JPS589651B2 - Culture solution PH value adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically adjusts the pH value of a culture solution used in hydroponic cultivation, and provides a device that has high electrolysis efficiency and can adjust the pH value quickly. It is.

A conventional culture solution pH value adjustment device using electrolysis using an ion exchange membrane uses a near-neutral solution in which a salt consisting of ions common to those composing the culture solution is dissolved in water as the electrolyte. It had many advantages, such as being able to adjust the pH value of the culture solution with high precision and gently, and having few mechanical parts such as solenoid valves, making maintenance easy.

However, depending on the cultivated crop, the pH value of the culture solution may change significantly, and if electrolysis is performed for adjustment, the pH value of the electrolyte solution will also change greatly in the same direction as the pH value of the culture solution. However, there were disadvantages in that the electrolysis efficiency decreased and the electrolysis time became longer.

For example, in the case of melons, the pH value of the culture solution decreases significantly from the middle stage of cultivation, and electrolysis is started to bring it back, so the electrode for electrolysis in the electrolyte becomes a positive electrode and the H+ ion concentration of the electrolyte increases.

When a cation conversion membrane is used, the ratio of H+ ions migrating into the culture fluid increases more than K+ ions, which are cations of neutral salts in the electrolyte, migrate into the culture fluid. Since the generated OH- ions are neutralized, the pH value of the culture solution becomes difficult to increase.

Also, when an anion exchange membrane is used, the proportion of H+ ions in the electrolyte passing through the membrane increases, making it difficult for the pH value of the culture solution to rise, similarly to the above.

Therefore, in order to increase the electrolysis efficiency, it is possible to increase the area of the ion exchange membrane or increase the current density, but the former would require a larger device, while the latter would affect the life of the ion exchange membrane. Not practical.

It is also possible to adjust the pH value of the electrolyte solution in the opposite direction to the expected change in pH value of the culture solution.
This means that it is not possible to deal with plants where the pH value changes in a complicated manner up and down, such as tomatoes, where the pH value decreases in the early stage of cultivation and increases from the middle stage of cultivation.

The present invention is a device that can completely overcome the problems, drawbacks, and practical difficulties seen in the above-mentioned conventional examples, and is a device that can completely overcome the problems, drawbacks, and practical difficulties seen in the above-mentioned conventional examples. It is characterized by electrolysis occurring between an electrode in the liquid and an electrode in the culture medium.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view when the culture solution pH value adjusting device according to the present invention is actually installed, and the culture solution 2 in the culture solution tank 1 is It is pumped up by the pump 3 and returns to the culture tank 1 via the cultivation tank 4.

The pH controller 5 detects the pH value of the culture solution 2 with the measuring electrode 6, and if the pH value is outside the desired range, the pH value is detected between the electrolytic electrodes 7 and 8 installed in the culture solution tank 1 or Send an electrolytic signal between 9 and 10.

Here, a part of the rectangular parallelepiped hollow container 11 is made of a cation exchange membrane 12, and a part of the container 13 is made of an anion exchange membrane 14, and the electrolytic electrodes 7, 8, and 9 are connected to each other through the respective membranes. In the electrolytic solution 15 in the container 11 that 10 is facing, for example, when dissolved in water, like MgO, if the solution tries to move in the direction of decreasing its pH value, it will liberate O}r ions. However, in addition to suppressing this, when the pH value exceeds a certain value, it contains an electrolyte that does not fix ions and exhibit strong alkalinity, that is, has little effect on the deterioration of the ion exchange membrane 12. In addition to MgO, an electrolyte such as Mg(OH)2, CaO2, Ca(OH)2, etc. may be included.

Next, when dissolved in water, the electrolyte 16 in the container 12 contains
If the pH value of the liquid itself continues to move and exceeds a certain value, 0}
It is sufficient to contain an electrolyte that does not exhibit strong acidity so as to fix r ions and suppress the pH value from exceeding that value, and to have little effect on deterioration of the ion exchange membrane 12. For example, MgS04, Ca It is sufficient if an electrolyte such as (NO3)2 is contained in combination with a weakly acidic electrolyte such as KHSO4.

