JP2005324076A - Sludge dehydrator and sludge flocculating/concentrating tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that an existing pressure dehydrator (filter press) is excellent in terms of dehydration performance since sludge is pressurized satisfactorily, but the equipment is complicated and the amount of the dehydrated sludge is increased since it is necessary to use a large quantity of an inorganic flocculant. <P>SOLUTION: The filtration surface of this pressure dehydrator (filter press) having a static filtering body is formed from a metallic material and vibrated when sludge is dehydrated. As a result, the dehydrated cake on the filtration surface can be exfoliated continuously while restraining the dehydrated cake from being clogged on the filtration surface. A high-molecular flocculant is added to the low-concentration sludge, in which a sedimentation promoting auxiliary such as an active carbonized material is mixed, just before the low-concentration sludge is supplied to a rotary flocculating/mixing tank having a metallic material-made filtration surface. As a result, the sludge can be not only flocculated efficiently but also concentrated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a sludge dewatering machine and a sludge aggregation tank in a wastewater treatment facility.

The proportion of low-concentration sludge in industrial waste is high, and its reduction and effective utilization technology are required. In the conventional technology, the pressure-type dehydrator (filter press) has the highest dewatering capacity, the water content of the dewatered cake can be reduced most, and the addition effect of slaked lime, which is used as a flocculant, has low odor and is easy to use effectively. It is evaluated as a machine.

There are many cases of sludge generated from small-scale wastewater treatment facilities in local governments and private companies that are in the state of concentrated sludge or are treated for industrial waste without concentration. If the dehydration process can be performed, the equipment investment can be recovered in a short period of time compared with the current industrial waste treatment cost. In addition, by improving odor countermeasures and fertilizer effects of dehydrated cake, farmland can be returned near each small-scale wastewater treatment plant, so a sludge decentralized recycling system can be realized.

The existing pressure dehydrator (filter press) is superior in dewatering capacity because it can sufficiently pressurize sludge compared to the belt press type and screw type, but it has a filtration surface clogging and filtration resistance due to dehydrated cake. In order to increase, the supply of sludge is stopped for each batch, and the cleaning process of the filtration surface and the delamination process of the dehydrated cake are required. As a result, the pressure dehydrator has a problem of complicated facilities. In addition, in order to improve the peelability of the dehydrated cake, it is necessary to use a large amount of inorganic flocculants such as slaked lime and ferric chloride (about 50% in terms of solids), so operation is difficult and sludge after dehydration There is also a problem that the amount increases.

There is an example in which a concentrator for various low-concentration sludges (Patent Document 1) has been developed, and a dehydrator is installed at the subsequent stage of the concentrator. However, existing pressurized dehydrators are expensive to construct and require additional facilities such as a dewatering cake conveyor, sludge storage tank, and deodorization equipment. Due to the complexity of the equipment and the need for maintenance, many small-scale sewage treatment plants do not have dewatering equipment and are often treated with industrial sludge without concentrated sludge or without concentration.

If sludge can be easily converted into a dehydrated cake without any hassle, it can be used as a fertilizer, etc. as a farmland reducing agent, and recycling of the dehydrated cake is realized.

As a prior patent, a vibration dehydrator used for draining seed swollen with water has been filed (Patent Document 2), but the structure is completely different from the dehydrator of the present invention. In addition, although a method for separating solid sludge such as feces from organic concentrated wastewater such as livestock manure has been filed (Patent Document 3), it relates to a treatment system and not to the structure of the apparatus.

Patent No. 2929528 Sludge Concentration Method and Apparatus Japanese Patent Application No. 8-238654 Vibration Dehydrator Patent application 2000-145851 Organic thick wastewater treatment method and apparatus

In order to solve the above problems, the present inventor conducted a basic study of a sludge dewatering machine with a fixed filter body, and used a filter cloth as a metal filtration surface and vibrated it to suppress clogging on the filtration surface. It was confirmed that the dehydrated cake on the filtration surface could be continuously peeled off.

In addition, by supplying low-concentration sludge mixed with a sedimentation improvement aid such as a polymer flocculant or activated carbide to a swirl type sludge agglomeration concentration tank, the sludge, the polymer flocculant and the sedimentation improvement aid are It was confirmed that coagulation and mixing can be carried out efficiently, the coagulation and sedimentation of the sludge is amplified, and the highly concentrated sludge and the clear separation liquid can be taken out efficiently.

If the sludge concentrated in the sludge agglomeration concentration tank of the present invention is supplied to the dehydrator of the present invention, it becomes a dehydrator capable of continuous pressure dehydration with a simple structure due to the filtration improvement effect of the settling improvement aid, Since the dehydration with a high weight-reducing effect can be performed with a small amount of the polymer flocculant, the operation of the dehydrator becomes easy.

