JP2011189308A - Active-sludge treatment apparatus and operation method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active sludge treatment apparatus which is little in aeration power required for physical cleaning of a membrane surface and also capable of highly packing a dipping type membrane separation apparatus in a treatment tank, and to provide an operation method of the active sludge treatment apparatus. <P>SOLUTION: The active sludge treatment apparatus has the dipping type membrane separation apparatus 1 and an air diffuser 3, which are dip arranged in a treatment tank 5 storing a liquid to be treated, wherein the dipping type membrane separation apparatus 1, having a plurality of flat membrane elements 2 which is arrayed keeping a space in the vertical direction and in parallel each other and has an opening part in the horizontal direction, is arranged so as to approach the bottom surface of the treatment tank 5, and the air diffuser 3 is arranged in the side direction of at least one opening part of the dipping type membrane separation apparatus 1, so as to approach a side defined by the side surface and the bottom surface of the treatment tank 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus used in wastewater treatment by a membrane separation activated sludge method and an operation method thereof.

  As an activated sludge treatment apparatus for wastewater treatment by a membrane separation activated sludge method, for example, an apparatus in which a membrane separation apparatus in which a plurality of flat membrane elements are arranged in parallel at appropriate intervals is immersed in a treatment tank is known (Patent Document 1). , 2). This type of submerged membrane separation apparatus is generally used in a state in which a plurality of liquids to be treated in a treatment tank are arranged in parallel and spaced apart at a predetermined interval. Each flat membrane element has a membrane permeate flow path on the membrane permeation side. By applying negative pressure to the flow path by suction or the like, suspended substances such as activated sludge floc in the water to be treated are filtered. A clean membrane permeate that has been captured by the membrane, permeated through the filtration membrane and flowed into the membrane permeate channel is taken out of the processing tank. In addition, an air diffuser is provided below the submerged membrane separator, and the upward flow parallel to the membrane surface is generated between the membrane elements by the rising of air supplied from the air diffuser, and this upward flow is filtered. By removing the deposits on the membrane surface and simultaneously performing physical cleaning of the membrane surface, it is possible to stably filter sludge while preventing clogging of the membrane. A downward flow is generated around the outer periphery of the submerged membrane separator, and a swirling flow is formed integrally with the upward flow between the flat membrane elements in the submerged membrane separator.

The submerged membrane separation apparatus as described above is excellent in performance of stably filtering activated sludge for a long period of time, but the following problems remain.
1) Aeration power of air required for physical cleaning of the film surface is high.
2) Since it is necessary to secure a sufficiently large space in the outer periphery of the side of the submerged membrane separator so that the downward flow can move smoothly, the filling rate of the submerged membrane separator in the processing tank cannot be increased. .

JP-A-7-275668 Japanese Patent No. 3937620

  The present invention provides an activated sludge treatment apparatus and an activated sludge treatment apparatus operating method that require less aeration power required for physical cleaning of the membrane surface and that can arrange an immersion type membrane separation device in a treatment tank at a high filling rate. There is.

In order to solve the above problems, the present invention has the following configuration.
(1) An activated sludge treatment apparatus in which a submerged membrane separation device and an aeration device are immersed in a treatment tank storing a liquid to be treated, wherein the submerged membrane separation device has a plurality of flat membrane elements in a vertical direction. Are arranged in parallel with each other and have openings in the horizontal direction, and the immersion type membrane separation device is disposed so as to be close to the bottom surface of the treatment tank, and at least one of the immersion type membrane separation devices The air diffuser is disposed beside one opening so as to be close to a side defined by a side surface and a bottom surface of the processing tank.
Also,
(2) The activated sludge treatment apparatus according to (1) is operated by controlling the liquid level of the liquid to be treated so as to be close to the upper end of the submerged membrane separation apparatus.

