JPH11226549A - Production of sewage sludge incineration ash lightweight solidified material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a sewage sludge incineration ash lightweight solidified material which has small specific gravity, higher strength in comparison with lightweight concrete and others, and high quality. SOLUTION: A clay-like kneaded material 1 containing a large amount of bubbles is prepared by a method in which sewage sludge incineration ash added with a polymer flocculant, an acid solution, and a foaming agent are mixed/ kneaded. The material 1 is molded and solidified by drying naturally, or a prescribed amount of the material 1 is put into a form 2, heated, expanded, and solidified. A kind of powder which generates gas by water or an dilute acid such as sodium hydrogen carbonate, powdered aluminum, and powdered iron is used as the foaming agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a light-weight solidified sewage sludge ash from a sewage sludge ash to which a polymer flocculant has been added.

[0002]

2. Description of the Related Art The amount of sludge generated by sewage treatment increases with the spread of sewerage, and landfill disposal has become increasingly difficult in recent years due to a decrease in landfills, which are the main disposal sites. There is a need to reduce the volume and volume of sewage sludge for reduction.

[0003] Further, it is desired to establish resource recycling technology for effective use of sewage sludge, not limited to weight reduction and volume reduction.

[0004] As a method of treating sewage sludge, it is common to dewater sewage sludge, compost it and use it as an organic soil amendment, landfill disposal, incineration of a dewatered cake, and landfill disposal.

On the other hand, recently, as a more advanced processing method,
A method is employed in which sewage sludge incineration ash is compression-molded into a brick shape and fired to produce a product, or sewage sludge or sewage sludge incineration ash is melted at a high temperature to produce aggregate.

However, the production of these fired bricks and molten aggregates requires a large amount of heat and special equipment.

Further, sewage sludge or a mixture of sewage sludge incineration ash and cement used in the fields of civil engineering and construction considered to be suitable for large-scale treatment is not sufficient in terms of strength, and is not suitable for general use. is there.

In order to solve the above-mentioned problems, the present inventors conducted various experiments, and as a result, the following facts were found.

That is, the sewage sludge incinerated ash to which the polymer-based flocculant has been added, when kneaded with an acid, reacts and changes its shape into a rubbery state, and eventually becomes a clay-like substance. A hardened product is eventually obtained by hardening, but the sewage sludge incineration ash has a remarkable reaction with sulfuric acid. In addition, adding a polymer flocculant to the sewage sludge incineration ash usually involves a high water content of the concentrated sludge in the sewage treatment process, and it is not possible to apply the polymer flocculant to the dehydration step as it is. This is for obtaining dewatered sludge having a reduced water content.

In addition, although the composition of the sewage sludge incineration ash in each treatment plant is different, in the case of the sewage sludge incineration ash to which a polymer-based flocculant is added, the sewage sludge incineration ash is sufficiently mixed with sulfuric acid in an amount and concentration suitable for the composition. When kneading and drying, the reaction and action are not clear, but various sulfates are generated, and the water in the solution becomes crystallization water or the like, and the free water in the solidified product is very small. Therefore, even if this solidified product is left in water, the elution and absorption of acid are very small and stable for a long time.

Although a clay-like substance can be formed by using hydrochloric acid or phosphoric acid, the strength is considerably weaker than that using sulfuric acid, and sulfuric acid is inexpensive in price. It is.

[0012] Based on this fact, the present inventors have disclosed a solidified sewage sludge incinerated ash and a method for producing the same as disclosed in Japanese Patent Application No. 7-316392 on December 5, 1995.
Filed a patent application by date.

After that, the present inventors have filed a Japanese Patent Application No. 9-26980.
No. 1714, a method for producing a solidified sewage sludge incineration ash having higher quality and higher efficiency than that described in the specification of September 17, 1997
A patent application was filed on the 6th.

The sewage sludge incineration ash solidified product disclosed in Japanese Patent Application No. 7-316392 is composed of a kneaded product of sewage sludge incineration ash to which a polymer-based flocculant is added and acid. It is manufactured by kneading sewage sludge incineration ash to which a polymer-based flocculant has been added and a sulfuric acid solution, followed by drying.

A method for producing a solidified sewage sludge incineration ash disclosed in Japanese Patent Application No. 9-261714 is disclosed in Japanese Patent Application No. 7-261714.
When manufacturing the solidified sewage sludge ash disclosed in the specification of 316392, the temperature is adjusted so that the sewage sludge incinerated ash, acid, and kneaded material do not exceed a predetermined temperature.

The composition of the sewage sludge incineration ash used in each of the above applications is shown in Table 1, and the physical properties of the obtained sewage sludge incineration ash are shown in Table 2.

