and a water treatment method capable of purifying water to be treated containing a nitrogen compound at low cost.

The present invention that solves the above problems is reverse to nitrification means in which nitrification is performed by nitrifying bacteria, denitrification means in which denitrification is performed by denitrifying bacteria, and physical filtration means for capturing organic substances in the nitrification means or water to be treated. A water treatment apparatus comprising: a backwash water supply means for supplying wash water; and a decomposition means for solubilizing organic matter contained in backwash water that has passed through the nitrification means or the physical filtration means , wherein the decomposition The means has a decomposition tank into which treated water does not flow, the backwash water is supplied to the decomposition tank, and the organic matter solubilized in the decomposition tank is supplied to the denitrification means. a water treatment device according to.

In short, the present invention utilizes treated water containing nitrogen compounds (proteins, amino acids, lipids, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, etc.) using nitrification by nitrifying bacteria and denitrification by denitrifying bacteria. The organic matter captured by the nitrification means or the physical filtration means is recovered by backwashing the nitrification means or the physical filtration means, and the recovered organic matter is supplied to a decomposition tank into which the water to be treated does not flow. After being decomposed and solubilized in the decomposition tank, it is characterized in that it is used as a carbon source for the denitrifying bacteria.

  The organic matter is also supplemented by the nitrifying bacteria carrier carrying the nitrifying bacteria, but in the present invention, the organic matter supplementing means constituted by a filter medium other than the nitrifying bacteria carrier and the denitrifying bacteria carrier is referred to as a physical filtering means. . Protein skimmers that remove organic substances such as proteins are also included in the physical filtration means.

  Nitrifying bacteria are a group of microorganisms involved in oxidizing ammonia nitrogen to nitrate nitrogen (for example, ammonia oxidizing bacteria that oxidize ammonia nitrogen to produce nitrite nitrogen, oxidize nitrite nitrogen, Nitrite-oxidizing bacteria that produce nitrate nitrogen. Most of the nitrifying bacteria belong to chemosynthesis autotrophic bacteria that actively activate and proliferate under aerobic conditions.

  Denitrifying bacteria are a group of microorganisms involved in reducing nitrate nitrogen or nitrite nitrogen to nitrogen (for example, nitrate-reducing bacteria that produce nitrogen by reducing nitrate nitrogen or nitrite nitrogen, sulfur oxidative desorption). It is a general term for nitrifying bacteria. Many of the denitrifying bacteria belong to facultative anaerobic heterotrophic bacteria that can act and grow under anaerobic conditions. In the present invention, sulfate-reducing bacteria that coexist with sulfur-oxidizing denitrifying bacteria are also included in the denitrifying bacteria. Sulfate-reducing bacteria produce sulfate ions and thiosulfate ions by reducing sulfates. Sulfur ions and thiosulfate ions are used for denitrification by sulfur oxidizing denitrifying bacteria.

  According to the present invention, it is possible to omit or reduce the labor of sewage treatment of contaminated water generated by backwashing of nitrification means or physical filtration means, and further, organic matter and electron donation necessary for denitrifying bacteria. Since it leads to saving of the body, it becomes possible to purify the water to be treated containing nitrogen compounds at low cost.

In the present invention, a decomposition means for solubilizing the organic matter is provided, the organic matter contained in the backwash water that has passed through the nitrification means or the physical filtration means is solubilized by the decomposition means, and the solubilized organic matter is removed from the dewatering means. Supply to Nitrogen means. If it does in this way, the activity and proliferation of denitrifying bacteria will become active.

  When the nitrification means is provided in the middle of a circulation channel for circulating the water to be treated in the breeding aquarium, and the denitrification means is provided in parallel with the nitrification means, It is good to supply 5 to 10% of the amount of treated water taken up to the denitrification means. Further, when the nitrification means is provided in the middle of a circulation channel for circulating the water to be treated in the breeding aquarium, and the denitrification means is provided at a subsequent stage of the nitrification means, the nitrification It is good to supply 5 to 10% of the to-be-processed water which passed the means to the said denitrification means. If it does in this way, the density | concentration of the nitrogen compound in a breeding aquarium can be maintained at the density | concentration suitable for growth of a breeding organism.

