GB2359301A

GB2359301A - Photocatalytic treatment of water

Info

Publication number: GB2359301A
Application number: GB0012488A
Authority: GB
Inventors: Toshiyuki Sakiura
Original assignee: NAKAJIMA SUISAN CO Ltd
Current assignee: NAKAJIMA SUISAN CO Ltd
Priority date: 2000-02-21
Filing date: 2000-05-24
Publication date: 2001-08-22
Also published as: NO20002744D0; NO20002744L; GB0012488D0; CA2310265A1; JP2001231395A

Abstract

A system for feeding fries with feeding water treated with a photocatalyst without administering medicines, such as vaccines, etc. to drastically improving a death rate of the fries. In the fry death rate improving system according to the present invention a photocatalysis body is contacted directly to water to feed the fries. A photocatalysis device of the fry death rate improving system according to the present invention comprises a photocatalysis tank(11), a light source(10) for radiating a photocatalyst, an inlet(30) for feeding water provided in the photocatalysis tank, an outlet(40) for the photocatalyzed feeding water and a preserve tank(20) disposed below the outlet(40). A plurality of partition plates(70) with a fabric adhered to having the photocatalysis body applied to by flame spray coating are juxtaposed with each other in the photocatalysis tank(11) in a manner which contacts the feeding water, causing turbulent flows in the feeding water.

Description

1 1 2359301 FRY DEATH RATE IMPROVING SYSTEM USING PHOTOCATALYST

BACKGROUND OF THE INVENTION

The present invention relates to a system for feeding fries of fishes, such as fresh water fishes, sea water fishes, etc. with feeding water photocatalyzed for a lower death rate of the fries.

In order to lower death rates of fishes, such as fresh water fishes, sea water fishes, etc., in their fry stage due to diseases, etc. while being fed and grown, required vaccines have been administered, and dipping has been performed, or antibiotics have been administered. No special vaccine has been used for IHN of the rainbow trout. The IPN (Infectious Pancreatic Nucleotide) etc. of the rainbow trout has simply resorted to natural healing. Accordingly, a death rate of rainbow trout has often reached even 20%. Safety of medicines administered to edible fishes has been already confirmed, but it is said that preferably the medicines are not administered. But, under the current circumstances, such medicines must be used.

Howeverf even under the above-described circumstances, it is preferable from the viewpoint of the safety of the human body that medicines, such as vaccines, etc., are not administered to lower death rates of fishes whiletheir feeding and growing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially broken perspective view of the photocatalysis device and a preserve tank used in the fry death rate improving system using a photocatalyst according to the present invention.

FIG. 2 is a graph comparing a non-dissoluble photocatalyst used in the fry death rate improving system according to the present invention with a conventional dissoluble antibacterial agent in dissolution and their function changes.

2 FIG. 3 is a partially broken perspective view of a preserve tank of the fry death rate improving system according to the present invention in which fries are discharged.

FIG. 4 is a partially front broken perspective view of a photocatalysis device used in the fry death rate improving system according to the present invention.

FIG. 5 is a front view of a partition plate (substrate) having a sheet adhered to both sides, the sheet having a photocatalyst applied to, which is disposed in a photocatalysis tank of the photocatalysis device to photocatalyzing feeding water.

SUMMARY OF THE INVENTION

In view of the above, an object of the invention of the present application is to provide an improved fish feeding and growing system wherein photocatalysis devices juxtaposed with each other in a flowing water-type (open type) or a closed c irculat ing- type fish preserve, water tank or others to enhance disinfection of vicious bacteria, and purification and activation of inflow water (feeding water) into the fish preserve, water tank or others, whereby a death rate of death of fries due to diseases, etc., which is higher especially in comparison with those of adult fishes, can be lowered.

In the fr y death rate improving system according to the present invention, photocatalysis bodies are juxtaposed in feeding water in which fries are discharged for feeding, in direct contact with the feedingwater forphotocatalysis soas to feedthefries in the feeding water photocatalyzed.

DETAILED DESCRIPTION OF THE INVENTION

The fry death rate improving system using a photocatalyst according to the present invention will 3 be explained below.

First, fishes, to which the present invention relates, are both fresh water fish and sea water fish. The fresh water fish here contains decorative fresh water fish, cultured fresh water fish, etc. The decorative fish contains gold carps, goldfish, tropical fish, etc. The fresh water cultured fish contains rainbow trout, ayu, eel, etc. The freshwater fish contains high-class sea foods, such as lobster.

etc.