[0017]

[Table 1]

[0018]

[Table 2]

Of the specimens shown in Table 2, A-1, A-2,
A-3 is a solidified sewage sludge incinerated ash disclosed in the specification of Japanese Patent Application No. 7-316392, and B-1, B-2 and B-3.
Indicates a solidified sewage sludge incineration ash disclosed in Japanese Patent Application No. 9-261714.

[0020]

The solidified sewage sludge incinerated ash in each of the above-mentioned applications is superior in bending strength to ordinary cement-based solidified matter, but is light weight concrete and woody material in unit volume weight. , Heavy compared to plastic materials.

On the other hand, the solidified sewage sludge incineration ash has many applications that require lightness in addition to the demand for strength. In such a case, the solidified sewage sludge incineration ash has a unit volume of It is desirable that the weight is small.

In view of the above-mentioned circumstances, the present invention provides a sewage sludge incineration system which has a small unit weight and a high strength as compared with lightweight concrete and is capable of producing a high-quality sewage sludge incineration ash lightweight solidified product. An object of the present invention is to provide a method for producing a light-weight solidified ash.

[0023]

Processes leading to the invention The inventors of the present invention actually applied the method disclosed in Japanese Patent Application No. 9-261714 to produce sewage sludge incinerated ash solidified material, and foamed the kneaded material. It has been found that by mixing the agent to form bubbles, a lightly solidified sewage sludge incineration ash having a small unit weight is obtained.

[0024]

SUMMARY OF THE INVENTION According to the present invention, a method for producing a lightweight solidified sewage sludge incineration ash is provided by mixing and kneading a sewage sludge incineration ash to which a polymer-based flocculant is added, an acid and a foaming agent. A clay-like kneaded material containing a large amount of air bubbles is prepared, and the kneaded material is molded, air-dried, and solidified.

Further, the method for producing a lightly solidified sewage sludge incineration ash according to the present invention comprises mixing a sewage sludge incineration ash to which a polymer-based flocculant has been added and a foaming agent together with an acid, and kneading to form a large amount of air bubbles. A kneaded material containing clay is prepared, and a predetermined amount of the kneaded material is placed in a mold, heated, expanded, and solidified.

Therefore, in the present invention, the flexural strength is higher and the amount of acid is smaller than that of lightweight concrete, etc.
In addition, it is possible to produce a high-quality light-weight solidified sewage sludge incineration ash with a small unit volume weight corresponding to a wide range of shapes with a small amount of acid elution.

[0027]

Embodiments of the present invention will be described below.

Sewage sludge incineration ash 30 having the chemical composition shown in Table 1
The sulfuric acid solution previously prepared and stored in the room is added to gr, and mixed while cooling so that the temperature does not exceed 35 ° C. Here, the sulfuric acid solution is a mixture of 3.3 cc of concentrated sulfuric acid containing 97% sulfuric acid and 10 cc of water.

When the sewage sludge incineration ash and the sulfuric acid solution are uniformly mixed, a foaming agent is added and mixed so as to be uniform again.
Thereafter, the foaming agent was mixed with the uniformly mixed sewage sludge incineration ash and sulfuric acid solution to form a clay-like kneaded material containing bubbles.

As the foaming agent, powders which generate gas by water or dilute acid, for example, sodium hydrogen carbonate, aluminum powder, iron powder and the like are used.

When the kneaded material formed as described above is fully filled in a mold, molded, and left to cure naturally,
A lightweight solidified sewage sludge incineration ash containing bubbles is obtained.

Alternatively, when a kneaded material having a smaller volume than the volume in the mold is put in the mold and heated to a predetermined temperature, the kneaded material expands to fill the volume in the mold as the bubbles expand. In addition, a sewage sludge incineration ash lightweight solidified product that faithfully follows the shape in the formwork can be obtained. In this case, various weights of sewage sludge incinerated ash can be obtained over a wide range depending on the amount of clay-like kneaded material to be put in the mold or the degree of heating.

By the way, in order to know the physical properties of the sewage sludge incineration ash lightweight solidified material produced as described above, a width of 30 mm was used.
A test specimen having a length of 80 mm and a thickness of 10 mm was prepared and subjected to a comparative test.

Table 3 shows that each specimen A-1, A-2, A-
3, B-1, B-2, B-3 Sewage sludge incineration ash and sulfuric acid 9
The amounts of concentrated sulfuric acid containing 7%, water and a foaming agent (NaHCO ₃ ) are shown. Table 4 shows the specimens A-1, A-2, A-3 and B-
1 shows the physical properties of B-2 and B-3.