  The denitrification means may be provided with a plurality of denitrification tanks provided in parallel. If it does in this way, it will become possible to increase the amount of denitrification processing.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to purify the to-be-processed water containing a nitrogen compound at low cost.

It is a circulation filtration system diagram for demonstrating the water treatment apparatus which concerns on embodiment of this invention. It is a circulation filtration system diagram for demonstrating the modification of the water treatment apparatus which concerns on embodiment of this invention.

The water treatment apparatus A according to the embodiment of the present invention contains nitrogen compounds (such as suspended suspended matter (SS) derived from excrement and residual food of domesticated organisms, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen). The breeding water (treated water) W ₀ in the breeding water tank T contained is purified using nitrification by nitrifying bacteria and denitrification by denitrifying bacteria. As shown in FIG. , Backwash water supply means 2, decomposition means 3, denitrification means 4, physical filtration means 5, water temperature adjustment means 6, sterilization means 7, oxygen supply means 8, and circulation means (flow paths 91 to 91). 96, pumps 97 to 99). In the present embodiment, it illustrates the case where the rearing aquarium T of closed circuit to breeding water W ₀ seawater applying the water treatment apparatus A, is not intended to limit the scope of the water treatment apparatus A.

The nitrification means 1 oxidizes (nitrifies) ammonia nitrogen to nitrate nitrogen. In the nitrification means 1 of the present embodiment, physical filtration of suspended suspended matter (SS) derived from the excrement and residual food of the rearing organisms is also performed. The nitrification means 1 is provided in the middle of the circulation channel 91 starting from the breeding water tank T and returning to the breeding water tank T. The breeding water W ₁ that has passed through the nitrification means 1 is supplied to the water temperature adjustment means 6. The nitrification means 1 of the present embodiment includes a nitrification tank 11, a nitrifying bacteria carrier 12, an inlet valve 13, and an outlet valve 14.

The nitrification tank 11 is a sealed container that receives a part of the breeding water W ₀ taken from the breeding tank T. In the present embodiment, an inlet is provided above the nitrifying bacteria carrier 12 and an outlet is provided below the nitrifying bacteria carrier 12 so that the water flow in the nitrification tank 11 faces downward. In addition, although illustration is abbreviate | omitted, an inflow port may be provided under the nitrifying bacteria support | carrier 12 and an outflow port may be provided above so that the water flow in the nitrification tank 11 may become upward.

  The nitrifying bacteria carrier 12 carries nitrifying bacteria (such as ammonia oxidizing bacteria and nitrite oxidizing bacteria), and is filled in the nitrifying tank 11. The nitrifying carrier 12 functions as a biological filtration means that oxidizes ammonia nitrogen to nitrate nitrogen by the nitrifying action of the nitrifying bacteria fixed therein. That is, nitrite nitrogen is generated by the action of ammonia oxidizing bacteria that oxidize ammonia nitrogen, and nitrate nitrogen is generated by the action of nitrite oxidizing bacteria that oxidize nitrite nitrogen. Since most nitrifying bacteria belong to chemically synthesized autotrophic bacteria that actively activate and proliferate under aerobic conditions, it is desirable to maintain the inside of the nitrifying bacteria carrier 12 in an aerobic atmosphere.

Nitrifying bacteria carrier 12 of the present embodiment is made of a collection of small filtration sand uniformity coefficient, physically capturing stray suspended matter in breeding water W ₀ (SS). Although there is no restriction | limiting in the material of filtration sand, It is preferable to set it as inorganic materials, such as a natural stone and glass. Note that, for example, a down-flow hanging sponge (DHS) may be used in place of the filter sand.

The inlet valve 13 adjusts the amount of the breeding water W ₀ flowing into the nitrification tank 11 from the circulation channel 91, and the outlet valve 14 is the breeding water W ₁ flowing into the circulation channel 91 from the nitrification tank 11. The amount of water is adjusted. The inlet valve 13 and the outlet valve 14 are opened when biological filtration is performed (hereinafter referred to as “normal time”), and are closed during backwashing.

The backwash water supply means 2 supplies backwashing water (backwash water) W ₂ to the nitrifying bacteria carrier 12, and includes a tank (water source) 21, a pump 22, and an on-off valve 23. It is configured.

The tank 21 stores backwash water. The tank 21 of the present embodiment stores treated water (bred water W ₈ that has passed through the aeration means ₈ ).

