JP4875292B2 - Sludge recovery system and sludge recovery treatment method - Google Patents

Description

The present invention relates to a sludge collection system and a sludge collection treatment method, and more particularly to a sludge collection system and a sludge collection treatment method for collecting various types of sludge generated by treatment of domestic wastewater and industrial wastewater.

Domestic wastewater generated from human daily life and industrial wastewater containing a large amount of organic substances generated in the manufacturing process of food and the like are generally treated by a wastewater treatment method called an activated sludge method. In addition, as a method of removing suspended substances in various waste water and waste liquid, for example, fine bubbles generated by depressurizing pressurized and dissolved air are attached to suspended substances, and the floating density is reduced by reducing the apparent density. There are known processing methods such as a pressurized flotation separation method and a coagulation sedimentation method in which suspended substances are adsorbed or encapsulated in flocs formed by adding a flocculant to drainage and settling. When performing such wastewater treatment and waste liquid treatment, excess sludge is generated from the activated sludge method,
Aggregated sludge is produced from the pressurized flotation method and the coagulation sedimentation method.

Sludge generated in the waste water treatment and waste liquid treatment is usually recovered using a dehydrator. Various types of sludge dehydrators are used, such as vacuum dehydrators (belt type, drum type), pressure dehydrators (filter press type, belt press type), centrifugal dehydrators (
Decanter type, etc.), screw press dehydrator, multiple disk type dehydrator, multi-plate outer cylinder type screw press dehydrator having the characteristics of screw press and multiple disk type are known (for example, non-patent literature) 1).

Next, a conventional representative dehydrator will be described. FIG. 3 is a cross-sectional view schematically showing a main part of a conventional belt-type vacuum dehydrator.
The belt-type vacuum dehydrator 50 includes a bat 51 to which sludge is supplied, a stirrer 52 disposed at the bottom of the bat 51, a rotary drum 53 that is partially immersed in the sludge in the bat 51, and an outer periphery of the drum 53. A filter cloth 54 that covers the dewatering cake 55, an escape roll 56 that peels the dehydrated cake 55, a filter cloth tension roll 57, a filter cloth meandering correction roll 58, and a filter cloth cleaning device 59.

Next, a method for dewatering sludge using the belt-type vacuum dehydrator 50 will be described. When the inside of the drum 53 is adjusted to a predetermined negative pressure by a vacuum pump (not shown) and about 30% of the surface area of the drum 53 is immersed in sludge in the bat 51, a cake layer is formed on the surface of the filter cloth 54 in the immersed portion. 55a is formed. When the drum 53 is rotated in accordance with the speed at which the cake layer 55 a is formed, the cake layer 55 a is dehydrated in the air and is peeled from the filter cloth 54 by the dewatering roll 56. The filter cloth 54 from which the dewatered cake 55 has been peeled is washed by a filter cloth washing device 59 to prevent clogging, and is immersed again in sludge while being wound around the drum 53, and the process is continuously repeated. ing.

FIG. 4 is a cross-sectional view schematically showing a main part of a conventional belt press type dehydrator. The belt press type dehydrator 60 includes a first filter cloth 61, a second filter cloth 62, a sludge supply unit 63 that supplies agglomerated sludge onto the second filter cloth 62, and a first filter cloth 61 and a second filter cloth 62. A plurality of second pressurizing units for pressing and dewatering the coagulated sludge sandwiched between the first filter cloth 61 and the second filter cloth 62. The pressure roll 65, the escape roll 67 which peels the dewatering cake 66, and the filter cloth washing | cleaning apparatus 68 are comprised.

Next, a method for dewatering sludge using the belt press type dehydrator 60 will be described. First filter cloth 61
When the flocculent sludge to which the polymer flocculant is added is supplied in a state where the second filter cloth 62 is continuously moved, the free water between the flocs is filtered by gravity. Furthermore, the sludge that has moved is dewatered in the free water and floc particles by pressing the first filter cloth 61 and the second filter cloth 62, and finally moved between the second pressure rolls 65 in a wave shape, It peels from the 1st filter cloth 61 in the escape roll 67 (pressure dehydration part). The first filter cloth 61 and the second filter cloth 62 from which the dewatered cake 66 has been peeled are washed to prevent clogging, and the same process is repeated continuously again.

The vacuum dehydrator (belt type vacuum dehydrator 50) and the pressure dehydrator (belt press type dehydrator 60) described above have a start adjustment time and an end work time in consideration of the operation time of a factory or a processing facility. Selected based on the machine's ability to complete the required throughput in the time deducted,
In order to reduce the water content (65 to 85%) of the dehydrated cake in a short time, a reduced pressure (vacuum) treatment or a pressure treatment is forcibly performed. Therefore, the solid matter passes through the filter cloth, and a large amount of solid matter is contained in the filtrate, so that the recovery rate of the solid matter is likely to decrease, and the same filter cloth is repeatedly used many times. The filter cloth was easily clogged, and the filter cloth had to be constantly washed.

Furthermore, the amount of the filtrate and filter cloth cleaning liquid resulting from such an operation process is surprisingly large.
It is said that it will reach 5-10% of the amount of sewage normally treated at sewage treatment facilities, and since the concentration of the sewage is very high, it cannot be discharged as it is and is treated again at the treatment facility together with the raw water of the sewage treatment facility. Had to do.

The amount of surplus sludge generated from the sewage treatment facility varies depending on the operation method of the facility and the method of biological treatment, but when converted to approximately 40% per removed BOD, the amount of extracted sludge (concentrated sludge: 98%
The water content is 1% or less. That is, the waste liquid including the filter cloth cleaning liquid for recovering 1 to 2% of solid matter in the drawn sludge corresponds to a 10% load amount of the processing facility capacity.
When such a large amount of filtrate and filter cloth cleaning solution are added again, the capacity of the original wastewater treatment facility is greatly reduced, and there is a problem that the operation of factories and the like may be hindered.

In addition, the filter cloth used in the vacuum dehydrator and pressure dehydrator has a significant drop in filtration performance over the course of use. The amount of flocculant added should be adjusted appropriately according to the properties of the product, etc., and it takes time to make adjustments. Must be cleaned. This means that if the dehydration work is not performed under the operation management by the manager at all times, the planned dehydration effect cannot be obtained, and it is very difficult to perform unattended operation (automation). was there.

