JPH08266171A - Treatment of culture solution in hydroponic culture - Google Patents

Abstract

PURPOSE: To effectively treat a culture solution for hydroponic culture, remove a growth-inhibiting substance secreted by the plant, etc., prevent the lowering of growth in continuous cropping and enable the continuous use of the culture solution over a long period by circulating the culture solution through a treating layer composed mainly of a fibrous activated carbon. CONSTITUTION: A culture solution for the hydroponic culture of plants such as green vegetables, fruits and flowers is treated by circulating the solution through a treating layer composed mainly of a fibrous activated carbon such as a fibrous activated carbon having a specific surface area of 500-2,000m<2> /g and a volume of pores having pore diameter of <=30Å accounting for >=90% of the total pore volume.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a nutrient solution in hydroponics of plants such as vegetables, fruits and flowers. More specifically, it relates to a nutrient solution used in hydroponics for a long period of time. The present invention relates to a method for treating a nutrient solution that enables repeated use over a long period.

[0002]

2. Description of the Related Art Generally, plants are cultivated using soil as a medium such as fields and rice fields, and water and nutrients are absorbed from the roots through the soil. However, since water and nutrients are supplied by spraying water and nutrients on the soil, the efficiency of absorption by plants is low and the loss of water and nutrients is large.

On the other hand, hydroponics of plants such as vegetables, fruits and flowers has been actively used in recent years. Hydroponic culture is rock wool instead of soil, plastic foam,
A fibrous material is used as a medium, and nutrients necessary for plants such as nitrogen, phosphoric acid, and potassium are dissolved in water to adjust the concentration of predetermined components, and then the medium is pumped.
For this reason, hydroponics can be labor-saving and mechanized, that is, it does not require labor such as hoe and plow, and does not require labor such as weeding. It does not require soil replacement or location change to eliminate continuous crop failure. Since the fertilizer is dissolved in water and circulated, there is no waste such as fertilizer outflow, and the required nutrients can be efficiently provided as necessary. It is difficult to be influenced by weather conditions and the cultivation density is high. It is possible to
It has advantages such as effective use of land and increased yield per unit area.

Hydroponics takes advantage of the above advantages,
In recent years, the cultivated area has rapidly increased, and in addition to vegetables, mass production through factoryization has also progressed. However, as hydroponics has been applied to various plants, if the plant is operated only by topdressing without changing the nutrient solution for a long period of time, some plants may suffer from the problem of poor growth, in which the growth is significantly delayed. ing. At present, measures such as empirically replacing the nutrient solution with a new one are taken before such a problem occurs, but such a measure has a problem that the cultivation cost increases. Moreover, when the nutrient solution is replaced, if nutrient-rich water is directly discharged into the river, it causes eutrophication of the river and lakes, so it is necessary to treat and discharge the nutrient solution.

The cause of poor growth of plants in hydroponics is thought to be due to accumulation of growth-inhibiting substances such as phenolic substances and organic acid substances secreted from the plants under cultivation in the nutrient solution. Attempts have also been made to improve the growth of plants by treating the used nutrient solution with granular activated carbon.

However, when a large amount of granular activated carbon is used, the resistance of the liquid is large and it is difficult for the liquid to pass through. The powder of granular activated carbon leaks into the liquid, and if the filtration filter is made fine as a measure against leakage, clogging occurs and the liquid pressure is reduced. Of the granular activated carbon after treatment increases the treatment cost because it cannot be incinerated because there is a danger of dust explosion and it becomes industrial waste, and the granular activated carbon has a wide pore distribution. Moreover, since many of the large pores are distributed, useful nutrients for plants are adsorbed, and the amount of nutrients supplied to the nutrient solution is increased, and the adsorption capacity for the desired growth inhibitory substances is reduced. Yes, there was such a problem.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and even if the nutrient solution in hydroponics is circulated for a long period of time, the plant does not grow poorly, and the treatment layer is granular activated carbon. It is a technical subject to provide a method for treating a nutrient solution in hydroponic culture, which has no such problems in use.

[0008]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventor has found that fibrous activated carbon has a property of selectively adsorbing a growth inhibitor of plants selectively and satisfactorily. If the nutrient solution is filtered through a treatment layer containing activated carbon as a main component, the replacement life of the nutrient solution can be significantly extended.
The present invention has been achieved by finding that the growth of plants is good and there is no problem in use such as granular activated carbon.

