JPS59145100A - Caking method for sewage sludge - Google Patents

Abstract

PURPOSE:To accelerate the development of strength after hardening, by mixing 100pts.wt. Portland cement, 5-50pts.wt. specified aluminum sulfate, 5-50pts.wt. gypsum and 0-3pts.wt. a hardening retardant in sewage sludge. CONSTITUTION:A cement composition is prepared by mixing 100pts.wt. Portland cement, 5-50pts.wt. aluminum sulfate whose main component is represented by Formula I (wherein n is 9-30), 5-50pts.wt. gypsum and 0-3pts.wt. a hardening retardant with each other. Said cement composition in an amount of 5-20wt% based on sludge is added to sewage sludge, and the sewage sludge is caked by maturing it for 1-3 days. Aluminum sulfate represented by Formula I pref. contains the main component in an amount above 30wt% in terms of 3Al2O3.4SO3. As said retardant, a gluconate is esp. preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for solidifying sewage sludge.

In recent years, with the spread of sewage treatment facilities, the amount of sludge discharged from sewage treatment facilities, that is, sewage sludge, has increased rapidly, and its disposal has become a problem. 2. Methods for disposing of sewage sludge include landfill disposal, incineration and landfill disposal, effective use, and composting, but currently incineration is used for economic reasons. most often end up in landfills.

In addition, when disposing of sludge in a landfill, conventionally the sludge was disposed of at sea or land without any treatment. Recently, methods of solidifying sludge and disposing of it in landfills have been attracting attention.

Water sludge is the sludge that is generated when urban sewage is purified, and its properties vary slightly depending on the properties of the wastewater flowing into the sewer and the purification method, but generally the water content is 65 to 65.
It is characterized by an extremely high content of 85% by weight, and a high content of organic matter in the solid content of 20-90% by weight.

When such sewage sludge is solidified and disposed of in a landfill, an appropriate amount of solidifying agent is added to the sludge, mixed with a mixer, cured for 1 to 3 days, and then the hardened material is transported by truck.
The waste will be dumped in a landfill and cleared using wetland bulldozers. In addition, if there is an incineration plant for water sludge nearby, some of the incinerated ash is added to the sludge in order to reduce the water content of the sludge, and a solidifying agent is further added to solidify it before it is disposed of in a landfill. However, in this case, the amount of solidifying agent added can be reduced.

In the past, all that was required was to solidify this sewage sludge as quickly as possible, for example, it was necessary to have enough supporting capacity to operate a wetland bulldozer 3 to 7 days after mixing, but recently, the following As such, there is a growing demand for solidification characteristics that take into account the destruction of the structure of the cured product due to transport, dumping, etc. That is, the solidification treatment method (kneading and 1
~3 days later), the strength is such that it can be transported by truck (--axial compressive strength of O, 1 kgf/cm').
(more than
After 0 days, the supporting force (-axial compressive strength-(0.5 kg g f /
cm' or higher) is now required.

As mentioned above, sewage sludge has a high moisture content, so it cannot be assimilated even if ordinary cement is added, and a special solidifying agent is required to solidify it. Many solidification materials have been developed for not only sewage sludge but also industrial waste, but depending on these known solidification materials,
Even once solidified, the structure of the cured product, such as the network structure of ettringite needle crystals that is formed completely in the early stage of hardening, is destroyed due to mechanical impact or compression when carried out by truck or dumped, and it continues to recrystallize over a long period of time. As a result, the subsequent development of strength is extremely slow, or the desired strength is not developed even after a long period of time.

The main object of the present invention is to provide a novel assimilation material that can withstand the above-mentioned harsh conditions and rapidly develops desired strength, and a method for assimilating sewage sludge using the same. It is.

The above object is achieved by the present invention - that is, for aqueous sludge, portland cement ioo s: part, the main component is of the general formula: % formula % [where n is 9 or 30 aluminum sulfate 5] This can be achieved by a method for solidifying water sludge, which is characterized by adding a cement mixture containing ~50 parts by weight, 5 to 50 parts by weight of gypsum, and 0 to 3 parts by weight of a hardening retarder. .

Next, the present invention will be explained in detail.

