JP7176365B2 - Method and apparatus for inhibiting nitrification of nutrient solution - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for inhibiting nitrification of a nutrient solution, and in particular, to prevent the occurrence of physiological disorders in the roots of plants due to the growth of nitrite bacteria and the accumulation of nitrite ions in a nutrient solution tank. It relates to a method and apparatus for inhibiting nitrification of a nutrient solution.

Hydroponics (also referred to as hydroponics), in which plants are cultivated using a nutrient solution without using soil, has been put to practical use. Compared to soil cultivation, hydroponic cultivation allows extremely strict control of various conditions such as fertilizer, light, air, and temperature, so it is possible to obtain products with standardized quality standards. Industrial production is possible.

In this hydroponic culture, once the nutrient solution decomposes or pathogens develop, they rapidly spread to plants in containers of the same lineage. A sterilizer is used to prevent disease when the liquid is recycled.

A sterilization method using metal ions or ozone is known. For example, in Patent Document 1, various metals are contained in a polymer electrolyte having a crosslinked structure in the form of salt bonds or in the form of coordinate bonds. A method of controlling pests by putting the containing composition into a supply port of a nutrient solution to a plant cultivation bed, a supply port of raw water such as tap water, agricultural water or well water, a nutrient solution tank or a plant cultivation bed. Have been described.

Further, in Patent Document 2, by continuously or intermittently aerating an ozone gas phase into a culture solution for hydroponic cultivation of plants, there is no decomposition of the nutrient solution and no generation of pathogenic bacteria, and furthermore, plant roots are treated. It is proposed to improve the growth of stems and leaves.

Further, Patent Document 3 describes sterilization and activation of service water by a vibrating stirrer equipped with vibrating blades or fixed plates with sterilizing surface treatment or photocatalytic surface treatment.

Further, Patent Document 4 describes sterilizing the water supplied to the nutrient solution by adding silver ions to the water supplied to the nutrient solution.

On the other hand, nitrifying bacteria (ammonia-oxidizing bacteria (nitrite bacteria) that oxidize ammonia to nitrite, and nitrite-oxidizing bacteria that oxidize nitrite to nitrate) are essential for biological filtration in aquariums, although they are not pathogenic bacteria. Bacteria (nitrate bacteria), also called nitrifying bacteria) are known. Typical nitrite bacteria are bacteria of the genus Nitrosomonas, and typical nitrate bacteria are bacteria of the genus Nitrobacter. These nitrifying bacteria obtain the energy necessary for life maintenance and growth by oxidizing ammonium ions and nitrite ions. It exists widely in soil, rivers, lakes, etc., and plays an important role in biologically removing nitrogen compounds that cause environmental pollution in sewage treatment plants, and is a useful microorganism for solving environmental problems. .

In the cultivation of plants, the nitrifying action of nitrifying bacteria converts ammonium nitrogen in liquid fertilizer into nitrate nitrogen (Patent Document 5), and the activity of nitrifying bacteria in soil is controlled to control the growth state of plants. (Patent Document 6) has been proposed.

JP-A-60-120922 JP-A-4-121123 JP-A-2003-339270 Japanese Patent No. 6178940 JP-A-2004-97093 JP-A-2002-325511

In hydroponic culture, when the capacity of the hydroponic tank is large compared to the daily watering amount, the ammonia in the fertilizer component is nitrified, the pH is lowered and the nitrite ion is increased, and the plant roots found to cause problems in Although this problem was not recognized in the past, it was confirmed that in small-scale fields, the pH of the nutrient solution decreased, nitrite ions accumulated, and physiological disturbances occurred in the plants. This problem is particularly likely to occur when materials made of organic matter are added to the nutrient solution.

For example, in a field where the amount of watering per day is 1.5 times the capacity of the nutrient solution tank under the condition that materials made of organic matter are added, nitrite ions accumulate and the amount of watering per day is twice the capacity of the nutrient solution tank. No nitrite ions accumulated in the field. In addition, it is considered that the ratio of the amount of watering to the capacity of the nutrient solution tank that causes problems varies depending on various conditions such as the amount of watering per time, the frequency of watering, and the liquid temperature.

Some of the additive materials necessary for cultivation contain organic matter as a component, and if added to the nutrient solution, they will rot, clog the irrigation tubes, and damage the roots of the plants. Therefore, materials containing organic matter as a component can only be applied to plants by foliar spraying, which is troublesome.

However, the conventional sterilizers are all intended for pathogenic bacteria, not for nitrifying bacteria that denature the nutrient solution.

The present invention has been made to solve the above-mentioned conventional problems, and the growth of nitrite bacteria and the accumulation of nitrite ions in a nutrient solution tank for mixing the uncirculated nutrient solution with the raw water. An object of the present invention is to prevent the occurrence of physiological disorders in the roots of plants, etc.

