JPH0152080B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of drying sludge in a drying treatment tank, and aims to significantly accelerate the drying rate and to do so in an energy-saving manner.

[Conventional technology]

Conventional methods for drying sludge include filling a filter bed with sludge water, draining the water from the filter bed, and drying it by evaporation under the sun. A method is used in which the solid-liquid is separated by providing a solid-liquid.

[Problem to be solved by the invention]

When using the above conventional method, the sludge in the sludge water that has been pumped will settle over time and separate into clear supernatant water and sludge, and a vertical concentration gradient will occur in the sludge due to gravity and filtration. In addition to preventing moisture from moving downward, dehydration progresses locally on the sand surface, creating a highly concentrated, impermeable layer several centimeters thick, which impedes filtration and dehydration.

According to a measurement example, when the sludge height is 40 cm after 2 days of sludge filling, the average concentration is 3.1%, the concentrations in the upper, middle, and lower layers are 1.9%, 2.2%, and 5.2%, and the concentration on the filter bed surface is 14.2%. It was %.

For this reason, in conventional solar drying beds, the proportion of water removed by filtration and dehydration is small, generally 20-40%, 20-40% by supernatant water discharge, and 30-40% by evaporation.
It will be 40%.

As described above, the proportion of water removed by evaporation is large, and the amount of evaporation is small at 3.5 to 7 mm/day in summer and 1.5 mm/day or less in winter, so drying takes time. The present invention was made in view of such evaporation conditions.

[Means to solve the problem]

In order to solve the above-mentioned problems, this invention has a sludge treatment tank having several permeable filter beds arranged in parallel. Air agitation by the air blowing means provided in the machine, scraping of the impermeable sludge layer on the filter bed surface by a fixed plate installed on the machine as the machine moves, and mixing and stirring with the sludge water by the above-mentioned blown air. After the filtration and dehydration treatment is completed, the sludge is sequentially promoted to generate cracks by making cuts and to accelerate evaporative drying by scraping off the dry surface layer.

[Effect]

The sludge spread on the filter bed is prevented from settling due to the peeling of the impermeable layer due to the movement of the fixed plate and air agitation, and dewatering is promoted.

Further, after the filtration and dehydration treatment is completed, evaporative drying is promoted by making incisions in the sludge layer and scraping off the drying surface.

〔Example〕

The sludge drying method of the present invention will be explained below based on embodiments shown in the drawings.

The means for promoting filtration, dehydration, and drying of the present invention is as shown in FIG. Consists of. The traveling machine used here utilizes a traveling machine system that travels over tanks in plating equipment, sedimentation tanks for sludge treatment, and the like. Air is the best way to stir sludge water efficiently, so if you run the traveling machine back and forth across the entire width of the filter bed while blowing air out of several air pipes, uniform agitation can be achieved with a small amount of air. The sludge concentration in the vertical direction becomes uniform.

Furthermore, it is necessary to remove the highly concentrated, water-impermeable layer formed on the filter bed surface, but for this purpose, scraping with a fixed plate is reliable, and no power other than the power of the traveling machine is required. The poorly permeable sludge scraped off by the fixed plate is pulverized by air agitation and is homogenized with the surrounding sludge.

With this filtration and dehydration promoting means consisting of the air pipe 1 for air blowing and the fixed plate 2, the traveling machine starts running while the sludge is being filled, so no supernatant water is produced, but generally the height reaches 100 cm within 10 days. If you are stuck in
25 to 10 cm and a concentration of 2 to 5% becomes 15 to 25%.

Figure 2 shows experimental data for several types of sludge at a travel distance of 10 m.

In this way, the amount of air in the filtration and dehydration promoting means in the traveling machine is 100 to 200 Nl/min per 1 m width, which is 10 m.
When running, the amount of air required is 10 to 20 Nl/min ^per square meter, which is extremely energy-saving.
The distance that can be traveled varies depending on the sludge, and is generally 10
~20m.

Also, the amount of water removed until the end of filtration and dehydration is 90 to 95.
% is the amount of filtration and dehydration, and is also relative to the total amount of water removed.
It accounts for 80-85%. Therefore, the amount of water removed by evaporation of the amount of water removed by filtration is 15 to 20%.

When the viscosity of the sludge d increases and almost no filtrate is produced (at the end of filtration and dehydration), this traveling machine lifts the filtration and dehydration accelerator, moves to the next tank, fills it with sludge, and starts reciprocating travel. do. The sludge that has undergone the previous filtration and dewatering process is evaporated and dried.
Cracks begin to appear after ~3 days. In this way, when cracks begin to appear in the sludge, the traveling machine is moved to this tank again, and the vertical cutting attachment of the evaporative drying accelerating means attached to the traveling machine, for example, by the claw 3 as shown in Fig. 3a, is used to artificially cut the sludge. By creating a crack in
Evaporation is promoted by increasing the size and number of cracks to increase the evaporation area. This vertical cutting attachment is removably attached to the traveling machine.
It shall be removed during the filtration and dehydration promotion process.

