JPH0478675B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a soil activating material that can be used as a soil conditioner that improves water retention capacity or the like, or as a silicate lime fertilizer containing phosphorus. <Problems to be solved by conventional techniques and inventions> In general, it is possible to improve the structure and water retention capacity of soil, and
Soil conditioners and various fertilizers are used to replenish nutrients. For example, perlite, vermiculite, etc. are used to improve the water retention capacity and air permeability of soil, but these are generally expensive. Furthermore, chemical fertilizers are generally used for fertilization. However, there is a problem in that all the raw materials for phosphorus fertilizer, which is one of the three major nutrients and essential for crop growth, are imported, and phosphorus resources are depleted worldwide. In view of these circumstances, it is an object of the present invention to provide an inexpensive soil activating material that can be used as a soil conditioner that can improve water retention capacity, etc., or as a fertilizer containing phosphorus. <Means for Solving the Problems> The soil activating material according to the present invention that achieves the above object is a foamed material obtained by foaming and curing a water slurry consisting of a siliceous raw material and a calcareous raw material in the presence of a foaming agent. Obtained by hydrothermal reaction treatment of cured product and
It is characterized by being made of a porous contact material mainly composed of porous calcium silicate hydrate having a porosity of 50 to 90%, and being used for the treatment of organic wastewater containing at least phosphorus compounds. . Here, the action of the soil activating material according to the present invention will be explained. The porous contact material, which is the base of the soil activating material, is porous and has a porosity of 50 to 90%, so when it is mixed into soil, it improves its water retention capacity, air permeability, etc. In addition, such a porous contact material creates a favorable environment for microorganisms to live in when treating organic wastewater using the biofilm method, crystallizes out phosphate ions, and maintains a pH suitable for nitrification. It is useful for treating wastewater. That is, a large amount of microorganisms and phosphorus and nitrogen are attached to the porous contact material after wastewater treatment. Furthermore, the porous contact material itself becomes a source of silicic acid and lime. Therefore, by mixing the porous contact material into the soil after it has been used for sewage treatment, it becomes a source of replenishment of various nutrients. In addition, the phosphorus component adhering to the porous contact material here is obtained by crystallizing phosphate ions in the wastewater in the form of calcium hydroxyapatite. In other words, phosphorus is in a form that is difficult to dissolve in water, but it is decomposed by weak acids produced from plant roots.
Therefore, the soil activator of the present invention is useful as a slow-release phosphorus fertilizer. Next, the porous contact material that is the base material of the soil activating material according to the present invention will be specifically explained. This porous contact material is, for example, a calcium silicate water obtained by adding a foaming agent such as aluminum powder to a water slurry whose main raw materials are silicic raw materials and calcareous raw materials, and performing a hydrothermal reaction treatment under high temperature and high pressure. A molded product made of silica or a crushed product obtained by crushing this molded product with a porosity of 50 to 90%, or a water slurry whose main raw materials are silicic raw materials and calcareous raw materials under high temperature and high pressure. A granulated or molded product with a porosity of 50 to 90% made of calcium silicate hydrate, which is granulated or molded by inserting air bubbles into the powder obtained by crushing the powder after hydrothermal reaction treatment. . Here, calcium silicate hydrate is prepared by combining a silicate raw material and a calcareous raw material at a predetermined CaO/SiO ₂ molar ratio (0.5~
2.0) and is obtained by curing at high temperature and high pressure under the required pressure and temperature in an autoclave according to a conventional method. Silica raw materials include silica stone, silica sand, cristobalite, amorphous silica, diatomaceous earth, Powder such as ferrosilicon dust, white clay,
Examples of calcareous raw materials include powders such as quicklime, slaked lime, and cement. The calcium silicate hydrate thus obtained is one or more selected from the group consisting of tobermorite, xonotlite, CSH gel, phosiyaite, gyalolite, heleprandite, and the like. Also, among these, tobermorite, xonotlite, and CSH gel have high PH buffering ability and a specific surface area of 20 to 400 m ² /g.
