JPS6150646B2 - - Google Patents

Description

[Detailed description of the invention] Excess sludge from human waste treatment plants and sewage treatment plants has a large amount of organic components, so it is difficult to remove water by vacuum dehydration alone, and pressure dehydration is necessary. Tertiary treatment sludge generated from tertiary treatment equipment that uses so-called coagulation and sedimentation, which is treated by adding metal salts such as sulfuric acid, has a high water content if it is treated with a vacuum dehydrator alone, so pressurized dehydration is necessary even if it is to be incinerated or disposed of in a landfill. It is better to use them together to lower the moisture content. Furthermore, the freeze-thaw method is currently used in wastewater treatment equipment at water treatment plants, but depending on the water source of the water treatment plant, suspended solids may be low and may contain algae as a component.
Even if the sludge particles become coarse due to reformation caused by the freeze-thaw treatment, dewatering becomes difficult. In other words, even if this molten sludge is dehydrated using a vacuum dehydrator, the water content still remains low.
When squeezed by hand at a high rate of 75-80%, a considerable amount of water is squeezed out, which also requires pressure dehydration.
For this reason, sludge dewatering is generally carried out by continuously operating a dewatering apparatus that uses both vacuum dehydration and pressure dehydration.

On the other hand, in the treatment of sludge by the freeze-thaw method, a pair of freeze-thaw tanks are generally used to perform alternate freezing and thawing cycles, and one batch of molten sludge is discharged at the end of the thaw cycle. In this way, the freeze-thaw tank operates in batches and the dewatering equipment operates continuously, so the thawed sludge discharged from the freeze-thaw tank is temporarily stored in a storage tank and the required amount is continuously sent to the dewatering equipment. There is a need to. In other words, the basic flow of dewatering thawed sludge by the freeze-thaw method is as shown in Figure 1, and the sludge that has been alternately treated in a pair of freeze-thaw tanks 1 and 1' is discharged through the respective discharge valves 2 and 2'.
By opening the sludge, one batch of molten sludge is stored in storage tank 3.
The sludge is stored in the sludge supply pump P and continuously supplied to the dewatering device 4. By the way, the molten sludge is reformed and concentrated from fine particles to coarse particles, which improves its sedimentation properties and deposits at the bottom of the storage tank, so only the sludge around the suction pipe can be sucked, and the sludge supply pump P Therefore, it becomes impossible to continuously supply water to the dewatering device 4, which causes problems in the flow of sludge treatment. In order to prevent sedimentation of the reformed sludge in such a storage tank, it is generally done to stir the molten sludge in the storage tank using an agitator or circulate it using a circulation pump. Even in this case, considerably strong agitation is required to effectively prevent sedimentation of the reformed sludge. However, if the molten sludge is strongly stirred, the coarse sludge particles will be broken down and made finer again, which will promote clogging of the cloth in the dewatering equipment, resulting in a decrease in dewatering capacity and an increase in the water content of the dehydrated cake. However, if the agitation is weak, the effect of sedimentation will appear, and although the supply to the dewatering equipment will not become impossible, the concentration of the supplied sludge will become uneven, the thickness of the dehydrated cake will fluctuate, and the moisture content of the dehydrated cake will also be inconsistent. will occur.

Furthermore, regarding dehydration equipment that operates continuously, as mentioned above, depending on the nature of the sludge to be treated, a vacuum dehydrator alone is insufficient, and in the case of freeze-thaw sludge with a high moisture content, a low vacuum blower is used to reduce the It is desirable to use a continuous dehydration device that performs vacuum dehydration and then pressure dehydration.

The present invention provides a continuous system of sludge treatment equipment by disposing a storage tank between a freeze-thaw tank and a continuous dewatering device to solve the above-mentioned problems in molten sludge treatment. be. That is, the sludge treatment equipment according to the present invention includes at least a pair of freeze-thaw tanks provided to alternately perform freezing and thawing treatment cycles and discharge molten sludge at the completion of each thawing cycle; A rotating drum-type storage tank that receives the molten sludge and stores the coarse sludge particles without destroying them, a sludge delivery pump that draws out the stored molten sludge and continuously supplies it to a dewatering device, and an endless cloth belt that runs continuously. and a continuous dewatering device that receives the continuous supply of the molten sludge and performs low-vacuum dehydration using a vacuum blower in the first half, and pressurized dewatering using an endless pressure belt in the second half. It is characterized by this.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows the processing flow by the sludge treatment equipment of the present invention, in which at least one pair of freeze-thaw tanks 1, 1' alternately performs a freezing and thawing treatment cycle, and when the thawing cycle is completed, valve 2 or 2 is opened. ' is opened and the molten sludge flows into the inlet pipe 13.
through which it is discharged into a rotating drum type storage tank. Although this molten sludge contains coarse particles with a high water content, it is stored inside a storage tank that rotates at a slow speed without settling and condensing and without destroying the coarse particles. As shown in FIGS. 3 and 4, the rotating drum type storage tank is composed of a closed drum body 5 consisting of a body 6 and end plates 7, 7'. It is rotatably supported by a pair of guide rolls 9, 9, and is constructed so that a sprocket 10 on the outer periphery of the body 6 is driven to rotate at a slow speed by a deceleration motor 12 via a drive chain 11. The drum body 5 can receive one batch of molten sludge with about 40% of its volume, and is driven to rotate at a slow peripheral speed of 10 to 15 m/min. The end plate 7 has an inlet pipe 13 opened from the center of rotation into the drum body 5, and the inlet pipe 13 is connected to a freeze-thaw tank, and is used to collect one batch of molten sludge to be discharged. can be introduced into Also, the other end plate 7'
The sludge drawing pipe 15 of the sludge delivery pump 14 is introduced into the drum body 5 from the center of rotation thereof, and is suspended to open near the inner wall of the body 6. A perforated or non-perforated scraper plate 16 may be provided on the inner wall of the drum body 6 of the drum body 5 radially or slightly inclined at a required pitch, but in this case, a part of the scraper plate 16 is cut out and the part The open end of the sludge drawing pipe 15 is made to face. As the sludge delivery pump 14, it is advantageous to use a single-shaft eccentric pump that does not exert destructive force on coarse sludge particles of the molten sludge.

