Patent Application
20120192487
The present invention relates to a nutriculture system for subjecting plants to nutriculture and to a water treatment apparatus and, particularly to a nutriculture system suitable for hydroponic culture and a water treatment apparatus for sterilization and purification purposes.
As the nutriculture system of this type, a nutrient solution circulation system 1 shown in
A nutrient solution circulation system 11 of
In a nutriculture apparatus used in a nutriculture method disclosed in Patent Document 1, a drainage tank is connected to culture beds, and a sterilization apparatus is connected to the drainage tank. The sterilization apparatus is provided therein with a hollow fiber membrane module with which bacteria and impurities in the drainage tank are removed. On the other hand, a raw water flow passage is connected to the culture beds via an ozone sterilization apparatus, and raw water ozone-treated with the ozone sterilization apparatus is supplied to the culture beds.
In addition, Patent Document 2 discloses an ozone sterilization apparatus for hydroponic culture. The sterilization apparatus is equipped with a culture solution tank storing culture solution circulation-supplied to plant culture channels, an ozone water production tank for producing ozone water supplied to the culture channels and an ozone generator. With this configuration, the culture solution from the culture channels is accumulated in the culture solution tank, and the culture solution in the culture solution tank is ozone-treated. The culture solution in the culture solution tank and the ozone water in the ozone water production tank are alternately supplied to culture plants in the culture channels.
Patent Document 1: JP-A 2001-299116
Patent Document 2: JP-A 2002-191244
However, since the nutrient circulation system 1 of
The nutrient solution circulation system 11 shown in
On the other hand, in Patent Document 1, when ozone treatment has been performed only with the ozone sterilization apparatus, the nutrient solution is likely to be acidified to possibly make the pH regulation difficult and induce a ozone fault relative to the plants. In addition, the acidification has caused the plumbing system to corrode and the plants to induce a growth defect. In the case where the hollow fiber membrane module is used to perform drainage water sterilization and impurity removal, it has been necessary to frequently carry out cleaning in order to prevent clogging due to sliminess of organic substances.
Also in the sterilization apparatus of Patent Document 2 for hydroponic culture, since the sterilization has been performed only with supplied ozone, the culture solution has been likely to be acidified to make the pH control difficult. Moreover, since the ozone concentration is thick, there is a possibility of an ozone fault being induced similarly to Patent Document 1.
The present invention has been developed in view of the aforementioned state of affairs and in consequence of keen studies, and the object thereof is to provide a nutriculture system that enables the circulation of a nutrient solution while preventing the proliferation of pathogenic bacteria and can promote the growth of plants effectively and steadily while preventing the change in components of the nutrient solution and to provide a water treatment apparatus for sterilization and purification purposes, which is made compact in size.
To attain the above object, the invention according to claim 1 relates to a nutriculture system for circulating a culture solution that is a liquid fertilizer between a nutrient solution tank containing the culture solution and culture beds, which comprises a water treatment apparatus disposed between the nutrient solution tank and the culture beds for sterilizing and purifying only a culture solution having flowed through the culture beds, wherein the water treatment apparatus comprises a unit having an ozone supply function for supplying ozone to the culture solution, an ultraviolet ray irradiation function for irradiating the culture solution with ultraviolet rays, and a photocatalyst-acting function for allowing a photocatalyst to act.
The invention according to claim 2 relates to the nutriculture system further comprising an effluent tank disposed on an upstream side of the nutrient solution tank for containing the culture solution having flowed through the culture beds and a sterilization and purification unit connected to the effluent tank.
The invention according to claim 3 relates to the nutriculture system wherein the sterilization and purification unit is provided with a branched flow passage for supplying directly to the effluent tank the culture solution having been sterilized and purified with the sterilization and purification unit.
The invention according to claim 4 relates to a water treatment apparatus for sterilization and purification purposes, comprising a discharge ozonizer, a separate reaction vessel having an ultraviolet lamp embedded therein, and an air separator with an air vent valve with which ozone water having ozone produced with the ozonizer mixed with treated water is effluent-ozone degassed to form treatment ozone water that is supplied the reaction vessel.
The invention according to claim 5 relates to a water treatment apparatus for sterilization and purification purposes, wherein the reaction vessel has a flow passage provided therein with a photocatalyst.
The invention according to claim 6 relates to a water treatment apparatus for sterilization and purification purposes, wherein the air vent valve of the air separator has a degassing port provided with a cleaning rod operable from outward.
