JPS62183898A - Method for dephosphorization of sewage containing phosphorus - Google Patents

Abstract

PURPOSE:To efficiently remove phosphorus, by packing a column with a porous treatment material having a specific void ratio and containing calcium silicate as a main component and contacting phosphorus-containing sewage with said porous treatment material. CONSTITUTION:A foaming agent such as an aluminum powder is added to a slurry containing a silicious stock material and a carcareous stock material as main stock material and the resulting mixture is subjected to hydrothermal reaction treatment under a high temp. and high pressure condition to obtain a porous body with a void ratio of 50-90%. A column is packed with the porous treatment agent and phosphorus-containing sewage is passed through the packed column to perform contact reaction. By this method, the removal of phosphorus can be efficiently performed. The porous treatment material reduced in phosphorus removal effect can be utilized as phosphorus fertilizer.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention easily and efficiently removes phosphoric acid or phosphates (hereinafter simply referred to as phosphorus) contained in wastewater such as livestock urine wastewater and miscellaneous wastewater. This invention relates to a method for dephosphorizing wastewater that can be removed.

<Prior art> Phosphorus contained in sewage such as livestock urine sewage and household wastewater causes eutrophication that induces "blue water" and red tide in lakes and inland seas. Therefore, coagulation-sedimentation methods and crystallization methods have traditionally been used as methods to remove phosphorus from wastewater. An example of the processing steps of the coagulation-sedimentation method is shown in Figure 8 (a). By adding slaked lime to phosphorus-containing wastewater and stirring it, the PHt of the wastewater is raised, and phosphorus is precipitated and removed in the form of calcium hydroxyanomatite produced by the reaction of phosphoric acid and calcium. However, since the treated water after this first precipitation has a high - and contains a large amount of lime, it is necessary to neutralize and remove calcium.1 Usually, the solubility of calcium carbonate is the lowest. 9,3~10
．． primary carbonation to 0 and removal of calcium carbonate precipitates,
Furthermore, post-treatment steps of secondary carbonation until neutralization and filtration of calcium carbonate are required.

In addition, in the crystallization method, as shown in Figure 8(b), an example of the treatment process, the Ca concentration and Oi 1 degree (pl
-1) After delicately controlling the amount of phosphate, calcium hydroxyapatite is removed by passing water through the contact material layer containing "crystalline seeds" similar to phosphoric acid or calcium hydroxyapatite. However, as a pre-treatment step to delicately control the above-mentioned ca"m degree and OH9 degree, if the wastewater contains carbonaceous substances, decarboxylation is usually performed with sulfuric acid. After that, - and Ca are adjusted using slaked lime or gypsum, and CaCO3 and insoluble matters in the treated solution are precipitated and removed.

<Problems to be solved by the invention> In the coagulation-sedimentation method described above, a large amount of chemical (slaked lime) is used.
The use of sludge inevitably increases the amount of sludge generated, and requires the complicated post-treatment described above.
As mentioned above, the crystallization method requires complicated pretreatment to delicately control the 9 degrees and -, and also requires a special contact material that serves as a crystal seed for crystallizing calcium hydroxyapatite. .

As described above, all of the conventional dephosphorization methods have complicated processes and have many problems in terms of equipment, operation management, cost, etc.

In view of these circumstances, an object of the present invention is to provide a method for dephosphorizing phosphorus-containing wastewater, which does not require complicated treatment steps and can efficiently remove phosphorus through simple and easy treatment.

Means for Solving the Problems〉 As a result of various studies to achieve the above object, the present inventors have discovered that calcium silicate hydrate, a food constituent, is capable of absorbing phosphate ions in the liquid phase. The present invention was completed based on the discovery that there is a deep relationship between

The structure of the present invention is to form a packed bed by filling a column or a packed tank with a porous treatment material mainly composed of calcium silicate hydrate and having a porosity of 50 to 90%. It is characterized by passing wastewater containing phosphorus into the layer and bringing it into contact with the layer.

The configuration of the present invention will be explained in detail below.