It is especially preferable because it is large. The porous contact material that is the base material of the soil activator according to the present invention has a porosity of 50 to 90%.
When obtaining calcium silicate hydrate, a foaming agent such as a metal foaming agent such as aluminum powder or a foaming agent such as an AE agent is added to a slurry of a silicic material and a calcareous material, and then heated at a high temperature. Hydrothermal reaction treatment may be performed under high pressure. Here, the metal foaming agent generates gas through a chemical reaction, and its usage ratio varies depending on the amount of air bubbles and water entrained in the slurry, but can be derived from the chemical reaction equation. Specific examples of foaming agents include resin soaps, saponins, synthetic surfactants, hydrolyzed proteins, and polymeric surfactants, which mainly introduce air bubbles physically through the action of surfactants. There are two types of foam: one is to create foam by simply mixing it with the raw material and stirring, and the other is to create stable foam using a special stirring tank or foaming device, measure the volume of this foam, and mix it with the raw material. There is. When using such a foaming agent, it is necessary to test the stability of the foam and then determine the amount to be added. In addition, if you obtain calcium silicate hydrate with a small porosity, if it is a molded product, you can adjust the porosity by adding air bubbles during the granulation or molding process after pulverizing it. . In other words, an aqueous solution of a polymer resin sizing agent such as an acrylic resin emulsion is added to powdered calcium silicate hydrate, a foaming agent is added if necessary, the mixture is kneaded, and the resulting mixture is granulated using a pan pelletizer. It can be molded using a mold. As the drying method here, either natural drying or heat drying may be employed. Moreover, here, as the powdered calcium silicate hydrate, a powder obtained by crushing a molded product with voids in it as described above may be used. In addition, when forming a porous contact material with a high porosity, it is preferable to employ mold molding. The soil activating material of the present invention is obtained after using such a porous contact material for treating organic wastewater. Here, a preferred method of using the porous contact material for wastewater treatment will be explained. For example, when treating organic wastewater containing phosphorus compounds, nitrogen compounds, and organic substances, a porous contact material is filled into an aerobic bed tank, and the organic wastewater and/or anaerobic treatment is transferred to this aerobic area. Water is passed through and brought into contact with the porous contact material in the presence of air to produce aerobic treated water, and then this aerobically treated water is brought into contact with a hydrogen donor substantially in the presence of air to produce anaerobic treated water. do. To be more specific, first, organic wastewater that has undergone primary treatment to remove floating matter and sediment is passed through an aerobic bed tank filled with the above porous contact material without dilution while being aerated. This method uses a membrane method to remove organic substances. That is, as a result, microorganisms live on the surface of the porous contact material and it becomes a water purification material, and this water purification material removes organic matter by the biofilm method. Similarly, the removal of phosphorus,
Nitrification of NH ⁺ ₄ −N is also carried out at the same time, and further,
Treated water containing NO ^- ₂ -N and NO ^- ₃ -N, in which NH ⁺ ₄ -N has been nitrified, is introduced into an anaerobic bed tank, and a hydrogen donor such as methanol is added to denitrify bacteria in an aerated anaerobic state. Biological denitrification can be performed by reducing NO ^- ₂ -N and NO ^- ₃ -N to N ₂ gas. Here, the porous contact material filled in the aerobic bed tank has fine irregularities on the surface of calcium silicate hydrate crystals or gel, so microorganisms are easily immobilized and biofilms are formed. A weakly alkaline pH state of 8 to 9, which is easy to form and is the optimal pH for microorganisms, which alleviates the pH drop caused by lower fatty acids such as lactic acid, butyric acid, and acetic acid, which are decomposition products of organic matter (microbial metabolites). can be produced stably. Therefore, in this aerobic bed tank, the activities of bacteria and protozoa that contribute to the decomposition of organic matter, as well as nitrite bacteria and nitrate bacteria that perform nitrification, become active, making it possible to perform high-load treatment. Even if the organic sewage has a high concentration similar to urine sewage from a general pig farm, dilution is not necessary. Moreover, the dephosphorization that is simultaneously carried out in such an aerobic bed tank is due to the following action. The porous contact material in the aerobic bed tank supplies Ca ²⁺ necessary for crystallization of calcium hydroxyapatite from the surface of the calcium silicate hydrate crystal or gel that forms it, and also reduces the pH of the contact material.