According to the present invention, as shown in FIGs. 1 and 3, photocatalysis device 1, is disposed in flowing water or a closed circulating-type fish preserve tank 2, 20 in which fishes are discharged to be fed and grown, or an installed water purification equipment. Feeding water W is supplied through an inlet 3, 30 connected to the photocatalysis device 1 to be photocatalyzed, and the feed water photocatalyzed is supplied into the f ish preserve tank 2, 20 through an outlet 4, 40. Fries discharged in the fish preserve tank are fed in the feeding water which has thus vicious bacteria in the feeding water W sterilized and has been purified and activated. A death rate of the thus-fed fries due to diseases, etc.

can be drastically lowered.

Achievements of the Photocatalmsis The photocatalyst is a catalyst of a specific compound, such as titanium oxide (e.g. T'02) or others, the surf ace of which is activated by radiation of light, such as sunlight, illumination or others, to act on a substance in contact therewith. The photocatalyst is noted by its much superior purification, disinfection, antibacterial action, disodorization, etc.

First, the functions of the photocatalyst will be explained. The photocatalyst functions basically with water (water content) as a medium; electrons e- 4 are taken into positive holes h' from anions (OW.

C021-F Cl-, etc.) in water, and the electrons are transformed to conduction electrons e-. These electrons are taken into cations (H+, Ca 2+ ' Mg2+r etc.), the anions C10-, and dissolved oxygen 0,. Here, C10is a source of lime chloride smell derived from disinfecting chloride.

It is presumed that the anions having electrons taken off change as follows.

20W-2e-= H20+(l/2)02 C03 2 --2e- = C02+(l/2)02 Cl--e- = (l/2)C12 C10-+H20--e- = Cl+C102-+2W On the other hand, the cations, the C10- and the 15 dissolved 02. which have been given the electrons change as follows.

H++e-= (l/2)H2 Ca 2 ++2e-- Ca Mg2++2e- Mg 02+e- = 0202+2H20+4e- = 40W 2C10+e- = 2Cl- +02The photocatayst thus causes many reactions. It is presumed that these reactions generate a large 25 number of OH radicals. According to published experimental results, for example, the use of a photocatalyst increases a pH of water from 7.2 to 7.8, making the water alkaline. Furthermore, a dissolved oxygen concentration in the 30 water is decreased from 7.5 mg/liter to 7.35 mg/liter, and an oxidation-reduction potential is decreased from 610 to 530 (reducing power is improved). This state can be retained. As a result, the function of disinfecting bacteria continuously for a long period 35 of time in high-temperature and high-humidity environments which are suitable for germs to be generated(See Tsukasa SAKURADA, Photo-Semiconductor Sterilization by Low-Temperature Melt Injection Method, HYOMEN GIJUTSU (Surface Technology), Vol. 4 9, No.5, 1998, pp.15-20).

As shown in FIG. 2, the photocatalyst is generally non-dissoluble. A metal carried on a photosemiconductor powder of the photocatalyst functions as an electrode, and the disinfection effect is exerted by OH radicals generated in the presence of water.

In contrast to this, the conventional dissoluble antibacterial agent, e.g., a mixture of zeolite carrying a metal, such as silver, copper, lead or others, which are antibacterial, and a binder is applied to a required portion and dried. The metal which is antibacterial is immediately dissolved into liquid to be immediate effective. However, the effect is reduced for a short period of time. Besides, the portion f rom which the metal has been dissolved becomes a nest of bacteria, to the contrary affecting the environment.

In contrast to this, although the photocatalyst is often inferior to the antibacterial agent in the immediate ef f ect, the photocatalyst is non-dis soluble, and is not substantially dissolved into liquid and remains effective for a long period of time.

The photocatalyst makes a cluster of water smaller, which is thought to have good influence on lives in water, e.g., on living environments of cultured f is hes.

It is well known that water freezes at OOC at 1.01325x10-5 Pa. In ice, the so-called clusters each of 4 water molecules hydrogen-bonded in a regular tetrahedral shape around one water molecule are spread in three-dimens ions. It is experimentally confirmed that clusters of pseudo ice are present in water.

Underground water, etc. are also known as magnetized water having the cluster structure which is approximate to that of ice.

Magnetized water has small 6 molecules collected in meshes. Bacteria are trapped by the meshes, and cannot easily increase. Magnetized water has the function of preventing increase of algae, moss, bacteria, etc. The photocatalyst thus makes water clusters smaller, and the water can prevent increase of bacteria, etc. as does magnetized water.

According to the findings of the inventor of the present application, water is clustered to thereby improve living environment of fishes. Comfortable conditions are provided to living bodies, and stress given to fishes is drasticalLy decreased, which gives good influence on growth, etc. of fishes.