The invention of claim 1 includes a dehydrator housing that surrounds the filter body, collects the filtrate and discharges it to the outside, and a dewatering cake discharge port for discharging the dehydrated cake in the downstream portion of the filter body. A dehydrator with a filtrate outlet for discharging the filtrate in the housing and a sludge supply port for receiving low-concentration sludge into the filter body. By adjusting the pressure difference with the filtrate chamber created between the machine housing and the water head of 2 to 20 m, the sludge is continuously pressurized and dehydrated without clogging the pores or slits of the filter medium. It is an invention.

In the sludge filtration and dehydration, the pores or slits of the filter body are easily clogged because the solid sludge aggregates on the filtration surface. Further, the aggregated solid sludge obstructs the approach of the filtrate to the filtration surface, and the continuation of the filtration becomes increasingly difficult. However, by vibrating the filtration surface, sludge aggregation on the filtration surface can be prevented, and the route of the filtrate can be secured.

However, when the pressure on the inner surface of the filter body is too high, the density of the solid sludge on the filtration surface becomes extremely high, and the filtrate cannot reach the filtration surface. This makes the sludge dehydration operation impossible. On the contrary, if the pressure on the inner surface of the filter body is too low, the filtration time becomes long and the dewatering of the sludge becomes insufficient. Therefore, it is necessary to adjust the pressure difference between the inner surface of the filter body and the pressure on the filtrate side to an appropriate value of 2 to 20 m.

A method for adjusting the pressure on the inner surface of the filter body will be described. When the filter body is sealed and the dewatered cake outlet on the upstream side of the filter is throttled, the amount of filtrate discharged is controlled by the control valve at the filtrate outlet. The sludge pressure on the inner surface of the body and the differential pressure on the filtrate side can be adjusted. There is no special control valve at the outlet of the dehydrated cake, but the pressure loss during the discharge of sludge passing from the upstream side to the downstream side of the filter as dehydrated cake is large, and the inner surface of the filter is pressurized. It will be in the state.

The invention of claim 2 differs from the invention of claim 1 in the pressure control method for the inner surface of the filter body. The filtrate extraction side is open to the atmosphere, and a control valve is attached to the dewatered cake outlet. When the opening of the control valve is reduced to reduce the amount of the dehydrated cake extracted, the pressure on the inner surface of the filter increases due to being pushed by the sludge supplied from the upstream of the filter. The filtrate comes out of the pores or slits of the filter body, and the pressure rise is suppressed accordingly, but there is resistance to the filtrate passing through the coagulated sludge layer on the inner surface of the filter body and the pores or slits of the filter body, The pressure in the filter body is maintained. On the other hand, when the opening degree of the control valve is increased and the amount of the dehydrated cake extracted is increased, the pressure inside the filter body is released and the pressure is reduced.

Next, a method for applying vibration to the filtration surface will be described. The filtration surface of a conventional pressure dehydrator uses a filter cloth, whereas the dehydrator of the present invention uses a steel material such as punching metal or wire mesh. For this reason, when vibration is applied by the vibration device, vibration energy is sufficiently transmitted to the filtration surface.

There are two methods for applying vibration to the filtration surface: a method of vibrating the entire dehydrator, that is, the filter body and the dehydrator housing together, and a method of vibrating only the filter body. In the former method, the entire dehydrator is placed on a vibrating table. Alternatively, the entire dehydrator is placed on an elastic body, and a vibration device is attached to the dehydrator housing to apply vibration. Use a flexible joint to connect the sludge supply piping, filtrate extraction piping, and dewatering cake extraction piping so that the vibration of the dehydrator does not affect the surrounding equipment. In addition, the dehydrator is prevented from falling down, and the upper part of the dehydrator is sandwiched between elastic members and is gently fixed.

The latter method of vibrating only the filter body uses an elastic body at the joint between the dehydrator housing surrounding the filter body and the filter body, and the base plate vibrates only the filter body while the dehydrator housing is fixedly supported. Put it on and shake it. In this case, a method of mounting the filter body on the elastic body and attaching the vibration device to the filter body main body may be used. Thereby, only the filter body can be vibrated without the dehydrator housing vibrating. As for the connection pipe, a flexible joint is used for the sludge supply pipe connected to the vibrating filter body and the dewatered cake extraction pipe. The filtrate extraction piping connected to other dehydrator housings shall be fixed piping.

