JP2002011497A - Biological nitration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological nitration device of novel constitution showing stable nitration ability. SOLUTION: The biological nitration device is used for reducing ammonia- form nitrogen and nitrite-form nitrogen in circulating water or breeding of an aquarium or a land breeding facility. The device is provided with a carrier 6 stuck with aerobic autotrophic bacteria of <=1 specific gravity in the water and an aerator 5 at a bottom thereof. The preferable carrier is charcoal or natural pumice or foamed concrete pumice of 3 to 10 mm grain size. The preferable bacteria-stuck carrier is a carrier on which the bacteria are seeded and immobilized by suspending seed bacteria in an organic polymer solution, coating a carrier surface with the organic polymer and subjecting the polymer to gelation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological nitrification apparatus for reducing ammonia nitrogen and nitrite nitrogen in circulating water or breeding effluent of an aquarium or an onshore aquaculture facility.

[0002]

2. Description of the Related Art In aquariums and onshore aquaculture facilities,
Water quality is significantly deteriorated by excretion of fish and other breeding organisms, SS (suspended suspended solids) derived from residual food, ammonia nitrogen, and the like. Water treatment is required in closed-circulation aquariums and onshore aquaculture facilities, because the deterioration of water quality has an adverse effect on reared fish. The SS is separated and removed in a sand filtration tank, etc., and the ammonia and the nitrous acid that is oxidized by the ammonium oxidizing bacteria and nitrite oxidizing bacteria attached to the sand in the sand filtration tank and the carrier in the nitrification tank. Nitrified to nitric acid. However, these nitrifying bacteria are autotrophic bacteria, grow very slowly, and it takes several weeks for the filtration tank or nitrification tank to exhibit stable nitrification ability.

[0003]

By circulating seawater containing ammonium nitrogen, nitrifying bacteria spontaneously grow on the surface of the carrier in the filtration tank and are used. Besides this, a method of adding commercially available nitrifying bacteria to circulating water to promote it has been used, but the time has not been reduced significantly.

[0004] On the other hand, at the site, the exhibited fish may be unavoidably carried in before the nitrification capacity is stabilized. If the amount of the carried fish exceeds the nitrification capacity at that time, the ammonia and nitrite in the circulating water may be removed. Concentrations may exceed the acceptable levels for fish, causing harm.

[0005] Since nitrifying bacteria are autotrophic bacteria, SS or the like as an organic substance adversely affects the growth of the bacteria.
There are reports that the nitrification capacity is rate-limiting, but in the case of growth in sand filter tanks and circulation routes in aquariums, nitrification bacteria show higher nitrification capacity by coexisting with heterotrophic bacteria that depend on organic matter. There is also.

[0006] As described above, nitrifying bacteria play a very important role in purifying water in a closed circulation system, but there are still many issues to be studied in their use.

[0007] In view of the above, it is an object of the present invention to provide a biological nitrification apparatus having a novel configuration exhibiting a stable nitrification ability.

[0008]

SUMMARY OF THE INVENTION A biological nitrification apparatus according to the present invention is a biological nitrification apparatus for reducing ammonia nitrogen and nitrite nitrogen in circulating water or breeding wastewater of an aquarium or an onshore aquaculture facility. And an aerobic autotrophic bacterium-adhering carrier having a specific gravity of 1 or less in water, and a diffuser provided at the bottom.

The carrier for adhering the aerobic autotrophic bacteria is preferably charcoal, natural pumice or expanded concrete pumice having a particle size of 3 to 10 mm.

[0010] In addition, the aerobic autotrophic bacteria-adhering carrier is prepared by suspending a seed bacterium in a solution of an organic polymer, coating the organic polymer on the surface of the carrier and gelling the carrier, thereby inoculating and immobilizing bacteria on the carrier. It is preferred that it is.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The porous mineral pumice carrier is suitable for the attachment of nitrifying bacteria as well as fine sand. In addition, since the carrier itself floats on water, the storage tank can be used three-dimensionally and efficiently without any special structural measures. Very suitable. As in the case of a sand filter tank, the filter has nitrification ability mainly in the surface layer of the filter sand, and there is no phenomenon that the sand in the deep portion does not contribute much to nitrification. In addition, clogging and accompanying growth inhibition due to accumulation of organic substances, or occurrence of partial anaerobic conditions can be avoided.

When the present invention is carried out in a circulating aquarium of an actual aquarium or an onshore aquaculture facility, a part of the pumice carrier is pre-cultured in a circulating device to which about 200 mg / l or less of ammonia nitrogen is added. Nitrifying bacteria are attached in advance. The obtained seed carrier is stored together with the above-mentioned pumice carrier in a nitrification apparatus in an actual circulation type water tank. The amount of the carrier, the capacity of the nitrification tank, and the quantity are determined from the total amount of ammonia nitrogen predicted from the quantity of fish and the like stored in the breeding aquarium.

