JP4819841B2 - Membrane separator - Google Patents

Description

  The present invention relates to a membrane separation apparatus, and more particularly to a membrane separation apparatus for wastewater treatment equipment.

  Conventional membrane separation wastewater treatment equipment is mainly used to perform membrane treatment by installing a membrane unit in a water tank. For example, when BOD processing is targeted, an “oxidation tank” for oxidizing BOD is installed, and a membrane unit is immersed therein to perform solid-liquid separation. In addition, when performing advanced treatment including nitrogen treatment, two treatment tanks, a “denitrification tank” that performs denitrification while maintaining an anaerobic state, and a “nitrification tank” that performs solid-liquid separation by nitrification and membranes, are used as treatment tanks. It is installed and treated water is circulated between these two tanks.

  However, when advanced processing is performed using two tanks, there is a problem that additional equipment for performing liquid feeding, circulation, stirring, and the like is required, which increases costs.

  For this reason, in recent years, an apparatus for performing advanced processing using only one tank has been developed. For example, Patent Document 1 proposes a membrane separation apparatus in which a plurality of membrane units are arranged in an endless processing tank. In this membrane separation apparatus, a plurality of membrane units are arranged at predetermined intervals in the flow direction of the water to be treated. For this reason, a filtration process can be performed in multistep. Furthermore, since the membrane surface of the membrane unit is arranged parallel to the flow direction of the swirling flow, accumulation of sludge and the like on the membrane surface can be prevented.

Patent Document 2 proposes a membrane separation device in which a diffuser is disposed below a membrane unit and a swirl flow is formed by utilizing an air lift effect of the diffuser. According to this membrane separation apparatus, a swirling flow can be formed by performing aeration with the aeration means, and power consumption can be reduced.
JP-A-6-285339 JP 2001-47046 A

  However, the membrane separation apparatus that performs the advanced treatment with only one tank has a problem that the treatment performance is low.

  For example, in the membrane separation apparatus of Patent Document 1, the BOD in the treated water supplied from the raw water supply pipe is consumed as a nutrient source for anaerobic bacteria (for example, denitrifying bacteria) contained in the sludge in the treated water. The BOD concentration decreases as it goes downstream of the raw water supply pipe. For this reason, there existed a problem that the performance of anaerobic processing fell as it became the downstream of a raw | natural water supply pipe | tube.

  In the membrane separation apparatus of Patent Document 2, since a swirl flow is formed by the air lift effect, there is a problem that the flow rate of the water to be treated is insufficient and the membrane surface cleaning effect is small. As a result, there has been a problem that the accumulation of sludge on the film surface cannot be sufficiently prevented, the film surface is blocked in a short period of time, and the processing performance is lowered.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to improve processing performance in a membrane separation apparatus that performs advanced processing only with one processing tank.

In order to achieve the above object, the invention according to claim 1 is an endless treatment tank in which treated water is biologically treated and a swirling flow of the treated water is formed, and the treated object. In the membrane separation apparatus provided with a membrane unit that is immersed in water and membrane-separates the water to be treated, a baffle plate is provided on each of the upstream side and the downstream side of the membrane unit, and the upstream baffle plate The upper end protrudes higher than the liquid level, the lower end is disposed with a predetermined gap from the bottom surface, and the downstream baffle plate is disposed at a position where the upper end is lower than the liquid level. The lower end is fixed to the bottom surface, and the treatment tank has a deep portion with a large water depth at the installation position of the membrane unit, and a diffuser is provided at the bottom of the deep portion.

  According to invention of Claim 1, since the deep part of the processing tank was provided in the installation position of the membrane unit, and the aeration means was arranged in this deep part, the air bubbles diffused by the aeration means come into contact with the water to be treated. The time will be longer. Thereby, the dissolution efficiency of oxygen in water to be treated can be improved, and aerobic treatment performance such as nitrification can be improved.