In the present invention, as the Portland cement, ordinary Portland cement, early strength Portland cement, ultra early strength Portland cement, moderate heat Portland cement, etc. can be used. These cements may be used as a single type or as a combination of four types.

Furthermore, the main component of the aluminum sulfate used in the present invention has the general formula 3AKL203*4S03·nH2O.
(In the formula, n is 9 or 30). In this aluminum sulfate, it is desirable that the content of the above-mentioned main components is 30% by weight or more as 3A203.4SO3. Main component content is 3A sentence 203・
Although it is possible to use 4S03 containing 30% by weight non-cat, in that case it is necessary to increase the amount added in order to bring the strength of the cured product to a practically sufficient level. It will be economically disadvantageous.

The particle size of aluminum sulfate used in the present invention varies depending on the properties of the target sludge, but generally ranges from 0°001 to 0.000°.
The thickness is preferably 1 mm. If the particle size is smaller than 0.001 mm, the curing force will proceed faster than necessary, as will be described later, making it difficult to achieve the object of the present invention. Also, 0
．． If l/X is larger than 1 mm, the reaction becomes extremely slow, which is disadvantageous in practice. Furthermore, it is desirable that the particle size of this aluminum sulfate be uniform in terms of ease of controlling the curing rate.

In addition, common aluminum sulfates other than those listed above include:
It is difficult to achieve the objective of the present invention. For example, easily soluble aluminum sulfate (for example, one whose main component is A. Because the reaction is extremely fast and almost complete before the cured product is transported, the resulting structure is destroyed between the time the cured product is transported and the rolling compaction, and the subsequent formation of a structure due to the ettringite production reaction occurs. I can't expect much.) Therefore, in this case, there is no choice but to rely on Portland calcium cementate hydrate to develop long-term strength, and early construction of a landfill site is impossible.

゛] The second point is that anhydrous aluminum sulfate [main component: A2 (SO4)a]. Or grilled meat buns [Main ingredient: KA
JI (SOa) 3], etc., can be used in almost the same way.

The gypsum used in the present invention can be arbitrarily selected from any of the following forms: anhydrite, hemihydrate, and aqua regia.・Also natural gypsum, chemical gypsum (phosphate gypsum,
Gypsum such as flue gas desulfurization gypsum (fluoric acid gypsum, titanium gypsum, etc.) can also be used. The fineness of these gypsums is desirably 2800 crr+'/g'- or less in Blaine specific surface area.

A setting retarder is not essential in the cement formulation for solidifying sewage sludge used in the present invention. however,
If the hardening of sewage sludge by the solidification treatment method of the present invention progresses too quickly, especially if the ettringite production reaction progresses too much before the hardened material is transported or dumped, the hardening rate can be increased by using a hardening retarder. can be adjusted.

As curing retarders used for the above purposes, gluconate-based ones are particularly desirable, but commonly used curing retarders such as polyol complex-based, oxycarboxylate-based, lignin sulfonate-based, alkylaryl sulfonate-based, etc. Retarders can also be used. Although these retarders can be used in liquid or powder form, they are preparative with Portland cement, aluminum sulfate, and gypsum! Powdered products are desirable from a practical standpoint, such as when using kongo.

The Portland cement/aluminum sulfate gypsum (hardening retardant) based cement mixture used as a solidifying agent in the present invention is composed of the above-mentioned components. , each component is in a specific proportion, i.e. 10 parts of Portland cement
5 to 0 parts by weight of aluminum sulfate of the above general formula
50 parts by weight, 5 to 50 parts by weight of gypsum, and 0 to 50 parts of hardening retardant.
It is necessary that the amount is 3 parts by weight.

In the present invention, the method of solidifying sewage sludge using the Portland cement/aluminum sulfate/gypsum (hardening retardant)-based mixture described in "-" is usually carried out by adding A method is used in which 20% by weight of the above-mentioned formulation is added and cured for 1 to 3 days. The cured material is then transported, dumped in a landfill, and compacted. The amount of the solidifying agent added to the sewage sludge is desirably selected based on the water content and organic matter content of the sludge to be solidified. When the water content and organic matter content of sludge are high, it is generally desirable to increase the amount added. Note that when incineration ash is used in combination when hardening sewage sludge, the water content of the sludge is reduced, so the amount of solidifying agent added can be significantly reduced. Therefore, the combined use of incinerated ash can be said to be particularly advantageous.

