JP2008149261A - Denitrification accelerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a denitrification accelerator with little loss by evaporation of components or flowing out, having a large contact area and high treating efficiency, when performing denitrification treatment in a wastewater treatment after the secondary treatment of sewage, or service water treatment of rivers, artificial ponds, fish firms or aquariums. <P>SOLUTION: The denitrification accelerator is formed of dispersion containing fatty acid metal salts dispersed in an aqueous solvent. The accelerator is directly charged into a treatment system of wastewater or service water and collected by a filter and fixed, to activate bacteria related to denitrification. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to the treatment of wastewater such as sewage, or water taken out of either rivers or artificial ponds, or from fish farms and ornamental water tanks, and water to be used after returning to treatment. More particularly, the present invention relates to a denitrification accelerator for performing denitrification of waste water or water and a denitrification method using the same.

  Conventionally, wastewater treatment using methanol is widely known in the field of denitrification technology using biological filtration. Similarly, a method using a low-molecular carboxylic acid or the like or a saccharide as a water-soluble denitrification promoter is already known. As insoluble denitrification accelerators, those using biodegradable resins, those using higher fatty acids and higher alcohols, and the like are already known.

Japanese Patent Laid-Open No. 10-314782 JP-A-6-126298 JP-A-9-299986 Japanese Patent Laid-Open No. 10-85782 JP 2000-33-4492 A

  Conventional water-soluble denitrification accelerators such as methanol and low-molecular sugars have a concern that when they are added, the concentration of soluble organic carbon is remarkably increased, which has a great impact on the ecology. In addition, these water-soluble denitrification accelerators are lost in a large amount during the treatment due to transpiration due to volatilization and outflow from the treatment system, and this has been a factor of reducing the treatment efficiency. In addition, since all of the conventional insoluble denitrification accelerators are difficult to form into fine particles, it is difficult to improve the processing capacity of these accelerators by increasing the contact area (namely, surface area) with water. Met. Furthermore, the insoluble denitrification accelerator has a problem that the denitrification ability is lowered due to a change in the interface of the denitrification accelerator during continuous treatment, and a stable effect is not sustained.

  The present invention has been made in view of the problems of conventional denitrification accelerators, and is a desorption provided in a form having a small amount of organic carbon dissolved at the time of addition, a smaller volatility, and a larger surface area. An object is to provide a nitrogen promoter.

  As a result of intensive studies by the present inventors, it has been found that these conventional problems can be effectively solved by using a fatty acid metal salt (particularly, metal soap), and has come up with the present invention. That is, the present invention provides a denitrification accelerator in which a dispersoid containing a fatty acid metal salt is dispersed in an aqueous solvent. The denitrification promoter may be provided as a suspension (also referred to as a suspension) in which the dispersoid is a solid phase.

  The fatty acid metal salt preferably contains 10% by weight or more of hydroxy fatty acid. Here, the weight of the hydroxy fatty acid corresponds to the weight of a portion derived from the hydroxy fatty acid (for example, an anion of the hydroxy fatty acid) in the fatty acid metal salt.

  The fatty acid metal salt preferably contains 5 to 70% by weight of a fatty acid having 8 or less carbon atoms. Here, the weight of the fatty acid having 8 or less carbon atoms corresponds to the weight of a portion derived from the fatty acid having 8 or less carbon atoms (for example, an anion of the fatty acid having 8 or less carbon atoms) in the fatty acid metal salt.

  The fatty acid metal salt includes at least one metal selected from aluminum and iron (hereinafter, this metal is referred to as “metal A”), and includes 1% by weight or more and less than 50% by weight of the metal A. It is preferable. Here, the weight of the metal A corresponds to the weight of a portion derived from the metal A (for example, a cation of the metal A) in the fatty acid metal salt.

  The denitrification promoter of the present invention uses a mixed crystal substance in which metal ions such as aluminum and iron are dispersed at a molecular level in a fatty acid matrix as a dispersoid, and forms fine particles having a size of about 0.1 μm to 500 μm. It takes the form of a dispersion system dispersed in an aqueous solvent which is a liquid phase. When the denitrification promoter of the present invention is introduced into the target treated water system, the solid phase portion is well dispersed and suspended in water and adsorbed on the surface when there is a filter medium. Filter bacteria will eventually settle on the surface of the solid phase portion, and the denitrification reaction proceeds using the dispersoid component as a carbon source. Therefore, according to the denitrification promoter of the present invention, the less volatile dispersoid stays in the treated water system and exhibits a denitrification effect well over a relatively long period of time. In addition, since the dispersoid is dispersed in water and hardly dissolved in water, the denitrification accelerator of the present invention has a small amount of loss during treatment, and eliminates or reduces problems caused by dissolution. be able to.