  According to a third aspect of the present invention, in the second aspect of the present invention, the upstream side of the deep portion is formed in a tapered shape.

  According to the membrane separation apparatus of the present invention, the processing performance of the membrane separation apparatus that performs advanced treatment in one tank can be improved by providing the deep part of the tank in the position of the membrane unit.

  Hereinafter, preferred embodiments of a membrane separation apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view showing a membrane separation apparatus in which the present invention is applied to a nitrification / denitrification apparatus.

  As shown in the figure, the membrane separation apparatus 10 is mainly composed of a raw water tank 12 and a treatment tank 14. The raw water tank 12 is formed in a substantially rectangular shape, and a treatment tank 14 is formed so as to surround the raw water tank 12. That is, the processing tank 14 is formed in an endless shape, and the raw water tank 12 is provided inside thereof. To-be-treated water is stored in the raw water tank 12, and this to-be-treated water is supplied to the treatment tank 14 via a supply pipe 16 described later.

  The treatment tank 14 is provided with a stirrer 18. By driving the stirrer 18, a swirl flow in which the water to be treated swirls around the raw water tank 12 is formed. The stirrer 18 may be driven only at the start of operation. That is, the stirrer 18 may be stopped when the swirl flow is stably formed by the air lift effect described later.

  The treatment tank 14 is provided with a plurality of membrane units 22, 22. The membrane unit 22 is disposed at a predetermined interval in the flow direction of the swirl flow.

  As shown in FIG. 2, the membrane unit 22 includes a plurality of membrane elements 24, 24. Each membrane element 24 has a membrane 26 such as an organic flat membrane attached to both surfaces of a water-permeable material (not shown) formed in a rectangular plate shape, and its outer peripheral portion is sealed with a seal member (not shown). Consists of. Each membrane unit 22 is arranged in parallel with a predetermined interval, and is installed so that the membrane 26 of each membrane unit 22 is parallel to the inner wall of the treatment tank 14 (see FIG. 1).

  A water collecting pipe 28 is connected to the upper end of the membrane element 24. The water collecting pipe 28 communicates with the inside of the membrane element 24, and the tip thereof is connected to a pump (see FIG. 1) 20. Therefore, by driving the pump 20, a suction action is activated inside each membrane element 24, and the water to be treated is sucked inside through the membrane 26. And the treated water which permeate | transmitted the film | membrane 26 is drained through the water collection pipe 28. FIG. Although FIG. 1 shows an example in which a separate pump 20 is connected to each membrane unit 22, a plurality of membrane units 22 may use a common pump. FIG. 2 shows an example in which the water collecting pipe 28 is connected to the upper part of the membrane element 24. However, the water collecting pipe may be connected to both left and right ends of the membrane element 24 so that the treated water is drawn out in the horizontal direction. Good.

  As shown in FIG. 3, a deep portion 34 having a large water depth is formed on the bottom surface of the treatment tank 14 at the position where each membrane unit 22 is installed. The water depth in the deep portion 34 is configured to be approximately twice the water depth of other portions. The membrane element 24 described above is formed in a vertically long shape in accordance with the deep portion 34. Instead of providing the vertically long membrane element 24, normal (small height dimension) membrane elements may be arranged in a plurality of layers in the vertical direction.

  A diffuser tube 30 is provided below the membrane unit 22, and the diffuser tube 30 is connected to the blower 32. When air is supplied from the blower 32, countless bubbles are diffused into the water to be treated. Since the diffused bubbles rise between the membrane elements 24, 24, an upward flow of water to be treated is formed by the air lift effect. Thereby, a cross flow is given to the film | membrane 26, and the film | membrane 26 is wash | cleaned. Therefore, it is possible to suppress deposits from being deposited on the film 26.

