JPS5834420B2 - Koukasei Soseibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses construction bentonite waste mud water and sewage sludge burnt ash, which are generated in large quantities and are extremely difficult to treat.
This invention relates to a method for treating construction bentonite waste water, which aims to utilize it effectively through extremely simple treatment.

BACKGROUND ART Conventionally, when various special construction methods using bentonite mud (for example, methods such as beds, reverse circulation, continuous walls, and mud shields) are employed during construction, a large amount of waste bentonite mud is discharged.

This bentonite waste mud water is a colloidal dispersion of bentonite with a water content of about 85 to 95% at the time of initial construction, and is mixed with a dispersant (e.g., sodium ligninsulfonate) and a thickener (e.g., carboxymethyl cellulose). CMC, etc.) and has a specific gravity of approximately 1.05~
It is about 1.20, but after the construction is completed,
Because it comes into contact with the local ground, gravel, silt, clay, etc. are mixed in.
In addition, various metal cations and even cement materials are mixed in from the contact ground, and the more the liquid is recirculated, the more
The liquid composition becomes complex and exhibits a gelation phenomenon, making separation of water and solid content extremely difficult.

Therefore, since solid-liquid separation is not possible in the treatment of such waste mudwater, it is necessary to dilute it with a large amount of water and perform extremely complicated water treatment operations such as coagulation and sedimentation, filtration, and dewatering. Currently, construction companies are at a loss as to how to dispose of waste muddy water, as the treatment costs are prohibitive, and there is no use for the separated solids, and there are few suitable disposal sites. It is.

On the other hand, those involved are having difficulty disposing of the ash obtained by incinerating the large amounts of sewage sludge produced at sewage treatment plants, as there is no suitable use for it or a place to dispose of it.

Therefore, the present invention has been made with attention to the current situation, and aims to convert sewage sludge with high water absorption into waste bentonite slurry for construction with a moisture content of 70% or more, with or without adding cement. The present invention provides a method for treating construction waste water characterized by adding and mixing burnt ash.

The details are described below.

In this invention, the bentonite waste mud water for construction (hereinafter abbreviated as waste mud water) refers to one or two of the following: sand and gravel, silt, clay, various metal ions, cement materials, dispersants, thickeners, etc.
It is a muddy water with an extremely complex composition in which more than one species coexist, usually has a water content of 70% or more, and contains bentonite, making solid-liquid separation extremely difficult. is obtained by firing sewage sludge at a temperature of usually 1000°C or higher, with a porosity of 70φ or higher and a true specific gravity of 2.98.
It is a powdery substance with a water absorption rate of about 80%, and has an extremely high water absorption rate.

Therefore, if waste mud water and fired ash are mixed, the moisture in the waste mud water is absorbed by the fired ash, and at the same time, the solid content in the waste mud water causes a solid phase reaction with the fired ash, and solidifies by curing. do.

In this invention, a curable composition can be obtained by simply mixing and curing waste mud water, which is extremely difficult to separate from solid-liquid, and fired ash, which does not solidify even by adding water, thereby simultaneously solving the drawbacks of both. The curable composition obtained is a fill cementing material or its raw material, or
Since it is useful as a raw material for low-strength injection mortar, the effects of this invention are significant, considering not only the simple processing method but also the usefulness of the resulting composition. it is obvious.

The term "fill cement material" as used herein refers to a material that has a compressive strength of 2 h/- or more when compacted and cured in wet conditions for 7 days.

Low-strength injection mortar has a viscosity of 400 at 20°C.
0 to 5000 cps, the breathing rate after 3 hours after mixing the raw materials is 5% or less, and the compressive strength increases depending on the number of days of curing, and the compressive strength after 28 days is 2-5#/c
Refers to something that is on a song.

In order to obtain a low-strength injection mortar from the curable composition obtained by the method of the present invention, it is sufficient to mix an appropriate amount of cement by adjusting the amount of calcined ash mixed depending on the bentonite content.

For example, 400 to 280 Ay of calcined ash and 200 kf of cement may be mixed per 1 m3 of waste mud water having a bentonite content of 20 to 50 ky/m'.

Further, in order to form fill cement, the amount of mixed burned ash may be adjusted so that the value of moisture/(burned ash + bentonite) is about 0.75.

If high strength is desired, a hydraulic material such as cement, quicklime or calcined gypsum may be added.

Therefore, if the mixing ratio of waste mud water and fired ash in this invention and the amount of hydraulic material added are adjusted appropriately,
Cured compositions exhibiting arbitrary properties can be obtained.

Example 1 A low-strength pouring mortar was obtained by mixing 1 l of bentonite liquid wastewater with a bentonite content of 43.5 ky/m3, 3.8 l of calcined ash, and 2 kg of cement.

The physical properties were as follows.

That is, the viscosity at 20°C is 4500 c
ps Pleasing rate after 3 hours 0.63 Multi-compression strength is as shown in Table 1.

Table 1 Moist curing days Compressive strength ky/cd 72.2 14 4.328
7,556
10.7 Example 2 1 (l) of bentonite waste slurry having a bentonite content of 42 ky/m3 was mixed with 13 i' of burned ash to obtain a fill cement material.

The compressive strength of this sample after wet curing is shown in Table 2.

Table 2 Wet curing days Compressive strength ky/crti32.5 73.0 14 3.328
3.756
4.9 Example 3 A soil cementing material was obtained by mixing 10 tons of bentonite waste mud with a bentonite content of 44 h/rn', 12 tons of burned ash, 9 and 0.6 # of calcined ash.

The compressive strength of this sample after wet curing is shown in Table 3.

Table 3 Wet curing days Compressive strength kf/c12
13.0 7 16.5

Claims (1)

[Scope of Claims] 1. A method for treating construction bentonite waste water, which comprises adding and mixing burnt ash of sewage sludge to construction bentonite waste water. 2. A method for treating construction bentonite waste water, which comprises adding and mixing together cement and burned ash of sewage sludge with construction bentonite waste water.