KR101203691B1 - Preparation method of complex media for water treatment and complex media thereby - Google Patents

Abstract

The present invention comprises the steps of preparing a sulfur mixture by mixing 50 to 200 parts by weight of sulfur with respect to 100 parts by weight of the mixture of the siliceous raw material and the calcareous raw material having a CaO / SiO ₂ molar ratio of 0.5 ~ 1.5; Preparing a slurry by mixing 50 to 65 parts by weight of an aqueous magnesium salt solution at a concentration of 2.0 to 4.0M and 0.05 to 0.20 parts by weight of aluminum based on 100 parts by weight of the sulfur mixture; Preliminary curing of the slurry; and Hydrothermal reaction of the pre-cured slurry; relates to a method for producing a composite material for water treatment, characterized in that consisting of.

According to the composite material for water treatment of the present invention, since it is possible to efficiently remove nitrate nitrogen, ammonia nitrogen, phosphorus and suspended solids present in sewage treatment plant effluent as well as waste water, it is very effective in preventing environmental pollution and protecting water resources. It is expected to be.

Water treatment, composite media, tobermolite, sulfur, desulfurization, struvite, apatite

Description

Preparation method of composite media for water treatment and composite media produced by the same {Preparation method of complex media for water treatment and complex media thereby}

The present invention relates to suspended solids present in wastewater and waste water. nitrogen And it relates to a method for producing a composite media for water treatment that can efficiently remove phosphorus and a composite media produced thereby.

The importance of wastewater treatment is emphasized as the generation of various wastewaters such as domestic sewage, industrial wastewater, and animal wastewater increases rapidly due to the increase in population, industrial development and the improvement of living standards. Effluents, including nitrogen and phosphorus, can accelerate eutrophication of lakes and reservoirs, and are therefore important nutrients to be particularly careful in the discharge of waste water. High nitrogen concentrations in treated effluents can lead to depletion of dissolved oxygen (DO / dissolved oxygen) in water resources, toxicity to aquatic organisms, and impact on the efficiency of chlorine disinfection, which will have a negative impact on whether sewage can be reused. Can be.

In general, biological removal is the most preferred method among various methods for removing nitrogen and phosphorus from wastewater such as industrial wastewater, livestock manure, leachate, sewage, sewage, etc. having various properties. This is because the potential treatment efficiency is high, the stability and reliability of the process is high, the treatment process is relatively easy, the land area required for the wastewater treatment plant is small, and the operating cost is economical.

 As a biological treatment process to remove nitrogen and phosphorus in wastewater, A2 / O method, Bardenpho method, University of Cape Town (UCT) method, and Virginia Initiative Plant (VIP) method have been developed and widely used. have. However, in order to treat nitrogen and phosphorus by this method, the ratio of organic carbon source, nitrogen and phosphorus in raw water should be maintained, and C / N should be present at about 5/1. However, in the case of Korean wastewater, organic matter concentration is lower than that of nitrogen or phosphorus, and in particular, since industrial wastewater often contains a large amount of nitrogen and / or phosphorus, it is difficult to effectively remove nitrogen or phosphorus by the above method. In order to solve this problem, wastewater is treated by adding an external carbon source such as methanol, but it is not only economically deteriorated, but it is difficult to properly control the amount of methanol added and methanol is toxic. An additional problem arises, such that it must be managed so that it does not remain.

Recently, autonomous denitrification using sulfur has been attracting attention as a new technology that can compensate for these drawbacks. Denitrification consists of the conversion of nitrous and nitrous nitrogen to nitrogen gas. Sulfur denitrification is carried out using various sulfur compounds (S ^2- , S, S ₂ O ₃ ^2- , S ₄ O ₆ ^2- , SO) using sulfated microorganisms represented by Thiobacillus denitrificans . ₃ ^2- ) is oxidized to sulfate (SO ₄ ^2- ) and at the same time the nitrate nitrogen is converted to nitrogen gas and removed. Since sulfur oxidizing microorganisms are autotrophic microorganisms, they do not require external carbon sources, so they can induce denitrification economically and stably even for waste waters with low C / N ratios and have relatively low sludge generation. The autotrophic denitrification process using sulfur oxidizing microorganisms can be described by Scheme 1 below.