The pump 22 sends backwash water in the tank 21 to the nitrification tank 11. The on-off valve 23 opens and closes the flow path 94 from the tank 21 to the nitrification means 1 and opens during backwashing and normally closes. Incidentally, the flow path 94, so that the flow direction of the backwash water in nitrifying bacteria carrier 12 is reversed and the flow of the rearing water W _1, leads to the lower side of nitrifying bacteria carrier 12.

The backwash water supply means 2 is operated with the inlet valve 13 and the outlet valve 14 of the nitrification means 1 closed. Operating the backwash water supply means 2, nitrifying bacteria carrier 12 is backwashed by backwash water W _2, backwash water W ₂ which has passed through the nitrification unit 1 _'is adhered to the nitrifying bacteria carrier 12 organics At the same time, it is supplied to the disassembling means 3. That is, when the backwash water supply means 2 is operated, the organic matter attached to the nitrifying bacteria carrier 12 can be recovered.

The decomposition means 3 solubilizes organic substances contained in the backwash water W ₂ ′, and is interposed between the nitrification means 1 and the denitrification means 4. The backwashing water W ₂ ′ that has passed through the nitrifying bacteria carrier 12 is supplied to the decomposition means 3, and the backwashing water W _{3 that} has passed through the decomposition means 3 is supplied to the denitrification means 4. The decomposition means 3 of the present embodiment includes a decomposition tank 31, an inlet valve 32, and an outlet valve 33. The concentration of the solubilized organic substance is continuously monitored with an absorptiometer or the like.

  In the decomposition tank 31, the organic matter is solubilized by the action of the solubilizing bacteria. The solubilization means is not limited, and the organic substance may be solubilized with acid, alkali, enzyme, heat, ozone, ultraviolet light, photocatalyst, microorganism, or the like.

  The inlet valve 32 opens and closes the flow path 95 from the nitrification means 1 to the decomposition tank 31 and opens during backwashing and closes during normal operation.

  The outlet valve 33 opens and closes the flow path 96 from the decomposition tank 31 to the denitrification flow path 92, and opens when supplying the organic matter in the decomposition tank 31 to the denitrification means 4, and otherwise Close the valve.

  It is desirable to adjust the salt concentration in the decomposition tank 31 to 1 to 2%. Nos. 1 to 3 in Table 1 are the results of an experiment in which a sample obtained by adding fish surimi to granule sludge (simulating backwash water) was solubilized in an anaerobic state. No. 0 is a comparative example in which only sludge is added. In the experiment, artificial seawater (salt concentration of 1%, 2%, 3%) was used, and granule sludge and surimi were charged into a vial so as to have the same amount in terms of COD (chemical oxygen demand). Moreover, the anaerobic state was simulated by sealing nitrogen gas in the gas phase part of the vial. Such a vial was immersed in a 25 ° C. water bath for 10 days while rotating at 100 rpm, and then COD and nitrogen components were analyzed.

  As shown in Table 1, when solubilized under conditions of a salt concentration of 1 to 2%, the value obtained by dividing the soluble COD concentration by the ammonia nitrogen concentration (COD / N in Table 1) was 30.9 to 37.3. It becomes. That is, when solubilized under the condition of a salt concentration of 1 to 2%, production of ammonia is suppressed, so that the nitrogen component can contribute as an organic substance necessary for denitrifying bacteria. In addition, when an organic substance is solubilized under the condition of a salt concentration of 3%, the production ratio of ammonia is increased (COD / N = 7.3), so that there is a possibility that a nitrogen component is used to assimilate ammonia. .

The denitrification means 4 reduces (denitrifies) nitrate nitrogen or nitrite nitrogen to nitrogen. The denitrification means 4 is provided in parallel with the nitrification means 1. That is, the denitrification means 4 is provided in the middle of the denitrification flow path 92 that bypasses the nitrification means 1, and the breeding water W _{4 that} has passed through the denitrification means 4 is supplied to the water temperature adjustment means 6.

  The denitrification means 4 of this embodiment comprises a plurality of denitrification tanks 41, 41,... Provided in parallel and denitrifying bacteria carriers 42, 42,.