Due to the buffering capacity, the pH of wastewater is low and even if the pH value fluctuates, it always maintains a stable state of pH 8 to 9, so phosphate ions in wastewater contain Ca ²⁺
and crystallizes on the surface of the contact material in the form of calcium hydroxyapatite. At this time, the voids in the porous contact material act to disturb the flow of wastewater in one direction and to moderate the flow velocity on the surface of the contact material, so calcium hydroxyapatite formed by phosphate ions and Ca ²⁺ The precipitation or growth of is promoted. In addition, this porous contact material does not contain "crystal seeds" similar to calcium phosphate or calcium hydroxyapatite;
Because it has adsorption ability, it adsorbs the generated calcium hydroxyapatite at the initial stage of water flow, and after that, its surface has a structure that is convenient for the nucleation of calcium hydroxyapatite, and its micro cavities and pores are absorbed. It forms a core of calcium hydroxyapatite in the part. When the porous contact material after sewage treatment, that is, the soil activating material according to the present invention, is observed with a scanning electron microscope, it is seen that a large number of microorganisms are implanted and living inside the void and on the crystal surface. Amorphous crystals were also observed and identified as calcium hydroxyapatite using EPMA (X-ray microanalyzer). As is clear from this, the pores and cavities of the porous contact material have a great effect on microbial settlement and dephosphorization, and the porous contact material is the base material of the soil active material of the present invention. A vacancy rate of 50 to 90%, preferably 60 to 80% is desirable for microbial implantation and dephosphorization. The porosity of this porous contact material is 50%
If the vacancy rate is less than 90%, the specific surface area is small, making it difficult for microorganisms to settle and the phosphorus removal rate is low. On the other hand, if the vacancy rate exceeds 90%, sewage floats up due to introduction of wastewater into the aerobic bed tank and aeration, and strength decreases. In addition, the PH buffering capacity and the durability of the phosphorus removal effect deteriorate significantly, which is not preferable. Furthermore, the size of the porous contact material also has a large effect on the phosphorus removal performance. If the diameter of the contact material is smaller than 0.5 mm, it will be easily clogged by SS and crystallization, so it cannot be used for a long period of time.On the other hand, if the diameter is too large, the phosphorus removal rate will decrease due to the reduction of the contact area. Both are undesirable. Therefore, it is desirable that the porous contact material has a size of 0.5 to 10 mm. Here, an example of a method for treating organic wastewater to obtain the soil activating material according to the present invention is shown in FIGS. 1 and 2. The example shown in FIG. 1 is an example in which an anaerobic bed tank is placed next to an aerobic bed tank. As shown in the figure, organic sewage that has been primarily treated in a screen settling basin 1 and a vibrating sieve 2 is introduced into an aerobic tank (aerobic bed tank) 3 filled with the above-mentioned porous contact material to remove organic matter. , dephosphorization and nitrification are performed. Next, the water is introduced into a stirring tank 4 and methanol or organic wastewater is added thereto, denitrified in an anaerobic tank (anaerobic bed tank) 5, and drained through a re-aerobic tank 6 and a disinfection tank 7. FIG. 2 is an example of a circulating treatment process. As shown in the figure, organic wastewater that has been primarily treated in a screen settling tank 1 and a vibrating sieve 2 passes through an agitation tank 13 and an anaerobic tank 14, and then is introduced into an aerobic tank 15 filled with a porous contact material. , and further circulated to the stirring tank 13. This performs organic matter treatment, dephosphorization, and denitrification. This treated water is drained through a re-anaerobic tank 16 and a disinfection tank 7. As is clear from the above, the method of treating organic wastewater using the porous contact material that is the base material of the soil activating material of the present invention can significantly reduce the number of steps and operation management compared to the conventional method. It becomes easier. The soil activating material used up through such sewage treatment can be reused as a lime silicate fertilizer and a soil improvement material, which is very economical. Below, a manufacturing example of a porous contact material that is the base material of the soil active material of the present invention and a test example showing the effects of the present invention are shown. Manufacturing example of porous contact material (1) CSH gel contact material 4 parts by weight of silica powder, 2 parts by weight of quicklime powder, 1 part by weight of slaked lime powder, and 3 parts by weight of ordinary Portland cement (CaO/SiO ₂ molar ratio = 1.5) with metal A water slurry was prepared by adding 7 parts by weight of water to a mixture containing 0.008 parts by weight of aluminum powder.