^{_{NO 3 - + 1.1S + 0.4CO 2}} + 0.76H 2 O + 0.08NH 4 +

→ 0.5N ₂ ↑ + 1.1SO ₄ ^2- + 1.28H ⁺ + 0.08C ₅ H ₇ O ₂ N [Scheme 1]

As can be seen in Scheme 1, when 1 mol of nitrate nitrogen is denitrated with nitrogen gas, 1.28 mol of hydrogen ions are generated and the pH of the reaction solution is reduced, which affects sulfur oxidizing microorganisms as denitrification proceeds. There is a problem that the efficiency is lowered.

In order to solve this problem, there have been attempts to denitrify by adding an alkaline substance from the outside, but it is difficult to control the amount of alkali added, and when the ratio of the added alkali and the sulfur to be eluted does not match, the denitrification efficiency is reduced or Since Ca ²⁺ and SO ₄ ^2- formed are precipitated and hardened, there is a new problem that prevents inflow of raw water. Thus, a method of producing particles by pressing by mixing sulfur and limestone has been proposed, but the binding strength between the powders is weak, so that it is easily dispersed in water and spilled.

In Korea Patent Registration No. 10-0448891, sulfur, calcium carbonate (CaCO ₃ ) and magnesium oxide (MgO) are mixed, melted, made homogeneous, and then quenched to produce a sulfur carrier to eliminate the above problems and at the same time remove phosphorus It was intended to provide a carrier which can be. Calcium carbonate contained in the carrier of the registered patent not only supplements alkalinity lowered during the denitrification process, but also serves to remove phosphorus by generating phosphorus in wastewater and apatite by the following Reaction Scheme 2 as a source of calcium ions eluted. Do it.

^{_{CaO + H 2 O → Ca 2+}} + 2OH -

10Ca ²⁺ + 6PO 4 ^3- + 2OH ⁻ → Ca ₁₀ (OH) ₂ (PO ₄ ) ₆ [Scheme 2]

Magnesium oxide contained in the carrier also removes ammonia nitrogen and phosphorus by reacting with ammonia nitrogen and phosphorus in wastewater as a source of magnesium ions (Scheme 3) to produce struvite.

Mg ²⁺ + NH ₄ ⁺ + PO ₄ ^3- → MgNH ₄ PO ₄ [Scheme 3]

However, since the yellow carrier prepared by the above method has little pores, sulfur oxidizing microorganisms are difficult to adhere and grow at a high concentration on the carrier, so that the denitrification efficiency is low. In addition, as shown in the struvite reaction scheme, magnesium must be present in the ionic state to generate struvite, but magnesium oxide (MgO) is a stable oxide, so that its solubility is almost insoluble in water at about 0.62 mg / 100 g. Does not. Therefore, the concentration of magnesium ions is very low, there is a disadvantage that the removal efficiency of ammonia nitrogen and phosphorus through the generation of struvite (struvite) is lowered.

The present invention provides a method for producing a composite media for water treatment that can efficiently remove nitrate nitrogen present in the waste water of various properties by attaching and growing sulfated microorganisms in high concentration to the porous composite media having high porosity and absorption rate and The purpose is to provide a composite material produced through this.

Another object of the present invention is to provide ammonia nitrogen present in the wastewater of various properties by promoting the production of apatite and struvite in water treatment by providing calcium ions and ionic magnesium from various sources. It is to provide a method for producing a composite filter for water treatment that can efficiently remove the wine and the composite filter produced through this.

In another aspect, the present invention provides a method for producing a composite material for water treatment that can efficiently remove suspended solids present in the waste water of various properties by using the biofiltration function of the porous composite media, and the composite media produced through the same Another purpose.

The present invention for achieving the above object is a step of preparing a sulfur mixture by mixing 50 to 200 parts by weight of sulfur with respect to 100 parts by weight of the mixture of the siliceous raw material and the lime material having a CaO / SiO ₂ molar ratio of 0.5 to 1.5; 50 to 65 parts by weight of an aqueous magnesium salt solution at a concentration of 2.0 to 4.0 M and 100 parts by weight of the sulfur mixture Preparing a slurry by mixing 0.05 to 0.20 parts by weight; Preliminary curing of the slurry; and Hydrothermal reaction of the pre-cured slurry; relates to a method for producing a composite material for water treatment, characterized in that consisting of.