The denitrification tank 41 is a sealed container that receives the breeding water W ₀ taken from the breeding water tank T. The oxidation-reduction potential (ORP) of the denitrification tank 41 is preferably adjusted to a range of −300 (mV) to −100 (mV). Hydraulic retention time in the denitrification tank 41 (HRT) may be set as appropriate depending on the concentration of nitrate nitrogen and nitrite nitrogen contained in the rearing water W ₀ in the breeding aquarium T. Incidentally, the concentration of sodium nitrate in breeding water _{W 0} in the breeding aquarium T 40 ^- when it is _{(NO 3 -N mg / L)} , hydraulic retention time was set to 10 hours, the denitrification tank 41 The concentration of sodium nitrate in the breeding water W ₄ that passed through was about 2 (NO ₃ ⁻ —N mg / L) (average removal rate 95%).

  The denitrifying carrier 42 carries denitrifying bacteria (nitrate-reducing bacteria, sulfur-oxidizing denitrifying bacteria, sulfate-reducing bacteria, etc.), and is filled in the denitrifying tank 41. The denitrifying carrier 42 of the present embodiment functions as a biological filtration means for reducing nitrate nitrogen or nitrite nitrogen to nitrogen by the denitrifying action of the denitrifying bacteria fixed inside. Since most of the denitrifying bacteria belong to facultative anaerobic heterotrophic bacteria that can be activated and proliferated under anaerobic conditions, it is desirable to maintain the inside of the denitrifying carrier 42 in an anaerobic atmosphere.

  As the denitrifying carrier 42, porous material such as porous glass, porous ceramic, coral sand, sponge made of natural resin or synthetic resin, activated carbon, or nonporous material such as natural rock or glass should be used. Can do. In the case of a fixed bed system, it is desirable to use a material having a specific gravity of 1 or more (more desirably, a granular material having a specific gravity of 1 or more and a diameter of 1 to 3 mm) as the denitrifying bacteria carrier 42, and a fluidized bed. In the case of the system, it is desirable to use a material having a specific gravity of 1 or less (more desirably, a cylindrical material having a specific gravity of 1 or less and a diameter and height of 3 cm or less) as the denitrifying carrier 42. Examples of the material having a specific gravity of 1 or more include natural sand (sand derived from rock), coral sand, silica, glass, ceramic, clay, activated carbon, and general-purpose plastic. Examples of the material having a specific gravity of 1 or less include natural resin or synthetic resin sponge, foamed concrete, charcoal, general-purpose plastic, and biodegradable plastic. In addition, the denitrifying carrier 42 may be inoculated and fixed by inoculating and fixing granules in which the inoculum is acclimatized and suspended.

  The denitrifying carrier 42 is supplied with the organic material solubilized by the decomposition means 3. The organic matter supplied to the denitrifying bacteria carrier 42 is used as a carbon source for the denitrifying bacteria. The solubilized organic substance (carbon source) is desirably added so that the carbon ratio (C / N ratio) in the denitrifying carrier 42 is 2 to 5. In addition, when the quantity of the organic substance supplied from the decomposition | disassembly means 3 is insufficient, it is desirable to supply sodium acetate, methanol, glucose etc. used as the carbon source of denitrifying bacteria.

The breeding water W ₀ supplied to the denitrification means 4 is the total amount of breeding water W ₀ supplied to the nitrification means 1, the denitrification means 4 and the physical filtration means 5 (that is, the breeding water taken from the breeding aquarium T). 1-20% of the amount of water), more preferably 5-10%. By the way, if the breeding water W ₀ supplied to the denitrification means 4 is less than 1% of the amount of breeding water taken from the breeding aquarium T, the possibility that the denitrification process cannot catch up increases and exceeds 20%. In addition, the hydraulic residence time (HRT) in the denitrification means 4 is shortened and the possibility that the denitrification treatment is not sufficiently performed increases, and the possibility that the apparatus becomes excessive increases. However, this value varies depending on which level the quality of the breeding water W ₀ is maintained. In order to make the amount of the breeding water W ₀ supplied to the denitrification means 4 smaller than the breeding water W ₀ supplied to the nitrification means 1, for example, the discharge amount of the pump 99 of the denitrification flow path 92. May be made smaller than the discharge amount of the pump 97 in the circulation channel 91 or the pump 99 may be operated intermittently.

