WO2001025157A1

WO2001025157A1 - Material for use in denitrification for the purpose of removing nitrate nitrogen and method for preparing the same

Info

Publication number: WO2001025157A1
Application number: PCT/JP2000/006777
Authority: WO
Inventors: Tomomichi Gunji; Atsushi Yatagai; Toru Oishi
Original assignee: Nitchitsu Co., Ltd.; Nippon Steel Chemical Co., Ltd.
Priority date: 1999-10-01
Filing date: 2000-09-29
Publication date: 2001-04-12

Abstract

A material for denitrification which is used in decomposing a nitrate nitrogen in a waste water by sulfur-oxidizing bacteria utilizing sulfur and a carbonate as nutrients and which comprises a composition having sulfur and calcium carbonate particles dispersed therein or a uniform mixture of calcium carbonate particles and sulfur particles; a method for preparing the material for use in denitrification which comprises admixing a powder containing calcium carbonate and having a Blaine's value of 2000 to 5000 cm2/g and a powder containing sulfur and having an average particle diameter of 0.01 to 2 mm in a weight ratio of 3:1 to 1:2, to provide a powdery mixture, and subjecting the powdery mixture to press forming under a pressure of 30 to 90 Mpa; and a material for use in denitrification wherein a powder containing sulfur and calcium carbonate and mineral fibers are formed in one piece.

Description

Description: Denitrifying material for removing nitrate nitrogen and method for producing the same

(Technical field)

The present invention relates to a material for removing nitrate nitrogen (hereinafter, also referred to as a material for denitrification) for removing nitrate nitrogen such as nitrate ions and nitrite ions by microorganisms, and a method for producing the same. . This material for denitrification is used as a substrate for water purification or microbial culture solution. In detail, it is independent from agricultural drainage, horticultural drainage, underdrainage drainage, hydroponics drainage, livestock drainage, metalworking drainage such as stainless steel manufacturing, combined septic tank drainage, various sewage treatment drainage and groundwater, lakes, rivers and oceans It relates to a denitrification material for removing nitrate nitrogen by vegetative denitrification bacteria and the like.

(Background Art) Generally, heterotrophic denitrification and autotrophic denitrification are known as techniques for removing nitrate nitrogen from wastewater or environmental water.

Heterotrophic denitrification is a method of denitrification using the organic carbon source in methanol-sludge as a hydrogen donor. The heterotrophic denitrification method is problematic in that it is easily affected by decomposition systems other than the target bacterium, and the denitrification efficiency per substrate is low. Autotrophic denitrification is a method of denitrifying mainly sulfur and sulfur compounds as a nutrient source. In this autotrophic denitrification method, bacteria that denitrify using sulfur as a substrate, such as Thiobacillus Denitrificans, are used. Alternatively, since denitrification is selectively performed by the action of denitrifying microorganisms that use sulfur (collectively, denitrifying bacteria), the denitrification efficiency per substrate is high. Also, if the product sulfate ion is completely neutralized, it will not be a limiting factor in the water quality environment, and the effect of wastewater on ecosystems outside the reaction system will be small.

When using Thiobacillus denitrificans or the like as a denitrifying bacterium, for example, the following reaction formula is known.

1.114 S + NO a ~ + 0.669 H ₂ O + 0.337 C〇 ₂ + 0.0842 HCO ₃ "

-→ 0.0742 C ₅ H ₇ NO 2 + 0.5 N ₂ + 1.114 SO ₄ ² "+ 1.228 H +

As methods of autotrophic denitrification using sulfur and sulfur compounds, for example, Japanese Patent Publication No. 62-56798, Japanese Patent Publication No. 63-45274, Japanese Patent Publication No. 60-3876, Japanese Patent Publication No. 3 Each method described in 1958, Japanese Patent Publication No. Hei 04-9119, Japanese Patent Laid-Open No. 04-74598, Japanese Patent Laid-Open No. 04-151000, Japanese Patent Laid-Open No. 04-197498, and Japanese Patent Laid-Open No. 06-182393. Has been proposed.

As a material for removing nitrate nitrogen which causes denitrifying bacteria to act using the sulfur and sulfur compounds, the present inventors have identified the same source of sulfur as the nutrient source of denitrifying bacteria and the carbon source necessary for cell synthesis. A composition for denitrification coexisting in the composition has been previously proposed (WO 00/18664).

