JP2005185902A - Method and equipment for treating sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating sludge which is suitable for the treatment of the sludge produced particularly in a small scaled water treatment plant and by which the treatment efficiency is improved, and equipment for treating the sludge which promotes cost saving and space saving. <P>SOLUTION: The method for treating the sludge is provided with a concentration process for concentrating the sludge M by a concentration means 2 and a drying process for supplying the concentrated sludge N concentrated in the concentration process with a water content nearly as it is to a drying means 4 and drying. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a sludge treatment method and treatment equipment suitable for treating sludge such as clean water sludge generated particularly at a water purification plant.

In this type of sludge treatment, a concentration step for concentrating sludge by a concentration means, a dehydration step for dewatering the concentrated sludge concentrated in this concentration step by a dehydration means, and a dehydration step for dewatering the concentrated sludge in this dewatering step. In addition, the moisture content of the sludge is sequentially reduced and reduced by a drying process in which the sludge is further dried by a drying means. Here, in Patent Document 1, in the treatment of water sludge generated in the purification process of waterworks at a water purification plant, a pressure levitation concentration tank is used as a concentration means, and a filter press is used as a dehydration means, for example. It is described.
JP-A-6-182348

  However, the amount of water sewage sludge generated in such a water purification plant is small compared to, for example, the amount of sewage sludge generated in a sewage treatment plant, and is particularly small in a small water purification plant. However, in order to treat such a small amount of water sludge, conventionally, the treatment must be performed in three steps of concentration, dehydration, and drying. Concentration means, dehydration means, and drying are performed for each step. Since measures are required and facilities increase, it is difficult to save cost and space even in small water treatment plants. In particular, when a filter press as described in Patent Document 1 is used as a dehydrating means in the dehydration step, the treatment in the dehydration step must be a batch type (batch type), and such a filter Since dehydration by the press may take a long time, there was a limit to improving the sludge treatment efficiency.

  The present invention has been made under such a background, and is particularly suitable for use in the treatment of sludge generated in a small-scale water purification plant, and is capable of improving the treatment efficiency, and The object is to provide a sludge treatment facility that can promote cost saving and space saving of the facility.

  In order to solve the above problems and achieve such an object, the sludge treatment method of the present invention comprises a concentration step of concentrating sludge by a concentration means, and the concentrated sludge concentrated in this concentration step as it is. And a drying step of supplying to the drying means at a moisture content of and drying. Further, the sludge treatment facility of the present invention comprises a concentration means for concentrating the sludge, and a drying means for drying the concentrated sludge by supplying the concentrated sludge concentrated by the concentration means at a substantially moisture content. It is characterized by.

  Therefore, in the sludge treatment method and treatment equipment configured as described above, the sludge concentrated to a predetermined moisture content by the concentration means in the concentration step does not pass through the dehydration step by the dehydration means such as a filter press. Since it is supplied to the drying means in the drying process at a concentrated almost intact moisture content, it is effectively applied to treat a small amount of water sludge generated in a small-scale water purification plant. Therefore, it is possible to promote continuous and efficient sludge treatment by omitting the treatment by the dehydration process. Further, since no dehydrating means such as a filter press is required, the cost can be saved and the space can be saved by omitting this.

  Here, the concentration means is preferably a means for concentration by filtering the sludge. In addition, in order to smoothly supply the concentrated sludge concentrated by the concentration means in the concentration step to the drying means in the drying step, the sludge treatment method includes the concentration step, the drying step, and the like. It is desirable to temporarily store the concentrated sludge at a substantially unchanged moisture content, and in the treatment facility, the concentrated sludge is kept at a substantially unchanged moisture content between the concentration means and the drying means. It is desirable to provide a temporary storage tank for temporary storage. That is, by temporarily storing concentrated sludge in this way, for example, even if fluctuations occur in the amount of sludge processed in the concentration step, a constant amount of sludge can be supplied to the drying step, and continuous processing is maintained. Stable dry sludge can be generated.