  Compared to the prior art, the water depth of the treatment tank in which the submerged membrane separation apparatus is housed is shallow, so that air can be discharged under low water pressure, and the aeration power for physical cleaning of the membrane surface can be reduced. . Further, the physical cleaning power required per membrane surface can be reduced because the physical cleaning can be performed twice by the swirl flow generated by the bubbles supplied from the air diffuser so as to reciprocate the membrane surface in the horizontal direction.

  In addition, the space required for maintaining the swirling flow outside the submerged membrane separation apparatus in the processing tank is small, and the submerged membrane separation apparatus can be arranged in the processing tank with a high filling rate.

  Even if improper operation such as continuing to supply an excessive amount of air from the diffuser, the depth of water is shallow and there is no aeration from the lower part of the membrane element. Reduce to.

  Since the water depth is shallow, maintenance such as inspection and replacement of the membrane element becomes easy.

  Since the liquid capacity of the treatment tank can be reduced, the chemical liquid cleaning of the submerged membrane separation apparatus in which the chemical liquid is filled in the treatment tank can be easily performed with a small amount of waste liquid.

It is a schematic block diagram of the activated sludge processing apparatus which concerns on this invention.

  In FIG. 1, the structure of the activated sludge processing apparatus of this invention is shown notionally.

  The activated sludge treatment apparatus shown in FIG. 1 includes a treatment tank 5 for storing activated sludge and performing biological treatment, a wastewater supply pump (not shown) for supplying wastewater into the treatment tank 5, and the inside of the treatment tank 5. A sludge extraction pump (not shown) for discharging sludge out of the system, a submerged membrane separation apparatus 1 for solid-liquid separation of biologically treated water biologically treated with activated sludge, and filtering sludge through a membrane For this purpose, a flat membrane element 2, a tube 9, a water collection pipe 8, a permeate pipe, and a suction pump for sucking the filtrate side are provided (both are not shown). The submerged membrane separator 1 is immersed in the water to be treated in the treatment tank 5. The processing tank 5 in which the submerged membrane separation apparatus 1 is housed may be used exclusively for sludge solid-liquid separation, and another aerobic processing tank may be used in addition to the processing tank 5. Further, as a treatment tank other than the treatment tank 5, another biological treatment tank, for example, an anaerobic tank, an oxygen-free tank, or the like may be provided independently and used in combination.

  Here, in the present invention, the submerged membrane separation device 1 is configured so that a plurality of flat membrane elements are spaced apart from each other in the vertical direction so that the liquid flow 7 in the two directions of the swirling flow in the horizontal direction can be effectively utilized. It is set as the structure which is arranged in parallel and has an opening part in a horizontal direction. The submerged membrane separation apparatus 1 is disposed so as to be close to the bottom surface of the treatment tank 5, and the air diffuser 3 is disposed on the side of at least one opening of the submerged membrane separation apparatus 1. It arrange | positions so that it may adjoin to the edge prescribed | regulated by a side surface and a bottom face. In operation and use, the liquid level 4 of the liquid to be treated is preferably controlled so as to be close to the upper end of the submerged membrane separation apparatus.

  As a submerged membrane separator closest to the present invention, there is disclosed a membrane unit in which aeration means is provided on the side of a module consisting of a group of flat membrane elements perpendicular to the flat membrane elements (Japanese Patent No. 3937620). ), The installation mode of the membrane unit in the processing tank and the pattern of the swirling flow are the same as those of the prior art, and unlike the configuration of the present invention, it is not a technology that can be called energy saving and high filling rate.

  The flat membrane element 2 used in the present invention may be any as long as it has a flat surface that does not cause the resistance to the swirling flow, an element in which the flat membrane is welded and fixed to both surfaces of the support plate, and a flow path. Examples include an element in which both sides of the material are covered with a flat membrane and the periphery is sealed, and a sheet-like element without a support plate in which the membrane is directly fixed on both sides of the flow path material.

  In order to smoothly generate a swirl flow between the flat membrane elements 2 and to align the physical cleaning conditions of the membrane surface, the plurality of flat membrane elements 2 need to be arranged in parallel to each other at intervals in the vertical direction. The distance between the flat membrane elements 2 is preferably in the range of 4 mm to 30 mm, more preferably 6 mm to 15 mm in consideration of the effect of resistance to swirling flow and the membrane filling rate of the apparatus.

