JPH03115387A - Soil activator - Google Patents

Abstract

PURPOSE:To obtain a low-cost soil activator which can be utilized for treating an organic waste water containing a phosphorus compound and as a fertilizer by using a porous contact material composed mainly of a specified porous hydrated calcium silicate. CONSTITUTION:An objective soil conditioner comprises a porous contact material composed mainly of a porous hydrated calcium silicate (e.g. tobermorite, xonotlite, CSH gel, foshagite, gyrolite or hillebrandite) having a porosity of 50-90%, prepared by foaming and hardening an aqueous slurry of a siliceous raw material and a carcareous raw material in the presence of a foaming agent and subjecting the hardened foam thus obtained to hydrothermal reaction.

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 improving material that improves water retention, etc., or as a silicate lime fertilizer containing phosphorus.

<Prior Art and Problems to be Solved by the Invention> Generally, soil conditioners and various fertilizers are used to improve the structure and water retention capacity of soil, and to replenish nutrients.

For example, perlite and vermiculite 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 fertilizing. 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, the present invention can be used as a soil conditioner that can improve water retention capacity, etc., or as a fertilizer containing phosphorus.
The purpose is to provide inexpensive soil activating materials.

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 an aqueous slurry consisting of a siliceous raw material and a calcareous raw material in the presence of a foaming agent. Treatment of organic wastewater consisting of a porous contact material mainly composed of porous calcium silicate hydrate obtained by hydrothermal reaction treatment of a cured product and having a porosity of 50 to 90%, and containing at least a phosphorus compound. It is characterized by being used for.

Here, the action of the soil activating material according to the present invention will be explained.

The porous contact material that is the base of the soil active material is porous and has a
Since it has a porosity of ~90%, when 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, as well as 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 content 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 can be broken down by weak acids produced from plant roots.

Therefore, the soil activating material 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 a polyester resin, or a crushed product obtained by crushing this molded product, with a porosity of 50 to 90.
%, or calcium silicate water that is granulated or molded by adding air bubbles to the powder obtained by crushing a water slurry whose main raw materials are silicic raw materials and calcareous raw materials after hydrothermal reaction treatment under high temperature and high pressure. It is a granulated or molded product made of a compound with a porosity of 50 to 90%.

Here, calcium silicate hydrate is prepared by combining a silicate raw material and a calcareous raw material at a predetermined Cab/SiO2 molar ratio (0.5 to 2.0
The required pressure and
It is obtained by curing under high temperature and high pressure, and silicic raw materials include powders such as silica stone, silica sand, cristobalite, amorphous silica, diatomaceous earth, ferrosilicon dust, and white clay, and calcareous raw materials include quicklime, slaked lime, and cement. Examples include powders such as. Calcium silicate hydrate obtained in this way is tobermorite, xonotlite, CSH gel, foshagite, gyrolite,
It is one or more types selected from the group consisting of hireplandites and the like. Among these, tobermorite,
Zonotlite and CSH gel are particularly preferred because they have a high pH buffering ability and a large specific surface area of 20 to 400 m/g.

The porous contact material that is the base of the soil activating material according to the present invention has a porosity of 50 to 90%, but when this porosity is obtained during the production of calcium silicate hydrate, silicic substances and calcareous substances are used. A foaming agent such as a metal foaming agent such as aluminum powder or a foaming agent such as an AE agent may be added to the slurry, followed by hydrothermal reaction treatment at high temperature and 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 involved 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 surfactant action. In some cases, the foam is simply mixed with the raw material and stirred, and in other cases, stable foam is created using a special stirring tank or foaming device, and this foam is measured by volume and mixed 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. Also, if a calcium silicate hydrate with a small porosity is obtained, if it is a molded product, can it be powdered? The porosity may be adjusted by introducing air bubbles during the process of bicontact, granulation, or molding. 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. Further, here, as the powdered calcium silicate hydrate, a powder obtained by crushing a molded product with voids 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 in an aerobic hearth tank, and the organic wastewater and/or anaerobic wastewater is transferred to this aerobic area. Treated 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 aerobic treated water is brought into contact with a hydrogen donor substantially in the presence of air to produce anaerobic treated water. Make it.

To make a further comment, first, organic wastewater that has undergone primary treatment to remove floating matter and sediment is passed through the aerobic hearth tank filled with the above-mentioned 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.

In the same way, the removal of phosphorus and the nitrification of NH-N are performed simultaneously, and the treated water containing NH: -N is nitrified, -N, and No-N is fed into an aerobic furnace. No", -N, No"3-
Biological denitrification can be performed by reducing N to N2 gas.