According to the invention set forth in claim 1, by sterilizing and purifying the culture solution with the water treatment apparatus having the ozone supply function, ultraviolet ray irradiation function and photocatalyst-acting function to produce a synergistic effect, by which a strong sterilization action and an organic decomposition action are manifested to enable the nutrient solution to be circulated while suppressing the proliferation of pathogenic bacteria. At this time, since only the culture solution having flowed through the culture beds can be sterilized and purified, it is possible to prevent the components of the nutrient solution from being changed to contribute steadily to the effective growth promotion of the plants. Furthermore, since space-saving of the entire system can be realized and since the running cost is suppressed, the present invention is excellent in economy.
Particularly, since the water treatment apparatus of the present invention is of a promotion and oxidation type, ozone is appropriately decomposed to obtain an effect of steadily utilizing the apparatus. As a result, a sterilization effect and a function of adding dissolved oxygen are attained to exert a promotion effect of plant growth.
According to the invention set forth in claim 2, since the culture solution having flowed through the culture beds accumulated in the effluent tank is sterilized and purified and the resultant culture solution is supplied to the nutrient solution tank, it is possible to maintain the state in which the culture solution in the nutrient solution tank has flowed to enable the culture effect by the culture solution to be heightened.
According to the invention set forth in claim 3, since culture solution sterilized and purified with the sterilization and purification unit can be sent directly to the nutrient solution tank, a time lag up to the supply of the culture solution to the nutrient solution tank is smaller than in the case where the culture solution once accumulated in the effluent tank is sterilized and purified, it becomes possible to supply the sterilized and purified culture solution to the nutrient solution tank immediately from the operation start.
According to the invention set forth in claim 4 or 5, the separation structures of the ozonizer and reaction vessel produce the following effects. To be specific, a large amount of ozone is needed when a fluid contains many organic substances. Even in such a case, addition in number of ozonizers enables ozone to be produced twice or thrice. Inversely, when the amount of residual ozone in the fluid is increased, addition of the reaction vessel (ultraviolet lamp) proceeds with promotion oxidation and decomposition of the residual ozone can treat the fluid more steadily.
In addition, since the electrode portion of the ozonizer is exposed to strong oxidation, the operation life thereof is shorter than other equipment. However, since the present invention adopts the separate structures, the electrode portion etc. can be exchanged extremely easily.
Integral formation of the apparatus results in a product of particularly high capacity or high output to make it difficult to form a minute gap of quartz glass and need an expensive dual quarts glass. However, the separate structures adopted in the present invention make it sufficient that only the ultraviolet transmission portion is made of quarts glass.
Furthermore, since the separate structures are adopted in the present invention, a glass tube (borosilicate glass tube, for example) for generating the same amount of ozone can be made small. In addition, since the high-pressure electrode can be produced by metal processing, the dimension stability can be enhanced dramatically. Therefore, ozone is stably produced steadily.
According to the invention set forth in claim 6, it is possible to eliminate clogging by a calcium component and carry out clogging prevention with ease.
Embodiments of a nutriculture system according to the present invention and a water treatment apparatus used, for example in the system, for sterilization and purification purposes will be described hereinafter in detail with reference to the drawings.
The supply lines 24 in the system main body 20 are for supplying the culture solution 21 from the nutrient solution tank 22 to the culture beds 23, and the flow passage of each thereof is midway branched to form a nutrient solution slot 24a, from which the culture solution 21 can be supplied to the culture bed 2123. On the other hand, the return lines 25 are for returning the culture solution 21 from the culture beds 23 to the nutrient solution tank 23 and are connected to the nutrient tank 22 in a state in which they converge from the exit sides of the culture beds 23 into a single flow passage.
The effluent tank 27 is connected to between the supply lines 24 and the return lines 25 and disposed at a lower position on a downstream side from the culture beds 23 and at a higher position on an upstream side from the nutrient solution tank 22 in a state having a difference in height. The culture solution 21 having flowed through the culture beds 23 is accumulated in the effluent tank 27. The water treatment apparatus 30 is connected to the effluent tank 27, sterilizes and purifies only the culture solution 21 having flowed through the culture beds 23 and is adapted to supply the resultant culture solution to the nutrient solution tank 22.
In the figure, the water treatment apparatus 30 is connected to the effluent tank 27 with a nutrient solution supply line 36 and a nutrient solution return line 37. The culture solution 21 is supplied from the effluent tank 27 into the water treatment apparatus 30 via the nutrient solution supply line 36, sterilized and purified with the water treatment apparatus 30 and then returned to the effluent tank 27 via the nutrient solution return line 37.