This denitrification composition enables efficient denitrification.Also, calcium ions and sulfate ions generated in the denitrification system can be kept approximately neutral in almost equal amounts, It is preferable because the denitrification capacity does not decrease due to the decrease.

In addition, by increasing the diameter, air bubbles can be removed while standing, and the generated nitrogen gas can be prevented from staying between particles or covering the entire particle with nitrogen gas. . Therefore, when performing denitrification treatment of wastewater, etc. No degassing is required, and the denitrification reaction does not stop without a special reaction tank or degassing tank. Therefore, maintenance-free denitrification can be performed without a power source, and running costs are almost negligible.

The denitrification composition is obtained by heating and melting sulfur, mixing it with calcium carbonate powder or other powder raw materials, and rapidly cooling the slurry-like mixed composition. It is disclosed to be manufactured.

In this method of manufacturing by heating and melting sulfur, a composition excellent in strength can be obtained by rapidly cooling and solidifying a material obtained by sufficiently melting and mixing the raw materials, and other powder raw materials can be added to the sulfur matrix. The structure can be uniformly dispersed, and the solidified body can be crushed to form a fractured surface with many microprojections.

However, in the production method by heating and melting the sulfur, it is necessary to continue stirring while maintaining the mixture temperature at 120 to 180 ° C so that the sulfur dissolved in the heating kneader is not solidified again. Therefore, even if denitrifying bacteria and micronutrients are added during production, they cannot coexist satisfactorily due to their death or thermal decomposition.

By coexisting denitrifying bacteria and trace elements in the material for denitrification, it is easy and reliable to discharge water from vegetable cultivation factories with low density of denitrifying bacteria, industrial wastewater, and groundwater, etc. It can be used.

In the method of WO2000 / 18694, the present inventors have also proposed a denitrification material which can be in contact with wastewater even at the time of water and can always maintain a high denitrification rate.

This is a composite denitrification material consisting of a mixture of mineral fibers and a denitrification material coexisting with calcium carbonate-containing substances and sulfur. For example, the inclusion of granular rock wool and denitrifying materials ensures water retention and a home for denitrifying bacteria. And stable nitric nitrogen denitrification is realized.

Therefore, the present invention does not require the supply of an essential carbon source for microorganisms, has excellent balance in the system before and after the reaction, and has a stable function with little influence of pH and chemical substances on water bodies. An object of the present invention is to provide a material for denitrification for removing nitrate nitrogen by a microorganism that exerts its effect.

Another object of the present invention is to provide a method for producing the above-mentioned denitrification material, which can produce sulfur as a main raw material in powder form by pressure molding.

At the same time, the present invention provides a method for producing a denitrifying material that can efficiently coexist with denitrifying bacteria without killing or pyrolyzing denitrifying bacteria and other micronutrients. Aim.

It is a further object of the present invention to provide a denitrifying material capable of holding an appropriate amount of water or suspension. '

(Disclosure of the Invention) The present invention relates to a method in which a powder containing calcium carbonate and a powder containing sulfur are used as main raw materials, and the mixture is mixed to form a powder mixture. And a method for producing a material for removing nitrate nitrogen. Further, the present invention provides a powder containing 2,000 to 5000 cm ² Zg of calcium carbonate as a Blaine value and a sulfur-containing powder having an average particle size of 0.01 to 2 mm in a weight ratio of 3 ::! This is a method for producing a nitrate-nitrogen-removing material in which a powder mixture is mixed at a ratio of 1: 2 to form a powder mixture, and the mixture is press-molded at a molding pressure of 300 to 900 kg Zcm ² (about 30 to 90 MPa). In the production of the nitrate-nitrogen-removing material, in addition to the main raw material, a powder in which denitrifying bacteria are supported on a porous body is mixed with the main raw material as an additive. It is advantageous to use them.

Further, the present invention is a material for removing nitrate nitrogen, in which sulfur, mineral fibers or a powder containing mineral fibers and calcium carbonate are integrated.

In addition, the present invention uses a powder containing sulfur and a powder containing mineral fibers or mineral fibers and calcium carbonate as main raw materials, and melts and mixes them at a temperature equal to or higher than the melting temperature of sulfur. A method for producing a nitrate-nitrogen removing material in the form of a lump or a particle having a predetermined shape or size. It is advantageous that these materials for removing nitrate nitrogen contain an additive selected from a cation-exchange-capability retaining substance, a flame retardant, and a microporous substance. As mineral fibers, mineral fibers such as wool containing calcium are advantageous.