  Further, as the concentration means, it is desirable to use a higher concentration efficiency in consideration of the processing efficiency in the drying process. For example, one end is connected to the filtration means disposed in the concentration tank, and the other end is A filtrate discharge pipe opened at a position lower than the filtration means outside the concentration tank is provided, the sludge supplied to the concentration tank is filtered by the filtration means, and the filtrate is naturally flowed through the filtrate discharge pipe. It is desirable to use a siphon type filtration concentration apparatus that discharges and produces the concentrated sludge on the surface of the filtration means. And when a siphon type concentrating device is used as the concentrating means in this way, the filtrate discharge pipe connected to the filtering means by disposing the concentrating tank of the concentrating means above the drying means. The difference in height between one end of the filter and the other end that opens outside the filtration tank can be ensured, that is, the siphon force can be reliably ensured to concentrate the sludge more efficiently. Even if the moisture content is reduced and the concentrated sludge is directly supplied to the drying step, it is possible to obtain a reliable dry sludge, and it is possible to promote more efficient treatment.

  1 and 2 show an embodiment of the sludge treatment facility of the present invention. While describing the treatment facility, one embodiment of the sludge treatment method of the present invention using the treatment facility will be described below. Also explained. The treatment facility of the present embodiment treats the sewage sludge such as the sludge of the washing drainage discharged from the membrane filtration treatment facility of the water in the relatively small water purification plant as described above, The drainage tank 1 in which the washing waste water W is held, a siphon type concentrating device 2 as a concentration means, a temporary storage tank 3, and a stirring blade built-in type indirect heating dryer 4 as a drying means in the present embodiment. ing. The siphon type concentrating device 2, the temporary storage tank 3, and the stirring blade built-in type indirect heating dryer 4 are arranged in this order from top to bottom as shown in FIG. A siphon-type concentrating device 2 as a means is disposed above a stirring blade built-in type indirect heating dryer 4 as a drying means.

  Among these, first, the drainage tank 1 holds the cleaning wastewater W after washing the membrane module made of a hollow fiber membrane or the like for filtering the clean water in the membrane filtration processing equipment as described above. The sludge M that has settled on is supplied to the siphon type concentrator 2 by the pump 11, and the relatively clear supernatant water C is returned to the membrane filtration equipment after the crypts are sterilized by, for example, ultraviolet rays. Here, the moisture content of the sludge supplied from the drainage tank 1 to the siphon type concentrator (concentration means) 2 is about 98 to 99 wt%.

  The siphon type concentrating device 2 has a filtering means 22 disposed in a concentrating tank 21 provided with a discharge port 21A at the bottom, and one end of a filtrate discharge pipe 23 is connected to the filtering means 22. Yes, the other end of the filtrate discharge pipe 23 is routed outside the concentration tank 21 and extends downward from the filtration means 22, and then is branched into two directions. One of the filtrate discharge pipes 23 is fed to the filtrate tank 24 via a valve 23A. While being opened, the other is connected to the vacuum pump 25 via a valve 23B. The discharge side of the vacuum pump 25 can be connected to the filtrate tank 24 as well.

  The concentrating tank 21 has a cross-sectional home base type whose bottom side is an inverted triangle, and the discharge port 21A is provided with a valve 21B. The valve 21B is provided with the temporary storage as shown in FIG. As shown in FIG. 2 (b), the tank 3 is connected to the unconcentrated sludge discharge tank 21C in a switchable manner. Further, in the filtering means 22, for example, a filter cloth 22B is stretched outside the filter plate 22A, and a filtrate discharge pipe 23 is connected to the filter plate 22A so that the one end is opened inside the filter cloth 22B. A plurality of such filter plates 22 </ b> A are provided in the concentration tank 21 so as to be suspended from the bottom portion.