When the cement composition (solidification material) of the present invention is added to sewage sludge or a mixture of it and incineration ash, it is assumed that acicular crystals of ettringite are gradually generated through a reaction as shown in the following formula. This reaction lasts for a relatively long period of time, for example up to 10 days after crosstalk.

13Ca (OH) 2+3AJ120a ・4SO3
・ nH26+5 (CaSO4・mH2O) Jubun H2
0+ 3 (3CaO*Al2O3~3CaS
O4" 30-32 H20) Such a network structure of ettringite crystals partitions and includes the solid content of sewage sludge and incineration ash, and is further generated by hydration of calcium silicate in Pol I land cement. It is presumed that the calcium silicate hydrate that is used in this process will develop strength that lasts for an even longer period of time.

In the above reaction formula, Ca (OH) 2 is produced by the water utilization reaction of lime compounds in Portland cement, and 3Au203@4SO3* nH2
O, Ca5o4*mH2O and H2O are supplied from aluminum sulfate, gypsum and sewage sludge, respectively.

Therefore, when solidifying sewage sludge using the cement mixture of the present invention, if the blending ratio of Portland cement is too small, Ca (OH) required for the above reaction will be lost.
2 is 3AJlzO3# 4S03@nH2O and Ca
There will be a shortage of 5O,,*mH2O, and an excess of 3 A Jl 203・4503*nH2O
and Ca5Oa I mH2O remain as unreacted substances, making it difficult to generate ettringite necessary to form a sufficient network structure. Moreover, the amount of calcium silicate hydrate produced, which is necessary for developing long-term strength, is also insufficient. On the other hand, if the blending ratio of Portland cement is too high, 3Au203 @4so3@n'H2 necessary for the above reaction
Since the amounts of O and Ca S OaφmH 2 O are relatively insufficient, the amount of Etrin guide produced is insufficient.

In addition, in the case where the cement composition of the present invention contains a hardening retardant, the hardening reaction mechanism and the appropriate blending ratio of each component in a system where it is added to sewage sludge or a mixture of it and incineration ash are described. The effect of the curing retarder is almost the same as the case without the curing agent, but due to the effect of the curing retarder, the initial curing speed due to the cement mixture is not slowed down slightly, and the subsequent strength development is improved.

The appropriate proportion of the hardening retarder varies depending on the type of retarder and the properties of the sludge, but it is usually 0.5 to 11 parts of Portland cement Lot) as described above.
~3 parts by weight is desirable. Even if more than 3 parts by weight is blended, the effect may not be much different from that when less than 3 parts by weight is blended, or in some cases, it may not be possible to completely heat solidify.

The solidification material of the present invention having the configuration described above can be applied to sewage sludge that has a high water content and a large content of organic matter. The sewage sludge to which the solidifying agent of the present invention has been added has a hardened material structure contained in its initial hardened material.
Even if the hardened material is destroyed by impact during transportation or dumping, the structure of the hardened material is quickly regenerated after being dumped, so that the hardened material quickly becomes the desired strength before it is rolled and leveled.

In addition, the cured product obtained by adding the solidification material of the present invention to sewage sludge exhibits practically sufficient initial strength as well as excellent long-term strength, making it an effective landfill material for the early construction of sea-surface and land-based landfills. becomes.

Next, Examples and Comparative Examples of the present invention will be shown.

[Example 1] 100 parts by weight of ordinary Portland cement, aluminum sulfate (containing 3A 203Φ4S03/9H20 (7) m
: 3 A n 203” 4 S O3 L'T
: 75% by weight, average particle size 0.01mm) 20 parts by weight and gypsum phosphate (double salt, acid content of SO3 46.2% by weight, Blaine specific surface area 4200 cm'/g)
A solidifying formulation containing 30 parts by weight was prepared.

300 g of this blend was added to 2 kg of sewage sludge with a water content of 79.8% by weight and an organic matter content of 62.7% by weight in the solid content, and thoroughly kneaded. This kneaded material was placed in a polyethylene acid bag, sealed, and cured for 2 days in a constant temperature room at 20° C., and then kneaded according to JIS A1216 (Axial compression test method for soil). This re-kneading was carried out in a laboratory on the assumption that the structure of the cured product would be destroyed during the period from transportation of the cured product to rolling and leveling.