In addition, a large amount of inorganic flocculants such as slaked lime and ferric chloride is used to form a strong floc to reduce the moisture content of the dehydrated cake and to match the specific performance of the filter cloth used in the dehydrator. A dehydrated cake which is used and exhibits an abnormal pH value including chloride and the like is obtained. Therefore, it is difficult to uniformly consider the use of recovered sludge, and there is a problem that it is difficult to use even though its resource value is recognized.

FIG. 5 is a cross-sectional view schematically showing a main part of a conventional centrifugal dehydrator (screw decanter). The screw decanter 70 includes a rotating cylinder 71, a main electric motor 72 that rotationally drives the rotating cylinder 71, a screw conveyor 73 disposed in the rotating cylinder 71, and a screw conveyor 7.
3 is configured to include a differential 74 that rotates and rotates 3 with a slight rotational difference from the rotary cylinder 71, a sludge supply pipe 75, and a flocculant supply pipe 76.

Next, a method for dewatering sludge using the screw decanter 70 will be described. The rotating cylinder 71 is rotated at a high speed of 3000 to 6000 rpm, a strong centrifugal force of 2000 to 4000 G is applied, sludge conditioned with a polymer flocculant is supplied into the rotating cylinder 71, and a solid 77 having a large specific gravity is supplied to the rotating cylinder 7.
1 is accumulated on the inner wall surface, and the solid content 77 is transferred to the left by the action of the screw conveyor 73 having a slight rotational difference from the rotary cylinder 71 and discharged. Further, the separation liquid 78 having a relatively small specific gravity.
Is discharged from a discharge port provided in the right side plate of the rotary cylinder 71.

Centrifugal dehydrators do not require filter cloth washing like the vacuum dehydrators and pressure dehydrators described above.
It is said that relatively little washing water is required, and that automation is possible and maintenance is easy.
However, the automation increases the size of the device, and the price of the device increases dramatically. Also,
Since the centrifugal dehydrator is operated at an ultra-high speed rotation, the components such as the bearings and the timing gears are consumed very much, which inevitably increases the number of failure points, and the vibration and noise are also problems. In addition, there are many auxiliary machines, and even if a failure occurs, it cannot be repaired by an amateur,
Maintenance costs have also increased, and there has been a problem that it may become unusable after several years.

Moreover, the centrifugal dehydrator does not have a good separation performance with respect to excess sludge by the activated sludge method. Therefore, it is unlikely that the supply sludge with little difference in specific gravity between the solid and water will be injected with a pump, and sludge conditioned with a flocculant is supplied, but the sludge supply pipe diameter is small and clogged easily There was also a problem. As described above, the centrifugal dehydrator does not have a good SS (Suspendid Solid) recovery rate and is not used for general purposes.

In the development of conventional dehydrators, the main issue is how to reduce the moisture content of the dehydrated cake in a short time. The reason is that the volume of generated sludge decreases according to the logarithmic decay curve as the moisture content of the dehydrated cake decreases.If the moisture content of the sludge is decreased, handling of the dewatered cake becomes easier and disposal costs are reduced. This is because it can be reduced. On the other hand, for the separated filtrate produced in various dehydrators, a treatment system has been constructed on the premise that it can be returned to the wastewater treatment facility and reprocessed. There has been a problem that almost no measures have been taken to improve the quality of the separated filtrate and filter cloth washing water.
Fumizo Yoshimura, “Water treatment technology understood by this”, first edition, Industrial Research Council, Inc., September 15, 2002, p162-170

Means for solving the problems and their effects

The present invention has been made in view of the above-mentioned problems, and without requiring a large facility cost for a conventional large-sized apparatus, it is possible to save the sludge with labor-saving and low-cost equipment, and with less labor and maintenance costs. can be recovered very clear filtrate from the sludge can be separated directly and without filter cloth washing water discharge is generated, the sludge collection system that can the be reduced even load on the waste water treatment facilities, and The purpose is to provide a sludge recovery treatment method.

In order to achieve the above object, a sludge recovery system (1) according to the present invention includes a sludge recovery device that recovers surplus sludge prepared by activated sludge treatment conditioned with a flocculant by gravity filtration, and is transferred to the sludge recovery device. A flocculant addition means for adding a flocculant to the sludge water, and a sludge transfer means for transferring the sludge water conditioned with the flocculant to the sludge recovery device, wherein the sludge recovery device is an insulator. Consisting of non-woven fabric using patterned fibers, it is dense and excellent in water permeability, and a filtration member that adsorbs and captures excess sludge conditioned with the flocculant, and the filtration member is detachably mounted on the inner peripheral surface and inner bottom surface A main body portion, a sludge accumulation portion formed inside the filtration member attached to the main body portion, and a sludge injection portion for injecting excess sludge conditioned with the flocculant into the sludge accumulation portion, Pass through the filtration member and adjust with the flocculant. And a filtrate discharge section for discharging the filtrate separated from the excess sludge, and the sludge transfer means includes a suction pipe for sucking sludge water and a discharge pipe for discharging the sucked sludge water to the sludge recovery device. And a flocculant discharge pipe for injecting the flocculant from the flocculant addition means is connected to the discharge pipe of the sludge transfer means, and the length and the pipe diameter of the discharge pipe of the sludge transfer means are: In the discharge pipe, the discharged sludge water and the injected flocculant are set to react to form a floc .

According to the sludge recovery system (1), since the filtration member is attached to the inner peripheral surface and the inner bottom surface of the main body part constituting the sludge recovery device, the sludge recovery system is formed inside the attached filtration member. When surplus sludge conditioned with the flocculant is injected into the sludge accumulation section, the solid content of the surplus sludge injected (aggregated sludge) and free water (desorption) caused by sludge agglomeration (floc formation) Liquid) is separated at a moderate speed by the action of gravity through the filtering member. Therefore, by using the sludge recovery device, the recovery rate of excess sludge solids (aggregated sludge) can be saved with labor-saving and low-cost equipment without requiring a large facility cost due to the conventional large-scale device. it is high and can be constructed as a separate filtrate, a system capable of separating very clear filtrate which can be discharged together with treated water wastewater treatment facilities (tertiary treatment water).