  In the denitrification accelerator of the present invention, “fatty acid metal salt” refers to a metal salt of a fatty acid, specifically, soap (when the metal is an alkali metal) and metal soap (where the metal is other than an alkali metal). Is included). In the fatty acid metal salt, metal ions are dispersed in a matrix of fatty acids (and / or anions of fatty acids) at a molecular or atomic level in a ratio of 2 to 50% by weight.

  The denitrification accelerator of the present invention is a dispersion system in which a dispersoid containing a fatty acid metal salt is dispersed in an aqueous solvent. The dispersoid preferably contains a fatty acid metal salt as a main component. Specifically, the dispersoid preferably occupies 50% by weight or more of the dispersoid, and more preferably occupies 80% by weight or more.

  The “aqueous solvent” is a solvent containing 50% by weight of water as a main component, preferably water. The water is not particularly limited as long as it is commonly used in industry, and may be, for example, tap water, or ion exchange water or distilled water.

  The denitrification promoter of the present invention is preferably provided as a suspension in which the dispersoid is a solid phase. The dispersoid may be in another form (for example, colloid or liquid) as long as it does not dissolve in the treated water system but remains in the treated water system and exhibits denitrification ability.

  When the denitrification promoter of the present invention is introduced into the treatment system in the form of a suspension, the solid phase portion is preferably dispersed as fine particles in a state of good contact with water. Therefore, it is essential to introduce the carbon source that promotes the denitrification treatment not as a fatty acid but as a metal salt that is a fatty acid derivative (that is, soap or metal soap). Moreover, it is particularly desirable to satisfy any one of the following three conditions in order to increase hydrophilicity and act efficiently.

  The first condition is that the composition of the metal soap constituting the denitrification accelerator of the present invention contains at least 10% by weight of hydroxy fatty acid. By including the hydroxy fatty acid, the affinity with water can be improved by the effect of the hydroxyl group of the hydroxy fatty acid. If the hydroxy fatty acid content is 10% by weight or less, the effect may not be obtained effectively.

  The second condition is that a fatty acid having 8 or less carbon atoms is contained in an amount of 5 to 70% by weight in the composition of the metal soap constituting the denitrification accelerator of the present invention. Thereby, the hydrophilicity of the solid phase portion can be effectively improved. When the content of the fatty acid having 8 or less carbon atoms is less than 5% by weight, the improvement effect becomes small. On the other hand, when the content exceeds 70% by weight, the amount of fatty acids that are released from the solid phase matrix and migrate to the aqueous system increases, and the components lost due to transpiration or outflow from the system tend to increase.

  The third condition is that in the composition of the metal soap constituting the denitrification accelerator of the present invention, the metal is aluminum and / or iron, and aluminum and iron (one of them when only one of them is included) The total content is 1% by weight to 50% by weight. When the metal content is within this range, the hydrophilicity of the solid phase is improved and the dispersion in water becomes good. If the metal content is less than 1% by weight, the hydrophilicity may not be improved. When the metal content exceeds 70% by weight, the component separated from the solid phase matrix tends to increase as a metal oxide.

  In the denitrification promoter of the present invention, the ratio between the solid phase and the liquid phase is not particularly defined. However, when the liquid phase is removed and dried, the molecular structure changes, the wrinkles are dissolved, the hydrophobicity increases, and it becomes difficult to disperse again in water. Therefore, the ratio of the liquid phase is preferably 5% by weight or more.

  The denitrification promoter of the present invention can be used for the treatment of waste water and water. The waste water may be, for example, either domestic waste water or industrial waste water, and more specifically, sewage. The water for use may be either domestic water or industrial water, for example, water taken from rivers and artificial ponds. Alternatively, the irrigation water includes water that is actually used, and may be water taken out from a fish farm and an aquarium tank, for example, and may be used again after treatment. The water taken out from the fish farm and the ornamental water tank and discarded after the treatment is drainage.

  The denitrification treatment using the denitrification promoter of the present invention is carried out by bringing the denitrification promoter and water into contact. More specifically, when the nitrogen removal accelerator is put into, for example, a tank in which water to be treated is stored and the water is moved from the tank to another place through a pipe or the like, a filter is used. The denitrification treatment may be performed by collecting the dispersoid (fatty acid metal salt) with a filter. In that case, filtration bacteria settle on the surface of the dispersoid collected by the filter, and the denitrification reaction proceeds using the dispersoid components as a carbon source. Such a method is particularly suitable for continuously treating water.

