JPS58128197A - Stabilizing method of soft and weak sludge - Google Patents

Abstract

PURPOSE:To stabilize soft and weak sludge effectively in a short time by adding a solidifying agent consisting of specific ratios of portland cement, water soluble carbonates of alkali metal gypsym, calcium aluminate compds. and potassium sulfate to the soft and weak sludge in specific amts. CONSTITUTION:A compsn. consisting of 20-95wt% portland cement or mixed cement, 1-20wt% water soluble carbonates of alkali metal, for example, sodium carbonates, etc., 1-30wt% gypsum or the like, for example, dihydrate, 3-30wt% calcium aluminate compds., for example, commercial aluminum cement is defined as a component A. 0.01-5pts.wt. potassium sulfate based on 100pts.wt. the component A is defined as a component B. The cement-based solidifying agent consisting of the component A and the component B is added to soft and weak sludge contg. large amts. of org. materials at 1-30pts.wt. based on 100pts. wt. the sludge, whereby the stable solids are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an extremely effective stabilization method for soft sludge containing a large amount of organic matter, such as sewage, purified water sludge, beet sludge, urban river sludge, and the like.

In recent years, relatively weak sludge has been stabilized to make it easier to handle during transportation, and soft ground has been assimilated and stabilized for roads.

A method of adding lime and cement-based assimilating agents has been used to enable the construction of various buildings such as park facilities, factories, and residences. At present, there are few methods that satisfy these requirements.

It is difficult to assimilate sludge containing organic matter using cement or mixed cement alone, and many methods have been proposed, including adding hardening accelerators such as calcium chloride, lime, and sodium aluminate to cement, and adding gypsum to generate ettringite. However, stable assimilates cannot be obtained by adding small amounts.

For example, 3010' as a special clinker.

A technique has been disclosed in which ettringite is produced by mixing 3-stone 203.01804 and insoluble type 1 water gypsum with cement (Japanese Patent Laid-Open No. 56-92145). However, these clinkers and auxiliaries are generally expensive, and the balance between economy and performance is not necessarily satisfactory.

The present invention is intended to improve these points,
That is, 100 parts by weight of high-organic soft sludge is mixed with 20 to 95 parts by weight of Portland cement or mixed cement as component A.
% by weight, water-soluble alkali metal carbonate 1-20% by weight, gypsum 1-30% by weight, calcium aluminate compound 3-30% by weight, and potassium sulfate 0.01-5 parts by weight per 100 parts by weight of component A. This is a method for stabilizing soft sludge, which is characterized by adding and mixing 1 to 30 parts by weight of a cement-based assimilating agent having a composition of eight components.

Water-soluble alkali metal carbonates include sodium carbonate monobicarbonate and potassium carbonate.

Bicarbonate or a mixture thereof is suitable, and the amount thereof is 1 to 20% by weight, especially 2 to 20% by weight in the cement solidifying agent A component.
15% by weight is preferred. If the amount is less than 1% by weight, there is no effect of carbonate addition, and if it exceeds 20% by weight, the rapid setting property becomes strong, but the final strength decreases, and it is also economically unfavorable.

As the gypsum, anhydrous salts can be used in addition to the usual dihydrate salts and hemihydrate salts, but dihydrate salts which are easily available are particularly advantageous.

The blending amount thereof is 1 to 30% by weight, preferably 2 to 20% by weight of the assimilating agent A component. If it is less than 1%, the effect is weak.
If it exceeds 30% by weight, the strength of the solidified product will decrease.

Calcium aluminate compound has molecular formula X-01
0, Y-A? A commercially available alumina cement (Y/X ratio 0.6) is an example of an easily available composition that uses a composition in the range of Os (0,2<Y/X<2).

The blending amount is 3 to 30% by weight, preferably 5 to 20% by weight of the assimilating agent A component. If it is less than 3% by weight, the effect is small, and if it exceeds 30% by weight, it is uneconomical and the curing reaction is accelerated. This makes operations such as uniform mixing difficult.