  Baffles 36 and 38 are provided upright on the upstream side and the downstream side of the membrane unit 20, respectively. The baffle plates 36 and 38 are installed so as to be orthogonal to the side walls 14A and 14B (see FIG. 5) of the treatment tank 14. The upstream baffle plate 36 has an upper end protruding higher than the liquid level and a lower end disposed with a predetermined gap from the bottom surface. On the other hand, the downstream baffle plate 38 is arranged at a position where its upper end is slightly lower than the liquid level, and its lower end is fixed to the bottom surface. Therefore, when air is diffused from the air diffuser 30, an upward flow of the water to be treated is formed by the air lift effect of the diffused bubbles. Then, the water to be treated on the upstream side is sucked into the membrane unit 22 side so as to dive the lower end of the upstream baffle plate 36, and the water to be treated on the membrane unit 22 side is absorbed into the upper end of the baffle plate 38 on the downstream side. Over to the downstream side. As a result, a swirl flow in which the water to be treated swirls around the raw water tank 12 is formed. The upstream side of the deep portion 34 is formed in a tapered shape so that the water to be treated can smoothly enter between the two baffle plates 36 and 38.

  As shown in FIG. 1, the supply pipe 16 is connected to the processing tank 14 on the downstream side of each membrane unit 22 (that is, on the downstream side of each baffle plate 38). The supply pipe 16 is provided with a pump 40 and a valve 42, and the water to be treated in the raw water tank 12 is supplied to the treatment tank 14 by driving the pump 40. Further, the flow rate of the water to be treated flowing through the supply pipe 16 is adjusted by adjusting the opening degree of the valve 42 or the liquid feed amount of the pump 40. Thereby, the flow volume of the to-be-processed water supplied by each piping 16 for supply can be adjusted, respectively.

  In addition, it is preferable to arrange | position the front-end | tip of the piping 16 for supply in the liquid of to-be-processed water. Thus, since the water to be treated is supplied to the lower part on the downstream side of the baffle plate 38, it is possible to prevent the retention area of the water to be treated from being formed in this area.

  Moreover, the supply method of to-be-processed water is not limited to what was mentioned above. For example, as shown in FIG. 4, the supply pipe 48 may be connected to the upper part of the side wall of the raw water tank 12, and the weir 50 may be provided slidably up and down at the inlet of the supply pipe 48. In this case, when the water level of the raw water tank 12 rises and exceeds the upper end of the weir 50, the water to be treated is automatically supplied from the supply pipe 48 to the treatment tank 14. Moreover, the supply flow rate of to-be-processed water can be adjusted by changing the height position of the weir 50 manually or automatically. In addition, it is sufficient to provide an opening at the upper part of the side wall of the raw water tank 12 without providing the supply pipe 48.

  As shown in FIG. 5, movable walls 44 are provided on the side walls 14 </ b> A and 14 </ b> B of the processing tank 14. The movable wall 44 is provided on the side of the membrane unit 22 and is slidably supported in the width direction of the processing tank 14. The movable wall 44 is connected to a cylinder 46 and is moved in the width direction of the processing tank 14 by the cylinder 46. Therefore, the flow path of the swirling flow can be narrowed by the movable wall 44, and the flow rate of the water to be treated passing through the membrane unit 22 can be increased. Thereby, since the shearing force applied to the film 26 of the film unit 22 is increased, the peelability of the deposit adhered to the film 26 is improved, and the film 26 can be prevented from being blocked. In addition, it is preferable that the movable walls 44 and 44 slide on the side walls 14A and 14B by the same amount at the same time. Moreover, although it is preferable to provide the movable wall 44 in both side wall 14A, 14B, you may provide in only either one.

  Next, the operation of the membrane separation apparatus 10 configured as described above will be described.

  When the blower 32 is driven to diffuse air from the air diffuser tube 30, the water to be treated rises due to the air lift effect. Then, the water to be treated is sucked into the membrane unit 22 side from below the upstream baffle plate 36, and the water to be treated on the membrane unit 22 side flows out beyond the upper end of the baffle plate 38. As a result, a swirl flow in which the water to be treated swirls around the raw water tank 12 is formed. At this time, the swirl flow can be quickly formed by driving the stirrer 18.

