JPH08155476A - Nitration treatment method for seawater containing ammonical nitrogen - Google Patents

Abstract

PURPOSE: To efficiently nitrate ammomiacal nitrogen in seawater. CONSTITUTION: The nitration capacity per unit volume of ammoniacal nitrogen in seawater can be increased eminently by using a filler in which immobilized microorganisms 5 are stuck or deposited on the surface of oyster shell 6 as a filler for treatment by catalytic aeration, and an enough nitration capacity is kept even at low water temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitrification treatment method for ammonia-containing nitrogen seawater and an apparatus therefor, and particularly to an ammonia-containing nitrogen seawater in which oyster shells carrying immobilized microorganisms are used as a packing material for the contact aeration method. The present invention relates to a nitrification treatment method and a nitrification treatment device.

[0002]

2. Description of the Related Art From the viewpoint of purifying the natural environment, recently, considerable improvements have been made to fresh water by popularizing sewerage and improving purification facilities. However, regarding the purification of seawater, once the seawater is contaminated by contaminated wastewater, etc., it is located at the end, so purification does not proceed easily and the pollution accumulates in the seawater, and recently the use of the ocean As pollution increases, pollution is becoming a major problem in the sea area. By the way, up to now, seawater contains various components, so that it has not been possible to efficiently purify the seawater. In addition, since the object of purification treatment is a large amount of water (seawater), economically and technically effective means have not been provided. In particular, recently, the shift from catching fisheries to breeding fisheries has been promoted, and eutrophication feeds are used in aquaculture, and the sea area is polluted with a large amount of ammonia nitrogen and water quality such as squid. Due to the deterioration of fishery, a lot of fish, shellfish and shrimp have been killed. Therefore, there is a strong demand for development of a treatment technology for such ammonia-containing nitrogen seawater.

Usually, in order to purify water containing ammonia nitrogen, nitrification treatment (biological oxidation treatment of ammonia nitrogen to nitrite nitrogen or nitrate nitrogen) is carried out. Nitrification of water containing volatile nitrogen is carried out by keeping a high concentration of nitrifying bacteria in the filter sand by a sand filter treatment device. However, the nitrification treatment of water such as seawater, which has a high chloride ion concentration of 30,000 mg / liter, inhibits the activity of nitrifying bacteria by chloride ions,
This is more difficult than in the case of fresh water.

[0004]

The method of carrying out such nitrification treatment of water containing ammoniacal nitrogen by using a sand filtration treatment device while maintaining a high concentration of nitrifying bacteria in the filter sand is as follows. There's a problem. (1) In the sand filter, it is necessary to backwash the filter sand in order to prevent clogging, but most of the nitrifying bacteria flow out of the device by backwashing, and the nitrification efficiency is significantly reduced. As a result, untreated ammonia nitrogen is contained in the treated water for several days after backwashing. Such operations are complicated and costly. (2) Oxygen is supplied to nitrifying bacteria, which are aerobic bacteria, by dissolved oxygen contained in seawater. However, if the amount of dissolved oxygen is insufficient, or if microorganisms grow too much in the filter sand, nitrification is performed. The efficiency is significantly reduced. On the other hand, in the case of nitrification treatment of fresh water-based ammonia-containing nitrogen wastewater, a honeycomb tube or a corrugated plate-based plastic filler is used as a carrier to which microorganisms including nitrifying bacteria are attached.
This is called the contact aeration method. The conceptual configuration of the apparatus used in this method is shown in FIG. In the figure, 1 is a contact aeration tank, 2 is a filler such as a honeycomb tube, 3 is an air diffuser (aerator), and 4 is a partition. First, the aerator 3 supplies air from the bottom of the contact aeration tank 1 to the ammonia-containing nitrogen wastewater (raw water) introduced into the contact aeration tank 1.
As a result, in the contact aeration tank 1, the ammonia nitrogen in the wastewater was purified by nitrification on the surface of the packing material 2 to which microorganisms including nitrifying bacteria were adhered, and then clarified from the side of the partition wall 4 at the upper end. It is led out of the system as purified treated water. When this method of nitrification of freshwater-based ammonia-containing nitrogen wastewater was applied to nitrification of ammonia-containing nitrogen seawater,
Almost no adhesion of microorganisms was observed, and nitrification phenomenon was hardly observed. Thus, even if the facility for purifying fresh water is immediately used as a facility for seawater treatment, there is a problem that the desired effect cannot be obtained. On the other hand, the immobilized microorganism method is known as a method for increasing the concentration of microorganisms in the biological wastewater treatment method. In this method, as shown in the schematic diagram in FIG. 4, a group of immobilized microorganisms 5'is put into the aeration tank 1 and air is sent from the aerator 2 to perform biological treatment of wastewater. Purification by nitrification treatment of ammonia nitrogen is performed by nitrification treatment, and purified treatment water is led out from the side of the partition wall 4. Here, immobilized microorganism piece 5 '
In order to produce, a gelled substance is produced by mixing a concentrated microorganism with a heated solution of an immobilizing substance and then cooling it. The gelled substance is obtained by molding it into an appropriate size.