In the present invention, siliceous material, waste concrete fine powder, and lime powder may be used as the siliceous material, but lime, cement, and gypsum may be used as the raw material for lime, but is not limited thereto. In the hydrothermal reaction, a high-strength stable calcium silicate hydrate (5CaO? 6SiO ₂ ? 5H ₂ O), called tobermolite, is reacted with silica (SiO ₂ ) contained in the siliceous raw material and calcium contained in the calcareous raw material. Form. Tobermorite is a porous, lightweight and solid crystal phase that is most effectively produced when the CaO / SiO ₂ molar ratio is between 0.5 and 1.5. If the CaO / SiO ₂ molar ratio is out of the above range, the amount of tobermorite production is insufficient, resulting in a decrease in physical properties of the porous composite material of the present invention. In the case of the composite media of Comparative Examples 1 and 2 prepared below, the compressive strengths were 2.8 and 2.9 MPa, respectively. have.

In the preparation of the composite material, sulfur is used in an amount of 50 to 200 parts by weight based on 100 parts by weight of a mixture of siliceous raw material and lime material. If the content is less than 50 parts by weight, the efficiency of removing nitrate nitrogen by sulfated microorganisms is lowered. Porosity and absorption rate of composite media is lowered, which is disadvantageous to attach and grow sulfated microorganism.

The aqueous magnesium salt solution refers to an aqueous solution of magnesium salt consisting of magnesium sulfate and / or magnesium chloride, which are water-soluble magnesium salts. In the embodiment of the present invention, only the example using the salt water, which is a by-product of the liquid state obtained by collecting salt from the seawater with magnesium salt aqueous solution, is not limited thereto, and water in the concentration range of magnesium sulfate and / or magnesium chloride in place of the water Similar results were obtained when dissolved in. Brine water contains 15 to 19% by weight of magnesium chloride and 6 to 9% by weight of magnesium sulfate, and when converted into magnesium ions, it contains about 2.0 to 4.0 M concentration and can be easily used as an aqueous magnesium salt solution. Magnesium salt solution of 2.0-4.0M concentration is used 50 to 65 parts by weight based on 100 parts by weight of the mixture of siliceous raw material, lime raw material and sulfur, and less than 50 parts by weight of the foaming phenomenon by the blowing agent does not occur well porosity and absorption rate If lower than 65 parts by weight, the amount of tobermorite production is insufficient, resulting in a decrease in the physical properties of the porous composite material.

Aluminum is used as a blowing agent in an amount of 0.05 to 0.20 parts by weight based on 100 parts by weight of a mixture of siliceous raw material, lime raw material and sulfur. If the aluminum is less than 0.05 parts by weight, the desired foaming performance can not be expected, and if it exceeds 0.20 parts by weight, the foam is excessively excessive, resulting in a decrease in the physical properties of the porous composite material. In the embodiment of the present invention, the aluminum powder is used as the blowing agent, but is not limited thereto. An aluminum paste may be used.

In the preliminary curing step, the slurry is cured by the hydration reaction of the raw material to express the strength of the green body to facilitate demolding. When the preliminary curing temperature is lower than 25 ° C, the hydration reaction of the raw material is delayed, and the preliminary curing time for expressing the demolding strength becomes long. When the preliminary curing temperature is 80 ° C or higher, the fluidity of the slurry is caused by the rapid hydration exothermic reaction of the raw material. It is preferable to precure for 2 to 8 hours at 25-80 degreeC since it may fall or the raw material may collapse.

The hydrothermal reaction is preferably performed for 3 to 10 hours under a saturated steam of 10 to 20 atm. When the saturated steam pressure is low or the reaction time is short, the promotion of the hydration reaction is insufficient, and the toberlite is not effectively produced. Too high saturated steam pressure or too long reaction time will naturally affect the working efficiency.

The present invention also relates to a composite media for water treatment produced by the above method.

The composite material prepared by the method of the present invention has a porosity of 50 to 60% by weight, an absorption rate of 70 to 80% by weight, so that the sulfated microorganism is attached and grown at a higher concentration than the yellow carrier of the prior art, which has almost no pores. The nitrate nitrogen present in the wastewater can be efficiently removed. Although the compressive strength of the composite media of the present invention is 4.0 to 5.0 Mpa, despite the high porosity, the structure is solid and there is no fear of losing the structure in water.

Calcium oxide contained in the calcareous raw material of the composite media of the present invention reacts with water to elute calcium ions according to Scheme 2, and calcium ions react with phosphorus present in wastewater to produce apatite. Can be removed

Magnesium salt aqueous solution can provide a high concentration of magnesium in an ionic state to promote the generation of struvite to efficiently remove ammonia nitrogen and phosphorus.