This is because the filtration member is dense and excellent in water permeability, and has a structure that adsorbs and captures the coagulated sludge. Therefore, when the sludge is injected into the sludge accumulation part, the coagulated sludge is outside the filter member. Without being leaked to the inner surface layer of the filtration member, and the agglomerated sludge layer (
As the sludge is rapidly deposited, a more dense coagulated sludge layer is formed by the dead weight of the injected sludge. Free water from the sludge is filtered at a moderate rate through a dense coagulated sludge layer formed on the inner surface portion of the filtration member. Moreover, since suspended substances contained in free water that has passed through the agglomerated sludge layer are captured by the filtration member by an action such as adsorption,
From the separated filtrate, it is considered that a filtrate with a transparency as high as the treated water in the wastewater treatment facility is recovered.

Moreover, according to the said sludge collection system (1), the effect of depositing and forming a dense coagulated sludge layer on the inner surface of the filtration member is enhanced by the structure of the nonwoven fabric using the coconut shell fibers. Since the fiber is porous, the effect of adsorbing and capturing suspended substances in the free water that has passed through the coagulated sludge layer can be enhanced, and the clarification of the separated filtrate can be further enhanced.

In addition, the filtration member composed of a nonwoven fabric using the coconut shell fiber is a very inexpensive material compared to the filter cloth used in a conventional dehydrator, so even when disposable,
Running costs can be kept low. Moreover, if it is made disposable, in the conventional dehydrator, washing wastewater such as a filter cloth, which has been a problem, is not generated at all, and thus the load on the wastewater treatment facility can be reduced.

Further, if the filtration member composed of the nonwoven fabric using the coconut shell fiber can be used as it is as a packaging material for the recovered sludge, for example, it is processed into a bag shape, it becomes easy to store and carry out the recovered sludge. Moreover, the amount of recovered sludge can be further reduced by the storage. In addition, when applied to the treatment of surplus sludge with activated sludge, it is only necessary to add a small amount of a polymer flocculant as a flocculant, so that the recovered sludge can be widely used as a soil conditioner, fertilizer, or fuel. . Furthermore, if the filtration member comprised from the nonwoven fabric using the said coconut shell fiber is used as a packing material of collection | recovery sludge, the said filtration member will be utilized as an additive for ensuring the water retention of a soil improvement material, or a fuel. As an additive for adjusting the air and fuel ratio in this case, it can be used as it is without being discarded, and the utility of recovered sludge can be further enhanced.

The sludge collection system according to the present invention (2), in the sludge collection system (1), said filter member for use in the sludge collecting device, the opening diameter _{O 95} its apparent 0.8~1.2mm And / or having a function of a water permeability coefficient kt of 2.5 to 3.0 cm / s and capable of separating a filtrate having a transparency of 50 cm or more from the excess sludge.
According to the sludge collection system (2), wherein the filtration member, opening diameter _{O 95} of the apparent 0.8 to 1.2 mm, and / or permeability kt the function of 2.5～3.0Cm / s And having a permeability of 50 cm or more can be separated from the excess sludge, so that it has sufficient water permeability and long-term sufficient water permeability, and can collect a very clear filtrate. it can.
In the sludge recovery system (3) according to the present invention, in the sludge recovery system (1) or (2), the main body portion of the sludge recovery device is divided into two in the vertical direction and can be opened and closed. The said inner peripheral surface and inner bottom face of a part are comprised with the perforated steel plate, It is characterized by the above-mentioned.
According to the sludge recovery system (3), the main body part is vertically divided and can be opened and closed, and the inner peripheral surface and inner bottom surface of the main body part are made of perforated steel plates. The attachment / detachment work of the filtering member to the main body can be easily performed, and workability can be improved.

Moreover, the sludge recovery system (4) according to the present invention is the sludge recovery system according to any one of the sludge recovery systems (1) to (3), wherein the sludge recovery device accumulates in the sludge accumulation part. On the other hand, it is characterized by having a blowing means for applying wind pressure from above.
According to the sludge recovery system (4), the sludge recovery device includes a blowing means for applying wind pressure from above to the liquid level of the excess sludge that accumulates in the sludge accumulation section. By applying wind pressure in the sludge accumulation part, it is possible to increase the filtration rate of free water separated from the excess sludge by applying positive pressure to the liquid level of the excess sludge accumulated in the sludge accumulation part. The effect of consolidating the coagulated sludge can be increased, and the amount of sludge to be deposited can be increased.

The sludge recovery system (5) according to the present invention is the sludge recovery system (1) to (4), wherein the main body is disposed on a vibration means for vibrating the main body of the sludge recovery device. It is characterized by being installed.
According to the sludge recovery system (5), since the main body is disposed on the vibration means for vibrating the main body, the main body is vibrated by the vibration means, so The solid content (aggregated sludge) of the sludge injected into the water is promoted to be separated from free water to increase the sedimentation rate of the solid content of the sludge, and the filtration rate of free water can be increased. The amount of sludge to be deposited can be increased by increasing the effect of compacting the sludge. The vibration means includes a mechanical device that mechanically applies a circular, elliptical, or reciprocating motion to the main body by a cam or an eccentric shaft rotated by a motor or the like, or an electromagnetic to the main body. An electromagnetic device or the like that gives reciprocating motion is adopted.

In the sludge recovery system ( 6 ) according to the present invention, in any one of the sludge recovery systems (1) to (5), the sludge recovery device is also used as a transport container for transporting the recovered sludge. It is characterized by being.
According to the sludge recovery system ( 6 ), since the sludge recovery device is also used as a transport container for transporting the recovered sludge, a forklift can be used even when the sludge recovery device is enlarged. By using such a transportation vehicle, it is possible to easily carry heavy recovered sludge. In addition, the container for transportation can be stacked, for example, in the form of a box, so that these can be stacked and the collected sludge can be stored and managed without taking up space.

The sludge collection system according to the present invention (7), in the sludge collection system (6), the sludge collecting device is characterized by those which can be attached and detached from the vehicle.
According to the sludge recovery system ( 7 ), since the sludge recovery device is detachable from the vehicle, the sludge recovery device can be attached to the vehicle and transported as it is. The system can further improve the efficiency of transportation work.

The sludge recovery system ( 8 ) according to the present invention includes a plurality of the sludge recovery devices in any one of the sludge recovery systems (1) to ( 7 ), and deposits the sludge. It is characterized by comprising switching means for alternately switching between a filtration step for filtration and a dehydration step for leaving and dewatering the recovered sludge after the filtration step.