The total volume of the denitrification tanks 41, 41,... May be set according to the hydraulic residence time (HRT) and the target nitrate nitrogen concentration, but the breeding water W ₀ in the breeding tank T When the volume is 100 m ³ and the HRT in the denitrification means 4 is assumed to be 10 hours, it is preferable to set as shown in Table 2 according to the ratio of the breeding water W ₀ supplied to the denitrification means 4. .

Target value of the concentration of nitrate nitrogen in breeding water W ₀ may be appropriately set according to the type of breeding an organism, but 25 ^- if the target (NO ₃ -N mg / L) or less, de the total capacity of the denitrification tank 41, and at least 2% of the volume of the breeding water W ₀ in the breeding aquarium T, 5 a proportion of the breeding water W ₀ to be supplied to the denitrification unit 4 from the breeding aquarium T of breeding water is water intake It is desirable to set it to ˜20% (see Table 2). In order to save the space of the denitrification means 4, it is desirable that the total capacity of the denitrification tank 41 is less than 5% of the volume of the breeding water W ₀ in the breeding water tank T. while achieving space saving also in the rearing water W ₀ nitrate nitrogen concentration of 25 ^- in order to maintain the (NO ₃ -N mg / L) or less, breeding water W ₀ to be supplied to the denitrification unit 4 It is desirable to set the ratio of 5 to 10% of the breeding water taken from the breeding tank T.

  Here, an example of bacteria involved in denitrification in the denitrification tank 41 is shown in Table 3. Table 3 shows the results of the microflora analysis. In the microflora analysis, granular sludge collected from the denitrification tank 41 was used as a sample. A soil DNA extraction kit (ISOIL for Beads Beating; manufactured by Nippon Gene Co., Ltd.) was used for DNA extraction, and a cloning kit (TOPO TA Cloning kit; manufactured by Invitrogen Corporation) was used for cloning.

  In the case of Table 3, the dominant species of denitrifying bacteria is the Proteobacteria gate, among which is the Thauera species belonging to the Betaproteobacteria class and the Marino belonging to the Gammaproteobacteria class. The Binobu (Marinobacter) species is the dominant species. Thauera species are acetic acid-assimilating denitrifying bacteria and are also known as aromatic bacteria degrading bacteria. The Marinobacter species is a marine (halophilic) denitrifying bacterium.

The physical filtration means 5 physically captures organic substances such as proteins. The physical filtration means 5 is provided in parallel with the nitrification means 1 and the denitrification means 4. That is, the physical filtration means 5 is provided in the middle of a physical filtration flow path 93 that bypasses the nitrification means 1, and the breeding water W _{5 that} has passed through the physical filtration means 5 is supplied to the water temperature adjustment means 6.

  The physical filtration means 5 of this embodiment includes a protein skimmer 51, an inlet valve 52, and an outlet valve 53.

The protein skimmer 51 removes organic substances contained in the breeding water W ₀ by attaching fine bubbles generated inside to dissolved organic substances or suspended suspended substances and floating the bubbles. That is, the protein skimmer 51 physically captures organic matter and the like.

The inlet valve 52 adjusts the amount of breeding water W ₀ flowing into the protein skimmer 51, and the outlet valve 53 regulates the amount of breeding water W ₅ flowing out from the protein skimmer 51 into the physical filtration channel 93. To do.

The water temperature adjusting means 6 is for adjusting the water temperature of the breeding water W ₁ , W ₄ , W ₅ that has passed through the nitrification means 1, the denitrification means 4 and the physical filtration means 5 to an appropriate temperature. 4 and the physical filtration means 5 are provided downstream. The water temperature adjusting means 6 of the present embodiment is provided in the middle of the circulation channel 91, and the breeding water W _{6 that} has passed through the water temperature adjusting means 6 is supplied to the sterilizing means 7. In addition, there is no restriction | limiting in the structure of the water temperature adjustment means 6, It can comprise with a heater, a cooler, a heat exchanger etc. When the water temperature is not adjusted, the water temperature adjusting means 6 may be omitted.