Specimens A-1, A-2, A-3
Is a mold in which a kneaded material containing uncured clay-like air bubbles is fully filled in a mold frame, cured by standing naturally, and then demolded.

For the test pieces B-1, B-2, and B-3, a kneaded material containing a small amount of uncured clay-like air bubbles smaller than the inner volume of the mold is placed in the mold. Covered with lid and about 9
The kneaded material was heated at a temperature of 0 ° C. for 10 minutes to expand and knead the kneaded material to fill the mold, and then removed from the mold.

In the case of the specimens A-1, A-2 and A-3, after being cured by natural standing, demolding is performed by incineration of sewage sludge having a shape faithfully following the shape of a mold without cracks or distortion. This is to obtain a light-weight solidified ash.

In the case of the specimens B-1, B-2, and B-3, the heating was performed by expanding the mold to fill the mold regardless of the amount of the kneaded material put in the mold. This is to obtain a lightly solidified sewage sludge incineration ash shape that faithfully follows the shape of the frame. In this case, by adjusting the amount of the kneaded material to be put into the mold, it is possible to obtain a light weight solidified sewage sludge incinerated ash with various unit weights over a wide range.

[0039]

[Table 3]

[0040]

[Table 4]

Originally, sewage sludge incineration ash containing a high molecular surface flocculant having a fine, porous shape and a large surface area is modified by a sulfuric acid solution and becomes a kneaded material containing a large amount of bubbles by a foaming agent.

Further, since the kneaded material is clay-like, it has a high degree of freedom in molding and can cope with various molding shapes.

Further, even when a fiber reinforcing material such as glass fiber is added to and mixed with the clay-like kneaded material, various molded shapes can be similarly obtained.

The kneaded material is sufficiently self-cured even when left naturally at normal temperature, so that a high-quality light-weight solidified sewage sludge incinerated ash can be produced.

As described above, when a kneaded material smaller than the volume of the mold is placed in the closed mold and heated to expand the mold completely, the mold is first placed in the mold. By adjusting the amount of kneaded materials to be put, it is possible to obtain light weight solidified sewage sludge incinerated ash with different unit weights of unit weight, and to produce light weight solidified sewage sludge incinerated ash with various bending strengths. Can be.

The obtained lightly solidified sewage sludge incineration ash is slightly acidic, has a lower water absorption than cement mortar, and is completely nonflammable because it is an inorganic material.

Example 1 In the following examples, all operations were performed in a room at a room temperature of 20 to 25 ° C.

The sewage sludge incineration ash 30 having the chemical composition shown in Table 1
gr, 3.3 cc of concentrated sulfuric acid containing 97% sulfuric acid and 10 c of water
c and mixed with the sulfuric acid solution left in the room while cooling in a cooled thick ceramic bowl so that the temperature does not exceed 35 ° C. 0.3 gr was added, and the mixture was mixed well again. The mixture was sheared and kneaded with a screw kneader to obtain a brown clay-like kneaded material containing many air bubbles.

Next, the kneaded material 1 obtained as shown in FIG.
Was fully filled in the mold 2, left in the room for 2 hours, and the demolded kneaded material was naturally cured and cured for 14 days thereafter.

As a result, a light brown solidified incinerated sewage sludge ash was obtained. This corresponds to the specimen A-1 in Table 5.

Similarly, the amount of sodium bicarbonate added is set to 0.1.
The weight was set to 15 gr and 0.45 gr, and a light-weight solidified sewage sludge incinerated ash was produced as shown in FIG. The sample with the added amount of sodium hydrogencarbonate of 0.15 gr corresponds to the sample A-2 in Table 5, and the sample with the added amount of sodium hydrogencarbonate of 0.45 gr corresponds to the sample A-3 in Table 5.

Specimens A-1, A-2, A-3 shown in Table 5
The change in pH when water was permeated into tap water is shown by the solid line A in FIG.

As shown in FIG. 3, each specimen A-1, A-
Even if the A-3 is infiltrated into tap water for 10 days, a large p
No H change occurred, which was caused by specimens A-1, A-2, A-
3 indicates less elution of acid from 3.

Example 2 30 gr of sewage sludge incineration ash having the chemical composition shown in Table 1 and 3.3 cc of concentrated sulfuric acid containing 97% sulfuric acid
And a sulfuric acid solution mixed with 10 cc of water and allowed to stand in a room while being cooled in a cooled thick ceramic bowl so that the temperature does not exceed 35 ° C. 0.3 gr of sodium was added, and the mixture was mixed well again. The mixture was sheared and kneaded with a screw kneader to obtain a brown clay-like kneaded material containing many air bubbles.