Further, in the present invention, in treating wastewater free of denitrifying bacteria and a plurality of wastewaters including the existing wastewater, a nitrate state obtained by integrating calcium carbonate-containing powder with sulfur or a mineral fiber with sulfur or the same. Nitrogen-removing materials are selected from materials obtained by the melt-integration method, materials obtained by the press-integration method, and materials with additives added to them. is there. The denitrification material of the present invention is a material for removing nitrate nitrogen such as nitrate ions and nitrite ions. The material for denitrification of the present invention contains calcium carbonate and sulfur as essential components, and, if necessary, a powder having mineral fibers and denitrifying bacteria supported on a porous material; Contains microporous material. However, if the carbon source for denitrifying bacteria synthesis is sufficiently present in the water to be treated and the acidity of the treated water can be separately corrected, the blending of calcium carbonate can be omitted. However, when the blending of calcium carbonate is omitted, it is advantageous to blend mineral fibers containing calcium.

First, a method for producing a denitrification material according to the present invention, which does not require mineral fibers, is described. Will be described. This denitrification material is mainly composed of a powder containing calcium carbonate and a powder containing sulfur, which are mixed at a temperature lower than the melting point of sulfur, preferably at room temperature, by powder mixing. In this method, a powder mixture is pressed at a temperature lower than the melting point of sulfur, preferably at room temperature.

Powders containing calcium carbonate include calcium carbonate, limestone powder, shell powder, shell fossil powder, coral powder, eggshell powder, coral sand powder or crushed material, and other calcareous grains and calcareous fossil powder. One or two or more kinds of materials can be used. In particular, they do not matter in their purity, but they should be low in impurities because they serve as water purification and denitrification materials, but they weigh 70 weight. /. Moderate purity (excluding water) is acceptable.

Examples of the sulfur-containing powder include petroleum desulfurization and coal desulfurization brands, sulfur recovered from exhaust gas desulfurization brands, and natural sulfur. used. In particular, the purity of the powder is not limited, but it is preferable that the powder containing sulfur is also free of impurities, but the weight is 70 weight. /. A degree of purity (excluding water) is acceptable.

The average particle size of the powder containing calcium carbonate has a Blaine value of 2000 to 5000 cm ² / g, preferably 2500 to 4000 cm ² Zg. In addition, the average particle size of the sulfur-containing powder is preferably about 0.01 to 2 mm, more preferably about 0.05 to 1.5 mm.

In both cases, if the particle size is too coarse, the strength of the molded body will be reduced, and if it is too small, air will not easily escape during pressure molding, and the molded body will be destroyed at the same time as the pressure is reduced. The product yield is worse. In addition, if the difference between the two particle sizes is large, it is difficult to uniformly disperse the particles in the molded product.

Calcium carbonate and sulfur are almost equally consumed by the denitrification reaction. A ratio of around 1: 1 is preferable, usually a ratio of 3: 1 to I: 2, preferably 5: 2 to 2: 3, more preferably 6: 5 to 2: 1. Although it is good, it is desirable to consider the effects of the pH of the water to be treated and the coexisting additives, etc., and to mix them so that the water in the reaction tank during the treatment and the wastewater after the treatment can be kept approximately neutral. However, if the amount of carbonic acid is more than twice the amount of sulfur, the formability is deteriorated, and the denitrification material becomes more easily disintegrated in water. Therefore, it is preferable to limit the amount to at most three times the amount. The material for denitrification according to the present invention, which does not require mineral fibers, has a power of mainly using a powder containing calcium carbonate and a powder containing sulfur. Powder supported on the body can be blended. As the porous material for supporting the denitrifying bacteria, inorganic porous materials such as diatomaceous earth, zeolite, pumice, lengah, silica gel, soil and volcanic emissions can be used. However, clay minerals that swell with water are not suitable for use because they may cause the denitrification material to collapse in water. Carbonaceous porous materials such as activated carbon and rice husk charcoal are also useful, but care must be taken because nitrate nitrogen may increase from unburned matter.