  By performing aeration from the aeration tube 30, the installation position of the membrane unit 22 (that is, between the baffle plates 36 and 38) is in an aerobic state. Hereinafter, this area is referred to as an aerobic part. Moreover, since there is no contact with oxygen between an aerobic part and an aerobic part, it is in an anaerobic state (henceforth an anaerobic part).

  The water to be treated passes through the aerobic part and the anaerobic part alternately by turning in the treatment tank 14. Thereby, the nitrification action in the aerobic part and the denitrification action in the anaerobic part are alternately received, and the nitrogen component of the water to be treated is efficiently removed.

  When the pump 20 is driven in a state where a swirl flow of the water to be treated is formed, the water to be treated is sucked into the membrane element 24. Thereby, membrane filtration is performed and the treated water without a suspension can be obtained. As a result of the membrane filtration, the sludge concentration inside the treatment tank 14 increases, for example, a high sludge concentration of 10 g / L. Thereby, since the consumption amount of DO in an aerobic part becomes large, DO in an anaerobic part falls, and it can improve the processing performance in an anaerobic part.

  By the way, in an anaerobic part, the anaerobic process is performed using BOD in to-be-processed water as a nutrient source. Therefore, when the BOD concentration is lowered in the anaerobic part, there arises a problem that the processing performance in the anaerobic part is lowered. In the conventional apparatus, since the water to be treated (raw water) is supplied to the treatment tank at a single location, there is a problem that the treatment performance decreases as the anaerobic portion is located downstream of the supply position.

  In the present embodiment, in order to eliminate such problems, the water to be treated is supplied to each anaerobic part by connecting the supply pipes 16, 16... To the downstream side of the membrane units 22, 22. Yes. Thereby, since BOD is fully supplied to each anaerobic part, the processing performance in an anaerobic part can be improved.

  In addition, according to the present embodiment, since the film 26 is arranged in parallel with the flow direction of the swirl flow, the film 26 can be washed by the swirl flow, and deposits can be prevented from being deposited on the film 26. .

  Furthermore, in the present embodiment, the movable wall 44 can be protruded from the side wall of the processing tank 14 to narrow the flow path of the swirl flow, so that the flow velocity of the swirl flow applied to the film 26 is increased and the film 26 is washed. The effect can be increased. In the present embodiment, the movable wall 44 can be retracted as necessary to widen the flow path of the swirl flow. Therefore, for example, the swirling flow can be easily formed by widening the flow path at the start of operation. Further, the flow path of the swirling flow may be narrowed only when the membrane 26 is washed. In addition, by operating the stirrer 18, it is possible to increase the flow velocity of the swirling flow and enhance the cleaning effect of the membrane 26.

  Moreover, according to this Embodiment, since the deep part 34 is provided in the processing tank 14, and the diffuser pipe 30 is arrange | positioned in the bottom part of this deep part 34, the air bubble diffused from the diffuser pipe 30 turns into to-be-processed water. Longer contact time. Therefore, the dissolved oxygen concentration in the aerobic part can be improved. Thereby, even if it is a case where sludge density | concentration is high, DO can be increased reliably in an aerobic part and the processing performance in an aerobic part can be maintained.

  Moreover, in this Embodiment, since the raw | natural water tank 12 was provided inside the endless processing tank 14, the processing tank 14 and the raw | natural water tank 12 can be installed in a small space. Therefore, the processing performance per unit area of the site can be improved.

  Furthermore, by providing the raw water tank 12 inside the treatment tank 14, the supply of the water to be treated to the treatment tank 14 can be easily controlled. For example, as shown in FIG. 4, when the supply amount is adjusted using the weir 50, the same amount of water to be treated can be supplied to each supply pipe 48 just by aligning the height position of the weir 50. it can.