[0005]

Means for Solving the Problems The inventors of the present invention were able to confirm the nitrification phenomenon by conducting a nitrification experiment using oyster shells as a carrier to which microorganisms including nitrifying bacteria adhere.
At this time, when the state of attachment of the microorganisms inside the aeration tank was observed, it was found that the microorganisms were not attached but were deposited on the surface of the oyster shell. That is, this microorganism had extremely low stickiness. The present inventors have made various studies using such oyster shells to develop a nitrification treatment method of ammonia-containing nitrogen seawater used as a carrier for attaching or depositing microorganisms including nitrifying bacteria, and as a result, immobilized microbial method Ammonia-containing nitrogen seawater treatment equipment consisting of a contact aeration method with oyster shell as a packing material has an excellent treatment function, and the treatment method and treatment equipment have simple operation and great economic merit. The present invention has been completed by finding that not only the adverse effect on the environment is small but also an unexpectedly excellent action effect can be expected.

[0006] The present invention provides a novel water treatment method of ammonia-containing nitrogen seawater, which is a combination of an immobilized microbial method and a contact aeration method using oyster shell as a packing material, and a treatment apparatus suitable for the method. One of the objects of the present invention is to improve the nitrification performance by increasing the concentration of nitrifying bacteria in the contact aeration tank in the nitrification treatment of ammonia-containing nitrogen seawater. That is, the present invention comprises (1) an ammonium-containing state characterized by subjecting an ammoniacal nitrogen in water to a nitrification treatment, using a filler obtained by adhering or depositing immobilized microorganisms on the surface of an oyster shell as a treatment filler by contact aeration. Nitrogen seawater treatment method, and (2) Ammonia-containing nitrogen-containing filler which is obtained by contacting and aerating an immobilizing microorganism adhered to or deposited on an oyster shell surface as a nitrifying filler for ammonia-containing nitrogen seawater. It is a state nitrogen seawater treatment device.

Examples of the microorganism source in the present invention include activated sludge from sewage treatment plants, etc., but the microorganisms in the activated sludge are more resistant to chlorine ions by selecting a chlorine-resistant bacterium or applying a mutagenesis method. It can be used as a bacterium, or by introducing a useful gene by a gene recombination method to make it a more chloride-resistant bacterium, and a bacterium excellent in nitrification treatment ability can be selected. It is possible to obtain an excellent bacterium or to introduce a useful gene by a gene recombination method to obtain a bacterium having a higher nitrification treatment ability. Preferably, activated sludge in a sewage treatment plant or the like is cultured in the presence of ammonium ions or chloride ions to obtain a microorganism having improved chloride ion resistance and nitrification treatment ability. In this case, it is preferable that the chlorine ion concentration be gradually increased to finally reach the same level as seawater. As a method for immobilizing microorganisms, a method known in the art or a method modified by a method known to those skilled in the art can be applied, for example, a comprehensive method, a carrier binding method, a filtration method, etc. For example, in the encapsulation method, a natural polymer, a synthetic polymer or the like can be used, and a method such as a monomer method, a polymer method or a prepolymer method can be used. Further, for example, in the carrier binding method, a method such as a micropore or fine particle method, a method of using a porous material such as biomass support particles, etc. can be used, and a method of using a polymer membrane or a ceramic filter etc. is used in the filtration method. Can be mentioned.

Examples of the immobilizing substance include natural polymers such as sodium alginate, which are often used in the entrapping method, alginic acid, agar, and polysaccharides such as carrageenan, such as κ-carrageenan.
Examples of the photocurable resin prepolymer, urethane prepolymer, and the like, examples of the photocurable resin prepolymer include those in which isophorone diisocyanate or hydroxyethyl acrylate is bonded to both ends of polyethylene glycol or polypropylene glycol,
Examples of the urethane prepolymer include those in which toluene diisocyanate is bonded to both ends of polyethylene glycol or a copolymer of polyethylene glycol and polypropylene glycol. For example, in the case of alginic acid, the microorganism can be immobilized by contacting an aqueous solution of sodium alginate containing a microorganism with an aqueous solution containing a polyvalent metal ion such as calcium ion which is a gelling agent. Carrageenan, agar, etc. are heated, and the dissolved one is cooled in the presence of microorganisms, or metal ions,
The microorganism can be immobilized by contacting with a gelling agent such as amines.

The oyster shell is preferably used after being washed and then sized appropriately. The immobilized microorganisms can be attached or deposited on the oyster shell by immersing the immobilized microorganism-containing liquid in the oyster shell for a suitable period of time for attaching the microorganisms to the oyster shell pieces or depositing them on the surface. The oyster shell has the following advantages and is excellent as a filler for the contact aeration method. (1) Generally, the pH of treated water decreases due to the nitrification reaction,
Although the nitrification reaction itself may be adversely affected, when oyster shells are used, it is possible to prevent the pH of the treated water from decreasing by elution of calcium ions from the surface of the oyster shells. Therefore, the nitrification reaction is less likely to be adversely affected by the decrease in the pH of the treated water, and efficient operation is possible. (2) Originally, oyster shells, which are originally discarded as waste, are effectively used as a water treatment material. Therefore, an inexpensive material can be used. Also, since oyster shells are natural products, there are few environmental problems. The "seawater" referred to in the present invention is not limited to seawater in the ocean, and includes artificial seawater equivalent to that (made by adjusting salt, pH, etc. in water like seawater). It is a waste.