In order to carry the denitrifying bacteria on the carrier, the carrier may be immersed in a culture solution of the denitrifying bacteria for several days and then air-dried and pulverized. It is also possible to mix soil containing denitrifying bacteria. In this case, it is advisable to air dry the soil and use a decoration with openings of 75 m. The more the denitrifying bacterial carrier is prepared, the faster the denitrification reaction appears.However, the effect is sufficient until the growth of the bacteria begins.Therefore, the mixing ratio is about 10 wt% of the carbonated sulfur-sulfur mixture. You. The amount of the powder carrying the denitrifying bacteria in the porous body can be added within the range that can be pressed, but the sulfur content is about 1/3 to 2/3 of the whole, preferably 1 / 2 about 2 to 20 weight of the whole. /. Good degree. The denitrification material of the present invention, which contains a powder in which a denitrifying bacterium is supported on a porous body, is used for the water quality of a vegetable cultivation plant drainage or industrial wastewater having a low density of denitrifying bacteria, groundwater, etc. Suitable for purification.

The above-mentioned denitrification material is mainly composed of powder mainly composed of calcium carbonate and powder mainly composed of sulfur. It is also advantageous to incorporate a small amount of a substance, a substance having a cation exchange capacity, a microporous substance, a flame retardant substance, or the like, preferably 30% by weight or less. As for such compounding substances, those described below can be used.

Next, a method for producing the above-mentioned denitrification material will be described. The mixing of the main raw material and the raw material added as required is not particularly limited as long as the raw powder material can be sufficiently mixed. For example, the mixing can be performed using a known powder mixing device. . A liquid substance, for example, a liquid fertilizer for agriculture, may be used as a nutrient source of the denitrifying bacteria. In this case, the liquid substance may be stirred and mixed while being gradually dropped. However, in the case of a mixer mixed with a high-speed stirring blade, care must be taken to raise the temperature of the powder raw material.

When mixing the powder, some water such as an aqueous solution may be replenished as described above, but in this case, it is desirable to dry before press molding. However, the presence of a small amount of water is effective in providing a hard molded product.

The mixed powder mixture is pressed and hardened. Ί Te press molding pressure Nitsu Rere or, 300 ~ 900Kg / cm ² (about 30～90MPa), desired laid (or 400~ 700KgZ cm ² (yo when about 40～70MPa) with pressure molding les. The press Batch molding using a flat plate press, continuous molding using a roll briquetter, etc. can be applied to molding.If the molding pressure is low, the service life of the denitrification material is shortened, but an early manifestation of the denitrification effect can be expected. If the molding pressure is high, the effect is delayed, Long life of denitrification material can be expected.

For example, when the molding pressure is less than 300 Kgcm2 (about 30 MPa), the denitrification material becomes more disintegratable in water. Conversely, if the molding pressure is 900 KgZ cm ² (approximately 90 MPa) or more, a phenomenon occurs in which the molded body is destroyed when the pressure is gradually reduced, and the production efficiency is reduced. The temperature is not higher than the melting temperature of sulfur. However, when a denitrifying bacterium is contained, the temperature is not higher than the temperature at which it does not die, for example, not higher than 40 ° C., and preferably not higher than room temperature.

There is no limitation on the shape of the compact formed by press molding, such as granules and plates.However, it is advantageous to form the granules to increase the surface area. Debris can also be used.

Next, the denitrification material according to the present invention, which requires mineral fibers, will be described. The denitrification materials include those that require sulfur and mineral fibers as essential, and those that require sulfur and calcium carbonate powder and mineral fibers, which are integrated so as not to break even in water.

As the sulfur and calcium carbonate used here, the same sulfur and calcium carbonate as described above can be used.

As the mineral fibers, for example, one or more of rock wool, glass wool, ceramic wool, and carbon fiber can be used, but preferably they contain calcium and are inexpensive. It is easy-to-granulate, and has a wealth of experience as an agricultural medium. It contains slag wool as well as mouth wool. In particular, the water retentivity and granular voids of granular rock wool having a particle size of about 30 to 5 mm not only have a favorable effect on the good growth of microorganisms, but also make it easy to obtain granular materials of an appropriate size. Can be. Also, powdered rock wool provides a favorable effect. The rock wool field As raw materials, steel slag is used in addition to natural rocks. The rock is rich in mineral components such as Mn, Zn, Cu, Mo, Fe, B, etc., and has the effect of being dissolved to activate sulfur-oxidizing bacteria. It also has the effect of summing. Mineral fibers having large voids are suitable for breeding other microorganisms such as ammonia-utilizing bacteria and organic matter-degrading organisms such as protozoa.

In addition to the above essential components, it is also possible to add a cation exchange ability-retaining substance, a nutrient component, a flame retardant substance, a microporous substance, and the like, if necessary. It is preferable that the content of these components is 30 wt% or less of the whole. It is also desirable that the maximum particle size of the cation-exchange-capability retaining substance, the flame retardant substance, and the microporous substance be 1 mm or less.