The sterilizing means 7 includes microorganisms and bacteria contained in the breeding water W ₆ that has passed through the water temperature adjusting means 6 (bred water W ₁ , W ₄ , W ₅ that has passed through the nitrification means 1, the denitrification means 4 and the physical filtration means ₅ ). These are used to kill viruses and the like, and are provided downstream of the water temperature adjusting means 6. The sterilizing means 7 of this embodiment is provided in the middle of the circulation channel 91, and the breeding water W _{7 that} has passed through the sterilizing means 7 is supplied to the oxygen supply means 8. In addition, there is no restriction | limiting in the sterilization method, For example, an ultraviolet-ray, ozone, chlorine etc. can be used. If sterilization is not performed, the sterilization means 7 may be omitted.

The oxygen supply means 8 supplies oxygen to the breeding water W ₇ that has passed through the sterilization means 7 (bred water W ₁ , W ₄ , W ₅ that has passed through the nitrification means 1, the denitrification means 4 and the physical filtration means ₅ ). And provided downstream of the sterilizing means 7. That is, the oxygen supply means 8 is for adjusting the dissolved oxygen amount of breeding water W ₈ should be returned to the rearing water tank T (DO) and redox potential (ORP). There is no restriction | limiting in the structure of the oxygen supply means 8, It is good also as an aeration system and it is good also as an aeration system. The oxygen supply means 8 is a means necessary when the breeding water W ₇ that has passed through the sterilization means 7 is anaerobic, so that the aerobic breeding water W ₇ can be stably obtained. , May be omitted.

  The circulation means includes flow paths 91 to 96 and pumps 97 to 99. In this embodiment, pumps 97 and 98 are provided in the middle of the circulation passage 91 (in the present embodiment, upstream of the nitrification means 1 and downstream of the oxygen supply means 8), and in the middle of the denitrification passage 92 (this embodiment). Although the pump 99 is provided upstream of the denitrification means 4 in the form, it is not intended to limit the position and number of pumps. Moreover, the branch position and the merge position of the flow paths 91 to 96 can be changed as appropriate.

  In the water treatment apparatus A according to the present embodiment described above, since nitrification by nitrifying bacteria and denitrification by denitrifying bacteria are performed in parallel, ammonia nitrogen, nitrate nitrogen, and the like are stably and continuously performed. Can be removed. That is, according to the water treatment apparatus A, it is possible to reduce the frequency of water change and replenishment, and as a result, to reduce the maintenance cost of the breeding aquarium T (for example, the cost of taking and transporting seawater). Is possible.

Moreover, according to the water treatment apparatus A, the organic matter captured by the nitrifying bacteria carrier 12 can be recovered, and the recovered organic matter can be used as a carbon source (food) for denitrifying bacteria. it is possible to omit or reduce the trouble of sewage polluted water generated with the news, because leads to savings of organic materials and electron donor required for denitrifying bacteria, according to the purifying breeding water W ₀ Costs can be reduced.

  Moreover, in the water treatment apparatus A, the organic matter obtained by back-washing the nitrifying bacteria carrier 12 is decomposed by the decomposition means 3 and the solubilized organic matter is supplied to the denitrification means 4, so that it is easily taken into the denitrification bacteria. As a result, the activity and proliferation of denitrifying bacteria become active.

  Moreover, according to the water treatment apparatus A, since a plurality of denitrification tanks 41, 41,... Are provided in parallel, it is possible to increase the amount of denitrification compared to the case where a single denitrification tank 41 is provided. Become.

  Further, in this embodiment, 5 to 10% of the amount of breeding water taken from the breeding aquarium T is supplied to the denitrification means 4, but in this way, the concentration of the nitrogen compound in the breeding aquarium T is raised. It can be kept at a concentration suitable for the growth of organisms.

  In this embodiment, the case where the nitrifying carrier 12 in the nitrifying unit 1 is backwashed is illustrated, but the physical filtering unit 5 is backwashed together with or in place of the nitrifying carrier 12. Also good. For example, although illustration is omitted, if the backwash water supply means 2 and the decomposition means 3 are connected to the physical filtration means 5, the protein of the physical filtration means 5 is obtained by the backwash water sent from the backwash water supply means 2 The skimmer 51 is backwashed, and the backwash water that has passed through the protein skimmer 51 is supplied to the decomposition means 3. When the protein skimmer 51 is backwashed, the inlet valve 52 and the outlet valve 53 are closed.

  In this embodiment, the case where the nitrification unit 1 and the physical filtration unit 5 are provided in parallel is illustrated, but the physical filtration unit 5 may be provided upstream of the nitrification unit 1.