[0010]

EXAMPLES Next, the present invention will be described more specifically by showing examples. Example 1 (1) Cultivation of Chloride-Resistant Nitrifying Bacteria Activated sludge from a sewage treatment plant or the like was placed in a container having a predetermined capacity,
Ammonia agent (ammonium chloride), mineral substances, p
Add a prescribed amount of H-adjusting agent every day. Further, sodium chloride is added with chlorine ions at a concentration of several tens of mg / liter at the initial stage of culture, and the concentration is gradually increased to finally reach the chlorine concentration of seawater. The solution is continuously aerated and agitated and mixed, and simultaneously supplied with oxygen. The culture period is 2-3 months.

(2) Preparation of immobilized microbial solution The immobilized substance is dissolved in water to a concentration of 2-3% and heated to about 50 ° C. On the other hand, the chloride-resistant nitrifying bacterium cultivated in the above (1) is concentrated by centrifugation or the like, and the microbial solution containing the nitrifying bacterium and the immobilizing substance solution are stirred and mixed to be uniform. (3) Adhesion of immobilized microbial solution to oyster shell The washed oyster shell is dipped in the solution obtained in (2) above,
After allowing the immobilized microorganisms to adhere to the surface of the oyster shell, it is allowed to cool at room temperature. The oyster shell to which the immobilized microorganism is attached is schematically shown in FIG. In the figure, 6 indicates an oyster shell and 5 indicates an immobilized microorganism.

Example 2 (1) Continuous Treatment Method of Ammonium-containing Nitrogen Sea Water As shown in the conceptual diagram of the treatment apparatus in FIG. 1, the oyster shell 6 with the immobilized microorganisms 7 attached to the surface thereof is used as the filler 20. , Disposed in the aeration tank 1, air is fed from the aerator 3 at the lower part, nitrification treatment of ammonia nitrogen in the wastewater is carried out on the surface of the filling material 20 to obtain purified water, and the purified water is treated from the upper end. Derive. In the figure, 7 is a storage tank, 8 is a sand filtration tower,
P is a water pump and B is a blower. Ammonium-containing nitrogen Seawater with an ammonium-nitrogen concentration of at least 3 mg
/ Liter of aquaculture wastewater was used and the treated water amount was 4 cubic meters per day. The filtration rate in the sand filtration tower was 10 m / hr, and the filter layer thickness was 0.5 m. When the conditions of the contact aeration layer were such that the residence time was about 1.5 hours and the filling rate of the filler was 60%, the ammonia nitrogen concentration in the purified water was 0.5 mg / liter or less. As a result, it can be seen that 83% of ammonia nitrogen was removed.

[0013]

EFFECTS OF THE INVENTION According to the present invention as described above, (1) it is possible to retain microorganisms containing nitrifying bacteria in a high concentration in a contact aeration tank, and therefore, compared with the contact aeration method using only oyster shells. As a result, the nitrification capacity per unit volume of ammonia-containing nitrogen seawater can be significantly increased. (2) It has a sufficient nitrification capacity even for low-temperature seawater around 10 ° C. (3) The phenomenon of increasing the concentration of suspended solids in treated water due to exfoliation of microorganisms unlike the contact aeration method using only oyster shells is unlikely to occur. (4) It is possible to prevent the pH of treated water from decreasing by elution of calcium ions from the surface of the oyster shell.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a treatment apparatus for ammonia-containing nitrogen seawater according to an embodiment of the present invention.

FIG. 2 shows a schematic diagram of an oyster shell to which an immobilized microorganism is attached.

FIG. 3 shows a conceptual configuration diagram of a nitrification treatment apparatus by contact aeration.

FIG. 4 shows a conceptual diagram of processing by the immobilized microorganism method. [Explanation of symbols] 1: Aeration tank 2: Filler 3: Air diffuser (aerator) 4: Partition wall 5: Immobilized microorganisms 6: Oyster shell 7: Storage tank 8: Sand filtration tower B: Blower P: Water pump

Claims (2)

[Claims] 1. Ammonia-containing nitrogen seawater, characterized in that ammonia-nitrogen-containing seawater is treated by nitrifying ammonia-nitrogen in water by using a filler having immobilized microorganisms attached or deposited on the surface of an oyster shell as a treatment filler by contact aeration. Processing method. 2. Treatment of ammonia-containing nitrogen seawater, characterized by comprising a filler having immobilized microorganisms attached or deposited on the surface of an oyster shell as a nitrification filler of ammonia-containing nitrogen seawater by contact aeration. apparatus.