Examples of the cation-exchange capacity-retaining substance include zeolite powder not crushed, non-swellable to weakly swellable bentonite powder not crushed, acid clay powder and crushed, silica silicate powder not crushed and One or two or more of activated clay powder and crushed material, various types of landslides, tephra, tuff powder and crushed material can be used. Examples of the flame retardant include rock powders such as aluminum hydroxide, magnesium hydroxide, quartzite, granite and andesite, powders containing the surface soil of these rocks, and mineral powders such as feldspar-quartz 'alunite' tourmaline. , Fly ash, bami kiuraito concentrate or fine to fine granules

Examples of the microporous material include diatomaceous earth, diatomaceous earth fired particles and powder, minestone powder and crushed material, shirasu, shirasu balloon, perlite, sericite, brick powder, pottery powder, crystal ballite, One or more kinds of charcoal powder, activated carbon powder not yet, coat powder, sepiolite powder, and crushed material can be used. The preferred mixing ratio is 50 to 100 parts by weight of sulfur and 20 to 50 parts by weight of powder containing calcium carbonate, and 5 to 20 parts by weight of mineral fiber as granular wool. , cation exchange capacity retention substance, the case of adding a flame retarding material or micropores material, Shi desirable to add the total 10 to 30 wt% Rere ₀

If the content is not within this range, a composition integrated with the mineral fiber cannot be obtained, and the central portion of the fiber becomes untreated, or the composition becomes too dense and the significance of using mineral fiber is lost. I will.

Next, a method for producing a denitrification material according to the present invention, which requires mineral fibers, will be described. Press forming as described above is possible in some cases, but if a certain amount or more of mineral fiber is contained, the product obtained by press forming will collapse in water and become slushy. A method is preferred in which a powder or other component containing mineral fiber or calcium carbonate is blended, impregnated or mixed, and then cooled with water, solidified, or crushed.

The denitrification material obtained in this way is suitable for water purification related to the removal of nitrate nitrogen, and the mineral fibers work effectively as a habitat for sulfur oxidizing bacteria, and the high denitrification ability is long-term. Is stably expressed over a period of time. Also, a large amount of sulfur-oxidizing bacteria can be carried, facilitating the early start of denitrification.

Further, if non-binder treated granular rock wool is used for mineral fibers, not only can a granular denitrification material be easily obtained, but also powder generation during crushing can be significantly suppressed. The yield of products with a particle size of 2.5 mm or more can reach 90% or more.

The denitrification material of the present invention contains nutrients for sulfur oxidizing bacteria having an action of denitrifying nitrate nitrogen and is consumed when denitrification. It can also be referred to as a microbial activity imparting composition or a nitrate nitrogen denitrifying substrate. Here, nitrate nitrogen means nitrate ion and nitrite ion.

There is no particular limitation on the shape of the denitrification material of the present invention, but the denitrification material itself is prevented from flowing out in order to increase the contact area with raw water and wastewater to be denitrified. Therefore, it is advantageous to have a certain size and a surface area as large as possible. Therefore, a shape such as a lump, a granule, and a molded product is preferably mentioned. Here, the molded product refers to a product having a certain shape such as a plate shape, a rod shape, and a honeycomb shape. When agglomerated, those with a particle size of 0.25 to 1 mm, a particle size of 1 to 3 mm, and a particle size of 3 to 5 mm have immediate effect, but those with a particle size of 0.25 to: Imm have the fastest effect. Excellent. However, if the particle size is small, blockage and outflow loss increase, etc., so the preferred size differs depending on the use mode. For practical use over a long period of time, an average particle size of about 2 to 50 mm is appropriate, but it is advantageous that the average particle size does not exceed 100 mm.

This denitrification material is suitable for water purification of nitrate nitrogen, is excellent in removing high concentration of nitrate nitrogen, and the pH of treated water does not become strongly acidic.

The denitrification water treated with the denitrification material of the present invention has a substantially improved neutrality and a high pH because the measured pH is almost neutral. Nitrogen can be reliably denitrified, which can greatly contribute to the improvement of the water environment.

The material for denitrification of the present invention can be used for treating wastewater containing nitrate nitrogen. For example, it is used for treatment of agricultural drainage such as factory drainage, city drainage, and farm culvert drainage. The method of use includes a method of putting it in a basket or a net and immersing it in drainage, a method of filling it in a column, and a method of dispersing it in a tank. For long-term use by immersing in running water The method is also advantageous. If the wastewater has a relatively low concentration such as agricultural wastewater, it can be used continuously for several years.