As shown in
In
In the same figure, by charging the metal bar 50 with high-pressure electricity and allowing the treated water to serve as a ground electrode 55, silent discharge is induced in the space (gap) 51 between the metal bar 50 and the dielectric 52, and air or high-concentration oxygen is fed into the space 51 to constitute the ozonizer 43.
As shown in
In addition, two or three ozonizers 43 having the same concentration are disposed in parallel to enable the flow rate of ozone generation air or high-concentration oxygen to be increased. On the other hand, the ozonizers 43 are disposed in series to enable the ozone concentration to be heightened.
In
The protective cylinder 62 on the outer periphery of the ultraviolet source 61 is formed of quartz glass, borosilicate glass or high silica glass, for example. Of these, particularly the borosilicate glass and high silica glass are comparatively inexpensive and can be used without modification. From the standpoints of ultraviolet ray transmission, heat resistance and strength, however, quartz glass is the best material. An outer cylinder 64 having a predetermined inside diameter is disposed on the outer peripheral side of the protective cylinder 62, and a flow passage 65 of the nutrient solution 21 is formed between the outer cylinder 64 and the protective cylinder 62. The flow passage 65 is provided therein with the photocatalysts 63.
The photocatalysts 63 are made of titanium dioxide, for example and formed on the front side of a material including titanium or titanium alloy including an unshown mesh, titanium line, aggregate of fibrous titanium materials or porous titanium material. The material is formed into a slender shape to enable a reaction area to be enlarged and make the reactivity the ozone good. The material may be a material other than titanium or titanium alloy. For example, it may be glass or ceramic and, on the surface of which the photocatalysts may be formed.
In the present embodiment, since the ultraviolet ray-photocatalyst unit 44 is provided at the center thereof with the ultraviolet source 61, it is possible to make the entire unit compact in size and effectively perform the irradiation of the ultraviolet rays from the ultraviolet source 61 onto the culture solution 21. Though not shown, the ultraviolet ray-photocatalyst unit may be provided on the outside thereof with the ultraviolet source and on the inside thereof with the photocatalysts. In this case, the nutrient solution 21 flows inside of the protective cylinder.
As shown in
In addition, the secondary side of the nutrient solution supply line 36 far from the bypass flow passage 68 is provided with a return flow passage 70. With the return flow passage 70, the nutrient solution supply line 36 and nutrient solution discharge port 60 are connected to each other. Furthermore, the return flow passage 70 is provided midway with the ejector 71 that is connected via a check valve 72 to the gas discharge port 58 with a gas supply passage 73.
The check valve 72 is provided in an appropriate manner and disposed for preventing a counter flow of ozone or oxygen supplied from the ozonizer 43. In addition, the ejector 71 is made, for example, of ceramic, metal or resin and formed in the shape of a ring for mixing the nutrient solution flowing from the return flow passage 70 with the ozone (and oxygen or air) flowing from the gas supply passage 73, thereby producing a mixed solution (ozone water) in a finely foamed state. At this time, the ozone and oxygen or air having flowed through the check valve 72 increase their flow rates in the presence of an unshown overflow passage in the ejector 71, are supplied to the nutrient solution supply pipe 36 and are dissolved in the nutrient solution in a foamed state.
On the other hand, in
The pH regulator (pH sensor) 32 is disposed for regulating the pH of the nutrient solution in the nutrient solution tank 22 and may be a generally used one. In the present embodiment, the pH regulator 32 is used to regulate the pH of the culture solution 21 in the nutrient solution tank 22 to around 6 to 6.5, for example. In addition, the EC regulator 33 is disposed for regulating the EC (Electrical Conductivity) of the nutrient solution in the nutrient solution tank 22 and may be a generally used one similarly to the pH regulator 32. When regulating the EC of the culture solution 21 with the EC regulator 33 to appropriate values, EC=0.5 in the case of strawberries and EC=1.0 in the case of tomatoes.
The pH sensor 75 sends to and receives from the water treatment apparatus 30 control signals 76 that include a signal for stopping the ozone supply portion 40 and operating the ultraviolet ray irradiation portion 41 and photocatalyst action portion 42 until acidic liquid approximates alkaline liquid and a signal for stopping the ultraviolet ray irradiation portion 41 and photocatalyst action portion 42 and operating the ozone supply portion 40 until alkaline liquid approximate acidic liquid.
The regulation methods using the pH regulator 75 include, besides the above example, intermittently operating the ozone supply portion 40, the ultraviolet ray irradiation portion 41 and photocatalyst action portion 42 and finely regulating the amount of ozone or ultraviolet rays appropriately, thereby controlling the pH value.