Furthermore, since only the portion of the sludge exposed to the air dries rapidly after that, layer cutting is performed using the layer cutting plate 5 as shown in FIG. 3b.
Promotes evaporative drying.

Furthermore, in winter, the surface of the sludge during evaporation drying freezes and thaws repeatedly, resulting in a fine powder of 1 to 2 cm.
It is covered by a layer of This layer prevents moisture movement from inside the sludge due to capillary reduction, so evaporation hardly progresses. Therefore, the dried sludge powder is further scraped off using a scraping plate 6 as shown in FIG. 3C to promote evaporative drying. The warp cutting attachments, for example, the claws 3, the plate 5 for layer cutting, and the plate 6 for scraping, can be attached separately to a rod hanging vertically on the traveling machine or to the air pipe 1 for feeding air, or can be used for layer cutting. It also serves as a plowing attachment and a vertical cutting attachment, and it is detachably carried on the traveling machine so that its mounting angle can be changed depending on the purpose of use. It is.

By employing such means for accelerating evaporative drying, the evaporative drying period is reduced to 3/4 to 2/3 in the summer and 1/3 to 1/2 in the winter compared to the case where the product is left to stand after filtration and dehydration.

Figure 4 shows an example of a traveling machine incorporating these air pipes and a fixed plate, which carries the air pipe and a fixed plate in place of the vertical cutting attachment, layer cutting plate, and skimming plate, and moves over the processing tank. This figure shows an example of a reciprocating traveling machine. Figure A is a side view of one tank pulled out, Figure B is a front view of Figure A, and Figure C is a plan view of multiple tanks arranged in parallel. be. Fourth
In the figure, 7 is a truck driven by a traveling motor M1 and runs on rails 8, 8, and an air blowing pipe 1 (for sending compressed air by a blower 9) is carried on this truck 7. The blowing pipe 1 (which branches off the main blowing pipe 1a into branch pipes) is moved as the truck travels. In addition, the trolley is equipped with a hoisting motor M2 to raise and lower a group of air pipes to enable movement between each floor.
Moreover, the blowing position of the air blowing pipe 4 is adjusted. By moving the traveling machine forward in this way, the poorly permeable sludge layer that forms on the filter bed surface is scraped off by the fixed plate, and the air blown in through the air pipe mixes with the sludge water to promote filtration. do. In C of the same figure, processing is performed in tank B, and when the processing in this tank is completed, the process moves to tank C and tank D, and when the processing in tank D is completed, the process returns to tank A.
In this way, when cracks begin to appear in the sludge, the traveling machine is moved to this tank again, and the vertical cutting attachment of the evaporative drying accelerating means attached to the traveling machine, for example, by the claw 3 as shown in Fig. 3a, is used to artificially cut the sludge. By creating cracks in the gas, the cracks are made larger and more numerous, increasing the evaporation area and promoting evaporation. When cracks occur in the sludge and become larger, when the mounting angle of the attachment is changed and the traveling machine is run further, this attachment acts as a layer cutting plate to cut the layers as shown in Figure 3a. Furthermore, if pulverized dried sludge powder is formed on the surface of the sludge during evaporation drying, it will impair evaporation drying and must be removed.
This dried sludge powder is used as a scooping plate by changing the angle of the attachment to remove the sludge powder. This layer cutting and clearance is performed by reciprocating movement of a traveling machine. This is done sequentially in each tank.

In the present invention, the drying process in one tank is carried out extremely efficiently, so that the drying process in all the tanks can be completed in an extremely short period of time.

〔Effect of the invention〕

According to the present invention, the filtration and dewatering action is promoted by stirring by blowing air and peeling off the hardly permeable sludge layer by the moving fixed plate, and at the same time, the sludge after the filtration and dewatering treatment is provided with incisions and the drying surface is Since evaporative drying is promoted by scraping, etc., drying can be carried out effectively. Further, since the sludge layer is scraped off by a fixed plate attached to the moving machine, it is possible to save energy without requiring special power.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the principle of the present invention, Figure 2 is a diagram of experimental data, Figure 3 a, b, and c are process diagrams.
FIG. 4A shows an example of the apparatus, and is a side view of one tank, FIG. 4B is a front view, and FIG. 4C is a plan view. 1 is an air blowing pipe, 2 is a fixed plate, 3 is an attachment (for vertical cutting), 4 is an air pipe (for vertical cutting), 5 is a plate (for layer cutting), 6 is a plate (for skimming), 7 is a trolley , 8 is the rail, 9 is the blower.

Claims (1)

[Claims] 1. In a sludge treatment tank with several permeable filter beds arranged in parallel, a traveling machine is installed so as to be movable to each filter bed in turn, the filter beds are filled with sludge water, and air is supplied by an air blowing means provided in the traveling machine. Stirring, scraping of the poorly permeable sludge layer on the filter bed surface by a fixed plate installed on the moving machine, promotion of filtration and dewatering by mixing and stirring the sludge water with the blown air, and filtration and dewatering. A sludge drying method characterized by sequentially performing on sludge after treatment, creating cracks by making cuts and promoting evaporative drying by scraping off the dry surface layer.