According to the sludge recovery system ( 8 ), switching means for alternately switching a plurality of sludge recovery devices between a filtration step of filtering the sludge while depositing the sludge and a dehydration step of leaving the recovered sludge after the filtration step. For example, when two sludge recovery devices are provided, the switching means and the dehydrating step are alternately switched every predetermined time (for example, 24 hours) by the switching means. , Each step can be performed independently for each device, and there is no need to continuously perform forced solid-liquid separation processing by conventional pressurization, decompression, or centrifugal treatment, etc., and labor-saving device The dewatered sludge can be easily and automatically recovered with configuration and maintenance costs.

Moreover, the sludge collection system ( 9 ) according to the present invention comprises a deposition level detection means for detecting the accumulation level of sludge in the sludge collection device in any of the sludge collection systems (1) to ( 8 ), The sludge transfer means is controlled based on the accumulation level of the sludge detected by the accumulation level detection means.

According to the sludge recovery system ( 9 ), since the control of the sludge transfer means is performed based on the sludge accumulation level detected by the accumulation level detection means, for example, the accumulation of sludge by the accumulation level detection means. When the level reaches the upper limit level, the transfer of sludge water is interrupted, and when the accumulation level drops from the upper limit level to a predetermined level, the transfer of sludge water can be resumed, and the sludge accumulation level is always constant. The range can be maintained, and the filtration process can be automated.

Moreover, the sludge collection | recovery processing method (1) which concerns on this invention uses any one of the said sludge collection | recovery systems (1)-( 8 ), and sludge which transfers sludge water to the said sludge collection | recovery apparatus, adjusting with a flocculant. A transfer step, a filtration step for filtering the transferred sludge water while depositing it in the sludge accumulation section, and a dehydration step for stopping transfer of the sludge water to the sludge recovery device and leaving the recovered sludge to dehydrate. It is characterized by containing.

According to the said sludge collection | recovery processing method (1), the sludge transfer process which uses any one of the said sludge collection | recovery systems (1)-( 8 ), and transfers sludge water to the said sludge collection | recovery apparatus, adjusting with a flocculant. And a filtration step of filtering the transferred sludge water while depositing it in the sludge accumulation section, and a dehydration step of stopping the sludge water transfer to the sludge recovery device and leaving the recovered sludge to dehydrate. As a result, it does not require a large amount of equipment costs due to a large-sized apparatus as in the prior art, and it is labor-saving and has low-cost equipment, so that the solid sludge content (aggregated sludge) is high and the separated filtrate. As a result, it is possible to separate an extremely clear filtrate that can be discharged together with the treated water of the wastewater treatment facility.

Moreover, the sludge collection | recovery processing method (2) based on this invention uses the said sludge collection | recovery system ( 8 ), It is characterized by operating several sludge collection apparatuses, switching to a filtration process and a dehydration process alternately. .

According to the said sludge collection | recovery processing method (2), since the said sludge collection | recovery system ( 8 ) is used and several sludge collection | recovery apparatuses are operated switching alternately with a filtration process and a dehydration process, for example, the said sludge collection | recovery When two apparatuses are provided, each process can be performed independently for each apparatus by processing while alternately switching the filtration step and the dehydration step every predetermined time (for example, 24 hours), There is no need to perform forced separation by continuous pressurization, decompression, or centrifugal treatment as in the past, and dewatered sludge can be easily and automatically recovered with labor-saving equipment configuration and maintenance costs. be able to.

Moreover, the sludge collection | recovery processing method (3) based on this invention uses the said sludge collection | recovery system ( 9 ), and is performing the transfer of sludge water, detecting the accumulation level of the sludge in the said sludge accumulation part. .

According to the sludge recovery treatment method (3), the sludge recovery system ( 9 ) is used to transfer the sludge water while detecting the sludge accumulation level in the sludge accumulation section. When the accumulation level reaches the upper limit level, the transfer of sludge water is interrupted, and when the accumulation level of sludge decreases from the upper limit level to a predetermined level, the transfer of sludge water is resumed, thereby Can be kept within a certain range at all times, the filtration process can be automated, and there is no need to perform processing using devices such as a pressurizing pump, vacuum pump, and filter cloth washing as in the past, and it is safer Automatic operation can be achieved.

It will be described with reference to engagement Ru sludge collection system of the present invention, and the embodiment of the sludge recovery processing method drawings.
FIG. 1 is a block diagram schematically showing a main part of a sludge recovery system according to an embodiment. Drawing 2 is a figure showing typically the sludge collection device adopted for the sludge collection system concerning an embodiment, (a) is a front view, (b) is a BB line sectional view in (a). It is.

As shown in FIG. 1, the sludge recovery system 1 includes a sludge transfer pump (sludge transfer means) 10, a flocculant addition device (coagulant addition means) 20, a sludge recovery device 30A, and a sludge recovery device 30.
B and the control part 40 are comprised.

The sludge transfer pump 10 quantitatively feeds sludge water from a sludge concentration tank (not shown) to the sludge collection device 30A and the sludge collection device 30B, and has a strong suction / discharge capability. A tube pump or the like can be employed. The sludge transfer pump 10 is connected to a suction pipe 11 for sucking sludge water from the sludge concentration tank and a discharge pipe 12 for discharging the sucked sludge water to the sludge collection device 30A and the sludge collection device 30B. When a tube pump is employed as the sludge transfer pump 10, the diameter of the pump tube in the sludge transfer pump 10 is preferably 25 mm or more, and preferably has a high transfer capability with a discharge amount of 8 L / min or more. .

If such a sludge transfer pump 10 is used, even if the sludge moving in the pipe contains fine earth and sand or a long fiber, the pipe can be closed by sedimentation or entanglement of the fiber. Smooth transfer can be performed without occurring. Further, a connecting member 13 is attached to the tip of the discharge pipe 12 so as to be detachable from the sludge recovery device 30A or the sludge recovery device 30B.