(Brief Description of the Drawings) FIG. 1 is a graph showing a change in the concentration of nitrate nitrogen in raw water when the materials for denitrification (A) to (F) are used. Fig. 2 is a graph showing the residual nitrate nitrogen in raw water when using the denitrification materials (H) and (I) prepared by changing the molding pressure in batch molding using a hydraulic press. It is. Fig. 3 shows the results of using the denitrification materials (J) and (K) mixed with a carrier for denitrification bacteria and the denitrification material (A) in distilled water with potassium nitrate and phosphorus. 4 is a graph showing the residual rate of nitrate nitrogen in synthetic raw water not containing denitrifying bacteria prepared by dissolving an acid salt. (G) is an example in which no denitrification material is used.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

Crystalline limestone powder (2900 cm ² / g in Blaine value) was used as calcium carbonate, and this was mixed with powdered sulfur (200 mesh) using a high-speed impeller to form a dry compound. It was compression molded at a pressure of 650 KgZ cm ² to obtain the denitrification materials (A) to (C) of the present invention.

The compounding and molding conditions of the prepared dry compound are as follows.

(A) Sulfur: calcium carbonate = 5: 6, batch forming by hydraulic press

(B) Sulfur: calcium carbonate = 1: 2, batch forming by hydraulic press (C) Sulfur: calcium carbonate = 5: 6, continuous forming by roll press machine Example 2 (Comparative example)

The following materials for denitrification (D) to (F) were obtained for comparison. The raw materials used are the same as in Example 1.

(D) Sulfur: calcium carbonate = 5: 6, heat and melt sulfur, disperse calcium carbonate, cool with water, crush and prepare

(E) Using only sulfur, batch-formed product by hydraulic press

(F) Batch molding using hydraulic press with only calcium carbonate Example 3 (denitrification test)

A denitrification test was performed using the above denitrification materials (A) to (F). As the raw water, a culture solution of denitrifying bacteria (concentration of nitrate nitrogen consisting of nitrate and nitrite: 18 mgZL, pH = 7.2) was used. The denitrification materials (A) to (F) were immersed in raw water 5 times in weight ratio to perform a batch test, and a change in the total amount of nitrate ions and nitrite ions was traced. For comparison, a test (G) that does not use a denitrification material was also performed.

Figure 1 shows the results. In an experiment using the denitrification materials (A) to (C) of the present invention and the denitrification material containing sulfur and calcium carbonate (D), the nitrogen concentration in the raw water was almost zero in 14 days. As can be seen, there was almost no pH change. In the experiments using (E) and (F), no change was observed in the nitrogen concentration in the raw water, but the pH after 14 days was 4.5 for (E) and 7.7 for (F).

Example 4

The same test as in Example 1 was conducted on a denitrification material molded using a dry compound of sulfur: calcium carbonate = 5: 6 and changing the molding pressure. Formed form the batch molding using a hydraulic press and molded at a molding pressure 880KgZcm ² De窒用material (H) and molded de窒用material eSOKgZcm ² (I) was prepared.

A denitrification test was performed in the same manner as in Example 3 using the above denitrification materials (H) and (I).

Figure 2 shows the results. The vertical axis in the figure indicates the residual rate (%) of nitrate nitrogen. Among the denitrification materials (H) and (I) of the present invention, the nitrification material (I) having a low molding pressure had almost zero nitrate nitrogen by 10 days after the start of the experiment. It took about 2 weeks to remove nitrate nitrogen in raw water with high-denitrification material (H). Example 5

Sulfur: Calcium carbonate 5: 6 dry co Npaun de of the denitrification bacteria responsible bearing member (a) or (b) mixing 5% by weight, other article obtained by press molding at a molding pressure 650KgZcm ² is as in Example 1 Thus, materials (J) and (K) for denitrification were obtained. The carrier for denitrifying bacteria (a) used for the denitrification material (J) and the carrier for denitrification bacteria (b) used for the denitrification material (K) were obtained as follows. It is a thing.

(a) is a field soil (black soil of a leek field in Fukaya, Saitama prefecture). The air-dried 60 mesh sieve is used as a carrier, and (b) is a zeolite (Okutama Industries: Tamalite (trade name: TZ-0503) was used as a carrier, and these carriers were immersed in the raw water used in Example 3 for 3 days to carry the denitrifying bacteria, then air-dried and pulverized. The mesh material was used as a carrier (a) or (b) for denitrifying bacteria.

