JP2000061496A - Sludge solidifying treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily solidify sludge even when organic matter is contained therein by mixing cement and gypsum into the sludge. SOLUTION: Sludge whose water content is adjusted is pulverized as necessary, and is kneaded with, which adding a suitable amount of water according to the water content of the sludge, cement and gypsum and is fed into a suitable mold to solidify it, thereby it can be treated as solid matter having a suitable shape. At this time, the total weight of both the cement and gypsum is set at about 300 kg per 1 m3 sludge. A weight ratio of the gypsum is set at about 10-50%, thereby the strength of the solid matter can be sufficiently enlarged. And a ratio of the weight of water to the total weight of both the cement and gypsum is set at about 150%, thereby the consistency or the slump is enlarged to enable to obtain good workability. Furthermore, as the cement, portland cement or the like can be used, and as the gypsum, natural gypsum, flue gas desulfurization gypsum, waste gypsum board waste material for building, or the like can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge solidification treatment method capable of easily solidifying sludge which is difficult to treat.

[0002]

2. Description of the Related Art Settled sludge generated from water purification plants and wastewater treatment plants, accumulated sludge accumulated in dam lakes, organic sludge containing pulp waste liquid generated from paper mills, sludge generated by dredging work at ports ( Hereinafter, simply referred to as sludge) is a fluid containing a large amount of water, and is extremely troublesome to handle.

Therefore, it is usual that such sludge loses its fluidity by being dried in the sun and is carried into an industrial waste treatment plant for disposal.

[0004]

According to the prior art, sludge has a transportation cost for transporting it to an industrial waste treatment plant and is easily re-fluidized by rainwater so that it is permanently solidified. There was a strong demand for establishment of a treatment method. It is difficult to solidify sludge only with cement, because the hydration reaction of cement is generally hindered by the contained organic matter.

Therefore, in view of the problems of the prior art, an object of the present invention is to provide a sludge solidification treatment method capable of easily solidifying the sludge by mixing the sludge with cement and gypsum. .

[0006]

The gist of the structure of the present invention for achieving the above object is to mix cement and gypsum with sludge.

The water content of the sludge may be adjusted before mixing the cement and gypsum.

Water may be added together with cement and gypsum.

The gypsum may be hemihydrate gypsum or dihydrate gypsum.

[0010]

According to the structure of the invention, the sludge can be easily solidified by mixing an appropriate amount of cement and gypsum, and can be molded into any solid material. That is,
Gypsum can accelerate the hydration reaction of cement,
Sludge can be quickly cured together with cement.

The amount of cement or gypsum used should be appropriately determined for sludge. Set against sludge 1 m ³ cement, the entire combined weight of gypsum to about 300 kg, by setting the weight ratio of gypsum to about 10-50%, it is possible to sufficiently increase the strength of the solid By setting the weight ratio of water to about 150% with respect to the total weight of cement, gypsum, the consistency and slump can be increased and good workability can be obtained. In addition to cement, other than Portland cement,
It is possible to use mixed cement such as blast furnace cement, silica cement, fly ash cement, special cement such as alumina cement and super rapid hardening cement. As the gypsum, in addition to natural gypsum and chemical gypsum, flue gas desulfurization gypsum generated in the desulfurization process of a thermal power plant, gypsum board waste material for construction, and the like can be used.

The sludge can be improved in handleability by adjusting the water content. Note that the sludge has a water content of 25 to 25 in addition to being dried in the sun, by adding slaked lime or mechanically removing water by using a filter press.
It is recommended to adjust the water content to about 50%.

By adding water together with cement and gypsum, the whole slump can be adjusted arbitrarily, and optimum workability can be realized regardless of the water content of sludge.

When gypsum is hemihydrate gypsum, the quality of hemihydrate gypsum is stable and the solidification reaction is easily controlled.

If gypsum is gypsum dihydrate, gypsum dihydrate can be flue gas desulfurization gypsum, gypsum board waste material, etc.
The cost required can be reduced.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The treatment procedure of the sludge solidification treatment method is as shown in FIG.

That is, the sludge is sun dried in the sun drying yard and the water content is adjusted appropriately. The sludge whose water content has been adjusted is crushed as needed, and together with cement and gypsum, an appropriate amount of water is added and kneaded according to the water content of the sludge, and the mixture is put into an appropriate mold and solidified to obtain an arbitrary shape Can be treated as a solid.