The flocculant addition apparatus 20 includes a flocculant dissolution tank 21 that adjusts the polymer flocculant solution, a flocculant supply pump 22, and a stirrer 24 for dissolving the polymer flocculant. A discharge pipe 23 is connected to the flocculant supply pump 22, and the tip of the discharge pipe 23 is connected to the discharge pipe 12 of the sludge transfer pump 10. Therefore, the polymer flocculant solution sucked by the flocculant supply pump 22 is injected into the sludge water discharged from the sludge transfer pump 10, and the sludge water and the polymer flocculant solution are mixed in the discharge pipe 12, Floc (size that can settle)
Aggregated sludge) is formed and supplied to the sludge recovery device 30A or the sludge recovery device 30B in the state of agglomerated sludge. The length of the discharge pipe 12 of the sludge transfer pump 10 is such that a floc is formed in the discharge pipe 12 by reacting the discharged sludge water with the injected polymer flocculant. And the pipe diameter is designed.

Polymer flocculants are classified into anionic, cationic, and nonionic depending on their electrical properties. Usually, organic sludges such as activated sludge are cationic, such as metal hydroxides. For such inorganic sludge, anionic or nonionic ones are used, and suitable ones are used depending on the type of sludge.

As shown in FIG. 2, the sludge collecting device 30A is dense and excellent in water permeability, and the filter cloth (filter member) 31 that adsorbs and captures the aggregated sludge and the filter cloth 31 can be attached to and detached from the inner peripheral surface and the inner bottom surface. A substantially cylindrical main body part 32 to be attached, a cylindrical sludge accumulation part 33 formed inside a filter cloth 31 attached to the main body part 32, and a sludge injection part 34 for injecting sludge into the sludge accumulation part 33. And a filtrate discharge part 35 that discharges the filtrate separated from the sludge through the filter cloth 31. In addition, since the sludge collection | recovery apparatus 30B is the structure similar to 30A of sludge collection | recovery apparatuses, suppose that the same code | symbol is attached | subjected to the component which has the same function, and the description is abbreviate | omitted.

The side surface portion of the main body portion 32 is composed of a perforated steel plate 32 a, and the perforated steel plate 32 b is also disposed inside the main body portion 32, so that the filter cloth 31 can be mounted independently on the main body portion 32. Has been. Further, the main body portion 32 has a side surface portion and an upper surface portion that are approximately 2 in the vertical direction so that they can be opened and closed.
It has a divided structure.

The sludge injection part 34 is formed on the upper surface of the main body part 32, and the discharge pipe 12 of the sludge transfer pump 10 is connected to the front end of the sludge injection part 34 via the connecting member 13, and the sludge accumulation formed by the filter cloth 31. Sludge water in which flocks are formed is injected into the portion 33. The filtrate discharge part 35 is formed on the bottom surface of the main body part 32, and its tip is connected to the filtrate pipe 36.
A filtrate pipe 36 is connected to a pipe (not shown) through which treated water from the wastewater treatment facility is discharged.

The filter cloth 31 attached to the main body 32 is a non-woven fabric using natural coconut shell fibers, for example, coconut shell fibers randomly arranged, entangled with needle punches, and further firmly bonded with a binder. As a packing material for dehydrated sludge, it is preferable that the material is sewn in a cylindrical bag shape so that it can be used as it is.

Further, the filter cloth 31 preferably has an opening diameter O ₉₅ of about 0.8 to 1.2 mm, preferably around 1.02 mm. The pore diameter is a particle diameter (O ₉₅ ) corresponding to a weight of 95% of the particle diameter accumulation curve, and is referred to as an apparent opening diameter <AOS> (Apparent Opening Size). Further, the filter cloth 31 has a permeability coefficient kt (cm / s) obtained by a vertical direction permeability test (unification test at the National Land Center) of about 2.5 to 3.0 cm / s, preferably 2.9 cm / s. Those having sufficient water permeability as well as long-term sufficient water permeability are preferable. In consideration of sludge storage capacity, properties of coagulated sludge, filtration conditions, etc., the thickness is about 3 mm to 20 mm. A thing is appropriately selected and used.

Further, the sludge recovery device 30A is provided with a level sensor 37 for detecting the accumulation level of the injected sludge water, and the amount of sludge water injected from the sludge injecting section 34 is the level A indicating the upper limit value. , And a decrease to a level B or less at which reinjection can be performed is detected. Based on these detection signals, the control unit 40 performs the sludge transfer pump 10.
In addition, drive control of the flocculant supply pump 22 is performed, and the sludge water is automatically controlled so as not to overflow from the sludge collection devices 30A and 30B.
The level sensor 37 only needs to be able to detect the level even in sludge water. For example, the level sensor 37 transmits the liquid head pressure to the chamber in the sensor body by the detection pipe, receives the air pressure by the diaphragm, and operates the micro switch. An operating pressure type level switch, a capacitance type level switch, a float type level switch, or the like may be employed.

Next, the sludge collection method in the sludge collection system 1 which concerns on embodiment is demonstrated.
First, the filter cloth 31 is attached to the sludge recovery device 30A and the sludge recovery device 30B, the discharge pipe 12 of the sludge transfer pump 10 is connected to the sludge recovery device 30A, and the flow rates of the sludge transfer pump 10 and the flocculant supply pump 22 are connected. After preparation for setting and the like, the sludge transfer pump 10 and the flocculant supply pump 22 are driven to quantitatively suck the sludge water and the polymer flocculant solution, respectively, and discharge pipe 12
The sludge water in which flocs are formed while mixing the sludge water and the flocculant in the sludge recovery device 30A
To send.

The sludge water sent to the sludge recovery device 30A is the sludge accumulation part 3 formed by the filter cloth 31.
3 is injected. When the sludge water is injected, the floc (aggregated sludge) in the sludge water is captured by the inner surface layer of the filter cloth 31 with almost no leakage to the outside of the filter cloth 31 (the filter cloth 31 is dense and excellent in water permeability, The structure is such that the agglomerated sludge is trapped by the surface part), so that the agglomerated sludge layer (rust) is quickly formed on the inner surface, and the sludge water that is injected is more dense due to its own weight. Is formed. Free water from the sludge water is filtered at a moderate speed through a dense coagulated sludge layer formed on the inner surface portion of the filter cloth 31, and the suspended matter contained in the free water that has passed through the coagulated sludge layer. Are captured by the filter cloth 31 by the action of adsorption, etc.
Filtrate with a transparency as high as or higher than the treated water (tertiary treated water) of the wastewater treatment facility is separated, and the separated filtrate is treated at the wastewater treatment facility from the filtrate discharge part 35 via the filtrate pipe 36. It is discharged with water as it is.