Next, this water slurry was poured into a mold, left to stand for 4 hours, and then removed from the mold, which was then crushed with a rotating brush.
After granulation with a pan pelletizer to a particle size of 5 to 10 mm, the mixture was hydrothermally treated in an autoclave at 150°C under 5 atm for 10 hours to obtain a porous contact material. The void ratio of this contact material was 70%. (2) Tobermorite contact material 5 parts by weight of silica powder, 2 parts by weight of quicklime powder, and 3 parts by weight of ordinary Portland cement (CaO/
_SiO2 molar ratio = 0.8) to metallic aluminum powder
7 parts by weight of water was added to the mixture formed by adding 0.008 parts by weight to form a water slurry. This water slurry was poured into a mold, left to stand for 4 hours, and then removed from the mold, which was then hydrothermally treated in an autoclave at 180° C. and under 10 atmospheric pressure for 10 hours. The obtained molded product was crushed using a crusher and sieved to a particle size of 5 to 10 mm to obtain a porous contact material. The empty rate for this item was 75%. (3) Zonotlite contact material Silica stone powder and quicklime powder are mixed so that the CaO/SiO ₂ molar ratio is 1.0, and
It was dispersed in 10 times its weight of water to form a water slurry, and then hydrothermally treated in an autoclave at 210° C. under 20 atmospheric pressure with stirring for 10 hours. Acrylic resin emulsion (solid content 10
%) was added 4 times by weight, kneaded, and then granulated to form 110
The mixture was dried and solidified at ℃ and sieved to particles with a particle size of 5 to 10 mm to obtain a porous contact material. The empty rate of this thing is
It was 73%. (4) Tobermorite contact materials with various void ratios Various tobermorite contact materials can be obtained by changing the addition ratio of metal aluminum powder and water as shown in Table 1 in the manufacturing method shown in (2) above. Ta.

[Table] Test example 1 As shown in Figure 3, a porous contact material was filled.
First tank 101 of 200×150×300mm and 200×150
The primary treated water of swine urine sewage, which has been subjected to solid-liquid separation and passed through a 0.3 mmφ steel vibrating sieve, is passed through the second tank 102 of ×290 mm in an upward flow. By performing aeration from below at a rate of 500 ml/min, the performance of water purification materials using various porous contact materials as base materials was investigated. Here, the above production example (1),
The porous contact materials manufactured in (2) and (3) are filled into the first and second tanks 101 and 102 to supply the primary treated water.
Test examples A-1, A-2, and A-3 were obtained by passing water at a flow rate of 10/day. For comparison, instead of the porous contact material, commercially available ballast, pumice, limestone, and polypropylene were used with particle sizes of 5 to 5.
Comparative Examples B-1, B-2, B-3, and B-4 were made using a 10 mm contact material as a contact material. These Test Examples A-1 to A-3 and Comparative Example B-1
~ After 2 to 3 months of B-4, the clarity, PH, BOD and T-P (total phosphorus) of the treated water,
Each concentration of NH ⁺ ₄ −N, NO ⁻ ₂ −N, and NO ⁻ ₃ −N was
The measurements were taken twice and the averages are shown in Table 2.

[Table] As shown in this result, BOD volume load 1.0Kg/
The BOD removal rate in the comparative example was 77-87% in high-load processing of ³ days/m3, while the method of the present invention had a BOD removal rate of 95%.