FIG. 2 shows a compounding example of the solid specimens 1, 2, ...
And the compressive strength F is shown in FIG. However, FIG. 2 and FIG.
In the above, sludge is sedimentation sludge of a water purification plant, and C1, C
2 and W are the unit amount of cement, hemihydrate gypsum, and water (kg / m ³ ) per 1 m ³ of sludge, respectively. Further, the solid line in FIG. 3 shows the compressive strength F at the age of 6 days or 7 days in the case of moisture curing in air, and the one-dot chain line shows the age of 27 days or 2 days.
The compressive strength F after 8 days is shown. The compressive strength F was measured using a cylindrical test piece having a diameter of 10 cm and a length of 20 cm based on the compressive strength test of JIS A 1108 concrete.

That is, the total unit amount of cement and gypsum for 1 m ^{3 of} sludge is C = C 1 + C 2 = 300 kg / m ³ ,
By setting the amount of hemihydrate gypsum C2 / C = 10 to 50%,
Compressive strength F ≧ 1.3N / mm ² , F ≧ 5.5Fa =
It was possible to obtain 5.5 × 0.235 N / mm ² . However, Fa = 0.235 N / mm ² is the minimum strength required for traveling of the dump truck when used as backfill soil. Further, by setting the water cement ratio W / C≈150%, the slump S≈19 to 27 cm, and good workability could be obtained.

Incidentally, in the specimens 1 to 8 of FIG. 2, the expansion coefficient δ smoothly changes with solidification depending on the amount of hemihydrate gypsum C 2 / C (FIG. 4). This is because cement is shrinkable and expands when gypsum is mixed in. Therefore, the expansion rate δ of the solid matter is set by setting the hemihydrate gypsum amount C2 / C≈30%.
≈0 can be achieved, and good dimensional accuracy can be realized and a large compressive strength F can be realized (FIG. 3). The expansion rate δ is such that the maximum expansion rate at C2 / C≈50% is about 1 / the maximum contraction rate at C2 / C≈0%.
It is 3 to 1/5. Therefore, C2 / C≈25
By setting to ~ 45%, compressive strength F ≧ 3.3N /
It is possible to secure mm ² and suppress the expansion coefficient δ to be small.

The sludge may be solidified using gypsum dihydrate instead of gypsum hemihydrate (FIGS. 5 and 6). However, in FIG.
In FIG. 6, the sludge is the sedimentation sludge of the water purification plant, and C1
, C3, and W are the unit amounts of cement, gypsum dihydrate, and water (kg / m ³ ) per 1 m ³ of sludge, respectively. Further, the solid line in FIG. 6 shows the compressive strength F at the age of 7 days in the case of moisture curing in air, and the alternate long and short dash line shows the compressive strength F at the age of 28 days. The compressive strength F is JIS
According to A 1108, the same cylindrical specimens as the specimens 1 to 8 were used for measurement.

That is, even if gypsum dihydrate is used, it is possible to easily realize a compressive strength F that is substantially the same as that when gypsum hemihydrate is used. Also, the expansion coefficient δ at this time is not much different from the case where hemihydrate gypsum is used.

Since the sludge solidified in this manner has a sufficiently high compressive strength F, it can be crushed and used as a backfill material, a roadbed material or the like. It can be appropriately molded and used as it is as various secondary products. The sludge may be kneaded together with cement and gypsum at the construction site and used as it is as a paving material, backfill material, filling material, or the like.

The present invention is suitable for solidification treatment of various types of sludge such as sedimented sludge generated from water purification plants and wastewater treatment plants, accumulated sludge accumulated in dam lakes, organic sludge from paper mills, sludge and the like. Can be applied.

[0026]

As described above, according to the present invention, by mixing cement and gypsum into sludge, the sludge solidifies to a sufficiently high strength through the gypsum and cement even if it contains organic substances. Therefore, there is an excellent effect that sludge can be easily treated as a reusable solid substance having a predetermined strength.

[Brief description of drawings]

[Figure 1] Process diagram

Figure 2 Chart showing characteristic data (1)

FIG. 3 is a diagram (1) showing characteristic data.

FIG. 4 is a diagram showing characteristic data (2)

FIG. 5 Chart showing characteristic data (2)

FIG. 6 is a diagram showing characteristic data (3)

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Claims (5)

[Claims] 1. A method for solidifying sludge, which comprises mixing cement and gypsum into the sludge. 2. The sludge solidification method according to claim 1, wherein the water content of the sludge is adjusted before the cement and the gypsum are mixed. 3. The method for solidifying sludge according to claim 1, wherein water is added together with cement and gypsum. 4. The method of solidifying sludge according to claim 1, wherein the gypsum is hemihydrate gypsum. 5. The method for solidifying sludge according to claim 1, wherein the gypsum is gypsum dihydrate.