  Alternatively, the denitrification treatment may be performed by supporting a denitrification accelerator on a carrier such as polyethylene foam and dispersing the carrier in water to be treated. The denitrification promoter can be supported on the carrier by, for example, dispersing the carrier in water to be treated in advance and introducing the denitrification promoter into it. Such a method is particularly suitable for treating water in batch mode.

The invention is illustrated in more detail in the examples given below.
The evaluation water used in each example is prepared by adjusting the water quality by the following procedure.

Example 1 and Example 2
Sewage raw water: A sewage after secondary treatment using potassium nitrate to adjust the total nitrogen amount to 200 mg / liter, and adjusting the pH value to neutral with a 1N sodium hydroxide aqueous solution.

Example 3 and Example 4
Water source water: Water whose potassium content is adjusted to 100 mg / liter using potassium nitrate, and the pH value is adjusted to neutral with 1N sodium hydroxide aqueous solution.

Example 5
Feeding raw water: tap water adjusted to neutral pH value using 1N hydrochloric acid and 1N aqueous sodium hydroxide solution.

  Moreover, in each Example, the following were used as a filter medium.

-Example 1, Example 2, Example 3
Foamed PE filter medium: 1 cm square foamed polyethylene manufactured by Sekisui Plastics Co., Ltd. Examples 3 and 4
Filter: Polypropylene cotton (1cm thick)
Example 4
Sprinkling filter bed: 5 layers of 1 cm thick polyethylene fiber sheets. Example 5
Ceramic filter media: A ring-shaped ceramic filter medium with a diameter of 2 cm for use in ornamental fish

(Example 1)
To 10 liters of water, 1 kg of stearic acid (cas No. 57-11-4) and 3 kg of sodium hydroxide were added and dissolved and reacted in a reaction kettle at a temperature of 90 ° C. Sulfuric acid band (cas No. 10043-01-3, containing 4% by weight as aluminum) 19 Kg was added thereto, and after sufficient reaction, the temperature was lowered to 50 ° C., and propionic acid (cas No. 79-09) was added. -4) 2 kg was added and reacted. After cooling to room temperature, the pH value was adjusted to neutral with 1N dilute sulfuric acid. Furthermore, by diluting with water, a denitrification accelerator comprising a suspension containing 3% by weight of aluminum soap was obtained. The produced denitrogenating agent is a white volatile suspension having a relatively low volatility in which the ratio of stearic acid to propionic acid is 1: 2, and the solid phase part contains 20% by weight of aluminum. there were.

  10 ml of this denitrification promoter was added to 10 L of raw sewage water and retained in the aeration tank 1 shown in FIG. 1 to perform an aeration process (aeration volume of 1 L / min), and the change in the total nitrogen quantity was measured. The aeration tank 1 includes a blower 2 and an aeration nozzle 3. In the aeration tank 1, the foamed PE filter medium 4 was dispersed. For comparison, the change in the total nitrogen amount when no denitrification accelerator was added was measured in the same manner. The results on the fifth day after the start of the test are shown in Table 1 as Example 1 and Comparative Example 1, respectively. As a result, in the sewage treatment to which the denitrification accelerator of this example was added, a significant decrease in the total nitrogen amount was recognized compared to the sewage treatment to which no denitrification accelerator was added.

(Example 2)
12 kg of 12 hydroxystearic acid (cas No. 106-14-9), 1.5 kg of potassium hydroxide, polyferric sulfate ferric liquid (chemical formula [Fe ₂ (OH) _n (SO ₄ ) _{3 -n / 2} ] _m , Using 4 kg of iron (containing 11% by weight as iron), a metal soap was produced by a general metathesis method. The obtained metal soap was dispersed in water to produce a denitrification accelerator which is a suspension containing 3% by weight of metal soap having a metal ratio of 30% by weight in the solid phase. The produced denitrification accelerator was a white suspension with faint browning and faint browning.

50 ml of this denitrification accelerator was put into the aeration tank 5 shown in FIG. 2 and subjected to continuous treatment. The specifications of the aeration tank are as follows.
・ Processed sewage amount 5 liters / day ・ Effective volume 10 liters ・ Used 1 liter of foam PE filter material ・ Aeration volume 1 liter per minute

  The raw sewage water stored in the substrate tank 9 was sent to the aeration tank 5 by the transfer pump 10, treated, and discharged as effluent water 11. The aeration tank 5 includes a blower 6 and an aeration nozzle 7. The foaming PE filter medium 8 adsorbs the denitrification accelerator of this example, and the denitrification reaction proceeded here. The change in the total nitrogen amount was measured for the effluent from this treatment tank. For comparison, the change in the total nitrogen amount was measured in the same manner for the effluent when no denitrification accelerator was added. The results are shown in Table 2 as Example 2 and Comparative Example 2, respectively. As a result, in the sewage treatment to which the denitrification accelerator of this example was added, a significant decrease in the total nitrogen amount was recognized compared to the sewage treatment to which no denitrification accelerator was added.