That is, the present invention is a method for treating a nutrient solution in hydroponics, characterized in that the nutrient solution used in hydroponics of plants is circulated through a treatment layer containing fibrous activated carbon as a main component. Is the gist.

The present invention will be described in detail below.

In the present invention, the main component of the treatment layer through which the nutrient solution used in hydroponics is passed is fibrous activated carbon,
The raw material of the fibrous activated carbon is not particularly limited and may be any one obtained from coal pitch, petroleum pitch, rayon, phenol fiber, acrylic fiber or the like. The specific surface area of the fibrous activated carbon is preferably 500 to 2000 m ² / g as measured by the BET method. When the specific surface area is less than 500 m ² / g, the number of pores becomes small and the amount of growth inhibitor adsorbed tends to decrease. Further, when the specific surface area exceeds 2000 m ² / g, the pores become large and the nutrients useful for plants are easily adsorbed.

Further, in the fibrous activated carbon, in the pore distribution obtained by the B, J, H method (the method of Barrett, Joyner, Halenda et al.), The volume ratio of the pores having a pore diameter of 30 Å or less is It is preferably 90% or more of the pore volume.
If the pore volume is less than 90%, the number of large pores that adsorb nutrients useful to plants increases, and for example, 20 to 30 pores with a diameter of 30 Å or more like commonly used granular or powdered activated carbon.
When it is present at 35%, the selective adsorption of growth-inhibiting substances becomes low, and moreover, useful nutrients are adsorbed, and the required amount of nutrients to be supplied to the nutrient solution tends to increase.

As the treatment layer used in the present invention, a raw cotton of fibrous activated carbon or a sheet formed by packing in a tank, a laminated sheet containing fibrous activated carbon as a main component, or a concentric cylinder of the sheet. Wound into a cartridge, a fibrous activated carbon and a binder dispersed in water and introduced into a mold to form a cylindrical or columnar cartridge, and the sheet formed into a corrugated or honeycomb shape. What was done can be used. Among them, the cartridge formed by winding a sheet containing fibrous activated carbon as the main component has less clogging and is easy to handle. When this cartridge is used as a treatment layer, it is preferable to mount the cartridge on the housing and pass the nutrient solution from the outer layer to the inner layer of the cartridge.

As a method of manufacturing the cartridge, it is preferable to mix fibrous activated carbon and other materials by a dry method or a wet papermaking method to form a sheet, and wind the sheet in a concentric cylindrical shape. Other materials used with fibrous activated carbon include low melting point polyester fiber, low melting point polyester as a sheath component, high melting point polyester as a core component composite fiber, polyolefin fiber, polyethylene as a sheath component,
Examples thereof include binder fibers such as composite fibers having polypropylene as a core component, inorganic fibers such as glass fibers and ceramics fibers, and natural fibers. One or more of these are blended with fibrous activated carbon, but the blending ratio is 40-
90% by weight and 60 to 10% by weight of other materials are preferable. If the amount of fibrous activated carbon is less than 40% by weight, the effect of adsorbing the growth inhibitory substance is likely to decrease. The amount of fibrous activated carbon is 90% by weight.
When it exceeds, it becomes difficult to mold it into a cartridge.

When a nutrient solution for hydroponics is used for a long time while being filtered in a treatment layer containing fibrous activated carbon as a main component, the nutrient solution has a high nutrient content, so that microorganisms propagate in the treatment layer to cause clogging. Problems may occur. In order to prevent such problems from occurring, a treatment layer is formed with fibrous activated carbon impregnated with 0.01 to 10% by weight of a poorly water-soluble silver compound and / or a binder fiber containing an antibacterial silver compound is used. When a treatment layer such as a cartridge is formed by using, it is possible to prevent the growth of microorganisms in the treatment layer.

Here, as the poorly water-soluble silver compound, silver chloride and silver oxide are easily obtained, which is preferable. As the antibacterial silver compound, silver oxide and silver-adsorbed zeolite are preferably used. A known method can be adopted as a means for impregnating or containing these silver compounds in the fibrous activated carbon or the treatment layer.

Generally, in hydroponics, a nutrient solution is pumped from a nutrient solution tank for preparing the nutrient solution to each medium of a hydroponic bed. The nutrient solution after being supplied to the plants is collected in the drainage pipe and returned to the nutrient solution tank, and after adjusting the nutrients, it is again delivered to each medium, and the nutrient solution is circulated and used.