The amount of pumice carrier per nitrification tank 1 m ³ is 0.3~0.5m ^3, nitrification capacity per the carrier 1 m ³ is about 200~300gNH ₃ -N / day. On the other hand, the nitrification capacity, which is a secondary function of the sand filter tank primarily intended for removing SS, is 2-3 m ³ of fine sand.
Per, which is about 150gNH ₃ -N / day. This makes it possible to perform nitrification treatment in a much more compact capacity than before, and the nitrification capacity after backwashing with fresh water as seen in a sand filtration tank (1/5 to 1
/ 10, which takes 4-5 days to recover). On the other hand, an appropriate amount of coral stone is spread at any time on the bottom of the nitrification tank, which is an empty area. This simultaneously plays the role of pH control and maximizing the use of the inside of the tank as a carrier for nitrifying bacteria.

Further, by increasing the amount of the seed carrier, the rate of nitrification can be accelerated, or a seed bacterium (pure or mixed strain) separately cultured in a solution of a polymer such as polyvinyl alcohol (PVA) on an inorganic medium can be used. It is possible to promote the inoculation, immobilization and growth of bacteria on the carrier by suspending PVA on the surface of the pumice carrier and gelling the PVA carrier. In addition to the effect of promoting the inoculation and growth of bacteria, the coating of the bacterial cell inclusion gel prevents the cells from peeling off from the carrier due to physical impact, and prevents the bacterial from organic matter that is an inhibitory factor for autotrophic bacteria. It also shows the effect of protecting. According to the above method, the stabilization and adjustment of the nitrification ability become easy, and a simple and inexpensive biological treatment apparatus for the purpose of nitrification alone can be constructed. According to the present invention, the sand filtration device that also served as nitrification can be replaced with a simpler and cheaper protein skimmer for the purpose of removing SS only, and the water treatment system that leads to filtration, nitrification, and denitrification is designed to be more compact. Will be able to

The present invention will be specifically described based on examples.

EXAMPLE 1 FIG. 1 shows a processing flow of breeding wastewater from a fish breeding aquarium. The breeding wastewater to be treated passes from a fish breeding aquarium (1) through a sand filtration device (2) or a protein skimmer, etc.
After SS removal in these, nitrification tank (3) as raw water
It is fed by a pump (4). The air diffuser (5) installed at the bottom of the nitrification tank (3) stirs the pumice carrier (6) and the wastewater in the tank. (9) is the air pump of the air diffuser (5), (10)
Is a coral stone laid on the bottom of the nitrification tank (3).

Nitrification is carried out under aerobic conditions according to the following reaction formula.

The ^{_{NH 4 + + 3 / 2O 2}} → NO 2 + H 2 O + 2H + + 39.5kcal NO 2 - + 1 / 2O 2 → NO 3 + 21.6kcal

The aeration amount, the size of the nitrification tank (3), will vary by the amount of carrier, 0.5 to nitrification tank of 1 m ³ capacity (3)
If charged with pumice carrier m ^3, preferably 50 to 200 l / min.

The treated water discharged from the nitrification tank (3) is partly circulated to the breeding aquarium (1) by a pump (8) via a denitrification unit (7), and the remainder through a denitrification unit (7).

Example 2 (Inoculation of bacteria on pumice carrier surface)
Immobilization) 200 ml of distilled water or 0.3% by weight of artificial seawater (both containing the ATCC medium for nitrifying bacteria shown in Table 1)
After adding 10 g of PVA having a high degree of polymerization (degree of polymerization of 2000 or more) and heating to about 90 ° C. to completely dissolve, the obtained solution is cooled to room temperature. Nitrifying bacteria separately cultured in an inorganic medium were added to 20 ml of this solution in an amount of 2 to 4 × 10 ^8.
/ Ml. The obtained suspension is mixed with 200 cm ³ of a pumice carrier having a particle size of about 5 mm, and the obtained mixture is frozen at −80 ° C. for 20 minutes and then returned to room temperature. In this way, the surface of the pumice carrier is coated with PVA and gelled, whereby the bacteria are inoculated and immobilized on the carrier.

[0022]

[Table 1]

[0023]

According to the present invention, it is possible to provide a biological nitrification apparatus exhibiting a stable nitrification ability.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a processing flow of breeding drainage from a fish breeding aquarium.

[Explanation of symbols]

 (1): Fish breeding aquarium (2): Sand filter (3): Nitrification tank (5): Aeration device (6): Pumice carrier (7): Denitrification device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Chitoyo Nakata 1-7-89 Minami Kohoku, Suminoe-ku, Osaka F-term in Tachibai Shipbuilding Co., Ltd. 4D003 AA05 AB02 BA02 CA02 CA08 EA14 EA19 EA22 EA23 EA25 EA28 FA02 4D040 BB04 BB42 BB56 BB82

Claims (3)

[Claims] An aerobic autotrophic bacterium having a specific gravity of 1 or less in water for reducing ammonia-nitrogen and nitrite-nitrogen in circulating water or breeding wastewater of an aquarium or an aquaculture facility. A biological nitrification apparatus comprising an attachment carrier and a diffuser at the bottom. 2. The biological nitrification apparatus according to claim 1, wherein the carrier is charcoal, natural pumice or foamed concrete pumice having a particle size of 3 to 10 mm. 3. An aerobic autotrophic bacterium-adhering carrier suspends a seed bacterium in a solution of an organic polymer, coats the organic polymer on the surface of the carrier and gels it, thereby inoculating and immobilizing bacteria on the carrier. The biological nitrification device according to claim 1 or 2, wherein