(Example 3)
12 kg of 12 hydroxystearic acid (cas No. 106-14-9), 2 kg of aluminum hydroxide (cas No. 21645-51-2), and a small amount of sodium hydroxide as a reaction agent, by a direct method. Soap was produced. The obtained metal soap was dispersed in water to produce a denitrification accelerator, which was a suspension containing 3% by weight of aluminum soap having a metal ratio of 40% by weight in the solid phase. The produced denitrification accelerator was a white suspension with easy precipitation.

100 ml of this denitrification accelerator was put into the aeration tank 12 of the water treatment system shown in FIG. 3 to perform continuous treatment. The specifications of the aeration tank 12 are as follows.
・ Processed sewage amount 5 liters / day ・ Effective volume 10 liters ・ Used 1 liter of foam PE filter material ・ Aeration volume 1 liter per minute
The specifications of the sedimentation tank are as follows.
・ Effective volume: 10 liters

  The raw irrigation water stored in the substrate tank 18 was sent to the aeration tank 14 provided with the aeration nozzle 14 and the blower 13 by a transfer pump 19 in a fixed amount, processed, and then flowed into the precipitation tank 16 from the path a. At this time, the sedimentary sludge was returned to the aeration tank through the path b by the transfer pump 17, and only the supernatant liquid was discharged as the outflow water 20. The denitrification promoter of the present example was adsorbed on the foamed PE filter medium 15, and the denitrification reaction proceeded here.

  For the effluent of this treatment system, the change in total nitrogen was measured. For comparison, the change in the total nitrogen amount was measured in the same manner for the effluent when no denitrification accelerator was added. The results are shown in Table 3 as Example 3 and Comparative Example 3, respectively. As a result, in the service water treatment to which the denitrification accelerator of this Example was added, a marked decrease in the total nitrogen amount was recognized as compared with the water treatment without addition.

Example 4
12 kg of 12 hydroxystearic acid (cas No. 106-14-9), 2 kg of stearic acid (cas No. 57-11-4), 2 kg of potassium hydroxide, sulfuric acid band (cas No. 10043-01-3), 4 as aluminum 10 kg of containing weight%), 3.7 kg of polyferric sulfate (chemical formula [Fe ₂ (OH) _n (SO ₄ ) _{3 -n / 2} ] _m , containing 11 wt% as iron) 3.7 kg According to such a metathesis method, metal soaps in which the ratio of 12 hydroxystearic acid, stearic acid, aluminum and iron in the solid phase was 20% by weight, 40% by weight, 20% by weight and 20% by weight, respectively. This metal soap was dispersed in water to produce a denitrification accelerator, which is a suspension containing 3% by weight of metal soap.

  One liter of this denitrification promoter was introduced mainly in the sprinkling filter bed 26 of the circulation filtration system shown in FIG. 4, and the change in the total nitrogen amount in the fish tank 21 was measured. Moreover, the change of the total nitrogen amount in the fish culture water tank 21 when not adding a denitrification promoter as a comparison was measured similarly. The capacity of the fish tank was 1 ton, and the amount of water used in all circulation systems was 1.2 ton. In the initial state, this was all filled with raw water. The throughput of the circulating filtration system is 20 liters per minute.

  In this circulating filtration system, the raw water flowing in from the fish tank 21 is first removed from the coarse particles by the filter 23 of the filtration tank 22, and sprinkled from the water nozzle 24 onto the water spray filter 26. The denitrification promoter of this example was adsorbed and accumulated on the trickling filter 26, and the denitrification reaction proceeded here. The treated water collected in the water tank 25 was passed through the oxygen supply unit 28 by the transfer pump 27 and returned to the fish tank 21.

  The results are shown in Table 4 as Example 4 and Comparative Example 4, respectively. As a result, in the service water treatment to which the denitrification accelerator of this Example was added, a marked decrease in the total nitrogen amount was recognized as compared with the water treatment without addition.

(Example 5)
1 kg of 12 hydroxystearic acid (cas No. 106-14-9), 1.5 kg of potassium hydroxide, 11 kg of sulfuric acid band (cas No. 10043-01-3, containing 4 wt% as aluminum) By 12 meta-decomposition method, 12 hydroxy stearic acid soap having an aluminum content of 30% in the solid phase was obtained. This metal soap was dispersed in water to produce a denitrification accelerator, which is a suspension containing 3% by weight of metal soap.