When the -axial pressure line strength was measured using some of the samples after this kneading, it was found to be 0.3 kg f/cm'
The results were obtained.

The remaining sample after kneading was packed into a cylindrical mold with a diameter of 50 m x 1% and a size of 100 m, the upper part of which was sealed with a polyethylene film, and then further cured in a thermostatic chamber at 20°C.

After 7 days had passed after kneading, the specimen was demolded and the unconfined compressive strength of the cured product was measured, and it was found to be 0.6 kg f /
cm' results were obtained.

[Example 2] The sewage sludge of Example 1 was changed to sewage sludge with a water content of 82.9% by weight and an organic matter content of 84.2% by weight in solid content, and the amount of solidification compound added was changed to 400g. A cured product was obtained in the same manner as in Example 1 except for the above.

The unconfined compressive strength of the sample immediately after being kneaded and the cured product 7 days after being kneaded was 0.3 kgf/cm' and 0.6 kgf/cm', respectively.
A result of cm' was obtained.

[Example 3] The sewage sludge of Example 1 was treated with a water content of 72.4% by weight and an organic matter content in the solid content of Ji 23.8, mainly 23. A cured product was obtained in the same manner as in Example 1, except that the sludge was changed to water sludge and the amount of the solidifying compound added was changed to 160 g.

When the unconfined compressive strength was measured for the obtained sample immediately after kneading and the cured product 7 days after kneading and kneading, the results were 0, 4 kgf/cm', and 0.9, respectively.
The result was k g f / cm'.

[Examples 4 to 6] 100 parts by weight of ordinary Portland cement, 20 parts by weight of aluminum sulfate (same as described in Example 1), 30 parts by weight of phosphogypsum (same as described in Example 1), A solidifying formulation containing 1 part by weight of sodium gluconate (commercial product, industrial grade) was prepared.

300 g [Example 4], 400 g [Example 5] and 160 g [Example 6] were added to 2 kg of sewage sludge of Examples 1, 2, and 3, respectively, and A cured product was obtained by the same treatment. ? T
When the axial compressive strength of the cured product was measured, the results shown in Table 1 were obtained.

Table 1 Immediately after kneading 7 days after kneading 4 0.2 0.85
0.2 0.86 0.3
1.0 [Examples 7 to 10] Portland cement l-100 parts by weight, Mt H aluminum (3Al, 03*4SO3-9H20tr) content: 3 8bun, 56% by weight as 03.4803, average particle size 0. An assimilation formulation was prepared by blending 40 parts by weight of 01 mm) and 15 parts by weight of flue gas desulfurization gypsum (industrial water salt, S03 content: 45.9% by weight, Blaine specific surface area: 3200 cm'/g).

However, Portland cement Portland cement [Example 7] 2, early strength Portland cement [Example 8], ultra early strength Portland cement [Example 9], and moderate heat Portland cement [Example 10] were used.

A cured product was obtained in the same manner as in Example 1 using 300 g of these blends. The unconfined compressive strength of the obtained cured product is shown in Table 2.

Immediately after kneading on the 2nd table 7 days after kneading 7 0, 3, 0,,
780, 3-0
, 89 0, 4 0.91
0 0, 2 0.6 [Examples 11 to 14] 100 parts by weight of Giltland cement, 40 parts by weight of aluminum sulfate (same as described in Examples 7 to 10), flue gas desulfurization gypsum (Examples 7 to 14) 15-fold nail part (same as described in LO), and sodium gluconate (commercial product,
A solidifying formulation containing 1 part by weight (industrial use) was prepared.

However, Portolan!・What about cement? Y-type Portland cement [Example 11], early strength Portland cement [Example 12], ultra early strength Portland cement [Example 13], and moderate heat Portland cement [Example 114] were used, respectively.

A cured product was obtained in the same manner as in Example 1 using 300 g of these blends. The axial compressive strength of the obtained cured product is t
It is shown in Table 53.