  The concentration process of sludge M by the siphon type concentrator (concentration means) 2 will be described with reference to FIG. 1. First, the sludge M is supplied and filled in the concentration tank 21 with the valve 21B closed, and then. The valve 23A is closed and the valve 23B is opened, and suction is performed from the filtrate discharge pipe 23 by the vacuum pump 25. Then, the sludge M in the concentrating tank 21 is filtered by the filter cloth 22B of the filtering means 22, and the filtrate L is led out of the concentrating tank 21 through the filtrate discharge pipe 23 and extracted below the filtering means 22. Therefore, when the valve 23B is closed and the valve 23A is opened to open the other end of the filtrate discharge pipe 23, the filtrate L is filtered by the siphon principle as shown in FIG. 2 (a) without driving the vacuum pump 25. While the discharge pipe 23 continuously flows down naturally and is discharged to the filtrate tank 24, the solid content in the sludge M is left on the surface of the filter cloth 22B of the filtration means 22 and concentrated to produce concentrated sludge N. The

  When the concentrated sludge N is generated in this way, as shown in FIG. 2 (b), the valve 21B is opened, the discharge port 21A is connected to the unconcentrated sludge discharge tank 21C, and the unconcentrated sludge P left in the concentration tank 21 is obtained. Is discharged. Next, the connection of the discharge port 21A is switched to the temporary storage tank 3 side, and the discharge side of the vacuum pump 25 is connected to the filtrate tank 24, so that the filtrate discharge pipe 23 has a filtrate tank as shown in FIG. The compressed air A discharged from the vacuum pump 25 is supplied from the other end opened to 24 toward one end to which the filtration means 22 is connected, and the concentrated sludge N generated on the surface of the filter cloth 22B is The compressed air A peels off the filter cloth 22B, falls to the bottom of the concentration tank 21, and is supplied to the temporary storage tank 3 from the discharge port 21A. Here, the water content of the concentrated sludge N obtained by concentrating the sludge M by this concentrating means is about 90 to 85 wt%.

  The temporary storage tank 3 is formed in a tank shape having a tapered bottom, and a discharge port 31 provided at the lower end of the bottom is provided with a stirring blade built-in type indirect heating dryer (drying means) via a damper 32 or the like. 4 is liquid-tight and air-tightly connected. The concentrated sludge N supplied to the temporary storage tank 3 is merely temporarily stored and its moisture content does not change. By opening and closing the damper 32, a predetermined amount of stirring blades are built in from the discharge port 31. It is supplied to the mold indirect heating dryer 4.

  On the other hand, the indirect heating dryer 4 with a built-in stirring blade is a vacuum vessel including a truncated cone-shaped main body 41 whose upper and lower sides are closed and whose lower peripheral surface gradually decreases in diameter as it goes downward. 41 is connected to the vacuum pump 25 via a valve 41A so that the pressure can be reduced to a vacuum state. In addition, the top plate portion 41B that closes the upper portion of the main body 41 is provided with a supply port 42 at a position slightly away from the center thereof, and temporarily maintains the vacuum state in the main body 41 via the damper 32. A discharge port 43 can be connected to the discharge port 31 of the storage tank 3, and a discharge port 43 is provided at the lower end portion of the main body 41. The discharge port 43 is also a damper 44 that can maintain the vacuum state in the main body 41. And is opened to a collection means 45 such as a container.

  Further, a rotation driving device 46 such as a motor is provided at the center of the top plate portion 41B, and a stirring blade 47 is attached along the rotation shaft 46A. The stirring blade 47 is rotatably attached by a rotation drive device 46. Furthermore, the peripheral surface portion of the main body 41 has a jacket structure 41C, and steam S can be supplied from a steam generating means (not shown) into the jacket structure 41C, or heated by an electric heater using oil as a medium. ing.

  In such a drying process by the stirring blade built-in type indirect heating dryer 4, in this embodiment, the inside of the main body 41 is evacuated by the vacuum pump 25 and the vacuum state is maintained via the damper 32. As it is, the concentrated sludge N is supplied from the temporary storage tank 3 into the main body 41. The concentrated sludge N thus supplied is heated by the steam S or the electric heater supplied into the jacket structure 41C while being stirred and mixed by the rotary driving device 46 around the central axis of the main body 41 by the stirring blade 47. The medium is indirectly heated from the inner peripheral surface of the main body 41, dried and granulated. Further, the dried sludge D thus dried and granulated is discharged from the discharge port 43 while the vacuum state in the main body 41 is maintained by the damper 44 and recovered by the recovery means 45 such as the container, and the crypts are sterilized. For example, it is effectively used as granulated dry soil. In addition, the moisture content of the dried sludge D having undergone the drying process in this way is set to about 40 wt%.