A denitrification test was performed using the above denitrification materials (J) and (K). In addition, a denitrification test using the denitrification material (A) and a test (G) using no denitrification material were performed.

The raw water used in this experiment was distilled water containing 0.51 g ZL and nitric acid. 0.18 g / L of sodium hydrogen oxyhydrate was dissolved to prepare a liquid without denitrifying bacteria (ion nitrate concentration 300 mg ZL, phosphate ion concentration 50 mg / L). This was added so as to be 5 times the weight of the denitrification material, and a change in water quality was tracked as in Example 3.

The results are as shown in Fig. 3. In any of the samples, little change was observed in the water quality until 7 days after the test, but the materials for denitrification (J) and (K) showed no denitrification effect after that. Was expressed.

Example 6

Using 50 parts by weight of crystalline limestone powder (T-200, manufactured by Niche Corporation, Brain value: 2900 cm ² / g) as calcium carbonate, 50 parts by weight of unsulfurized powder (200 mesh, manufactured by Karuizawa Co., Ltd.) 20 parts by weight, aluminum hydroxide (Heigelite, manufactured by Showa Denko KK), 10 parts by weight, and granular rock wool (S-fiber granular cotton, Shin-Nikka Chemical) 20 parts by weight of Rockwool Co., Ltd.) were mixed, heated and stirred at 180 ° C., then solidified in water to prepare a denitrification material (L) granulated to a diameter of about 5 to 10 mm.

Example 7

After thoroughly mixing 25 parts by weight of calcium carbonate and 75 parts by weight of sulfur, heat and mix at 180 ° C, and add 8 parts by weight of granular mouth wool to the mixture where the mixture has become a slurry, and heat and stir. The granulation wool was impregnated with slurry, and then 10 parts by weight of Zeolite (TZ0700, manufactured by Okutama Industries) and 10 parts by weight of aluminum hydroxide were added. went. When the slurry was almost completely impregnated in granular wool, it was quenched and solidified in water to obtain a denitrification material (M) with a particle size of 5 to 20 mm.

Example 8 The same procedure as in Example 7 was repeated except that 25 parts by weight of calcium carbonate, 75 parts by weight of sulfur, 9 parts by weight of granular wool, 14 parts by weight of zeolite, and 10 parts by weight of aluminum hydroxide were used. A 20 mm denitrification material (N) was obtained.

Example 9

37.5 parts by weight of calcium carbonate, 75 parts by weight of sulfur, 9 parts by weight of granular rock wool and 14 parts by weight of zeolite were used in the same manner as in Example 7 for denitrification with a particle size of 5 to 20 mm. The material (O) was obtained.

Example 10

75 parts by weight of sulfur was heated at 180 ° C., and 9 parts by weight of granular wool was added to the liquefied liquid, followed by heating and stirring. When the liquid sulfur was almost impregnated into the granular rock wool, it was quenched and solidified in water and granulated to obtain a denitrifying material (P) with a particle size of 5 to 20 mm.

Example 1 1

A denitrification material having a particle size of 5 to 20 mm as in Example 7 except that 37.5 parts by weight of calcium carbonate, 75 parts by weight of sulfur and 9 parts by weight of granular rock wool were used.

(Q) was obtained.

Example 1 2 (denitrification test)

Using the denitrification materials (L) to (Q) obtained as described above, a solution at a water temperature of 20 ° C adjusted to 90 mg / L of nitrate nitrogen was used to prepare Saitama, where sulfur-oxidizing bacteria are active. A denitrification experiment was performed using 10% by weight of Andosol in a leek field in Hitomi, Fukaya, Japan as raw water. A batch test was conducted using 50g of denitrification material for 300g of raw water. For comparison, Table 1 shows the results of an experiment that did not use a denitrifying agent. Table 1 shows that the initial nitrate nitrogen concentration was 90 mgZL, except for the experiment using no denitrification material. Understand

【table 1】

(Possibility of Industrial Use) According to the method for producing a nitrate-nitrogen-removing material that does not contain mineral fibers by press molding according to the present invention, heating is unnecessary, and not only batch-type but also continuous molding is possible. Since it can also be applied, productivity can be greatly improved. Further, a denitrification material capable of efficiently removing nitrate nitrogen from wastewater containing nitrate nitrogen can be manufactured. Also, by changing the press molding pressure, it is possible to adjust the period until the denitrification effect appears. Further, since the denitrifying bacteria carrier can be mixed, a denitrifying material capable of achieving the removal of nitrate nitrogen can be produced even in the water to be treated without the denitrifying bacteria.