To explain more specifically, the porous treated material used in the present invention is produced by adding a foaming agent such as aluminum powder to a slurry whose main raw materials are silicate raw materials and calcareous raw materials, and then hydrothermalizing the slurry with a foaming agent such as aluminum powder under high temperature and high pressure. A molded product obtained by reaction treatment or a crushed product obtained by crushing this molded product with an empty aS of 50 to
90mm or a slurry whose main raw materials are silicic raw materials and calcareous raw materials are subjected to a hydrothermal reaction treatment under high temperature and high pressure, and if necessary, the resulting powder is granulated or molded by adding air bubbles. The porosity of the granulated or molded product is 50 to 90.
It belongs to Chi.

Here, calcium silicate hydrate is prepared by combining a silicate raw material and a calcareous raw material at a predetermined Cab/5i02 molar ratio (0.5 to 2.0
degree) in an autoclave according to the usual method at the required pressure.
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 includes topamolite, xonotlite, C3H glu, huochasoyite, gyrolite,
It is one or more types selected from the group consisting of hireprundite sake. Among these, topamorite,
Zonolite and C8H Dal have a high buffering capacity and a specific surface area of 20 to 400n? /P is particularly preferable.

The porous treated material used in the present invention has a porosity of 50 to 90 cm, but when obtaining this porosity during the production of calcium silicate hydrate, a slurry of a silicic material and a calcareous material is used as a foam. It is preferable to add a metal foaming agent such as aluminum powder or a foaming agent such as AE μ as an agent and then perform a 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 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 surfactant action. in,
There are cases in which foam is created simply by mixing with raw materials and stirring, and cases in which stable foam is created using a special stirring tank or foaming device, and the volume of this foam is measured and mixed with raw materials. be.

When using such a foaming agent, it is necessary to determine the amount to be added after investigating the stability of the foam. Further, when a calcium silicate hydrate without voids is obtained, if it is a molded product, it may be powdered and then air bubbles may be added during the granulation or molding process to adjust the porosity. Add the entire aqueous solution of a polymer resin such as acrylic resin emulsion to powdered calcium silicate hydrate, add a foaming agent if necessary, and then knead and granulate using a non-pelletizer. It can be done by molding or molding. As the drying method here, either natural drying or 7Fll heat drying may be employed. Also here.

As the powdered calsila silicate pentahydrate, a powder obtained by crushing a molded product with voids as described above may be used. In addition, when preparing a porous treated material with a high porosity, it is preferable to employ molding.

The dephosphorization method according to the present invention is carried out by filling a column or a packed bed with the above-mentioned porous treatment material to form a packed bed, and passing wastewater containing phosphorus through the packed bed. The porous treatment material supplies Ca2+ necessary for the crystallization of calcium hydroxyanotite from the surface of the calcium silicate hydrate crystals or glue that forms it, and the PH buffering ability of the treatment material allows it to absorb wastewater. , H is low and its value changes fPIII IL Q&Iff
1% lr't P)l Q ~Q's 5-elf-fl
l Since winter is produced, phosphorus ions in wastewater are C.
It reacts with a and crystallizes on the narrow surface of the treated material in the form of calcium hydroxyanotite.

At this time, the pores in the porous treatment material act to disturb the flow of wastewater in one direction and to moderate the flow velocity on the surface of the treatment material, so that calcium hydroxyanomatite is generated by phosphate ions and Ca. Precipitation or growth is promoted.

Although the porous treatment material used in the present invention does not contain "crystal seeds" similar to calcium phosphate or calcium hydroxyapatite, it has an adsorption ability, so it adsorbs the generated calcium hydroxyapatite at the initial stage of water flow. After that, the surface has a structure suitable for nucleation of calcium hydroxyanoptite, and nuclei of calcium hydroxyanoptite are formed in the microscopic voids and pores.

A scanning electron microscope (S
When observed by EM), many calcium hydroxyanotite crystals are present on the inner surface of the void. As is clear from this, the porosity of the porous treated material has a large effect on the dephosphorization effect. As will be described later, when the relationship between the porosity of the treated material and the phosphorus removal rate was tested, it was found that the phosphorus removal rate was high when the porosity was 50 to 90%, preferably 60 to 80%. If the porosity of the porous treated material is less than 50%, the specific surface area is small, so the phosphorus removal rate is low, and if it exceeds 90%, the phosphorus removal rate due to floating during water flow decreases, and the strength decreases significantly. The sustainability of the phosphorus removal effect also deteriorates, which is not preferable.