Here, the porous contact material filled in the aerobic hearth tank has fine irregularities on the surface of calcium silicate hydrate crystals or gel, so microorganisms are easily immobilized and biofilm It has a slightly alkaline pH of 8, which is the optimum pH for microorganisms, and is easy to form, and also 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 (biological metabolites). The states of ~9 can be stably created. Therefore, in this aerobic hearth 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.
It is possible to process at high loads, and there is no need to dilute the organic sewage even if the concentration of organic sewage introduced is as high as urine sewage from a typical pig farm.

Moreover, the dephosphorization that is simultaneously carried out in such an aerobic hearth tank is due to the following action.

The porous contact material in the aerobic hearth tank supplies Ca necessary for crystallization of calcium hydroxyapatite from the crystal or gel surface of calcium silicate hydrate forming the porous contact material, and also increases the pH buffering capacity of the contact material. Due to the p of sewage
Since the H content is low and a stable state of approximately pH 8 to 9 is always created even if the value fluctuates, phosphate ions in the wastewater react with Ca and crystallize on the surface of the contact material in the form of calcium hydroxyapatite. will be analyzed. At this time, the voids in the porous contact material act to disturb the unidirectional flow of wastewater and to moderate the flow velocity on the surface of the contact material, resulting in precipitation of calcium hydroxyapatite due to phosphate ions and Ca. Growth is encouraged. In addition, although this porous contact material does not contain a "crystalline coating" similar to calcium phosphate or calcium hydroxyapatite, it does have adsorption ability, so it adsorbs the calcium hydroxyapatite that is generated during the initial period of water flow. Thereafter, the surface has a structure suitable for nucleation of calcium hydroxyapatite, so that nuclei of calcium hydroxyapatite are formed in the fine voids and pores.

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, a large number of microorganisms can be seen settling and living inside the pores and on the crystal surface. Amorphous crystals were also observed, and EPMA (X
It was identified as calcium hydroxyapatite using a line microanalyzer).

As is clear from this, the pores and voids of the porous contact material have a great effect on microbial settlement and dephosphorization, and the porous contact material that is the base of the soil active material of the present invention A porosity of 50 to 90%, preferably 60 to 80% is desirable for microbial implantation and dephosphorization.

If the porosity of this porous contact material is less than 50%, the specific surface area will be small, making it difficult for microorganisms to settle and the phosphorus removal rate will be low.On the other hand, if the porosity exceeds 90%, sewage will not be introduced into the aerobic hearth tank. Also, aeration causes floating and a significant decrease in strength, and the durability of the pH buffering ability and phosphorus removal effect also deteriorates, 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 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. Therefore, both are undesirable. Therefore, the porous contact material preferably has a size of 0.5 to 10+ms.

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 hearth tank is placed next to an aerobic hearth tank. As shown in the figure, screen settling basin 1
The organic sewage that has been primarily treated with the vibrating sieve 2 is then sent to an aerobic tank (aerobic hearth tank) filled with the above-mentioned porous contact material.
3, where organic matter removal, dephosphorization, and nitrification are performed. Next, it is introduced into a stirring tank 4 and methanol or camellia-containing sewage is added thereto, denitrified in an anaerobic tank (anaerobic hearth 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 sewage 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 activator used after such sewage treatment can be reused as a silicate lime fertilizer and a soil improvement material, which is very economical.

Below, an example of manufacturing 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.

(Production 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
parts by weight and 3 parts by weight of ordinary Portland cement (CaO
/SiO. A water slurry was prepared by adding 7 parts by weight of water to a mixture obtained by adding parts by weight of metal aluminum powders o and oos (molar ratio = 1.5). Next, this water slurry was poured into a mold and left to stand for 4 hours.The molded product was crushed with a rotating brush, granulated with a pan pelletizer to a particle size of 5 to 10 m, and then heated in an autoclave at 150°C and 5 atm. A porous contact material was obtained by hydrothermal treatment for 10 hours. The porosity of this contact material is 70
%Met.

(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/Si02% ratio = 0.8), by adding o and oos parts by weight of metal aluminum powder. 7 parts by weight of water was added to the mixture to form a water slurry.

This water slurry was poured into a mold, left to stand for 4 hours, and then molded, which was then hydrothermally treated in an autoclave at 180° C. and under 10 atmospheres for 10 hours. The obtained molded product was crushed using a crusher and sieved to a particle size of 5 to 10 to obtain a porous contact material. The porosity of this material was 75%.

(3) Zonotlite contact material silica powder and quicklime powder at a Cab/5i02 molar ratio of 1.
0 and dispersed in water 10 times the weight of the solid component to form an aqueous slurry, which was then hydrothermally treated in an autoclave at 210° C. under 20 atm with stirring for 10 hours. Acrylic resin emulsion (solid content 10%) was added 4 times by weight to the bone dry product of the xonotlite powder obtained in this way, and after kneading, granulation molding was carried out to obtain 110%
It was dried and solidified at <RTIgt;C,</RTI> and sieved to a particle size between 5 and 10 to obtain a porous contact material. The porosity of this material was 73%.