% or more. Further, the removal rate of phosphorus was less than 25% in the comparison column, which was hardly removed, but the method of the present invention had a high removal rate of more than 90%. Furthermore, in order to perform denitrification in the next step, it is necessary to nitrify organic nitrogen and NH ⁺ ₄ -N to NO ^- ₃ -N or NO ^- ₂ -N, but according to the method of the present invention, NH ⁺ ₄ -N volumetric load is 0.4Kg/day.
Nitrification has progressed completely even with high load treatment of m ³ .
The state is now ready for complete denitrification in the next step. On the other hand, in the comparative example, 10 to 30% NH ⁺ ₄ −N
remains, so even if a biological denitrification process is subsequently added, this remaining NH ⁺ ₄ -N will be flushed out as it is. Test Example 2 Using the same experimental equipment as in Test Example 1, the primary treated pig urine water was treated using various porous contact materials shown in Production Example (4), and the results were determined by the size of the porosity of the porous contact materials. The difference in purification was tested. Note that other conditions were the same as in Test Example 1. Similar to Test Example 1, the results are shown in Table 3, which is the average of four measurements over a period of 2 to 3 months.

[Table] As shown in Table 3, the porosity of the porous contact material is
When it is 50% or more, the effect of BOD removal and phosphorus removal is large and nitrification progresses sufficiently. In addition, the vacancy rate is 90%
If it exceeds this value, it will flow out of the tank due to the floating phenomenon when water is passed through, and at the same time, the strength will decrease significantly. These results show that the void structure of the porous contact material increases the chance of contact with organic wastewater and reduces the number of pores and voids.
This is extremely important for the implantation of microorganisms within the body. It is also extremely important for the crystal growth of calcium hydroxyapatite that crystallizes at the same time, and greatly contributes to the phosphorus removal effect. Therefore, used porous contact materials have a large amount of microorganisms attached to them, as well as phosphorus in the form of calcium hydroxyapatite, and since the matrix itself is porous, it cannot be used as a fertilizer such as phosphorus. It is useful and can also improve the water holding capacity and air permeability of soil. Moreover, since it is waste after being used for useful sewage treatment, it has great economic value. Test Example 3 A Komatsuna cultivation test (Wagner pot) was conducted using the coarsely crushed contact material used in Test Example 1 A-2 as phosphorus fertilizer. Note that ammonium sulfate and salt were applied simultaneously to each pot, and a porous contact material before use for sewage treatment was used as a comparative product. As a result of the test, as the growth progressed after germination, the growth gradually became better when the contact material was used after sewage treatment, and a clear application effect was observed. <Effects of the Invention> As explained above, the soil activating material according to the present invention has the effect of improving the water retention capacity and air permeability of soil, and in particular serves as a source of phosphorus, nitrogen, silicic acid, lime, etc. Moreover, it is very economical because it is waste after being subjected to a useful sewage treatment method.

[Brief explanation of the drawing]

Figures 1 to 4 are related to the present invention, Figures 1 and 2 are process diagrams showing an example of a method for treating organic sewage, Figure 3 is an explanatory diagram showing the apparatus used in the test example,
FIG. 4 is an explanatory diagram showing the sewage treatment apparatus used in the first embodiment. In the drawing, 3 and 15 are aerobic bed tanks, and 5 and 14 are anaerobic bed tanks.

Claims (1)

[Scope of Claims] 1. A foamed cured product obtained by foaming and curing an aqueous slurry consisting of a silicic raw material and a calcareous raw material in the presence of a foaming agent, and
It is characterized by being made of a porous contact material mainly composed of porous calcium silicate hydrate having a porosity of 50 to 90%, and being used for the treatment of organic wastewater containing at least phosphorus compounds. Soil activator. 2. The soil activating material according to claim 1, wherein the porous calcium silicate hydrate is one or more selected from the group of tobermorite, xonotlite, CSH gel, phosiyaite, gyalolite, and hireplandite.