The cements that make up the majority of assimilates are ordinary Portland cement, early strength Portland cement, etc.
Further, any mixed cement such as blast furnace cement or fly ash cement may be used.

Preferably, it is selected from ordinary Portland cement, early strength Portland cement, Class A blast furnace cement, and Class 8 blast furnace cement.

The daily ingredient potassium sulfate is 0.0% per 100 parts by weight of component A.
The amount is from 0.01 to 5 parts by weight, preferably from 0.01 to 3 parts by weight, and if it is less than 0.01 parts by weight, the effect will be weak, and if it exceeds 5 parts by weight, it will be difficult and uneconomical to add the slurry. When adding to sludge, it is preferable to add it in powder form, but in some cases it may be added and mixed in a slurry form.

The assimilation mechanism of the cement-based assimilation agent used in the present invention seems to be not much different from conventional products in terms of ettringite production, but it is unique in that sufficient compressive strength can be observed within a few hours.

That is, when about 10% of assimilating agent is added to sludge with a moisture content of about 80%, the time required to obtain a solidified product with the same compressive strength is reduced to about 1/4 of that of conventional products. The development of this strength is thought to be mainly due to the mutual effect of the metal carbonate and potassium sulfate, but the objective cannot be achieved even if one of the five components is missing, or with a mixing ratio other than the above. .

In terms of economy, it is extremely advantageous because gypsum dihydrate can be used, and gypsum produced as a by-product in various processes can be used, and only a small amount of solidifying agent can be used for cement. Such characteristics are suitable for solidifying high-organic soft sludge, which is difficult to solidify and tends to become a source of pollution. i.e. cement and plaster.

Conventional assimilation agents combined with lime, etc., have low water content,
It is effective for sludge with a low organic content, but the organic content is 10% by weight or more of the solid content.

In particular, it contains 15% by weight or more, and the water content is 30% by weight or more,
In particular, the effect was small on sludge with a high moisture content of 50% by weight or more and a high organic content, but according to the method of the present invention, stabilization is quickly achieved and a ground suitable for transportation and construction can be obtained.

The addition ratio of the assimilating agent to the sludge used in the method of the present invention varies depending on the organic content, water content, and the degree of improvement aimed at, but is usually 1 to 30 parts by weight per 100 parts by weight of sludge.
Preferably it is 5 to 25 parts by weight. All percentages in the following examples are percentages by weight.

Example 1 100 parts by weight of sludge from a sewage field in the eastern part of Amagasaki City (water content: 81%, organic matter content in solid content: 51%) was collected, and 12.5 parts by weight of each of assimilating agents and incineration ash of various compositions were added and mixed. death,
Fill a mold with a diameter of 50 = 111i and a width of 100.
The wide range 1.1 axial compressive strength was measured at a constant temperature of .degree. Table 1 shows the results.

Example 2 100 parts by weight of Amagasaki car reduction sludge (moisture content 76%, organic matter content in solid content 22%) was collected and placed in a polyethylene container with a capacity of 200 C. Experimental sample 2 used in Example 1 was collected. A penetration test was carried out in accordance with the method of JIS K2530-76 by adding an assimilating agent and Portland cement, etc., and culturing in a constant temperature room at 25°C. The results are shown in Table 2.

Test conditions: temperature 25°C, load 1001J.

Penetration time 5 seconds

Claims (1)

[Claims] Component A in 100 parts by weight of high-organic soft sludge: 20-95% by weight of Boltland cement or mixed cement Water-soluble alkali metal carbonate 1-20% by weight Gypsum lI
1 to 30% by weight Calcium aluminate compound 3 to 30% by weight Component B; Potassium sulfate 0.01 to 100 parts by weight of Component A
A method for stabilizing soft sludge, which comprises adding and mixing 1 to 30 parts by weight of a cement solidifying agent having a composition of 5 parts by weight.