The invention of claim 3 is an invention of a sludge coagulation concentration tank. This device can be used as a pretreatment device for low-concentration sludge supplied to a dehydrator, or can be used alone as a concentration device for low-concentration sludge. When low concentration sludge mixed with sedimentation improvement aids such as polymer flocculant and activated carbide is supplied to the sludge agglomeration concentration tank of the present invention, the sludge collects on the inner periphery of the outer cylinder due to the swirl effect, and the lower part of the outer cylinder More concentrated sludge can be taken out. By the way, when using activated charcoal of sludge with a large amount of ash as a sedimentation improvement aid, the true specific gravity is about 2 g / cm3, and the mixture with sludge greatly improves the sedimentation, together with the effect of the polymer flocculant, Sludge is easy to separate. Incidentally, ordinary activated carbon has a true specific gravity of about 1 g / cm 3, but activated carbide has a large amount of ash and a true specific gravity of about 2 g / cm 3, and is excellent as a sedimentation improving aid.

On the other hand, the separation liquid passes through the filtration surface on the side surface of the inner cylinder and is taken out from the upper part of the inner cylinder, but most of the solid sludge is separated and removed by the swirl flow effect of the sludge agglomeration and concentration tank. It becomes a very clear separation liquid by the filtration effect of the screen which consists of a material which has a side pore or slit.

Although the possibility of clogging of the filtration surface on the side surface of the inner cylinder is conceivable, the clogged solid is removed by the swirling flow outside the inner cylinder. Nevertheless, clogging during long-term operation is removed by regular backwashing.

A low-concentration sludge supply port at the upper part of the outer cylinder of the sludge aggregation tank is provided with a polymer flocculant inlet and a throttling mechanism so that the inflow rates of the polymer flocculant and sludge can be adjusted.

The concentrated sludge from the sludge coagulation concentration tank of the present invention can be efficiently dehydrated by supplying it to the dehydrator of the present invention due to another filterability improving effect of the settling improvement aid.

Moreover, when activated charcoal is used as a sedimentation improving aid, there is an effect of suppressing the odor of the dehydrated cake.

If the dehydrator of the present invention is used, sludge can be easily dehydrated without taking time and effort. It is easy to introduce even in a small-scale sewage treatment plant, and by installing the dehydrator of the present invention, an economical sludge recycling system in the region can be spread.

If the sludge coagulation concentration tank of the present invention is used, the effects of the polymer flocculant and the settling improvement aid are enhanced with a simple apparatus, and a high-concentration sludge can be taken out to obtain a highly clarified separation liquid.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view of a dehydrator according to the present invention shown in claim 1. Sludge is supplied from the sludge supply pipe 6 to the filter body 2 in the dehydrator housing 1, and the filtrate passes through the filtration surface having pores or slits around the filter body 2. The filtrate is collected in the filtrate chamber 9 in the meantime, and is extracted from the filtrate extraction pipe 7. On the other hand, the dewatered cake of sludge is taken out above the dehydrated cake extraction pipe 8 at the top of the dehydrator. A control valve 4 is provided in the middle of the filtrate discharge pipe 7 to detect a differential pressure between the pressure in the filtrate chamber 8 and the inner pressure of the filter body 2 or the pressure in the sludge supply pipe 6. A pressure controller 5 is provided for adjusting the opening degree of the. A vibration device 3 for vibrating the filter body 2 is attached to the side surface of the dehydrator housing 1.

FIG. 2 is an explanatory view of a dehydrator according to the present invention as set forth in claim 2. 1 is provided with a control valve 4 in the middle of the dewatering cake extraction pipe 8, and the pressure of the sludge supply pipe 6, which is substantially the same pressure as the inner pressure of the filter 2, is measured. The pressure controller 5 for adjusting the opening degree of the filter 2 is attached, and the inner pressure of the filter body 2 is controlled by adjusting the amount of the dehydrated cake extracted. The pressure on the filtrate side is open to the atmosphere.

FIG. 3 shows an example of the vibration device mounting form according to the present invention. In this method, the entire dehydrator A, that is, the filter body 2 and the dehydrator housing 1 are both placed on an elastic body 11 such as a spring or rubber, and the filter body 2 and the dehydrator housing 1 are vibrated together. The vibration device 3 is attached to the outer periphery of the dehydrator housing 1. In addition, the sludge supply pipe 6, the filtrate extraction pipe 7 and the dehydrated cake extraction pipe 8 are connected to the dehydrator A by a flexible joint 10 so that the vibration of the dehydrator A is not conducted to surrounding devices through the pipe. The dehydrator A is fixed to a stationary base 12 via an elastic body 11.

FIG. 4 shows another example of the attachment form of the vibration device according to the first aspect of the present invention. In this method, the entire dehydrator A is placed on a vibration table 13 with a vibration device 3, and the filter body 2 and the dehydrator housing 1 are vibrated together. Also in this case, the sludge supply pipe 6, the filtrate extraction pipe 7 and the dehydrated cake extraction pipe 8 and the dehydrator A are connected by the flexible joint 10 so as not to conduct from the vibrating dehydrator A to the surrounding equipment through the pipe. Yes.