In the present invention, sterilization equipment is installed in the nutrient solution tank, and sterilization is performed by detecting, for example, a decrease in pH.

Nitrite bacteria are thought to grow and proliferate not only in the nutrient solution, but also on the inner wall of the nutrient solution tank and on deposits on the inner wall. is required. Therefore, the sterilization equipment is installed not upstream or downstream of the nutrient solution tank, but by providing a route to enter and exit the nutrient solution tank or the nutrient solution tank.

The growth of nitrite bacteria and the accumulation of nitrite ions can be detected not only by actually measuring the nitrite concentration, but also by detecting a decrease in the pH of the nutrient solution. This is because nitrite ions NO ₂ ^- and hydrogen ions H ⁺ are generated when the ammonium ions NH ₄ ⁺ are oxidized as shown in the following formula, and the hydrogen ion concentration rises to lower the pH.
NH4++ ₃ / _2O2- > ^{NO2- +} 2H ⁺⁺ _H2O ( ₁ )

For sterilization in the nutrient solution tank, it is effective to add and stir a water-soluble sterilant, and possible sterilizers include hypochlorous acid, hydrogen peroxide, percarbonate, and ozone. Some of these fungicides and decomposition products of fungicides are harmful to plants. It is desirable to feed it inside, agitate and rinse before draining into the drain.

Nitrite bacteria are less tolerant to fungicides than plant pathogens, and can be sterilized under milder conditions than conventional sterilization methods aimed at killing pathogens. For example, hypochlorous acid is used at an effective chlorine concentration of 200-1000 ppm in normal hydroponics, but nitrification by nitrite bacteria is known to be suppressed at 2-3 ppm. Ozone requires a concentration of 3-5 ppm for sterilization of pathogenic bacteria, but nitrification by nitrite bacteria can be suppressed at 0.3 ppm. Therefore, the sterilization installation according to the invention can be simpler and less costly than conventional sterilization installations.

In addition, a sterilization method that uses a device such as ultrasonic waves is also conceivable, but in this case as well, nitrification by nitrite bacteria can be suppressed under milder conditions than pathogenic bacteria, so it can be simpler and cheaper than conventional sterilization equipment. .

In addition, according to the present invention, adverse effects caused by adding materials containing organic substances to the nutrient solution are less likely to occur. In other words, the decomposition of nutrient solution by organic matter is mainly caused by various types of bacteria that spoil the organic matter adhering to the nutrient solution tank. Can be sterilized under certain conditions. Therefore, if the inside of the nutrient solution tank is sterilized as in the present invention, the organic material can be supplied to the plants by addition to the nutrient solution in a labor-saving manner, instead of the time-consuming foliar spraying. Since organic acids are also generated by decomposition of organic matter, it is possible to prevent plants from being damaged by organic materials by detecting decomposition of organic matter based on a decrease in pH.

The present invention has been made based on the above findings. The above-mentioned problems are solved by a method for suppressing nitrification of a nutrient solution, characterized by sterilizing the nutrient solution when the pH in the nutrient solution tank is lowered to suppress nitrification of the nutrient solution by nitrite bacteria.

Here, the sterilization in the nutrient solution tank can be performed by injecting and stirring a sterilizing agent into the nutrient solution tank, and the washing water after sterilization can be discharged out of the nutrient solution tank.

The present invention also provides a nutrient solution tank for mixing the uncirculated nutrient solution with the raw water, a pH sensor for detecting the pH in the nutrient solution tank, and a pH sensor for detecting the pH in the nutrient solution tank. Means for injecting a sterilant into the nutrient solution tank at times, means for stirring the nutrient solution in the nutrient solution tank, and means for discharging the washing water after stirring and sterilization to the outside of the nutrient solution tank. A nutrient solution nitrification suppressing device characterized in that the inside of the nutrient solution tank is sterilized to suppress the nitrification of the nutrient solution by nitrite bacteria. .

The present invention also provides a nutrient solution tank for mixing the uncirculated nutrient solution with the raw water, a pH sensor for detecting the pH in the nutrient solution tank, and a pH sensor for detecting the pH in the nutrient solution tank. a sterilization tank into which the nutrient solution in the nutrient solution tank is sometimes introduced, means for agitating the nutrient solution in the sterilization tank, means for returning the nutrient solution sterilized in the sterilization tank to the nutrient solution tank, and sterilizing the inside of the nutrient solution tank to suppress nitrification of the nutrient solution by nitrite bacteria. is .