  As shown in FIG. 1, the submerged membrane separation device 1 may have two openings on the opposite side to the side close to the air diffuser 3 or only the side close to the air diffuser 3. But you can.

  If the water depth is too deep, the swirl flow in the intermediate region in the depth direction of the membrane surface becomes weak, and if it is too shallow, the membrane area per apparatus installation area decreases, more preferably 0.2 m to 1 m, It is preferable to control to 0.3 m to 0.7 m. The horizontal length of the submerged membrane separation device 1 is preferably long in order to make the most effective use of the horizontal movement effect of the swirling flow provided by the air diffuser 3, but if it is too long, it will cause energy loss. Since the speed of the swirling flow is decreased, it is preferable that the speed be in the range of 0.3 m to 3 m, more preferably 0.8 m to 2 m. Considering the water depth and the arrangement in the horizontal direction, the preferred flat membrane element 2 used in the present invention is preferably a horizontally long element having a height of 0.3 to 0.7 m and a length of 0.8 to 2 m.

  In order to effectively use the space of the treatment tank 5 and the physical cleaning effect of the swirling flow, the immersion type membrane separation apparatus 1 is disposed so as to be close to the bottom surface of the treatment tank 5, and the liquid to be treated is used during operation. It is preferable to control the liquid level 4 so as to be close to the upper end portion of the submerged membrane separation apparatus 1. In addition, although proximity is not specifically limited in the present invention, it means a distance within 0.3 m as a guide.

  The air diffuser 3 is arranged so as to be close to the side defined by the side surface and the bottom surface of the treatment tank 5 so that the liquid flow in the direction as shown in FIG. 1 can be efficiently generated. If the distance between the opening of the submerged membrane separator 1 and the air diffuser 3 is too large, the ratio of the swirling flow flowing between the flat membrane elements 2 of the submerged membrane separator 1 decreases, so that the submerged membrane separator 1 It is preferable that the opening and the air diffuser 3 be as close as possible. It is also possible to provide openings in two directions in the horizontal direction of the submerged membrane separator 1 and to install the diffuser 3 on both sides.

  The air discharge amount of the air diffuser 3 is discharged so that the liquid flow 7 is 0.2 m / s or more, more preferably 0.4 m / s or more in order to generate a swirling flow having a high physical cleaning effect. Good. On the other hand, even if the air discharge amount is excessively large, energy loss is caused. Therefore, the liquid flow 7 may be discharged so as to be 2 m / s or less, more preferably 1 m / s or less. The type of the air diffuser 3 is not particularly limited, but an air diffuser that generates bubbles with a large bubble diameter is more effective.

  INDUSTRIAL APPLICABILITY The present invention can be used as a membrane separation apparatus and a wastewater treatment method used in wastewater treatment by a membrane separation activated sludge method. In particular, it can be used as a membrane separation apparatus and wastewater treatment method when wastewater containing sewage and domestic wastewater is treated by the membrane separation activated sludge method.

1: Submerged membrane separator 2: Flat membrane element 3: Air diffuser 4: Liquid surface
5: Treatment tank 6: Bubble 7: Liquid flow

Claims (2)

An activated sludge treatment apparatus in which a submerged membrane separation device and an aeration device are immersed in a treatment tank storing a liquid to be treated, wherein the submerged membrane separation device has a plurality of flat membrane elements spaced vertically. At least one opening of the submerged membrane separator, the submerged membrane separator being arranged so as to be close to the bottom surface of the treatment tank An activated sludge treatment apparatus, wherein the diffuser is disposed on the side of the treatment tank so as to be close to a side defined by a side face and a bottom face of the treatment tank. The operation method of the activated sludge treatment apparatus according to claim 1, wherein the liquid level of the liquid to be treated is controlled so as to be close to an upper end portion of the submerged membrane separation apparatus.

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