Furthermore, the photocatalyst can be very simply formed by applying a photocatalysis body to a substrate by flame spray coating or other means. That is, the photocatalysis body is applied, without a binder, to polyester unwoven fabric, paper, woven fabric, plastics, an anti-corrosive metal plate, a ceramic ball, a ceramic plate or others, or is applied to a substrate as a binder-content paint.

When the photocatalysis body is applied to a substrate by flame spray coating of, e.g., about 18500C to form a coating, a corresponding amount (about 25%) of anatase-type crystals are present on the substrate, which produces the immediate disinfection effect.

In the fry death improving system using a potocatalyst according to the present invention, photocatalysis devices each having a photocatalyst formed by applying the above-described photocatlysis body are juxtaposed in a water tank holding feeding water in which fishes are discharged, for photocatalys is of the feeding water. That is, a woven fabric, an unwoven fabric, filters or others with the photocatalysis body applied to is disposed in an inlet of the feeding water or in an outlet or others of a already installed purification equipment. A substrate and a shape of the photocatalysis body with 7 the photocatalysis body applied to may be selected suitably for the already installed equipment. A scale of the photocatalysis body may be adjusted, corresponding to a f low rate of the feeding water, a size of a preserve tank or a water tank, by an intensity of the photocatalysis body or an amount of a woven fabric, an unwoven fabric, a filter or others with the photocatalys is body applied to by flame spray coating. -In water which has been contacted to the woven fabric, the unwoven fabric, the f ilter or others with the photocatalysis body applied to, disinfection of vicious bacteria (e.g., 0-157 colibacillus, etc.), decomposition (as of discharges of fishes, etc.), and water activation (e.g., enhancement of growth of Chlorella by photosynthesis) is enhanced. However, enteric bacteria of fries are not substantially influenced.

According to the present invention, decomposed components of water treated with a woven fabric, an unwoven fabric, a filter or others with the photocatalysis body applied to disinfects or decreases vicious bacteria, and additionally activates the water. Fries which are fed and grown with the water have a drastically improved death rates of death due to diseases.

An Example

An example of the fry death rate improving system using a photocatalyst according to the present invention will be explained below.

In this example, rainbow trouts were discharged and fed in a preserve tank (see TABLE 2 about the specifications) shown in FIG. 3 under the conditions shown in TABLE 1 for a corresponding period time. The results of the test are shown in TABLE 2.

8 TABLE 1 test fish Rainbow trout, 3 - 5 g/one (4 - 4 or 5 month-year old from egg collection, vibrio-unvaccinated Number 2000 Preserve tank made of concrete, water capacity: 752.4 1 Feeding water spring water 0.15 t/min (non-purified) average water temp.: 140C Feeding period 60 days of time Feeding times once/day The preserve tank 20 shown in FIG. 3 is formed of concrete, and has a 275 cm-length, a 76 cm-width and a 3 6 cm-height. Spring water W (f eeding water) treated with the photocatalyst was charged into the preserve tank 20 for the test.

TABLE 2

Photocatalysis tank 2 tanks, made of resin, 45cm(L)x30cm(W)x36cm(H), capacity: 48.61, 33.751 at water level (H) of 25cm Light source two NEC 15W black lights, 40Onm(A)-wavelength light quantity: two 15W x 2 x 0.14 = 8.4W (wavelength efficiency: 0.14) Photocatalysis body woven fabric-typ_e kind of flame spray Filter-type flame spray coated coated fabric and fabric, 0.2 mm/mm-square mesh area Roll net rolled in, area:

0.15 M2 x2=0.3 M 2 Unwoven fabric-type #150 flame spray coated fabric adhered to both sides of each partition plate, 8 partition plates set in one preserve tank, area:(0.25xO.3-0.03xO.75x4)x2x8 partition plates x 2 preserve tanks=2.112m' total area: 0.3+2.112--L.2.4m2 Photocatalysis body spring water amount: 0.15t/min, contact area: 2.4m' Water amount 0.15 2.4=0.0625t/m'/min =3.75t/m 2 /h 9 As shown in FIG. 4, the photocatalysis device 1 comprises two photocatalysis tanks 11 of plastics, light sources 10 of light of wavelengths of below 400 nm respectively mounted on the respective photocatlysis tanks 11. Each photocatalysis tank 11 has an inlet 30 for spring water (feeding water) and an outlet 40 for the spring water photocatalyzed. A photocatalysis body is applied to the inside wall of each photocatalysis tank 11 by flame spray coating, or a photocatalysis body-flame spary coated fabric is adhered to the inside wall of each photocatalysis tank 11. A plurality of partition plates (substrates) 70 each with the f lame spray coated-f abric adhered to both sides are vertically (shown in FIG. 4) or horizontally staggered alternately with respect to each other, defining open passages 71 of the spring water. The partition plates 70 may be any means as long as they can generate turbulent flows in the spring water (feeding water) passing the open passages 71 to maximize the contact amount of the spring water to the photocatalyst. For example, circular holes, slits or others may be arranged at random in the partition plates 70. It is also possible that a plurality of partition plates 70 are arranged in multi-stages to flow the spring water downward from above so as to contact the spring water to the photocatalyst.