The production of nitrite in the nutrient solution is caused by nitrite bacteria. ADVANTAGE OF THE INVENTION According to this invention, the nitrite bacteria which denature the nutrient solution can be effectively sterilized in the nutrient solution tank for mixing the uncirculated nutrient solution and the raw water . Therefore, regardless of the presence or absence of nutrient circulation, it is possible to prevent the accumulation of nitrite ions from causing physiological disorders in plant roots and the like. Nitrite bacteria are ubiquitous in ordinary environments and cannot be eradicated, but they cause damage to crops when they proliferate in large numbers. Therefore, according to the present invention, harm to plants can be avoided by sterilizing them before they proliferate in large numbers.

1 is a pipeline diagram showing the overall configuration of a first embodiment of the present invention; Flow chart showing the same sterilization procedure A pipeline diagram showing the overall configuration of a second embodiment of the present invention. Flow chart showing the same sterilization procedure

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the present invention is not limited by the contents described in the following embodiments and examples. In addition, the configuration requirements in the embodiments and examples described below include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Furthermore, the constituent elements disclosed in the embodiments and examples described below may be combined as appropriate, or may be selected and used as appropriate.

The first embodiment of the present invention mainly includes a nutrient solution tank 10, a solution supply line 20, and a field 30, as shown in FIG.

The nutrient solution (undiluted solution) is supplied to the nutrient solution tank 10 from the liquid supply port 12 and water (raw water) is supplied from the water intake 14 , and stirred by the stirring device 16 to produce the nutrient solution 18 .

The nutrient solution 18 in the nutrient solution tank 10 is supplied to the field 30 via the pump 22 , the valve 24 and the watering tube 26 of the supply line 20 .

In a farm field 30 , a plant 36 is planted in a cultivation medium (rock wool or the like) 34 of a cultivation bed 32 , to which the nutrient solution 18 is supplied from the watering tube 26 of the liquid supply line 20 . The nutrient solution 18 that has flowed out to the cultivation bed 32 is disposed of after being treated in compliance with regulations, or is recovered and returned to the nutrient solution tank 10 for circulation.

The nutrient solution tank 10 is provided with a pH sensor 40 according to the present invention and a sterilant tank 42. When the pH sensor 40 detects a decrease in pH, the nutrient solution tank 42 has an injection port 44. A disinfectant is injected into the nutrient solution tank 10 . In the figure, 46 is a discharge port for discharging washing water and rinsing water, which will be described later, and 48 is a pump therefor.

The sterilization procedure in the first embodiment will be described below with reference to FIG.

First, in step 100, when the pH sensor 40 detects that the pH of the nutrient solution 18 in the nutrient solution tank 10 has decreased, in step 110, the pump 22 is stopped and the valve 24 is closed to open the supply line. The water supply to 20 is stopped and the irrigation from the irrigation tube 26 is stopped.

Next, in step 120 , the sterilant is injected into the nutrient solution tank 10 from the sterilant tank 42 through the injection port 44 .

Next, in step 130 , the inside of the nutrient solution tank 10 is agitated by the agitator 16 . In addition, since it is desirable that the stirring during sterilization is performed with a stronger force than during normal stirring, a stirring device separate from the stirring device 16 during normal operation may be provided.

Next, in step 140 , the pump 48 is operated to discharge washing water from the discharge port 46 .

Next, in step 150 , only water is introduced into the nutrient solution tank 10 through the water intake 14 .

The processing from steps 120 to 150 may be repeated multiple times in order to enhance the sterilization effect, or the next step may be performed after confirming the sterilization result in some way.

Next, at step 160 , the agitator 16 is moved to rinse the inside of the nutrient solution tank 10 .

Next, at step 170, the pump 48 is driven to drain the rinse water from the outlet 46. FIG.

The processing from steps 160 to 170 may be repeated multiple times if it is difficult to discharge the sterilant once, or the discharge of the sterilant may be confirmed by some method before proceeding to the next step. .

Next, in step 180 , the nutrient solution 18 and water are introduced into the nutrient solution tank 10 through the liquid supply port 12 and the water suction port 14 .

Next, in step 190, the water and the nutrient solution 18 are stirred by the stirring device 16, and in step 200, the pump 22 is driven and the valve 24 is opened to restart the supply of the nutrient solution 18 to the irrigation tube 26 of the supply line 20. and resume irrigation.

According to the first embodiment, since the disinfectant is injected into the nutrient solution tank 10, the inner wall of the nutrient solution tank 10 can be reliably sterilized. The nutrient solution tank 10 can also be sterilized by irradiating ultrasonic waves instead of using a sterilant.

Next, a second embodiment of the present invention in which the inside of the nutrient solution tank 10 is sterilized by a sterilization tank provided outside the nutrient solution tank 10 will be described with reference to FIG.