  Further, in the present embodiment, the case where the nitrification means 1 and the denitrification means 4 are provided in parallel is illustrated, but the denitrification means 4 is disposed downstream of the nitrification means 1 as in the water treatment apparatus A ′ shown in FIG. May be provided. That is, the nitrification means 1 and the denitrification means 4 may be provided in series.

Also in the water treatment apparatus A ′, the denitrification means 4 is provided in the middle of the denitrification flow path 92, but the denitrification flow path 92 is branched from the circulation flow path 91 downstream of the nitrification means 1. Therefore, a part of the breeding water W ₁ that has passed through the nitrification means 1 flows into the denitrification means 4. Since the denitrification flow path 92 merges with the circulation flow path 91 upstream of the water temperature adjusting means 6, the breeding water W _{4 that} has passed through the denitrification means 4 is supplied to the water temperature adjusting means 6. The other configuration of the water treatment apparatus A ′ is the same as that of the water treatment apparatus A described above.

Incidentally, the amount of the breeding water W ₁ supplied to the denitrification means 4 is desirably set to ₁ to 20%, more preferably 5 to 10% of the breeding water W ₁ that has passed through the nitrification means 1. That is, it is desirable to supply ₁ to 20%, more preferably 5 to 10%, of the breeding water W ₁ that has passed through the nitrification means 1 to the denitrification means 4 and supply the rest to the water temperature adjustment means 6. If it does in this way, the density | concentration of the nitrogen compound in the breeding water tank T can be kept at the density | concentration suitable for growth of a breeding organism.

In the present embodiment has exemplified a case of applying the water treatment device A for purifying breeding water W ₀ in the breeding aquarium T, and I'm not intended to limit the scope of the water treatment apparatus according to the present invention. Although detailed description is omitted, the water treatment apparatus according to the present invention can also be applied to the case of purifying water to be treated containing nitrogen compounds such as factory wastewater, sewage, sewage, groundwater, manure and the like.

A, A 'Water treatment device 1 Nitrification means 12 Nitrifying bacteria carrier (physical filtration means)
2 Backwash water supply means 3 Decomposition means 4 Denitrification means 5 Physical filtration means 91 Circulation channel T Breeding water tank W ₀ Breeding water (treated water)

Claims (6)

Nitrification means for nitrification by nitrifying bacteria,
Denitrification means for denitrification by denitrifying bacteria,
Backwash water supply means for supplying backwash water to the nitrification means or physical filtration means for capturing organic matter in the water to be treated;
A water treatment apparatus comprising a decomposition means for solubilizing organic substances contained in backwash water that has passed through the nitrification means or the physical filtration means ,
The decomposition means has a decomposition tank into which treated water does not flow,
The water treatment apparatus is characterized in that the backwash water is supplied to the decomposition tank, and organic matter solubilized in the decomposition tank is supplied to the denitrification means. The water treatment apparatus according to claim 1, wherein the nitrification means has a nitrifying bacteria carrier that supports the nitrifying bacteria. The nitrification means is provided in the middle of a circulation channel for circulating the treated water in the breeding aquarium,
The denitrification means is provided in parallel with the nitrification means,
The water treatment device according to claim 1 or 2, wherein 5 to 10% of the amount of water to be treated taken from the breeding aquarium is supplied to the denitrification means. The nitrification means is provided in the middle of a circulation channel for circulating the treated water in the breeding aquarium,
The denitrification means is provided after the nitrification means,
The water treatment apparatus according to claim 1 or 2, wherein 5 to 10% of the water to be treated that has passed through the nitrification means is supplied to the denitrification means. The water treatment apparatus according to any one of claims 1 to 4 , wherein the denitrification means includes a plurality of denitrification tanks provided in parallel. A water treatment method for purifying water to be treated containing nitrogen compounds by nitrification by nitrifying bacteria and denitrification by denitrifying bacteria,
The nitrification means in which nitrification by nitrifying bacteria is performed or the physical filtration means for capturing the organic matter in the water to be treated is back-washed to recover the organic matter adhering to the nitrification means or the physical filtration means, and the collected organic matter is The water treatment method is characterized in that it is used as a carbon source for the denitrifying bacteria after being supplied to a decomposition tank that does not flow in, decomposed and solubilized in the decomposition tank .

Images