Further, the size of the porous treatment material used in the present invention also has a large effect on the phosphorus removal performance. The diameter of the treated material is 0.511I
If the diameter is too small, it will be easily clogged by SS and crystallized crystals, making it impossible to use it for a long period of time.On the other hand, if the diameter is too large, the removal rate of IJ will decrease due to the reduction in the contact area, so both are undesirable. . Therefore, the treated material is 0.5
A size of ~10IB is preferable.

As shown in Figure 1, the dephosphorization method according to the present invention allows wastewater containing phosphorus to be directly passed through a packed bed of porous treatment material without pretreatment such as pH adjustment in the conventional crystallization method. do it. In addition, the treated water has a neutral pH of 8 to 9 and does not contain slazo, so there is no need for post-treatment.

Furthermore, according to the method of the present invention, dephosphorization is possible even if the phosphate concentration in wastewater is high. However, it is necessary to adjust the flow rate of wastewater depending on the concentration of phosphate. For example, if the concentration of phosphate is 500 q/l, it is approximately 50 I/d.
19/A! In this case, it is possible to process up to about 6 tons/day/PF/. Note that the phosphorus removal rate at this time is 90 or more.

Furthermore, the method of the present invention was implemented over a long period of time.

Porous treated materials with reduced phosphorus removal effects are silicate lime fertilizers and phosphoric acid fertilizers.

Alternatively, it is economical because it can be reused as a raw material for phosphorus.

Production examples and test examples are shown below.

(Production example of porous treated material) (IIC8H glue treatment agent 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/5102 molar ratio; 1.5) 71 parts of water was added to a mixture of metal aluminum powder o, oos The molded product was subjected to hydrothermal treatment at 150'C and 15 atmospheres for 10 hours.The molded product was crushed using a crusher, and 2.
The particles were sieved to a particle size of 5 to 5 mm to obtain a porous treated material. The porosity of this treated material was 72 inches.

(2) Topamorite treated 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/5LO2-e/I/
A slurry was prepared by adding 7 parts by weight of water to a mixture obtained by adding metal aluminum powder o and oosl to the ratio -0.8). This 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. under 10 atm for 10 hours.

The obtained molded product is crushed with a crusher to a size of 2.5 to 5 m.
A porous treated material was obtained by sieving the particles to a particle size of 500 s. The porosity of this material was 75L%.

(3) Zonotlite-treated silica powder and slaked lime powder at a CaO/8102 molar ratio of 1.
0, and dispersed in water 10 times heavier than the solid components to form an aqueous slurry, and then placed in an autoclave at 210°C and 20 atm with stirring for 100 min.
Hydrothermally treated for hours. To the absolute dry matter of the nine zonolite powder obtained in this way, acrylic resin emulnoyon (solid content 10%) was added 41 times, and after mixing, granulation molding was carried out.
It was dried and solidified at 10° C. and sieved to a particle size of 2.5 to 5 yen to obtain a porous treated material. This person's hunger rate was 73chi.

(4) Topamorite-treated materials with various porosity In the production method shown in (2) above, various topamorite-treated materials can be obtained by changing the addition ratio of metal aluminum powder and water as shown in Table 1. Ta.

Table 1 material In the method (3) above, before granulation molding.

Using Gainzl (Sansui Chemical Manufacturing) as a foaming agent, the air bubbles created with a foam generator were added to the volume of the kneaded material by 80° and 1.
The same procedure was carried out except that 60% of each was added to obtain treated materials having the porosity shown in Table 2. In addition, when the amount of foam added was 160%, after kneading, the foam was poured into a mold having a depression with a diameter of 3 to 5+ seconds, and the foam was dried and solidified together with the mold.

2nd The one in which the amount of added surface foam was 0 was manufactured in (3).