In addition, the denitrification material of the present invention, which requires the mineral fiber as the essential component, is not limited to underdrainage from agricultural tracts where it is difficult to reduce fertilization; Also, it has excellent effect of removing nitrate nitrogen from wastewater that has been mineralized by primary treatment water of agricultural village wastewater and combined septic tank.

In addition, the denitrification material of the present invention containing a cation-exchange capacity-retaining substance, a flame retardant substance, a microporous substance, and the like can further enhance these effects and produce a substance during storage. It is possible to suppress the risk of combustion.

Further, the denitrification material of the present invention can be made suitable for various types of wastewater by changing its manufacturing method and the type and amount of additives. For example, in the treatment of a plurality of wastewaters such as wastewater without and without denitrifying bacteria, wastewater with high and low nitrate nitrogen concentrations, wastewater with high acidity and low wastewater, the denitrification material of the present invention or By selecting the production method of the present invention, an excellent nitrate nitrogen removal effect can be obtained for any wastewater.

The material for denitrification for removing nitrate nitrogen by the microorganism of the present invention has an excellent nitrate nitrogen removal rate because calcium carbonate and sulfur coexist, and it is necessary to supply an essential nutrient source of the microorganism. Instead, the in-system balance before and after the reaction can be kept good, and it can be used directly as a substrate for culturing microorganisms.

Claims

The scope of the claims

(1) Nitric acid characterized by using a powder containing calcium carbonate and a powder containing sulfur as main raw materials, mixing them to form a powder mixture, and press-molding this mixture. Method for producing a material for removing nitrogen.

(2) The weight ratio of the powder containing calcium carbonate having a Blaine value of 2000 to 5000 cm ² / g and the powder containing sulfur having an average particle diameter of 0.01 to 2 mm is 3::! To 1: 2. 2.The method for producing a material for removing nitrate nitrogen according to claim 1, wherein the mixture is press-formed at a molding pressure of 300 to 900 kg / cm ² (about 30 to 90 MPa). .

(3) A powder containing calcium carbonate and a powder containing sulfur as main raw materials, and a powder having denitrifying bacteria supported on a porous body mixed with the main raw material to obtain a powder. 2. The method for producing a material for removing nitrate nitrogen according to claim 1, wherein the mixture is press-formed.

(4) The method for producing a material for removing nitrate nitrogen according to claim 1, wherein the shape of the molded product obtained by press molding is granular.

(5) A material for removing nitrate nitrogen, which is a composition in which mineral fibers containing sulfur and calcium are integrated.

(6) A material for removing nitrate nitrogen, which is a composition in which powder containing calcium carbonate is integrated with sulfur and mineral fibers.

(7) The material for removing nitrate nitrogen according to (5) or (6), wherein the mineral fiber is rock wool.

(8) Calcium carbonate-containing powder is mixed with sulfur, and the sulfur is melted to add a mineral fiber while the whole mixture is slurryed, and heated and stirred. The slurry is impregnated and mixed into the fiber, quenched and solidified, and the solidified product is crushed to form a composition containing calcium carbonate-containing powder, sulfur and mineral fibers integrated. A method for producing a material for removing nitrate nitrogen, the method comprising:

(9) Sulfur is melted, mineral fiber containing calcium is added to the sulfur, the sulfur is impregnated and mixed in the fiber while heating and stirring, and this is quenched and solidified, and the solidified product is crushed to obtain sulfur. A method for producing a material for removing nitrate nitrogen, characterized in that the composition is obtained by integrating a mineral fiber with a mineral fiber.

(10) The material for removing nitrate nitrogen according to claim 8 or 9, wherein one or two or more additives selected from a cation exchange capacity retaining substance, a flame retardant substance, and a microporous substance are added together with mineral fibers. Manufacturing method.

(11) In the treatment of wastewater without denitrifying bacteria and multiple wastewater containing existing wastewater, removal of nitrate nitrogen by integrating calcium carbonate-containing powder with sulfur or mineral fiber with them Materials for nitrate nitrogen removal obtained by the melt-integration method, nitrate nitrogen removal material obtained by the press-molding integration method, and nitrate nitrogen removal obtained by mixing these with additives How to use nitrate nitrogen removal material selected from materials.