FIG. 5 shows another example of the attachment form of the vibration device according to the first aspect of the present invention. The vibration device 3 is attached to the filter body 2. The filter body 2 and the dehydrator housing 1 are connected by an elastic body 14 such as rubber, cloth, or plastic, so that the vibration of the filter body 2 is not conducted to the dehydrator housing 1. The dehydrator housing 1 is fixed to the gantry 12. The sludge supply pipe 6 and the dehydrated cake extraction pipe 8 and the filter body 2 are connected by a flexible joint 10 so that the vibration of the vibrating filter body 2 is not conducted to surrounding equipment through the pipe.

FIG. 6 is an explanatory view of the sludge agglomeration concentration tank according to the present invention shown in claim 3. 6A is a side view thereof, and FIG. 6B is a top view thereof. There is a sludge supply port 16 connected in a tangential direction at the upper part of the outer cylinder, and the supplied sludge flows downward while turning between the outer cylinder 14 of the sludge aggregation and concentration tank and the inner cylinder 15 of the sludge aggregation and concentration tank. During this time, the solid sludge mixed with the settling improvement aid and the polymer flocculant aggregates and increases in specific gravity and settles on the inner surface of the outer cylinder 14. Furthermore, it flows toward the lower side of the inner surface of the outer cylinder 14, is collected at the concentrated sludge discharge port 17 at the lower part of the outer cylinder 14 by the cone portion of the outer cylinder 14, and is extracted outside. The sludge having a diluted concentration passes through the screen 20 on the side surface of the inner cylinder 15, the remaining sludge is removed, and the sludge is taken out from the separated liquid discharge port 18 at the upper part of the inner cylinder. The sludge supply port 16 is provided with a throttling mechanism 18 and a polymer flocculant injection port 21 so that the inflow rate of sludge can be adjusted.

FIG. 1 is an explanatory view of a dehydrator according to the present invention shown in claim 1. FIG. 2 is an explanatory view of a dehydrator according to the present invention as set forth in claim 2. FIG. 3 shows an example of a mounting form of the vibration device according to the present invention. FIG. 4 shows another example of the attachment form of the vibration device according to the first aspect of the present invention. FIG. 5 shows another example of the attachment form of the vibration device according to the first aspect of the present invention. 6 (a) and 6 (b) are explanatory views of the sludge agglomeration concentration tank of the present invention shown in claim 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dehydrator housing 2 Filter body 3 Vibrating device 4 Control valve 5 Pressure controller 6 Sludge supply pipe 7 Filtrate extraction pipe 8 Dehydrated cake extraction pipe 9 Filtrate chamber 10 Flexible joint 11 Elastic body 12 Base 13 Shaking table 14 Sludge aggregation and concentration Tank outer cylinder 15 Sludge agglomeration and concentration tank inner cylinder 16 Sludge supply port 17 Concentrated sludge discharge port 18 Separation liquid discharge port 19 Throttle mechanism 20 Screen 21 Polymer flocculant inlet A Dehydrator B Sludge agglomeration concentration tank

Claims (3)

In a pressure filtration type dehydrator with a stationary filter body, it has a filter body with pores or slits made of steel plate connected to a vibration device for applying vibration, and the downstream side of the filter body has a sealed structure, and filtration A control valve is provided at the liquid discharge port, and the pressure difference between the pressure inside the filter body and the filtrate chamber that collects the filtrate is controlled to 2 to 20 m by controlling the amount of filtrate extracted with the control valve. A sludge dewatering machine characterized by In a stationary pressure filtration type dehydrator, it has a filter body with steel plate pores or slits connected to a vibration device for applying vibration, opens the filtrate outlet to the atmosphere, and resists the dehydrated cake outlet A control valve capable of adjusting the pressure, and controlling the inner pressure of the filter body or the head of the high pressure pump that supplies sludge to the dehydrator, and controlling the water head with a pressure difference between 2 and 20 m. Machine. An outer cylinder having a conical lower part and a cylindrical upper part, a cylindrical inner cylinder inserted into the outer cylinder, a sludge supply port provided in the upper part of the outer cylinder, and a lower part of the outer cylinder In a swirl type container provided with a concentrated sludge recovery port provided and a separation liquid discharge port provided at the top of the inner cylinder, a filtration surface using a material having pores or slits on the side surface of the inner cylinder Or the lower surface of the inner cylinder is made of a material having pores or slits, or the lower surface is closed, and the lower surface is closed to adjust the inlet of the flocculant and the sludge inflow rate to the sludge supply port. A sludge agglomeration and concentration tank comprising a mechanism.

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