(Test Example 1) As shown in Fig. 2, various types of experiments were carried out using an experimental device capable of passing the test solution to be treated from the bottom of an acrylic column with an inner diameter of 30 m and a length of 4001 m, filled with porous treatment material. The performance of porous treated materials was investigated.

A-1 and A-2 are the columns filled with 150 m of each treatment material produced in Production Examples (11 to (3)).

A-3, various types of raw water shown in Table 3 were passed through these columns at a flow rate of 3QQd/hr, and the treated water for the first week was -
and phosphate ion-reaction were measured. The results are also shown in Table 3.

In addition, as a test liquid, potassium monophosphate (K
H2PO4) was added to increase the phosphorus concentration to 5q/l.
The calcium ion @ 0 ~ 10
0a? # range, and - for sodium hydroxide (NaO)
The aqueous solution of l) was used, which was varied in the range of 5 to 10.

Also, for comparison, grain size 2.5 from Angaur Island in the South Pacific
~5+ gs of phosphate rock was placed in a column similar to the above at 150-
The same operation was carried out using the column B-1.

This result is also shown in the third light.

Furthermore, the influence of - of the test solution on the phosphorus removal rate (CC & concentration 60 m9/l constant) is shown in Figure 3, and the influence of the calcium ion concentration (-9 constant of the test solution) on the phosphorus removal rate is shown in Figure 4. As shown in the figure.

As shown in the above results, according to the method of the present invention, even if the - of the test solution changes, the - of the treated water is maintained at approximately 9 to 10, and a phosphorus removal rate of 80 or higher is always achieved. Although it is
In the comparative example, the phosphorus removal rate does not reach 80% unless p)( of the test liquid is 8.5 or more.In addition, in the method of the present invention, the phosphorus removal rate is 80% or more even if the Ca 9 degree in the test liquid is 0. However, in the comparative example, the ca'i+ concentration was 60af/A'
fi, the phosphorus removal effect will not occur unless it is heated. In addition, in the method of the present invention, the phosphorus removal rate is further improved when Ca is present in the test solution, and when Ca6K is present at 40111/1 or more, when using a topamorite-treated material (8-2
), the phosphorus removal rate is 100.

(Test Example 2) Using a real device similar to Test Example 1, production examples (4) and (
Phosphorus concentration 5Q/11. pH
7. Treatment with a test solution without calcium ion additives, depending on the porosity of the treated material 11 ~ Nord Soil 77'
1 4 - 7〉 Ah σ) One case was the same as Test Example 1. The results are shown in Figure 4 and Figure 5.

As shown in Table 4 and Figure 5, the porosity of the treated material is 50
A high phosphorus removal rate is achieved when the temperature is ~90 cm. Note that when the porosity exceeds 90%, the phosphorus removal rate decreases due to the floating phenomenon 9 during water passage, and at the same time, the strength decreases significantly. These results show that the pore structure of the treated material is extremely stable due to the increased contact opportunities between the treated material and phosphate ions and the crystal growth of calcium hydroxyatite that crystallizes within the pores and voids. , was found to greatly contribute to the phosphorus removal effect.

(Test Example 3) Using the same experimental equipment as in Test Example 1, the particle size of the topamolite-treated material of Production Example (2) was adjusted to 0.6-1.2° and 1.2-2.0°.
5. Phosphorus concentration of 5 capes/l by five types of treated materials adjusted to 2.5-5,5-10.10-1511B.

p)17. Process the test solution without adding calcium ions,
Changes in phosphorus removal rate due to differences in particle size of treated materials were tested. Note that other conditions were the same as in Test Example 1. The results are shown in FIG.

As shown in FIG. 6, the phosphorus removal rate decreased as the particle size of the treated material increased. 4) If the particle size was less than 0.5, clogging force occurred due to enlargement of the treated material due to SS and crystallization, and it could not be used for a long period of time.

(Test Example 4) Using the same experimental equipment as in Test Example 1, a test solution with a phosphorus concentration shown in Table 5 was applied to the topamolite-treated material manufactured in t(2) at 1800 m/day (12 t/day, i900 m1). /day (6t
/day・tt/), 300m/day (2t/day・a).