  Therefore, in the sludge M treatment equipment configured as described above and the sludge M treatment method using the treatment equipment, the concentrated sludge N obtained by concentrating the sludge M in the concentration step by the concentrating means is used as it is. The dried sludge D is supplied to the drying means at a rate and dried by the drying process, so that there is no need for a dehydration process by a dehydration means such as a filter press between the concentration process and the drying process as in the prior art. . For this reason, the processing equipment can reduce the cost and space for the dehydrating means as described above, and the processing method is generally sludge by eliminating a dehydrating process that must be a batch process. It becomes possible to perform the treatment of M continuously and it becomes efficient. For example, as in the present embodiment, the treatment of water sewage sludge in a small-scale water purification plant or the like that produces a small amount of sludge compared to a sewage treatment plant or the like It is particularly suitable when applied to.

  Further, in the treatment facility in the present embodiment, a temporary storage tank 3 is provided between the siphon type concentrating device 2 as the concentrating means and the stirring blade built-in type indirect heating dryer 4 as the drying means, In the treatment method of the present embodiment, the concentrated sludge N concentrated by the siphon type concentrator 2 is temporarily stored in the temporary storage tank 3 with the moisture content as it is, and then supplied to the indirect heating dryer 4 with a built-in stirring blade. It has been made so that. For this reason, for example, the amount of generated water sludge generated in the small-scale water purification plant or the like fluctuates, and accordingly, the amount of sludge M supplied to the concentration means and the concentration of the concentrated sludge N concentrated by the concentration means. Even if the amount also fluctuates, by adjusting the amount of concentrated sludge N stored in the temporary storage tank 3, the drying means is supplied with the concentrated sludge N having a constant water content with a substantially uniform supply amount. In the drying process by this drying means, for example, there is no need to increase or decrease the pressure of the steam S supplied to the jacket structure 41C or to change the drying conditions by adjusting the temperature of the electric heater. It becomes possible to dry the stable concentrated sludge N. However, the temporary storage tank 3 can be omitted when there is no possibility that the supply amount of the concentrated sludge N varies.

  Further, in the treatment facility of the present embodiment, as the concentration means, a filtration means 22 is disposed in the concentration tank 21 to which the sludge M is supplied, and one end of a filtrate discharge pipe 23 is connected to the filtration means 22. At the same time, the other end of the filtrate discharge pipe 23 is opened at a position lower than the filtration means 22 outside the concentration tank 21, and the filtrate L obtained by filtering the sludge M by the filtration means 22 is discharged by natural flow according to the siphon principle. Thus, a siphon type concentrating device 2 that generates concentrated sludge on the surface of the filtering means 22 is used. In this embodiment, the siphon type concentrator 2 is provided above the stirring blade built-in type indirect heating dryer 4 and the temporary storage tank 3 as drying means, that is, the siphon type concentrator 2, Since the temporary storage tank 3 and the indirect heating dryer 4 with a built-in stirring blade are arranged in this order in the vertical direction and the siphon type concentrating device 2 is located at the uppermost part in the processing equipment, the filtration means 22 and the filtrate A large difference in height from the other end of the discharge pipe 23 can be ensured, and the filtration capacity of the filtration means 22 can be improved. Therefore, the sludge M can be efficiently concentrated.

  On the other hand, in the present embodiment, as the drying means, the concentrated sludge N supplied in the main body 41 is mixed by the stirring blade 47 built in the main body 41 and heated indirectly to dry, and the stirring blade built-in type indirect The heat dryer 4 is used, and it becomes possible to produce the dried sludge D having a uniform moisture content and granulated to an appropriate particle size, and can be used more effectively as the above-mentioned dry soil. It becomes easy. Further, in the indirect heating dryer 4 with a built-in stirring blade of the present embodiment, the main body 41 is made into a vacuum vessel and connected to the vacuum pump 25, whereby the inside of the main body 1 is brought into a vacuum state (depressurized state), and concentrated sludge N It can be dried in vacuum, and even if the moisture content of the concentrated sludge N is high, it is possible to obtain a dry sludge D having a predetermined moisture content by efficiently drying.