The spring water passing the inside of the photocatalysis tank 11 passes in turbulent flows through the open passages 71 defined by the partition plates 7 0, whereby the spring water uniformly contacts the photocatalyst activated by radiation of the light source to be thereby treated. It is possible that a filter 60 with the photocatalysis body flame spray- coated is disposed at a suitable location inside the photocatalysis tank 11.

As shown in FIG. 5, the partition plates 70 disposed in the photocatlysis tank 11 may have fabric adhered to, which (fabric) has the photocatalyst applied to both sides by flame spray coating. A plurality of open passages 71 may be f ormed in the upper 5 end in, e.g., a digital shape, and the partition plates 7 0 may be alternately arranged so that the open passages 71 are defined vertical. A number of the partition plates 70, a number of the open passages 71, etc. vary depending on feeding conditions.

When required, sheets with the photocatalysis body applied to by flame spray coating may be suitably disposed in the preserve tanks 2, 20 without directly contacting the fries discharged in the preserve tanks 2, 20.

The test was made under the above-described conditions (for 1 month (November 15 to December 16, 1999), and the test results shown in TABLE 3 were obtained for the test area and a control area.

Surprisingly, the results proved that a death rate of the fries in the test area (photocatlyzed) was about 1/11 of that of the fries in the control area (vibrio-vaccinated).

That is, in comparison of death amounts of the fries in the test period of time between the test area and the control area, a number of dead fries were 19 (about 0. 1 kg) in the former area, while in the latter area a number of dead fries was 8, 9 3 6 (about 5 7. 0 kg) When these numbers are converted to death rates, that for the former is 0.45%, and that for the latter is 30 10.5%. The latter has a death rate which is about 11 times that of the former. This is because, as described above, the water is higher disinjected by the use of the activated photocatalyst, the clustered water provides very suitable living environments for the living bodies (fishes)and activates the feeding environment, whereby the f ed f ishes are exposed to far less stress.

11 As a result, the death rate of the fires is much decreased.

TABLE 3 test area control area preserve pond test pond No. 1 secondary fry pond 2-1 water amount (0.75 t) (19.2 t) Fry unvaccinated Vibrio vaccinated average weight at 4.6 g 4.6 g start number of 2, 000 About 76,000 discharged fries discharged fry 9.2 kg 350 kg weight average weight as 10.5 g 10.3 g of Dec. 16 feeding amount 9.0 kg 502 kg throughout test number of death 10 fries (0.07 kg) 56 fries (about throughout test for Nov. 15 to 30 0. 4 kg) for Nov. 15 9 fries (0.06 kg) to 30 for Dec. 1 to 20 980 fries (about 57.0 kg) for Dec.

1 to 20) 12

Claims

1. A fry death rate improving system using a photocatalyst for feeding fries with feeding water which has been photocatalyzed by contact to a photoatalysis body.

2. A fry death rate improving system according to claim 1, wherein the photocatalysis body is applied to an inside wall of the photocatalysis tank(ll), or is applied to a surface of a substrate disposed in the photoca.talysis tank(ll).

3. A fry death rate improving system according to claim 1, wherein a plurality of the substrates are arranged in the photocatalys is tank (11) through which the feeding water(W) flows, in a manner which causes turbulent flows so as to increase as much as possible a contact area of the feeding water with respect to the photocatalysis body.

4. A fry death rate improving system using a photocatalyst comprising:

photocatalysis tank(11); light source(I0) for radiating a photocatalyst; an inlet (3 0) f or supplying f eeding water, provided in the photocatalysis tank(11); an outlet(40) for photocatalyzed feeding water; and preserve tank (2 0) disposed below the outlet (4 0), photocatalysis body being applied to an inside wall of the photocatalysis tank(ll), a plurality of substrates each having a sheet with the photocatalysis body applied to adhered to both sides thereof being juxtaposed with each other in the photocatalysis tank(ll) in a manner which causes turbulent flows in the feeding water so as to contact the feeding water(W) to the photocatalysis body.

5. A fry death rate inproving system. substantially as herein described with reference to and as illustrated in any of the accompanying drawings.