  The membrane separation apparatus 10 described above has four main components (i.e., (1) supply of water to be treated in multiple stages, and (2) a raw water tank 12 provided inside the treatment tank 14. (3) The flow path is narrowed at the installation position of the membrane unit 22, and (4) the deep portion 34 of the treatment tank 14 is provided at the installation position of the membrane unit 22). If any one of the configuration requirements is satisfied, the processing performance can be improved. Below, each component requirement is demonstrated.

  The membrane separation apparatus shown in FIG. 6 is an example of an apparatus that satisfies the above-described constituent requirement (1). In the membrane separation apparatus shown in the figure, a raw water tank 52 is disposed outside a processing tank 54, and the raw water tank 52 and the processing tank 54 are connected via a supply pipe 56. The supply pipe 56 is branched at the tip on the processing tank 54 side, and each is connected to the processing tank 54 downstream of the membrane unit 22. In addition, each branch pipe portion of the supply pipe 56 is provided with a valve 58 capable of adjusting the flow rate. Therefore, the water to be treated in the raw water tank 52 is supplied to the inside of the treatment tank 54 via the supply pipe 56 by driving the pump 60 disposed in the supply pipe 56. At that time, each supply amount can be adjusted by adjusting the opening degree of the valve 58. Thereby, the to-be-processed water of the raw | natural water tank 52 can be supplied in multiple steps in the flow direction of a swirl flow.

  In the membrane separation apparatus configured as described above, the treated water can be supplied in multiple stages in the flow direction of the swirl flow, so the component distribution of the water to be treated in the swirl flow direction (particularly the BOD concentration distribution). Can be prevented.

  In addition, the supply position of to-be-processed water is not limited to the upstream of an anaerobic part, What is necessary is just to supply in multistep along a swirl flow. Therefore, for example, the water to be treated may be supplied to the upstream side of each aerobic part (that is, the upstream side of the baffle plate 36) to increase the DO.

  The membrane separation apparatus shown in FIG. 7 is an example of an apparatus that satisfies the configuration requirement (2). As shown in the figure, the treatment tank 64 is formed in a substantially oval frame shape, and the raw water tank 62 is formed in a substantially oval shape inside thereof. The water to be treated in the raw water tank 62 is supplied to the treatment tank 64 through the supply pipe 66. A membrane unit 22 is disposed in the treatment tank 64, and membrane filtration is performed by the membrane unit 22.

  According to this membrane separation apparatus, since the raw water tank 62 is disposed inside the processing tank 64, the processing tank 64 and the raw water tank 62 can be installed in a small space, and the processing performance per unit area of the site can be improved. Can be improved. The raw water tank 62 may be disposed inside the processing tank 64, and the shape thereof is not limited to the same shape as the inner wall of the processing tank 64. Therefore, as shown by a two-dot chain line in FIG. 7, it may be divided into two inside the treatment tank 64, one as the raw water tank 62, and the other as the tank for storing the treated water and sludge.

  In addition, the shape of the processing tanks 14 and 64 is not limited to the rectangular frame shape or the oval frame shape described above, but is an endless shape capable of forming a swirl flow such as a circumferential shape or a polygonal frame shape. If it is. However, since it is preferable to arrange the membrane unit 22 in a straight portion of the flow path of the swirl flow, in order to install the plurality of membrane units 22, 22... In a small site area, as shown in FIG. It is preferable to use a frame-shaped treatment tank 64. Moreover, the raw | natural water tanks 12 and 62 should just be a shape which can be arrange | positioned inside the processing tanks 14 and 64. FIG.

  8 and 9 are views showing another embodiment of the constricting means for constricting the flow path of the swirling flow.