In addition, when treating the wastewater by filling the composite media of the present invention in the reaction tank can be suspended by the biofilm filtration function.

 From this, when the porous composite media of the present invention is applied to the ultra-high treatment of the effluent and the effluent of the sewage treatment plant and the effluent of the sewage treatment plant, the water quality of the streams and lakes is improved, securing a stable water supply through the reuse of water, and the water circulation through solving the water shortage phenomenon. It is expected to contribute to improving the system.

Since the composite media for water treatment of the present invention has high porosity and absorption rate, it adheres and grows sulfated microorganisms at a high concentration, thereby increasing the amount of nitrate nitrogen present in the waste water of various properties compared to the prior art using the yellow carrier without pores. It can be removed efficiently.

In addition, the composite media for water treatment of the present invention provides calcium ions and ions of magnesium from various sources in the water treatment process to generate apatite and struvite, thus efficiently removing ammonia nitrogen and phosphorus present in the waste water. In addition, by using the biofiltration function of the porous composite media, it is possible to efficiently remove suspended solids present in the waste water of various properties.

The composite media for water treatment of the present invention is excellent in the bonding strength between the 4.0 ~ 5.0MPa particles of compressive strength, there is no fear of easily dispersed in water during the water treatment.

The composite media for water treatment of the present invention can efficiently remove nitrate nitrogen, ammonia nitrogen, phosphorus and suspended solids present in the sewage treatment plant effluent as well as industrial wastewater, livestock manure, leachate, sewage, sewage. Therefore, it is expected to have a very high effect in preventing pollution and protecting water resources.

The present invention will be described in detail through the following examples. However, these examples are for illustrative purposes only and the present invention is not limited thereto.

Manufacture of porous composite media

Silicate as a siliceous raw material Using the quicklime, cement, gypsum as a raw material for calcareous, composite composite materials of Examples and Comparative Examples were prepared under the conditions shown in Table 1. In Table 1, sulfur is part by weight based on 100 parts by weight of the siliceous raw material and the calcareous raw material, and brine and aluminum powder represent parts by weight based on 100 parts by weight of the mixture of siliceous raw material, calcareous raw material and sulfur. The silica sand used in the present example used silica sand powder (average particle size 20㎛ or less) of by-products generated during the manufacture of K company, and quicklime used CaO 90 wt% or more as the product of B company. Cement was used as one kind of cement of H company, and gypsum was used as by-product (average particle size of 20㎛ or less) generated by P-generation cogeneration plant. Sulfur used 99.9% purity product of M company and alumina powder used product of purity 99.7% or more of M company. And the water was obtained from B natural salt manufacturer.

More specifically, the slurry prepared by mixing all the raw materials according to the mixing ratio of Table 1 was added to a styrofoam box of 260 mm x 260 mm x 250 mm and then preliminarily cured at 50 ° C for 4 hours. Thereafter, hydrothermal synthesis for 2 to 10 hours according to the time shown in Table 1 under saturated water vapor pressure of 11 atm to prepare a porous composite media. The measurement results of the physical properties of the prepared porous composite material are shown in Table 2, and used to be crushed to a size of about 10 mm in diameter.

Investigation of Nitrogen and Phosphorus Removal Capacity of Composite Media for Livestock Wastewater

Using the composite media of Example 3 and Comparative Example 3 was investigated the removal ability of nitrate nitrogen, ammonia nitrogen, total phosphorus in livestock wastewater and the results are shown in Table 4. In addition, using the commercially available yellow carrier for the waste water treatment of J company, the results are shown together.

More specifically, an acrylic cylindrical cylinder having an effective capacity of 10 L was filled with the composite medium of Example 3 or Comparative Example 3, or the yellow carrier of J Company. The yellow carrier of J company was manufactured and used by the method as described in the Example of patent No. 448891. For seeding of sulfur oxidized microorganisms, aeration tank return sludge of D city sewage treatment plant was injected to acclimate sulfur oxidized microorganisms and attached sulfur oxidized microorganisms to the composite media. Thereafter, the concentration of the nitrate nitrogen, ammonia nitrogen, and total phosphorus according to the operation time of the reactor was analyzed while introducing the aeration tank treated water of the K municipal livestock waste treatment plant under the condition of 5 hours of residence time, and the results are shown in Table 4. Table 3 shows the results of the water quality analysis of the aeration tank treated water in the K municipal livestock waste public treatment plant used in this example.