Table 3 Immediately after kneading 7 days after kneading 110.20.8 12, 0.2 0.913
, 0.3 '1.014 0
,．． 2 0, 7 [Example 15.16] 100 parts by weight of Tingtong Portland cement, aluminum sulfate (3AM, O, -4SO, -30H20 content:
3 Al 20 g "4 S Oa To L Te" 50% by weight, average particle size 0.02 mm) 30 parts by weight,
- and phosphogypsum (same as described in Example 1)
) 30 parts by weight of a solidifying formulation [Example 15],
Also, 100 parts by weight of ordinary Portland cement, aluminum sulfate (3A AC 203.4 S O3" 30
H20 (7) content: 30 parts by weight as 3A Bun 2o3/4S03, average particle size 0.02 mm), 30 parts by weight of phosphogypsum (same as that described in Example 1), and sodium gluconate ( A solidification formulation [Example 16] containing 1 part by weight (commercial product, industrial use) was prepared.

A cured product was obtained in the same manner as in Example 1 using 300 g of these blends. [Example 15] and [Example 16]
The axial compressive strength of the cured product immediately after kneading is 0, 3 kg f/cm' and 0.2 k, respectively.
gf/crn', 0 and 6, respectively, 7 days after kneading
k g f / cm' and 0,8 k g f
/cm'-c was there.

[Examples 17-21 100 parts by weight of kobold land cement, 20 parts by weight of aluminum sulfate (same as described in Example 1), 2 parts by weight of gypsum
4 to 30 parts by weight and sodium gluconate (commercial product,
An assimilation formulation containing 1 part by weight (industrial) was prepared.

However, as for the gypsum, 24 parts by weight of gypsum distinate (anhydrous salt) [Example 17], 25 parts by weight of calcined gypsum (hemihydrate salt) [Example 18], 3 parts by weight of natural gypsum (technical water 1i) [ Example 19
], 30 parts by weight of titanium gypsum (industrial water salt) [Example 20], and 30 parts by weight of flue gas desulfurization gypsum (industrial water salt) [Example 21] were used, respectively. The Blaine specific surface areas of these plasters were all within the range of 2,800 to 3,000 cm'/g.

300 g of these blends and 200 g of sewage sludge incineration ash (the following sewage sludge incinerated at 750°C) were mixed into sewage sludge with a water content of 80.6% by weight and an organic matter content of 79.6% by weight in the solid content. 2 kg' and thoroughly kneaded. Thereafter, a cured product was obtained in the same manner as in Example 1. When the unconfined compressive strength of the obtained cured product was measured, the results shown in Table 4 were obtained.

Table 4 Immediately after kneading 7 days after kneading 17 0.2 0.818
0.3 0.719 0.2
0.820 0.3 0.
821 0, 2. 0,9 [Examples 22 to 26] 100 parts by weight of ordinary Portland cement, 40 parts by weight of aluminum sulfate (same as described in Example 1), 15 parts by weight of phosphogypsum (same as described in Example 1) Assimilation formulations were prepared containing 0.5 parts by weight and 0.5 to 2.0 parts by weight of a set retarder.

However, as the curing retarder, 1 part by weight of a polyol composite type (commercial product, industrial use) [Example 22], 1 part by weight of an oxycarboxylate type (commercial product, industrial use) [Example 23] ], lignin sulfonate-based products (commercial products,
Industrial use) 1 part by weight [Example 24], gluconate type (commercial product).

0.5 parts by weight (for industrial use) [Example 25] and 2.0 parts by weight of the same gluconate salt (commercial product, industrial use) [Example 26] were used, respectively. Using 300 g of these blends, a cured product was obtained in the same manner as in Example 1. Table 5 shows the unconfined compressive strength of the obtained cured product.

Table 5 Example Uniaxial compressive strength of cured product (kgf/am')
Immediately after kneading Nerigaeshi “・7 days after 22 0
．． 3 0.523 0.3
10.724 0.3 0.6
25 0.2 0.8 [Comparative example 1~
5] Early strength Portland cement, aluminum sulfate (3A text. Content of 03-4SO3 9H20 = 3A text. 75% by weight as 03Fist 4S03, average particle size 0.01 mm),
A solidifying formulation was prepared by adding phosphogypsum (salt water, S03 content: 46.2% by weight, Blaine specific surface area: 4200 cm'/g). However, the mixing ratio of each compounding component was as shown in Table 6.