Further, when the level sensor 37 detects that the sludge water level has risen with time and has reached the upper limit level A, the sludge transfer pump 10 and the flocculant supply pump 22 are detected. Is temporarily stopped. Thereafter, when it is detected that the liquid level of the sludge water has dropped to level B or less due to gravity filtration, the sludge transfer pump 10 and the flocculant supply pump 2
2 is driven again, sludge filtration is performed while the sludge water injection is resumed and the sludge water is controlled not to overflow (filtration step).

After a certain time (for example, 24 hours), the sludge transfer pump 10 and the flocculant supply pump 22 are stopped, and the discharge pipe 12 of the sludge transfer pump 10 connected to the sludge recovery device 30A is disconnected. Next, by connecting to the sludge recovery device 30B and driving the sludge transfer pump 10 and the flocculant supply pump 22 again, the filtration process described above is similarly performed in the sludge recovery device 30B.

On the other hand, the sludge recovery apparatus 30A enters a dehydration step in which the recovered aggregated sludge is left to dehydrate.
In the sludge recovery apparatus 30A, the water content of the recovered sludge after the filtration step is about 85 to 90%. If left for about 16 to 24 hours by this dehydration step, the sludge is compacted by its own weight,
The moisture content is reduced to about 80% by the leaching and dehydration due to the capillary action of the accumulated sludge and the filter cloth 31. The filter cloth 31 filled with dewatered sludge is taken out from the sludge recovery device 30A and a new filter cloth 31 is attached to prepare for the next filtration step until a certain time (for example, 24 hours) elapses.

After a certain time (for example, 24 hours), the sludge transfer pump 10 and the flocculant supply pump 22 are stopped, and the discharge pipe 12 of the sludge transfer pump 10 connected to the sludge recovery device 30B is disconnected. The sludge recovery device 30A is connected again, and the sludge transfer pump 10 and the flocculant supply pump 22 are driven, whereby the above-described filtration process is similarly performed in the sludge recovery device 30A, while in the sludge recovery device 30B, Then, the recovered sludge is allowed to stand and dehydrate. Thus, the sludge recovery process is performed while the sludge recovery device 30A and the sludge recovery device 30B are alternately switched between the filtration step and the dehydration step.

According to the sludge recovery system 1 according to the above-described embodiment, the filter cloth 31 excellent in the recovery of agglomerated sludge.
By using the sludge recovery devices 30A and 30B with a very simple configuration to which
The labor-saving and low-cost equipment eliminates the need for significant equipment costs as in the case of conventional equipment, and the solids recovery rate of the coagulated sludge is high. A system capable of separating a very clear filtrate that can be discharged with water can be constructed.

Further, in the sludge recovery system 1, the sludge recovery device 30A and the sludge recovery device 30B are alternately switched between a filtration step of filtering while accumulating the coagulated sludge and a dehydration step of leaving the coagulated sludge after the filtration step. Each process can be performed independently for each device, and there is no need to continuously perform forced solid-liquid separation processing by conventional pressurization, decompression, or centrifugal treatment,
It is possible to easily and automatically collect dewatered sludge having a reduced moisture content with a labor-saving device configuration and low maintenance cost.

Further, since the control of the sludge transfer pump 10 is performed based on the accumulation level of the sludge water detected by the level sensor 37, the accumulation level of the sludge water can be always kept within a certain range, and the filtration process can be automated. You can plan.

Moreover, since the main body part 32 of the sludge collecting apparatuses 30A and 30B is divided into two in the vertical direction and can be opened and closed, the work for attaching and detaching the filter cloth 31 to the main body part 32 can be easily performed, and the workability is improved. Can be made.

Moreover, since the filter cloth 31 is attached to the inner peripheral surface and the inner bottom surface of the main body 32 in the sludge recovery devices 30A and 30B, the sludge water is added to the sludge accumulation part 33 formed inside the attached filter cloth 31. Is injected, the solid content (aggregated sludge) of the injected sludge water and the free water are separated at a moderate speed via the filter cloth 31. Therefore, it is possible to separate a very clear filtrate that has a high solids recovery rate of sludge water and can be discharged together with the treated water of the wastewater treatment facility as a separated filtrate. Moreover, since the filter cloth 31 is comprised from the nonwoven fabric using a coconut shell fiber,
The effect of depositing and forming a dense agglomerated sludge layer on the inner surface of the filter cloth 31 is further increased. Further, since the coconut shell fiber is porous, the effect of adsorbing and trapping floating substances in the free water that has passed through the agglomerated sludge layer is enhanced. And the clarity of the separated liquid can be further increased.

In addition, the filter cloth 31 composed of a nonwoven fabric using coconut shell fibers is a very inexpensive material compared to the filter cloth 31 used in a conventional dehydrator. Running costs can be kept low. Moreover, if it is made disposable, since the washing | cleaning waste_water | drain of the filter cloth 31 etc. which became a problem will not arise at all in the conventional dehydrator, the load to a wastewater treatment facility can be reduced.

Moreover, since the filter cloth 31 comprised of the nonwoven fabric using the coconut shell fiber is processed into a form that can be used as it is as a sludge packing material, it is easy to store and carry out the dewatered sludge. Thus, the amount of recovered sludge can be further reduced.

In addition, when applied to the treatment of surplus sludge with activated sludge, it is only necessary to add a small amount of polymer flocculant as a flocculant, so inorganic substances (soil, sand) and coarse fibers (humus soil) are added to the collected sludge. , Wood chips), etc., can be used as organic fertilizers and soil conditioners. Moreover, if the coarse fiber (wood chip) etc. which give a void ratio are added, and it shape | molds and dries, it can also be set as a solid fuel and can be widely utilized as a soil improvement material, a fertilizer, and also a fuel.
Moreover, if anaerobic fermentation is performed, methane gas can also be collected and widely used as an organic resource that can be continuously secured.

Furthermore, since the filter cloth 31 comprised from the nonwoven fabric using a coconut shell fiber is comprised from the natural fiber, it does not generate | occur | produce a harmful substance at the time of disposal, but ensures the water retention property of a soil improvement material or a fertilizer. The filter cloth 31 can be mixed and used as it is as an additive for adjusting the air and the fuel ratio when used as a fuel, or as an additive for use as a fuel. Can be increased.