While actually raising the fish in the breeding aquarium 29, 100 ml of this denitrification promoter was used as shown in FIG.
And the change in the total nitrogen amount in the ornamental water tank 29 after the charging was measured. In addition, as a comparison, the change in the total nitrogen amount in the ornamental water tank 29 when no denitrification accelerator was added was measured under the same conditions. Fish breeding conditions are as follows.
・ Fish species and number of fish Comet (4cm long) 15 animals ・ Feeding dry pellets for goldfish (2mm diameter)
・ Feeding amount 30g / day ・ Aeration of 0.5L per minute with an air pump.

  The capacity of the ornamental aquarium was 100 liters, the amount of breeding water including all of the circulatory system was 130 liters, and this was all filled with breeding raw water in the initial state. The effective volume of the filtration tank 30 is 25 liters, and the throughput of the circulating filtration system is 5 liters per minute. 2 kg of ceramic filter medium 32 was used.

  In this circulation filtration system, after the coarse particles were removed by the filter 31, the water that flowed from the breeding water tank 29 through the path e into the filtration tank 30 was brought into contact with the ceramic filter medium 32. The denitrification promoter of the present example was adsorbed on the ceramic filter medium 32, and the denitrification reaction proceeded here. The treated water was returned to the breeding aquarium 29 by the transfer pump 33 from the path f.

  The results are shown in Table 5 as Example 5 and Comparative Example 5, respectively. As a result, in the service water treatment to which the denitrification accelerator of this Example was added, a marked decrease in the total nitrogen amount was recognized as compared with the water treatment without addition.

  The denitrification promoter of the present invention can remove or reduce nitrogen contained in sewage and the like, and is useful for treating industrial wastewater and domestic wastewater, and water for use, and is used in a system for treating such water. can do.

Plan view showing a closed aeration tank in sewage treatment Plan view showing a general aeration tank in sewage treatment Plan view showing an example of water treatment system in river water treatment The top view which showed an example of the circulation filtration system of the trickling filter type in the water treatment of a fish tank The top view which showed an example of the circulation filtration system in the breeding water processing of an ornamental water tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aeration tank 2 Blower 3 Aeration nozzle 4 Foaming PE filter material 5 Aeration tank 6 Blower 7 Aeration nozzle 8 Foaming PE filter material 9 Substrate tank 10 Transfer pump 11 Outflow water 12 Aeration tank 13 Blower 14 Aeration nozzle 15 Foaming PE filter material 16 Precipitation Tank 17 Transfer pump 18 Substrate tank 19 Transfer pump 20 Outflow water 21 Fish culture tank 22 Filtration tank 23 Filter 24 Sprinkling nozzle 25 Water tank 26 Sprinkling filter bed 27 Transfer pump 28 Oxygen supply machine 29 Ornamental water tank 30 Filtration tank 31 Filter 32 Ceramic filter medium 33 Transfer pump a path b path e path f path

Claims (10)

  A denitrification accelerator comprising a dispersoid containing a fatty acid metal salt dispersed in an aqueous solvent.   The denitrification promoter according to claim 1, wherein the dispersoid is a solid phase and is a suspension.   The denitrification promoter according to claim 1, wherein the fatty acid metal salt contains 10% by weight or more of a hydroxy fatty acid.   The denitrification accelerator according to claim 1, wherein the fatty acid metal salt contains 5 to 70% by weight of a fatty acid having 8 or less carbon atoms. The fatty acid metal salt includes at least one metal selected from aluminum and iron (hereinafter, this metal is referred to as “metal A”),
The denitrification promoter, wherein the fatty acid metal salt contains the metal A in an amount of 1 wt% or more and less than 50 wt%.   A denitrification treatment method comprising contacting the denitrification promoter according to any one of claims 1 to 5 with water to be treated.   The denitrification treatment method according to claim 6, wherein the denitrification promoter is supported on the carrier, and the carrier is brought into contact with the water to be treated, thereby bringing the denitrification promoter into contact with the water to be treated. A denitrification method comprising: attaching a denitrification promoter to a filter medium; and passing water to be treated through the filter medium to which the denitrification promoter is adhered.   The denitrification method according to any one of claims 6 to 8, wherein the water to be treated is drainage or irrigation water.   The denitrification according to claim 9, wherein the irrigation water is water taken from either a river or an artificial pond, or water to be taken out from either a fish farm or an ornamental aquarium and returned to the water after treatment. Processing method.

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