Table 6 I II II [110000 2100253 3100325 41006060 505050 Note) ■: Strong Portland cement ■: Aluminum sulfate ■: Phosphate gypsum Using 300 g of these blends, a cured product was obtained in the same manner as in Example 1. .

When the uniaxial compressive strength of the obtained cured product was measured, the results shown in Table 7 were obtained.

Table 7 Immediately after kneading 7 days after kneading i <o, i <o, t2
0.2. 0.33 0.2
0.24 0.3 0
．． 35 <0.1 <0.1 [Comparative Examples 6-7] Parts by weight of ordinary Portland cement hloo, 40 parts by weight of aluminum sulfate (same as those described in Examples 7-10), phosphogypsum (Example 1) (same as described in )1
A setting formulation containing 5 parts by weight and 5.0 parts by weight of a cure retarder was prepared.

However, as a curing retardant, sodium gluconate 2.
(commercial product, industrial use) [Comparative Example 6] and polyol composite type (commercial product, industrial use) [Comparative Example 7] were used.

A cured product was obtained in the same manner as in Example 1 using 300 g of these blends. The strength of the cured products of [Comparative Example 6] and [Comparative Example 7] is O, 1 kgf/c for both immediately after kneading.
m' or less, 7 days after kneading, respectively O, 3 kgf/
cm' and 0.1. kgf/cm' or less.

[Comparative Examples 8 to 12] 100 parts by weight of early-strength Portland cement, 40 parts by weight of various aluminum sulfates, phosphogypsum (same as described in Example 1), and sodium gluconate (commercial product, industrial use) A solidifying formulation containing the following was prepared.

However, as aluminum sulfate, 18-hydrate aluminum sulfate (commercial product, industrial use, main component A-2 (SO
4) 3.1.8H20) [Comparative Example 8] Anhydrous aluminum sulfate (18-hydrate aluminum sulfate at 500'C!
2 (SC) a) 3) [Comparative Example 9], alumite powder (naturally produced, main component K 20 ・3)
A l 203' 4 S O3'' 6H20) [Comparative Example 10], Yakimeban (alumite powder heated to 150°C,
Main component KA (SO4)2) [Comparative Example 11], Sodium Alunite (from Tenzu, main component Na2O* 3Au203)
@4S03*6H20) [Comparative Example 12] was used.

A cured product was obtained in the same manner as in Example 1 using 400 g of these blends. Table 8 shows the unconfined compressive strength of the obtained cured product.

Table 8 Immediately after kneading After kneading 70 8 0.2 0.29,
0.3 0.310 0.2
0.211 0.3
0.312 0.2 0.2
Patent Applicant Ube Industries Co., Ltd. Agent Patent Attorney Yasuo Yanagawa Procedural Amendment April 28, 1982 Patent Application No. 17541 2 Title of Invention Method for solidifying sewage sludge 3
Relationship with the case of the person making the amendment Patent applicant 4, agent 6 Number of inventions increased by amendment None We will amend the "Detailed description of the invention" column of the specification as follows.

Record Also good.

(2) Sulfuric acid on page 8, line 7 → Sulfuric acid (2)
Page 12, line 20 It's not a little late, → m-work on the lid (2)
Page 21, line 2 Phosphoric gypsum → Dan-ugly gypsum or higher

Claims (1)

[Claims] 100 parts by weight of Portland cement per 1° water sludge, main component - General formula: % formula % [where n is 9 or 30] Aluminum sulfate 5 to 50 1. A method for solidifying sewage sludge, which comprises adding a cement mixture containing parts by weight of gypsum, 5 to 50 parts by weight of gypsum, and 0 to 3 parts by weight of a hardening retardant. 2゜The content of the main component of the aluminum sulfate is 3Al. The solidification treatment method for F water sludge according to claim 1, characterized in that the amount of F water sludge is 30% by weight or more as 03/4S03. 3゜The curing retardant compound is Boltland Cememet 10.
The method for solidifying sewage sludge according to any one of claims 1 to 2, characterized in that the amount is 0.5 to 3 parts by weight relative to 0 parts by weight. A method for solidifying sewage sludge according to any one of claims 1 to 3, characterized in that incineration ash of 4°C water sludge is used in combination with the cement mixture.