In the above embodiment, the connection of the discharge pipe 12 of the sludge transfer pump 10 is switched by manual operation. However, in another embodiment, the sludge transfer pump 10 is provided for each sludge recovery device. Thus, a system for detecting a certain time by a timer or the like and controlling the driving of the sludge transfer pump 10 to be switched alternately, or the sludge transfer pump 10
In the middle of the discharge pipe 12, a flow path switching device capable of switching the sludge flow path to each sludge recovery device is provided, a predetermined time is detected, and the sludge flow paths are alternately switched by the flow path switching device. It can also be set as the system which controls to switch to, and can be set as the system which switches a filtration process and a dehydration process automatically. Moreover, although the said embodiment demonstrated the system equipped with two sludge collection apparatuses, you may use 3 or more sludge collection apparatuses.

Moreover, although the said embodiment demonstrated the case where the filter cloth 31 with which each sludge collection | recovery apparatus was mounted | worn was comprised from the nonwoven fabric using a coconut shell fiber, in another embodiment, the coconut shell fiber was used. In addition to the non-woven fabric used, the material is excellent in water permeability (low pressure loss), is dense and does not pass through flocs of agglomerated sludge, and is made of a material that continuously moves moisture by the capillary action of fibers, for example,
A non-woven fabric having the same pore diameter as that of the coconut shell fiber or a non-woven fabric using the coconut shell fiber and a water permeability coefficient comparable to that of the coconut shell fiber can also be applied.

In the above embodiment, the sludge injected into the sludge recovery devices 30A and 30B is separated at a moderate rate by the solid content (aggregated sludge) and free water by gravity action and capillary action, and the free water is filtered. However, in another embodiment, each sludge collection device 30A, 30
A blower (air blowing means) is disposed on the upper part of the main body 32 of B, and the wind pressure may be applied from above to the liquid level of the coagulated sludge accumulated in the sludge accumulation portion 33. For example, positive pressure can be applied to the liquid level of the sludge injected into the sludge accumulation section 33 to increase the filtration rate of free water separated from the sludge, and the effect of compacting the coagulated sludge can be increased. The amount of sludge to be increased can be increased.

In still another embodiment, the sludge recovery devices 30A and 30B may be configured to dispose the main body 32 on a vibration device (vibration means). According to such a configuration, the main body 32 is vibrated by the vibration device. By promoting the separation of the solid content of sludge injected into the sludge accumulation section 33 and free water, it is possible to increase the sedimentation rate of the coagulated sludge and increase the filtration rate of free water,
In addition, the effect of consolidating the aggregated sludge can be enhanced, and the amount of sludge to be deposited can be increased. The vibration device includes a mechanical vibration device that mechanically applies a circular, elliptical, or reciprocating motion to the main body 32 by a cam or an eccentric shaft that is rotated by a motor or the like, An electromagnetic vibration device or the like that gives a reciprocating motion is adopted.

Moreover, in the said embodiment, as the sludge collection | recovery apparatuses 30A and 30B, the moisture content 98-98.
5% of the concentrated sludge, assume that can be processed per day 3m ³ ~5m ^3, 300~5
Although the description has been given of the case where the apparatus having a substantially cylindrical shape is adopted so that about 100 kg of filtered sludge can be recovered, the shape of the sludge recovery apparatuses 30A and 30B is not limited to the above cylindrical shape, and the sludge recovery apparatus The sizes of 30A and 30B can also be individually accommodated according to the capacity of the sewage treatment facility, and can be increased in size.

In addition, when a sludge collection apparatus is enlarged (for example, collect | recovering filtration sludge of 1 t or more), since the weight of collection sludge becomes large, it becomes difficult to take out collection sludge from the sludge collection apparatus manually. Therefore, a container-type large-capacity transport container that can be transported by a forklift or the like can be adopted as the main body of the sludge recovery device. That is, by attaching a filter cloth to the inside of a transport container made of a perforated steel plate, and providing a filtrate outlet at the bottom of the container, the filtration step and the dehydration step can be performed as described above. After the dehydration process, the heavy sludge can be easily transported by directly transporting the container-type sludge recovery device to a predetermined storage location or recovery location by a forklift or the like.

Further, if the bottom portion of the transport container can be opened and closed, the sludge collected on the filter cloth from the lifted state using a forklift or an automatic charging machine can be directly input to the truck bed or the like. In addition, the container-type sludge recovery device can be stacked, for example, in the form of a box, so that these can be stacked and the recovered sludge can be stored and managed without taking up space.

In yet another embodiment, a vehicle detachable transport container that can be directly mounted on a loading platform such as a large truck can be applied as the main body of the sludge recovery device. Thus, it is possible to save the trouble of re-loading the sludge one by one on the collection vehicle or the like, and it is possible to obtain a system that improves the efficiency of the collection work.

Moreover, although the said embodiment demonstrated and assumed the case where the excess sludge produced | generated by activated sludge process was collect | recovered, the sludge collection | recovery system concerning this invention is applicable to collection | recovery of the various sludge produced by water treatment. It can also be applied to treatments for the purpose of recovering harmful sludge generated from wastewater treatment facilities for the purpose of removing harmful substances such as heavy metals.

Hereinafter, the sludge collection | recovery apparatus, sludge collection | recovery system, and sludge collection | recovery processing method which concern on an Example are demonstrated. An Example demonstrates the case where the sludge collection | recovery system 1 which concerns on the said embodiment is applied to collection | recovery of the excess sludge produced in the sewage treatment facility which processes about 1000 tons of sewage a day.
[Equipment and conditions of sludge recovery system]
Sludge transfer amount of the sludge transfer pump 10: 8 L / min, pipe diameter 30 mm
Flocculant supply amount from flocculant addition apparatus 20: 400 to 600 ml / min (200-fold dilution of cationic liquid polymer flocculant (Himoloc MX-8130, manufactured by Hymo Corporation))
Equipment for sludge recovery devices 30A and 30B: Non-woven fabric (needful) using a bottomed cylindrical (bag-shaped) coconut shell fiber having a height of about 100 cm, a diameter of about 60 cm, and a thickness of about 10 mm on the inner wall surface of the main body 32 The filter cloth 31 comprised from the mat | matte N-10: (made by Tanaka Co., Ltd.) was mounted | worn. About 30
Up to 0 L of dewatered sludge was collected.
Treatment cycle: The filtration step and the dehydration step are performed for about 24 hours each, and this is defined as one cycle.
Each step was alternately switched between the sludge recovery device 30A and the sludge recovery device 30B. During the filtration step, the level of the sludge water was detected by the level sensor 37, and the sludge transfer pump 10 and the flocculant supply pump 22 were controlled to perform automatic operation.