When the pH value of the culture solution 2 is low, electrolysis occurs such that the electrolysis electrode 7 in the culture solution 2 becomes a negative electrode and the electrolysis electrode 8 in the electrolyte solution 15 becomes a positive electrode. Begins via

Conversely, when the pH value of the culture solution 2 is high, the electrolytic electrode 7,
No electrolysis signal is sent to the electrolysis electrode 9 in the electrolytic solution 16.
Electrolysis is started via the anion exchange membrane 14 such that the electrolysis electrode 10 in the culture solution 2 becomes the negative electrode and the electrolytic electrode 10 in the culture solution 2 becomes the positive electrode.

As the electrolysis described above is carried out, the pH value of the electrolyte 15 tends to decrease and the pH value of the electrolyte 16 tends to increase, but each electrolyte has a change in its pH value. It has a buffering capacity in the direction of , and the pH of each electrolyte itself
Since changes in the values are suppressed, changes in the pH values of each electrolytic solution are extremely slow and do not change significantly until cultivation is completed.

Therefore, the electrolysis efficiency is good and the electrolysis time can be shortened.

According to experiments, in the case of melons, the amount of electricity required for pH correction during the cultivation period can be reduced by about 30 times compared to the electrolyte solution in the garage and without buffering capacity. Ta.

Next, FIG. 2 shows another embodiment of the present invention, and is a sectional view when electrolysis is performed outside the culture solution tank 17 to adjust the pH value of the culture solution.

The culture solution 18 is pumped up by the pump 19, passes through the culture solution chamber 21 of the electrolytic container 20, and returns to the culture solution tank 17.

The electrolyte chambers 22 and 23 have electrolytes 24 and 25 having properties similar to those of the electrolytes of the above embodiments, and ion exchange membranes 26 and 27 having different polarities.

In addition, 2B, 29.30 is an electrode for electrolysis, and 29 is a negative electrode when the pH value of the culture solution is low, and a positive electrode when it is high, and electrolysis is performed, thereby efficiently adjusting the pH value of the culture solution. can.

As described above, the culture solution pH value adjusting device according to the present invention has two electrolyte parts containing an electrolyte having a composition that has a buffering capacity against changes in the pH value of the electrolyte itself, and an ion exchange membrane of different polarity. , even for crops where the pH value of the culture solution changes in any direction, up or down, or for crops that change significantly in the same direction, faster control can be performed accurately and reliably. This device has extremely high practical value as it can fully respond to changes in pH and pH values.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a culture solution pH value adjustment device according to an embodiment of the present invention when actually installed, and FIG. 2 is a configuration diagram of a culture solution pH value adjustment device according to another embodiment of the present invention. . 1... Culture solution tank, 2... Culture solution, 3... Pump, 4...
Cultivation tank, 5... pH controller, 6... Measuring electrode, 7, 8
, 9.10...electrode for electrolysis, 11...hollow container, 12...
... Cation exchange membrane, 13 ... Container, 14 ... Anion exchange membrane, 15, 16 ... Electrolyte solution.

Claims (1)

[Scope of Claims] 1. A culture solution pH value adjustment device for hydroponic cultivation in which a culture solution is continuously or intermittently circulated to grow crops, which is in contact with the above-mentioned culture solution via a cation exchange membrane. An electrolytic solution section and an electrolytic solution section that is in contact with the culture solution via an anion exchange membrane are provided separately, and at least one electrode is placed in each of the two electrolyte sections in the culture solution. By disposing one electrode and performing electrolysis via the ion exchange membrane between the electrode in the electrolytic solution and the electrode in the culture solution, the pH value of the culture solution is adjusted to a desired range. A culture solution pH value adjusting device characterized by the following. 2. In the culture solution pH value adjusting device according to claim 1, MgO, Mg(OH)2 is used as an electrolyte in the electrolytic solution part, and the electrolytic solution part has a cation exchange membrane.
, CaO , and Ca(OH)2, which have properties that prevent the electrolyte from becoming acidic.
3) A culture solution pH value adjusting device characterized by containing an electrolyte having a property of resisting the electrolyte becoming alkaline as described in 2.