The makeup water line 34 is disposed for resupplying water to the nutrient solution tank 22 and, when the culture solution 21 has been reduced in amount because of the supply to the culture beds 23, an appropriate amount of water is resupplied via the makeup water line 34 to the nutrient solution tank. As a result, it is possible to compensate for the deficient amount of culture solution 21 and supply the culture solution 21 to the plants steadily.
The nutrient solution mixers 35 are connected to the nutrient solution tank 22 via supply pump 38 and unshown quantitative injectors, and a liquid fertilizer 74, for example, is accumulated in the nutrient solution mixers 35 as an undiluted solution constituting the component of the culture solution 21. When the amount of the culture solution 21 in the nutrient solution tank 22 decreases and when water is resupplied via the makeup water line 34 thereto, the pH and EC are measured with the pH regulator 32 and EC regulator 33, and the undiluted solution 74 having a predetermined ratio is appropriately injected from the nutrient solution mixers 35 into the nutrient solution tank so that the measured pH and EC may have the appropriate values, respectively.
The water treatment apparatus 30 may have an unshown timer embedded therein to use the timer to turn the operation on and off, perform intermittent operation or change the ozone concentration to control the amount of ozone to be supplied from the water treatment apparatus 30. In this case, it is possible to supply an appropriate amount of ozone, prevent acidification of the culture solution 21 due to excessive supply of ozone and prevent corrosion of the plumbing system and growth defect of the plants. In addition, an unshown feed pump may be disposed between the effluent tank and the nutrient solution tank. In this case, the culture solution 21 in the effluent tank 27 can be fed to the nutrient solution tank 22 without forming any difference in height between the effluent tank 27 and the nutrient solution tank 22.
Next, the function of the above embodiment will be described. In
In
In the ozonizer 43, air or gas having a higher oxygen concentration than air is supplied as the raw material from the air entrance port 57, with the metal bar 50, to which voltage is applied from an unshown high-pressure power supply in the ozone supply portion 40, charged with high pressure flows in the gap 51. At this time, the gap 51 constitutes a discharge space in the presence of the metal bar 50, dielectric 52 and ground electrode 55 to produce ozone in the gap 51. The ozone is discharged from the gas discharge port 58 via the discharge port 54 and, by the action of the ejector 71, mixed together with oxygen or air in the nutrient solution flowing through the nutrient solution supply line 36 from the return flow passage 70.
The culture solution 21 subsequently flows into the ultraviolet ray-photocatalyst unit 44 along with a culture solution that does not flow through the bypass flow passage 68. When the culture solution 21 passes through the ultraviolet source 61 and photocatalysts 63, it is sterilized and purified by means of the ultraviolet rays from the ultraviolet ray irradiation portion 41 and the photocatalyst action of the photocalysist action portion 42. In this case, the photocatalysts 63 enhances their photocatalytic action functions through the irradiation of the ultraviolet rays and have a higher sterilization-ability than ozone and an organic substance-decomposing ability.
The principle of the sterilization and purification actions by the photocatalysts 63 at this time will be described. When ultraviolet rays having a wavelength of 400 nm or less are irradiated onto the photocatalysists 63 made of titanium dioxide, etc., holes are generated in a valence band and, at the same time, electrons are generated in a conductance band. Since the oxidation potential of the holes is higher than that of ozone, hydrogen peroxide, etc., organic substance is completely oxidation-decomposed by photocatalyst action, finally into carbon dioxide and water completely. The photocatalyst 63 makes oxidation reaction by a hydroxyl radical (OH radical) rich in extremely reaction activity induced by reaction of holes produced when being irradiated with ultraviolet rays or the holes and water. At this time, reduction reaction among the holes induced in consequence of the irradiation of the ultraviolet rays, simultaneously generated electrons and oxygen gas proceeds in parallel.
Owing to the strong oxidation reaction, the photocatalyst 63 can exhibit a stronger sterilization ability than a conventional sterilizer, such as ozone, hydrogen peroxide, chlorine, etc. and has an ability to decompose organic substances. Furthermore, since the duration of life of the holes or OH radicals generated by irradiation is short, e.g. ns, the holes or OH radicals do not stay behind after treatment unlike an oxidizing agent including ozone, hydrogen peroxide, etc. Therefore, it is unnecessary to use any apparatus for treating a residual oxidizing agent. This is advantageous. In view of the above, the photocatalyst 63 can effectively sterilize and purify a mixed substance difficult to purify with the ozone remaining in the culture solution 21. In addition, since irradiation of ozone with ultraviolet rays produces OH radicals, it is possible to obtain a higher promotion oxidation effect.