Next, as shown in FIG. 2, 25 gr of the kneaded material 1 thus obtained was put into the mold 2, and the lid 3 was closed, and 90 ° C.
The kneaded material 1 was expanded to fill the mold 2 and hardened at the same temperature for 10 minutes, and was released after reaching a strength at which it could be removed from the mold 2 as a molded product. After that, natural curing was performed for 14 days, followed by curing.

As a result, a strong brown light-weight solidified sewage sludge incineration ash was obtained. This corresponds to the specimen B-1 in Table 5.

The kneaded material 1 similarly produced as described above
The amount of sewage sludge incineration ash was lightly solidified as shown in FIG. When the amount of the kneaded material 1 is 20 gr, it corresponds to the specimen B-2 in Table 5, and when the amount of the kneaded material 1 is 30 gr, it corresponds to the specimen B-3 in Table 5.

Specimens B-1, B-2 and B-3 shown in Table 5
The change in pH when water was permeated into tap water is shown by the solid line b in FIG.

As shown in FIG. 3, each specimen B-1, B-
2, B-3 can be infiltrated into tap water for 10 days,
No H change occurred, which was caused by specimens B-1, B-2, and B-3.
This indicates that the elution of the acid from the gel was low.

[0060]

[Table 5]

[0061]

According to the method for producing a lightly solidified sewage sludge incinerated ash according to the present invention, various excellent effects can be obtained as follows.

I) The obtained lightly solidified sewage sludge incinerated ash containing a polymer-based flocculant has a unit weight per unit weight similar to that of lightweight concrete and the like, and has a higher bending strength and a higher water absorption than lightweight concrete and the like. The amount of acid used is small, and the amount of acid eluted is also small. For this reason, a high-quality sewage sludge incineration ash lightweight solidified product can be obtained.

II) Sewage sludge incineration ash Light-weight solidified products are produced based on sewage sludge incineration ash containing a polymer-based flocculant, an acid solution, and a foaming agent. The required substances are unnecessary, and no special equipment is required.

III) By adjusting the amount of the foaming agent or the weight of the kneaded material to be put into the mold, the sewage sludge incineration ash lightweight solidified material having various unit weights over a wide range can be obtained. Can be manufactured.

IV) No by-products are generated at the beginning of the drainage, and no heat is required unlike melting and sintering.
Therefore, no special consideration is required for the device and operation.

V) The sewage sludge incineration ash lightweight solid is clay-like immediately after kneading, has a molding freedom like plastic, and is hardened in a short time, so that it can be molded into various shapes. It is also possible to mix fiber reinforcing materials such as glass fibers.

VI) By controlling the temperature in accordance with the method of molding and the shape of the sewage sludge incinerated ash lightweight solid, it is possible to make the kneaded material hardening speed appropriate.

VII) The fully cured sewage sludge incineration ash lightweight solids are weakly acidic and do not elute harmful substances. Since it is an inorganic material, it is nonflammable and does not generate gas at normal temperatures. Furthermore, since the unit volume weight is increased as compared with untreated sewage sludge incineration ash, handling is easy and the volume is significantly reduced.

VIII) Sewage sludge incineration ash lightweight solids
Unlike cement, it is acidic, and is also effective as a material in an acidic atmosphere that cement is not good at. Even when used in combination with a fiber reinforcing material such as glass fiber as a composite material, an alkali-resistant fiber reinforcing material such as for cement is not required.

IX) The sewage sludge incineration ash can be made into a new acid-resistant, fire-resistant, high-strength, lightweight material that is treated with an acid and has a high degree of freedom of molding, without turning ash from sewage sludge into waste. It is possible to make effective use of resources and resources.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a mold and a kneaded material charged therein according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state before heating of a mold and a kneaded material placed therein in Embodiment 2 of the present invention.

FIG. 3 is a graph showing a state in which acid is eluted from sewage sludge incineration ash lightweight solid matter and the pH changes with time in an example of the present invention.

[Explanation of symbols]

 1 kneaded material 2 formwork 3 lid

Claims (2)

[Claims] 1. A sewage sludge incineration ash to which a polymer-based flocculant has been added and a foaming agent as well as an acid are mixed and kneaded to prepare a clay-like kneaded material containing a large amount of air bubbles. A method for producing a lightly solidified sewage sludge incinerated ash, which is formed, air-dried, and solidified. 2. A sewage sludge incineration ash to which a polymer-based flocculant has been added and a foaming agent as well as an acid are mixed and kneaded to form a clay-like kneaded material containing a large amount of air bubbles, and a predetermined amount of kneading is performed. A method for producing a lightly solidified sewage sludge incinerated ash, which comprises placing an object in a mold, heating, expanding and solidifying the object.