In the processing equipment of the present invention, the above-mentioned rotating drum type storage tank includes a pair of freeze-thaw tanks that perform batch processing by repeating freeze-thaw treatment cycles alternately, and a dehydration device that combines low vacuum dehydration and pressure dehydration that operates continuously. placed between. One batch of molten sludge that has completed the thawing cycle from the freeze-thaw tank is intermittently introduced into the drum body 5 through the introduction pipe 13,
On the other hand, the amount of molten sludge required for continuous operation of the dewatering apparatus is continuously drawn out by the delivery pump 14 through the sludge drawing pipe 15. During this time, the storage tank is driven to rotate at a slow speed, and the particles of molten sludge that are about to be deposited are constantly lifted up and repeatedly dropped as shown in FIG. 5 (a), (b), and (c). Therefore, sludge does not accumulate near the open end of the sludge drawing pipe 15, and the molten sludge is continuously drawn out while maintaining a substantially constant concentration. Furthermore, since the slow rotation of the drum body 5 does not destroy coarse particles of the molten sludge, the operation of the dewatering apparatus can be made extremely stable.

The details of the continuous dewatering device 4 in the treatment equipment of the present invention are as shown in FIG. Supply port 20
It is configured to run from the sludge cake outlet 21 toward the sludge cake discharge port 21. The inside of the vacuum dehydration tank 17 located on the lower surface of the cloth belt 19 is led to a low vacuum blower 23 through an intake opening 22 and also to a drainage opening 2.
4. It is led to a drainage conduit 26 via a water seal 25. The pressurized dewatering tank 18, which is also located on the underside of the cloth belt 19, is led via a drainage opening 27 and a temporary water storage tank 28 to a drainage conduit 26'. The endless cloth belt 19 is supported almost horizontally by a large number of support rolls 29 at the location of the vacuum dehydration tank 17, and is supported under pressure between a number of support rolls 30 and pressure rolls 31 at the location of the pressure dehydration tank 18. The cloth belt 19 and the pressure belt 32 are supported in a meandering manner together with the belt 32, and the cloth belt 19 and the pressure belt 32 are driven by the motor 32 at the same speed.

As described above, molten sludge is continuously supplied to the molten sludge supply port 20 of the continuous dewatering tank 4 from the rotating drum type storage tank, and the supplied sludge is first fed to the vacuum dewatering tank 17.
In the step, low-vacuum dehydration is performed using a blower 23, and the slurry is turned into a soft cake on an endless cloth belt 19 and transferred to a pressurized dehydration tank 18. Next, in the pressurized dewatering tank 18, the sludge in the form of a soft mud cake is compressed between the pressurizing belt 32 and the cloth belt 19 to perform pressurizing dewatering, and the dehydrated cake is sent to the sludge cake outlet 21.
is continuously discharged from

As is clear from the above explanation, according to the sludge treatment equipment of the present invention, by disposing a rotating drum type storage tank between a freeze-thaw tank that performs batch treatment and a dewatering device that performs continuous treatment, By using a continuous dewatering device that has both low-vacuum dehydration and pressure dehydration functions, extremely stable continuous dewatering of molten sludge has become possible.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the basic flow of freeze-thaw sludge treatment, Figure 2 is an explanatory diagram of the entire sludge treatment equipment of the present invention, and Figures 3 and 4 are rotating drums forming part of the equipment of the present invention. A partially cutaway side view and a front view of the mold storage tank, Figure 5 A, B, and C are views of the molten sludge inside the rotating drum body, and Figure 6 is a continuous dewatering device that constitutes a part of the equipment of the present invention. FIG. 1, 1'... Freeze-thaw tank, 2, 2'... Discharge valve,
3... Storage tank, 4... Dewatering device, 5... Drum body, 6... Body, 7, 7'... End plate, 8... Foundation, 9... Guide roll, 10... Sprocket, 11 ... Drive chain, 12 ... Deceleration motor,
13...Introduction pipe, 14...Sludge delivery pump, 15
... Sludge drawing pipe, 16 ... Scraping plate, 17 ... Vacuum dehydration tank, 18 ... Pressure dehydration tank, 19 ... Endless cloth belt, 20 ... Melted sludge supply port, 21 ... Sludge cake discharge port, 22...Intake opening, 23...Low vacuum blower, 24...Drainage opening, 25...Water seal part,
26, 26'...Drainage pipe, 27...Drainage opening,
28... Temporary water tank, 29, 30... Support roll, 31... Pressure roll, 32... Pressure belt,
33...Motor.

Claims (1)

[Claims] 1 At least a pair of freeze-thaw tanks provided to alternately carry out freezing and thawing treatment cycles and discharge molten sludge upon completion of each thaw cycle; A rotating drum-type storage tank that stores molten sludge particles without destroying them, and a sludge delivery pump that draws out the stored molten sludge and continuously supplies it to a dewatering device.
A continuous dewatering system that has an endless cloth belt that runs continuously, receives the continuous supply of the molten sludge, performs low vacuum dewatering using a vacuum blower in the first half, and performs pressure dewatering using an endless pressurizing belt in the second half. A sludge treatment facility characterized by being equipped with a device in one system.