[Evaluation methods]
The transparency of the filtrate separated in the filtration step and the dehydration step (the height of the filtrate level that can be recognized by the mark on the bottom of the graduated cylinder) was periodically measured.
In addition, the water content of the sludge after the filtration step and after the dehydration step (sewage test method, Chapter 2, Chapter 4, Section 6 (
1997)), and the change in volume was measured.

As a result of collecting sludge with the above equipment and conditions, a very clear filtrate having a transparency of 50 cm or more could be collected through the filtration step and the dehydration step.
The water content of the recovered sludge after the filtration step was reduced to about 85 to 90%, and the water content of the recovered sludge after the dehydration step was reduced to about 80 to 83%. Moreover, the volume of the sludge after the dehydration process was reduced to about 1/8 to 1/10 of the 98% hydrous sludge volume, and the dewatered sludge was easily carried out from the main body 32.

In other words, labor is saved without requiring a large facility cost due to a large-sized device like the conventional one,
With low-cost equipment, the solids recovery rate of coagulated sludge is high, the volume can be reduced, and the dewatered sludge can be carried out easily. An extremely clear filtrate that could be discharged could be separated.

It is the block diagram which showed roughly the principal part of the sludge collection | recovery system which concerns on embodiment of this invention. It is the figure which showed typically the sludge collection | recovery apparatus employ | adopted for the sludge collection | recovery system which concerns on embodiment, (a) is a front view, (b) is the BB sectional drawing in (a). It is sectional drawing which showed typically the principal part of the conventional belt-type vacuum dehydrator. It is sectional drawing which showed typically the principal part of the conventional belt press type dehydrator. It is sectional drawing which showed typically the principal part of the conventional centrifugal dehydrator (screw decanter).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sludge collection system 10 Sludge transfer pump 20 Coagulant supply apparatus 30A, 30B Sludge collection apparatus 31 Filter cloth 32 Main body part 33 Sludge accumulation part 34 Sludge injection part 35 Filtrate discharge part 40 Control part

Claims (12)

A sludge recovery device for recovering excess sludge by activated sludge treatment conditioned with a flocculant by gravity filtration ;
A flocculant addition means for adding a flocculant to the sludge water transferred to the sludge recovery device;
A sludge transfer means for transferring the sludge water conditioned with the flocculant to the sludge recovery device,
The sludge recovery device is
Constructed from a nonwoven fabric using cocoon pattern fibers, a filtration member that adsorbs and captures excess sludge that is dense and excellent in water permeability and tempered with the flocculant,
A main body part in which the filtration member is detachably attached to the inner peripheral surface and the inner bottom surface;
A sludge accumulation portion formed inside the filtration member mounted on the main body portion;
A sludge injection section for injecting the excess sludge conditioned with the flocculant into the sludge accumulation section;
A filtrate discharge part for discharging the filtrate separated from excess sludge conditioned by the flocculant through the filtration member,
The sludge transfer means is connected to a suction pipe for sucking sludge water and a discharge pipe for discharging the sucked sludge water to the sludge recovery device,
A flocculant discharge pipe for injecting the flocculant from the flocculant addition means is connected to the discharge pipe of the sludge transfer means,
The length and the pipe diameter of the discharge pipe of the sludge transfer means are set so that the discharged sludge water reacts with the injected flocculant to form a floc in the discharge pipe. A sludge collection system characterized by that. The filtration member used in the sludge recovery device has an apparent opening diameter O. ₉₅ Having a function of 0.8 to 1.2 mm and / or a water permeability coefficient kt of 2.5 to 3.0 cm / s and capable of separating a filtrate having a transparency of 50 cm or more from the excess sludge. The sludge recovery system according to claim 1. The main body of the sludge recovery device is divided into two vertically and can be opened and closed.
The sludge recovery system according to claim 1 or 2, wherein the inner peripheral surface and the inner bottom surface of the main body are made of perforated steel plates. The said sludge collection | recovery apparatus is provided with the ventilation means which applies a wind pressure from the top with respect to the liquid level of the said excess sludge which accumulates in the said sludge accumulation part. The sludge collection system according to item. The sludge recovery system according to any one of claims 1 to 4, wherein the main body is disposed on a vibration unit that vibrates the main body of the sludge recovery device. The sludge recovery system according to any one of claims 1 to 5, wherein the sludge recovery device is also used as a transport container for transporting the recovered sludge. The sludge recovery system according to claim 6 , wherein the sludge recovery device is detachable from a vehicle. A plurality of the sludge recovery devices are provided,
The sludge recovery device includes a switching unit that alternately switches between a filtration step of filtering while depositing the sludge and a dehydration step of leaving and collecting the recovered sludge after the filtration step . The sludge recovery system according to any one of items 7 to 9. A deposition level detection means for detecting a deposition level of the sludge in the sludge recovery device;
The sludge recovery system according to any one of claims 1 to 8 , wherein the control of the sludge transfer means is performed based on a sludge accumulation level detected by the accumulation level detection means. . Using the sludge recovery system according to any one of claims 1 to 8 , a sludge transfer step of transferring sludge water to the sludge recovery device while refining with a flocculant,
A filtration step of filtering while transferring the sludge water that has been transferred to the sludge accumulation section;
And a dehydration step of dehydrating the sludge water by stopping the transfer of the sludge water to the sludge recovery device and leaving the recovered sludge to stand. Using the sludge recovery system according to claim 8 ,
A sludge recovery treatment method comprising operating a plurality of sludge recovery devices while alternately switching between a filtration step and a dehydration step. Using the sludge recovery system according to claim 9 ,
2. A sludge recovery treatment method, wherein sludge water is transferred while detecting a sludge accumulation level in the sludge accumulation section.

Images