This embodiment includes a sterilization tank 50 outside the nutrient solution tank 10, an injection port 52 for injecting a sterilant into the sterilization tank 50, and a nutrient solution 18 in the nutrient solution tank 10 into the sterilization tank 50. A liquid supply pipe 54, a pump 56 and a valve 58 for introduction, a stirring device 60 for stirring the nutrient solution 18 introduced into the sterilization tank 50 and the sterilant, and the nutrient solution 18 after sterilization is added to the nutrient solution again. A liquid feed pipe 62, a pump 64 and a valve 66 for returning to the tank 10, and a control device 70 for controlling them based on the pH sensor 40 similar to the first embodiment are provided.

Other configurations are the same as those of the first embodiment, so description thereof is omitted.

The sterilization procedure in the second embodiment will be described below with reference to FIG.

After watering is stopped in steps 100 and 110 similar to those of the first embodiment, the process proceeds to step 320 where the nutrient solution 18 in the nutrient solution tank 10 is supplied to the sterilization tank 50 using the supply pipe 54 , the pump 56 and the valve 58 . move to

Next, at step 330 , the inside of the sterilization tank 50 is stirred by the stirring device 60 .

Next, in step 340 , the nutrient solution 18 that has been sterilized is returned to the nutrient solution tank 10 by the supply pipe 62 , the pump 64 and the valve 66 .

Next, in step 350 , the inside of the nutrient solution tank 10 is agitated by the agitator 16 to sterilize the inside of the nutrient solution tank 10 .

Since the subsequent processing from steps 140 to 200 is the same as in the first embodiment, the same reference numerals are assigned and the description thereof is omitted.

In any of the above-described embodiments, if the toxicity of the disinfectant is low and there is no need to discharge the wash water, the discharge port 46, the pump 48, and the processing from steps 140 to 170 can be omitted. can. Especially when ultrasonic waves are used in the first embodiment, it is not necessary to discharge the cleaning water.

In the above-described embodiments, the pH sensor 40 is provided to detect the growth of nitrite bacteria and the accumulation of nitrite ions by decreasing the pH. It is also possible to sterilize the inside of the nutrient solution tank 10 by actual measurement.

Alternatively, it is also possible to periodically sterilize the inside of the nutrient solution tank 10 without measuring the nitrous acid concentration and pH. For example, it can be performed several times a week in summer and once in winter. This period can be changed by the concentration of ammonia in the nutrient solution 18 . When using rain water or tap water which is less likely to contain nitrite bacteria, the frequency can be lower than when using river water or well water.

DESCRIPTION OF SYMBOLS 10... Nutrient solution tank 16, 60... Stirrer 18... Nutrient solution 20... Supply liquid line 26... Irrigation tube 30... Field 32... Cultivation bed 34... Culture medium 36... Plant 40... pH sensor 42... Fungicide tank 50... Sterilization tank 70... Control device

Claims (4)

In cultivating plants using nutrient solution,
The inside of the nutrient solution tank for mixing the uncirculated nutrient solution with the raw water is sterilized when the pH in the nutrient solution tank drops to suppress the nitrification of the nutrient solution by the nitrite bacteria. A method for suppressing nitrification of a nutrient solution. 2. The nutrient solution tank according to claim 1, wherein the sterilization in the nutrient solution tank is performed by injecting and agitating a sterilizing agent into the nutrient solution tank, and the washing water after sterilization is discharged out of the nutrient solution tank. method for inhibiting nitrification of the nutrient solution. a nutrient solution tank for mixing the uncirculated nutrient solution and the raw water;
a pH sensor for detecting the pH in the nutrient solution tank;
means for injecting a disinfectant into the nutrient solution tank when the pH in the nutrient solution tank drops;
means for stirring the nutrient solution in the nutrient solution tank;
means for discharging washing water after agitation and sterilization to the outside of the nutrient solution tank;
with
An apparatus for suppressing nitrification of a nutrient solution, wherein the inside of the nutrient solution tank is sterilized to suppress nitrification of the nutrient solution by nitrite bacteria. a nutrient solution tank for mixing the uncirculated nutrient solution and the raw water;
a pH sensor for detecting the pH in the nutrient solution tank;
a sterilization tank into which the nutrient solution in the nutrient solution tank is introduced when the pH in the nutrient solution tank drops;
means for stirring the nutrient solution in the sterilization tank;
means for returning the nutrient solution sterilized in the sterilization tank to the nutrient solution tank;
with
An apparatus for suppressing nitrification of a nutrient solution, wherein the inside of the nutrient solution tank is sterilized to suppress nitrification of the nutrient solution by nitrite bacteria .

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