(4) Tobermorite contact material with a porosity of M (
In the manufacturing method shown in 2), various tobermorite contact materials were obtained by changing the addition ratios of metal aluminum powder and water as shown in Table 1.

Table 1 (Test Example 1) As shown in Figure 3, #200X was filled with porous contact material.
First tank 101 of 150X310m and 200X150
After performing solid-liquid separation in the second tank 102 of 290 m
．． The primary treated water of collagen sewage that has passed through the steel vibration nodes of 3 gardens φ is passed in an upward flow, and various 101.102
The performance of water purification materials using various porous contact materials as base materials was investigated by performing aeration from below at 500 mj for 7 minutes. Here, each of the porous contact materials manufactured in the above manufacturing examples (1), (2), and (3) was placed in the first and second tanks 101.
, 102 and passed the primary treated water at a flow rate of 101/day as Test Examples A-1, A-2 and A-3, respectively.

For comparison, comparative examples B-1 and B- were prepared using commercially available balas, pumice 2 limestone, and borip tetrapyrene with particle sizes of 5 to 10 m as the contact material instead of the porous contact material, respectively.
2, B-3°B-4.

These Test Examples A-1 to A-3 and Comparative Examples B-1 to B-4
After 2 to 3 months, the clarity of the treated water, p
H, BOD and T-P (total phosphorus), NHney N, No
The concentrations of Knee N and No;-N were measured four times each, and the averages are shown in Table 2.

Table 2 As shown in this result, BOD volume load 1.0 kg/day・
The comparative example has a BOD removal rate of 77 in high load processing.
While the removal rate was ~87%, the method of the present invention showed a high removal rate of over 95%. Further, the removal rate of phosphorus was 25% or less in the comparative example, which was hardly removed, but the method of the present invention had a high removal rate of 90% or more. Furthermore, in order to perform denitrification in the next step, organic nitrogen and NH-N
It is necessary to nitrify No';-N to N08-N, but according to the method of the present invention, NH-N volume load Kao,
Even with high load treatment of 4 kg/day, nitrification has progressed completely, and denitrification can be completed in the next step. On the other hand, in the comparative example, 10 to 30% of NHney-N remains, so even if a biological denitrification step is subsequently added, this remaining NHney-N will be flowed out as is.

(Test Example 2) Using the same experimental equipment as in Test Example 1, collagen-subprocessed water was treated using various porous contact materials shown in Production Example (4), and the porosity of the porous contact materials was determined. 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.

As shown in Table 3, when the porosity of the porous contact material is 50% or more, the effects of BOD removal and phosphorus removal are large and nitrification progresses sufficiently. Note that if the porosity exceeds 90%, the material 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 pore structure of the porous contact material is extremely important for increasing the chance of contact with organic wastewater and for allowing microorganisms to settle within the pores and voids. 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, the used porous contact material has a large amount of microorganisms attached to it, as well as phosphorus in the form of calcium hydroxyapatite, and since the matrix itself is porous, it is useful as a fertilizer with phosphorus, etc. At the same time, it can also improve the water retention 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 (Wagnerbot) was conducted using the coarsely crushed contact material used in A-2 of Test Example 1 as phosphorus fertilizer.

In addition, ammonium sulfate and salt were applied to each pot at the same time.
In addition, as a comparative product, a porous contact material before use for wastewater treatment was used.

As a result of the test, as the growth progressed after germination, the growth of the contact material using the contact material after 4. sewage treatment gradually became superior, 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, phosphorus, nitrogen, and silicic acid.

It is a source of lime, etc., and is very economical as it is waste after being subjected to a useful sewage treatment method.

[Brief explanation of the drawings] 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 wastewater, and Figure 3 is a diagram used for a test example. FIG. 4 is an explanatory diagram showing the sewage treatment apparatus used in the first embodiment. In the drawing, 3.15 is an aerobic hearth tank, and 5.14 is an anaerobic hearth tank.

Claims (2)

[Claims] (1) Hydrothermal reaction treatment of a foamed cured product obtained by foaming and curing an aqueous slurry consisting of a siliceous raw material and a calcareous raw material in the presence of a foaming agent, and with a porosity of 50 to 90%. 1. A soil activating material comprising a porous contact material containing porous calcium silicate hydrate as a main component, which is used for treating organic sewage containing at least a phosphorus compound. (2) Porous calcium silicate hydrate is tobermorite,
2. The soil activating material according to claim 1, which is one or more selected from the group of xonotlite, CSH gel, fociagite, gyrolite, and hireplandite.