  The constricting means shown in FIG. The swing plate 68 is provided on the side of the membrane unit 22 and is attached to a recess formed in the side walls 14A and 14B of the processing tank 14. The swing plate 68 is supported so as to be swingable about the shaft 70. The shaft 70 is installed so as to be orthogonal to the flow direction of the swirling flow passing through the membrane unit 22. For example, when an upward flow is formed at the position of the membrane unit 22 as described above, the shaft 70 is installed horizontally. Further, when the baffle plates 36 and 38 shown in FIG. 3 are not provided and a horizontal swirling flow is always formed, the shaft 70 is installed vertically. The swing plate 68 is supported so as to be swingable about the shaft 70 arranged in this way, and is swung by a driving means (not shown). When the swing plate 68 is swung and protruded from the wall surfaces 14A and 14B, the flow path of the swirling flow can be narrowed. Further, by adjusting the angle of the swing plate 68, the cross-sectional area of the flow path can be adjusted. Furthermore, it is also possible to expand the flow path by housing the swing plate 68 in the recess.

  The stenosis means shown in FIG. The airbag 72 is attached to the side walls 14 </ b> A and 14 </ b> B of the treatment tank 14, and is inflated by supplying air into the airbag 72. Thereby, the flow path of the swirl flow can be narrowed. The airbag 72 contracts by discharging air from the inside. Thereby, the flow path of a swirl flow can be narrowed. Note that a diffuser blower 32 (see FIG. 3) may be used as means for inflating the airbag 72.

  In the above-described embodiment, the flow path is narrowed in the width direction of the processing tank 14, but the narrowing direction is not limited to this, and the processing tank 14 is narrowed in the longitudinal direction or the height direction. May be. For example, the flow path may be narrowed by narrowing the interval between the baffle plates 36 and 38 shown in FIG.

  Moreover, although embodiment mentioned above demonstrated the example of the movable type constriction means, you may use a fixed type constriction means. For example, convex portions may be provided on the side walls 14A and 14B of the processing tank 14 to narrow the flow path.

The block diagram which shows typically the structure of the membrane separator which concerns on this invention Perspective view showing the configuration of the membrane unit Sectional drawing which follows the 3-3 line of FIG. Sectional drawing which shows the other supply method of to-be-processed water Plan view showing stenosis means The block diagram which shows the other membrane separator which supplies a to-be-processed water in multistep The block diagram which shows the other membrane separation device which has arranged the raw water tank inside the swirl flow Longitudinal sectional view showing another embodiment of constriction means Longitudinal sectional view showing another embodiment of constriction means

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Membrane separator, 12 ... Raw water tank, 14 ... Treatment tank, 16 ... Supply pipe, 18 ... Stirrer, 22 ... Membrane unit, 24 ... Membrane element, 26 ... Membrane, 28 ... Water collecting pipe, 30 ... Aeration pipe, 32 ... Blower, 34 ... Deep part, 36 ... Baffle plate, 38 ... Baffle plate, 40 ... Pump, 42 ... Valve, 44 ... Movable wall, 46 ... Cylinder, 48 ... Supply piping, 50 ... Weir, 52 ... Original Water tank 54 ... Processing tank 56 ... Supply pipe 58 ... Valve 60 ... Pump 62 62Raw water tank 64 ... Process tank 66 ... Supply pipe 68 ... Oscillating plate 70 ... Shaft 72 ... Air bag

Claims (2)

An endless treatment tank in which the water to be treated is biologically treated and a swirling flow of the water to be treated is formed, and a membrane unit that is immersed in the water to be treated and membrane-separates the water to be treated In a membrane separation apparatus comprising:
A baffle plate is provided on each of the upstream and downstream sides of the membrane unit,
The upstream baffle plate has its upper end protruding higher than the liquid level, and its lower end is disposed with a predetermined gap from the bottom surface,
The downstream baffle plate is arranged at a position where the upper end is lower than the liquid level, and the lower end is fixed to the bottom surface,
The said processing tank has a deep part with a big water depth in the installation position of the said membrane unit, and a diffuser is provided in the bottom part of this deep part, The membrane separator characterized by the above-mentioned. The membrane separation apparatus according to claim 1 , wherein an upstream side of the deep part is formed in a tapered shape.

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