By the composite medium of Example 3, nitrate nitrogen was continuously removed according to the operating time, 90% of the day 14, the highest 95% was removed. Ammonia nitrogen and total phosphorus decreased rapidly from the beginning of operation, resulting in 95% and 98% removal efficiency, respectively.

The composite media of Comparative Example 3 showed a removal efficiency of 75% with respect to the nitrate nitrogen, which is expected because of the low sulfur addition rate of the composite media of Comparative Example 3. On the other hand, the removal rate of ammonia nitrogen and total phosphorus was almost similar to that of the composite media of Example 3, which was performed by the contents of calcium oxide (CaO) and magnesium ions for the production of struvite and apatite. It is considered to be similar to the composite media of Example 3.

The sulfur carrier of Company J removed nitrate nitrogen with 85% efficiency because sulfuric acid microorganisms adhere and grow only on the surface of the yellow carrier because there is a sufficient amount of sulfur in the yellow carrier but there is little porosity of the yellow carrier. Ammonia nitrogen and total phosphorus were 80% and 98%, respectively. This is considered to be because the formation of struvite is not as easy as that of the composite media of the present invention because the magnesium component does not exist in the yellow carrier in an ionic state. In the case of the total phosphorus, since calcium oxide (CaO) was sufficiently present in the yellow carrier, it was mainly removed by the apatite production to a level similar to that of Example 8 and Comparative Example 10.

Through the above results, the porous composite media of the present invention have excellent porosity characteristics, so that sulfated microorganisms can attach and grow at high concentrations, and magnesium is present in an ionic state. It was confirmed that the removal efficiency is excellent.

Investigation of Nitrogen, Phosphorus, and Suspended Substances of Composite Media for Ultra-high Treatment

A cylindrical reactor made of acrylic material having an effective capacity of 10 liters was filled with the porous composite media having a diameter of 10 mm prepared in Example 3, and the effluent from the sewage treatment plant was treated to ultra high degree to remove nitrogen, phosphorus and suspended solids in the porous composite media. . For seeding of sulfur oxidized microorganisms, aeration tank return sludge of D city sewage treatment plant was injected to acclimate sulfur oxidized microorganisms and attached sulfur oxidized microorganisms to the composite media. Thereafter, the effluent from D sewage treatment plant was introduced under conditions of a residence time of 2 hours. Table 5 shows the results of the water quality analysis of the D city sewage treatment plant effluent used in this example. After acclimatization and adhesion of the sulfated microorganisms, the concentrations of nitrate nitrogen, ammonia nitrogen, total phosphorus, and suspended solids according to the reactor operation time were analyzed and the results are shown in Table 6.

The removal rate of nitrate nitrogen, ammonia nitrogen, total phosphorus, and suspended solids was 81%, 82%, 93%, 83%, respectively, so that the porous composite media of the present invention is highly polluted even when the concentration of pollutants such as effluent is low. It was confirmed that the material removal efficiency.

Claims (8)

Preparing a sulfur mixture by mixing 50 to 200 parts by weight of sulfur with respect to 100 parts by weight of a mixture of the siliceous raw material and the calcareous raw material having a CaO / SiO ₂ molar ratio of 0.5 to 1.5; Preparing a slurry by mixing 50 to 65 parts by weight of an aqueous magnesium salt solution at a concentration of 2.0 to 4.0 M and 0.05 to 0.20 parts by weight of aluminum based on 100 parts by weight of the sulfur mixture; And Precuring the slurry; And Hydrothermally reacting the precured slurry; Method for producing a composite media for water treatment, characterized in that consisting of. The method of claim 1, The siliceous raw material is a method for producing a composite media for water treatment, characterized in that at least one mixture selected from the group consisting of silica sand, waste concrete powder and stone powder. The method of claim 1, The calcareous raw material is a method for producing a composite material for water treatment, characterized in that at least one mixture selected from the group consisting of quicklime, cement and gypsum. The method of claim 1, The preliminary curing is a method for producing a composite media for water treatment, characterized in that 2 to 8 hours at 25 ~ 80 ℃. The method of claim 1, The hydrothermal reaction is a method for producing a composite media for water treatment, characterized in that made for 3 to 10 hours under saturated steam of 10 to 20 atm. A composite media for water treatment prepared by the method of any one of claims 1 to 5. The method of claim 6, Porosity of 50 to 60% by weight composite material for water treatment. The method of claim 6, Composite media for water treatment having an extrusion strength of 4.0 to 5.0 MPa.