  In addition, the supply port 42 for the concentrated sludge N and the discharge port 43 for the dried sludge D of the main body 41 are provided with dampers 32 and 44 for maintaining the vacuum state in the main body 41. The vacuum state in the main body 41 is not impaired every time it is discharged, and more efficient drying can be achieved. In addition, the vacuum pump 25 that evacuates the main body 41 is shared with the vacuum pump 25 that initially sucks the filtrate L from the filtration means 22 of the siphon type concentrator 2 as the concentration means through the filtrate discharge pipe 23. Therefore, it is possible to further reduce the cost and space of the processing equipment, which is efficient. However, in some cases, the concentrated sludge N may be dried at normal pressure without reducing the pressure inside the main body 41 in this way.

  Further, the lower side of the main body 41 is formed into a truncated cone shape that gradually decreases in diameter as it goes downward, so as to form a so-called mortar shape, and the peripheral surface portion thereof is indirectly heated as a jacket structure 41C, while the stirring blade 47 Is rotated around the central axis of the main body 41 within the truncated cone formed by the main body 41. Accordingly, the concentrated sludge N supplied from the supply port 42 at the top of the main body 41 to the indirect heating dryer 4 with a built-in stirring blade is stirred and mixed while being brought into sliding contact with the inner peripheral surface of the main body 41 by the rotation of the stirring blade 47. In addition to being dried to a more uniform moisture content, the lower portion of the main body 41 provided with the discharge port 43 has a small cross section perpendicular to the central axis, so that the amount of heat received is large, and more efficient and reliable drying can be achieved. It becomes possible. In this embodiment, in order to indirectly heat the concentrated sludge N in this way, the peripheral surface portion of the main body 41 is used as the jacket structure 41C to supply the heat medium such as S. For example, a heating wire is wound around the peripheral surface portion. The concentrated sludge N may be heated and dried by rotating or using oil as a medium by a heat transfer heater structure.

It is the schematic which shows one Embodiment of the processing equipment of the sludge of this invention. It is a figure which shows the concentration process in embodiment shown in FIG.

Explanation of symbols

2 Siphon type concentrator (concentration means)
3 Temporary storage tank 4 Indirect heating dryer with built-in stirring blade (drying means)
DESCRIPTION OF SYMBOLS 21 Concentration tank 22 Filtration means 23 Filtrate discharge pipe 24 Filtrate tank 25 Vacuum pump 32, 44 Damper 41 Main body of indirect heating dryer with built-in stirring blade 41C Jacket structure of main body 41 47 Stirring blade W Wash drainage M Sludge N Concentrated sludge L Filtrate D Dry sludge S Steam

Claims (6)

A sludge comprising a concentration step for concentrating sludge by a concentration means, and a drying step for supplying the concentrated sludge concentrated in this concentration step to the drying means with substantially the same moisture content and drying the sludge. Processing method. The method for treating sludge according to claim 1, wherein the concentration means is means for concentrating the sludge by filtering. The method for treating sludge according to claim 1 or 2, wherein the concentrated sludge is temporarily stored at a substantially unchanged moisture content between the concentration step and the drying step. A sludge treatment facility comprising: a concentration means for concentrating sludge; and a drying means for drying the concentrated sludge by supplying the concentrated sludge concentrated by the concentration means at a substantially unchanged water content. . The sludge treatment facility according to claim 4, wherein a temporary storage tank is provided between the concentrating means and the drying means to temporarily store the concentrated sludge at a substantially unchanged moisture content. The concentrating means is provided with a filtrate discharge pipe having one end connected to the filtering means disposed in the concentrating tank and the other end opened at a position lower than the filtering means outside the concentrating tank, and is supplied to the concentrating tank The filtered sludge is filtered by the filtering means, the filtrate is discharged by natural flow through the filtrate discharge pipe, and the concentrated sludge is generated on the surface of the filtering means. The sludge treatment facility according to claim 4 or 5, wherein a concentration tank is disposed above the drying means.

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