Next, in
Since the nutriculture system of the present invention has the water treatment apparatus 30 disposed between the nutrient solution tank 22 and the culture beds 23 and since only the culture solution 21 having flowed through the culture beds 23 is sterilized and purified on the upstream side of the nutrient solution tank 22 with the water treatment apparatus 30, it is possible to prevent the culture solution 21 containing pathogenic bacteria from being mixed in the culture solution in the nutrient solution tank 22 and prevent a change in component of the culture solution 21 in the nutrient solution tank 22. In addition, since the iron or Mn component of the culture solution 21 in the nutrient solution tank 22 is little oxidized and precipitated, it is unnecessary to resupply an iron or Mn component to the culture solution 21.
Furthermore, since the culture solution 21 is accumulated in the effluent tank 27, sterilized and purified in the effluent tank 27 and caused to flow into the nutrient solution tank 22, the culture solution 21 in the nutrient solution tank 22 can always be circulated to the circulation line 26.
Since the water treatment apparatus 30 utilizes the ozone supply function, ultraviolet ray irradiation function and photocatalyst action function to enable the culture solution 21 having flowed through the culture beds 23 to be sterilized and purified, their synergistic effect enables highly effective sterilization and purification. For example, the water treatment apparatus 30 can suppress the amount of ozone generated, purifies the culture solution 21 while supplying ozone steadily to prevent acidification. As a result, it is easy to perform the pH regulation and possible to prevent ozone obstacles of the plants. Furthermore, it can prevent corrosion of the plumbing system and growth defect of the plants only require periodic resupply of nutrient elements, thereby making it possible to produce a high yield of plants. Furthermore, since a minute amount of ozone can always be supplied, it is possible to suppress the growth of bacteria on the inner walls of the plumbing system and the biofilm development
Furthermore, since the water treatment apparatus 30 can always treat organic substances, clogging, corrosion and sliminess of the culture beds 23 by the organic substances are prevented, and the growth of the roots is promoted to enhance the growth of the plants. When the plants are strawberries, for example, corrosion of the roots of strawberries reduces the number of harvests. Since the root corrosion is prevented, stable harvests over a long period of time can be attained. In addition, since occurrence of organic substances is reduced, postharvest cleaning of the culture beds 23 is made easy.
Since the ejector 71 narrows a flow passage, the pathway 79 in
In the ozonizer utilized in the experiment, the ozone concentration and the current value have a substantially proportional relation until 1.1 A, and a mere change of the current value can regulate the ozone concentration. In addition, since the current value and ohmic value also have a proportional relation, the ozone concentration can easily be changed by changing the current value with a variable resistor (volume etc.).
Use of appropriate voltage with the electrode bar shown in
In the ozonizer of the present invention shown in
An air separator 85 with an air vent valve shown in
In the air separator 85 with the air vent valve shown in
In a gas-liquid separator 99 shown in
As described earlier, in
In
Use of the water treatment apparatus according to the present invention can reduce the count of general viable bacteria to allow vegetables or fruits to enjoy a long life-span. The counts of general viable bacteria and E. Coli occurring in the root of green onion were measured in comparison between the presence and absence of the present invention apparatus. As a result, according to the standard plate cultivation method, results (1) in comparative examples revealed 1,100/g and 12,000/g, whereas results (2) revealed 300 or less/g and 2,700/g. Thus, the count of the general viable bacteria was reduced more in the presence of the present invention apparatus. It was verified, in view of the conventionally known fact that reduction of general viable bacterial has allowed vegetables or fruits to enjoy a long life-span, the utilization of the present invention apparatus enabled the count of general viable bacterial to be reduced.
Table 1 includes green onion growth comparison data, from which it is understand that the green onions have different lengths and thicknesses between the presence and absence of the water treatment apparatus (sterilization and purification apparatus), that in either case, the facts of the presence exhibit the larger values and that the growth promotion effect can be confirmed. The reasons for the above are the following facts:
The water treatment apparatus for sterilization and purification purposes according to the present invention is applied not only to the nutriculture system, but also to hot springs, bathhouses, pools, for example, and can widely utilized as other water treatment apparatus.
20 System main body
21 Culture solution
22 Nutrient solution tank
23 Culture bed
27 Effluent tank
30 Water treatment apparatus
43 Ozonizer
44 Reaction vessel
102 Branched flow passage
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-231606 | Oct 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/067433 | 10/5/2010 | WO | 00 | 4/2/2012 |