150m1/day (1t/day・i), 75*/day (0,5
7 days a) Treatment was performed at C flow rate (the flow rate is in parentheses), and the influence of the test solution C phosphorus concentration and flow rate on the phosphorus removal rate was tested. Note that other conditions were the same as in Test Example 1. The results are also shown in Table 5.

As shown in Table 5, according to the method of the present invention, even when the phosphorus concentration is as high as 5,008,1711, phosphorus can be removed with high efficiency when the flow rate is reduced.

Example: A treated material whose main constituent is topamorite with a particle size of 5 to Bm, which was produced in the same manner as in Production Example (2) above, was
00x800ss was filled with 100J. Pig house sewage (solid-liquid separation of a mixture of pig manure and pig house washing water) is applied to this dephosphorizing sand in an upward flow at 12OA'/day (1,
Water was passed through the tube at a flow rate (flow rate) of about 7
The phosphorus concentrations of the pigsty wastewater and treated water were measured over a period of 9 months, and the results are shown in Figure 7.

As shown in the figure, the phosphorus concentration in the treated water was 3 ppm or less without being affected by the phosphorus concentration in the pigsty wastewater. As described above, according to the method of the present invention, a stable phosphorus removal effect can be obtained over a long period of time.

<Effects of the Invention> As specifically explained above along with test examples and examples, the method of the present invention can efficiently remove phosphorus through simple and easy treatment without requiring complicated steps, and can maintain It is also easy to manage. Therefore, it is possible to easily and economically carry out dephosphorization treatment on small and medium scales, which has been considered difficult until now, for industrial wastewater, sewage lines, livestock sewage, household wastewater, etc.

Note that the method of the present invention can be used for a long period of time.

The used porous treated material can be reused as a raw material for silicate lime fertilizer, phosphoric acid fertilizer, or phosphorus, which is more economical.

[Brief explanation of drawings]

Figures 1 to 7 are related to the present invention, Figure 1 is a process diagram of the method of the present invention, Figure 2 is an explanatory diagram of the nine experimental apparatus used in the test example,
Fig. 3 is a graph showing the relationship between the phosphorus removal rate and - of the test solution in Test Example 1, Fig. 4 is a graph showing the relationship between the phosphorus removal rate and the calcium ion concentration of the test solution in Test Example 1, and Fig. 5 The figure is a graph showing the relationship between the phosphorus removal rate and the porosity of the treated material in Test Example 2. Figure 6 is a graph showing the relationship between the phosphorus removal rate and the particle size of the treated material in Test Example 3.
The figures are graphs showing the results of the examples. Figure 8 (a) is a process diagram of the coagulation-precipitation method according to the prior art, and Figure 8 (b) is a process diagram of the crystallization method according to the prior art. .

Claims (1)

[Scope of Claims] 1) A column or a packed tank is filled with a porous treatment material containing calcium silicate hydrate as a main constituent and having a porosity of 50 to 90% to form a packed bed. A method for dephosphorizing sewage containing phosphorus, comprising passing the sewage containing phosphorus through a packed bed and bringing it into contact with the sewage. 2) Porous treated material is a molded product obtained by adding a foaming agent such as aluminum powder to a slurry whose main raw materials are silicic raw materials and calcareous raw materials, and subjecting it to hydrothermal reaction treatment at high temperature and high pressure.
Alternatively, the method for dephosphorizing wastewater containing phosphorus according to claim 1, which is a crushed product obtained by crushing this molded product. 3) Porous treated material is produced by adding air bubbles to the powder obtained by hydrothermal reaction treatment of a slurry whose main raw materials are silicic acid raw materials and calcareous raw materials under high temperature and high pressure, and pulverizing if necessary. The method for dephosphorizing sewage containing phosphorus according to claim 1, which is a granule or a molded granule or a molded product. 4) Calcium silicate hydrate is one or more selected from the group of topamorite, xonotlite, CSH gel, phosiyaite, gyalolite, and heleprandite. The method for dephosphorizing wastewater containing phosphorus according to item 3. 5) A method for dephosphorizing wastewater containing phosphorus according to claim 1, 2, 3, or 4, wherein the porous treatment material has a size of 0.5 to 10 mm.