In the above, according to the present invention, a tank provided with a treatment layer having a fibrous activity as a main component is provided in the middle of the drainage pipe, or the nutrient solution is provided between the nutrient solution tank and the tank provided with the treatment layer. A system separate from the circulation system of the nutrient solution is installed to circulate the nutrient solution, and the nutrient solution is passed through the treatment layer to adsorb plant growth inhibitory substances, and then the nutrient solution from which the growth inhibitory substances have been removed is transferred to the nutrient solution tank. Then, the solution is transferred to the medium.

[0019]

EXAMPLES Next, the present invention will be specifically described by way of examples.

Example 1 Specific surface area of 1650 m ² / g, pore volume of 0.84 ml / g, volume ratio of pores having a pore diameter of 30Å or less determined from pore distribution is 95% of the total pore volume. Coal pitch fibrous activated carbon 60% by weight
And 40% by weight of a composite binder fiber (Melty <4080> manufactured by Unitika Ltd.) containing low melting point polyester as a sheath component and high melting point polyester as a core component by card processing to produce a sheet with a basis weight of 40 g / m ^2. did.

This sheet is concentrically wound around a cylindrical iron pipe with an outer diameter of 30 mm to make a cylindrical cartridge with an outer diameter of 65 mm, and then heat treated, and then cut into 250 mm intervals to obtain an inner diameter of 30 mm, an outer diameter of 65 mm, and a long length. 250 mm in length, 55 g of fibrous activated carbon
A cylindrical cartridge containing was obtained.

Using the obtained cylindrical cartridge as a treatment layer, it was attached to a circulation system of 500 liters of nutrient solution for hydroponics of honeywort, and the solution was passed at a rate of 6 liters / min. Here, the honeywort used was Kansai white-stalked honeywort. Otsuka House fertilizer No. 1 and No. 2 (trade name) were used as the nutrient solution, and a new solution adjusted to the concentration of the garden trial formulation was used. A series of three consecutive production of honeywort without using activated carbon was used. It carried out about what used the liquid.

As a result of hydroponics for 30 days, the growth of Mitsuba was good, and the growth weight ratio of Mitsuba in the continuous crop liquid to the new liquid was 98%. Both liquids were in good operating condition with no pressure increase and no coal dust generation. In addition, the processed cartridge could be incinerated and no industrial waste was generated. Furthermore, the active layer in the nutrient solution was less adsorbed by the treated layer, and fine adjustment of the fertilizer was sufficient.

Comparative Example 1 The specific surface area is 965 m ² / g, the pore volume is 0.54 ml / g, and the volume ratio of pores of 30 Å or less determined from the pore distribution is the total pore volume.
Mitsuba was hydroponically cultivated in the same manner as in Example 1 except that 100 g of 78% coconut shell granular activated carbon was packed in a 50 mm × 150 mm tower to form a treated layer.

As a result of the hydroponic culture for 30 days, the growth weight ratio of the honeywort of the continuous liquid to the new liquid was 83%, which was smaller than that in Example 1. Although no increase in pressure loss was observed, black powder was generated due to leakage of granular activated carbon. If a filtration filter was installed to prevent this black powder, clogging due to the growth of microorganisms during long-term operation resulted in a large pressure loss. In addition, it was necessary to replenish the components effective for the growth of honeybees at the beginning of the passage.

Comparative Example 2 Hydroponics of honeywort was carried out in the same manner as in Example 1 except that the treatment layer containing fibrous activated carbon as a main component was not used. As a result, the growth weight ratio of honeywort to the new liquid was 60%.
In addition to the results obtained in Example 1, the number was significantly smaller than that in Comparative Example 1.

[0027]

EFFECTS OF THE INVENTION According to the present invention, growth inhibiting substances secreted by plants and the like can be effectively removed in the treatment layer mainly containing fibrous activated carbon. It can be used continuously over a period of time, and the treatment layer does not have the problem of use such as granular activated carbon.

Claims (2)

[Claims] 1. A method for treating a nutrient solution in hydroponics, wherein a nutrient solution used in hydroponics of plants is circulated through a treatment layer containing fibrous activated carbon as a main component. 2. The specific surface area of fibrous activated carbon is 500 to 2000 m ^2.
The method for treating a nutrient solution in hydroponics according to claim 1, wherein the volume ratio of the pores having a pore diameter of 30 g / g or less is 90% or more of the total pore volume.