JP2005152694A - Water cleaning treatment facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize the entire facility and to save energy by maintaining flux of a recovery system membrane filtration apparatus high, and reducing an installation area and power cost, in a water cleaning treatment facility provided with the recovery system membrane filtration apparatus by membrane filtration treatment of backwash water of a clean water system membrane filtration apparatus and recovering filtrate as raw water or clean water. <P>SOLUTION: This water cleaning treatment facility is provided with the clean water system membrane filtration apparatus 2 providing clean water by membrane filtration of raw water; the recovery system membrane filtration apparatus 3 for membrane filtration treatment of backwash waste water of the clean water system membrane filtration apparatus 2; and a recovering means 16(18) recovering the filtrate of the membrane filtration apparatus 3 as raw water or clean water. A tank immersed type membrane filtration apparatus with an external pressure type membrane module 5 immersed in a backwash waste water receiving tank 4, is used as the recovery system membrane filtration apparatus 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a water purification treatment facility that obtains purified water by subjecting raw water to membrane filtration, and in particular, tank immersion for recovering permeate as raw water or purified water by membrane filtration treatment of backwash wastewater of a water purification system membrane filtration device. The present invention relates to water purification equipment equipped with a mold membrane filtration device.

  In recent years, membrane filtration devices have come to be adopted as water treatment technology as compact treatment equipment that replaces conventional water treatment equipment that requires a large installation area, such as coagulation sedimentation and sand filtration. And, in order to effectively use the water source, membrane filtration treatment is performed with a membrane filtration device separately provided with backwash drainage of the water purification membrane filtration device, and the permeate is recovered as purified water or membrane filtration treatment raw water. .

For example, in the Ogosemachi water purification facility, the backwash wastewater from the casing storage type UF (ultrafiltration) membrane filtration device (fractionation molecular weight 13000 Da) of the main system (water purification treatment system) is recovered from the casing storage type MF (microfiltration). ) A membrane filtration treatment (pore diameter: 0.1 μm) is performed to collect permeate as purified water, thereby obtaining a recovery rate of 99% (Non-patent Document 1). In addition, it has also been proposed that the backwash drainage of the main system membrane filtration device is subjected to membrane filtration treatment with a rotating disk type membrane filtration device (semi-immersed membrane filtration device), and the permeated water is recovered as purified water (Patent Document 1). ). In addition, backwash wastewater is also collected by precipitation treatment.
Japanese Patent Laid-Open No. 7-21875 “Environmental Purification Technology” Vol. 2, no. 10, 2003, P33-37 “Cryptosporidium measures at Koshiocho Water Treatment Plant”

  However, when the backwash wastewater from the main system water purification system membrane filtration device is treated and collected, the sedimentation process requires a large area for the installation of the sedimentation tank, and the pathogenic protozoa such as Cryptosporidium and Giardia The removability was low, and as a result, these protozoa could be concentrated in the system.

  If it is a membrane filtration device, Cryptosporidium, etc. is excellent in removability and the quality of treated water is good, but the conventionally used casing storage type membrane filtration device needs to be installed on the ground, and the membrane filtration of the main system In addition to the apparatus, it is necessary to secure an installation area for this purpose, and when the cross flow flow rate is set large in order to increase the SS concentration rate, there are disadvantages that the maintenance cost (power cost) for that rises.

  Even in the case of a rotating disk type membrane filtration device (semi-immersed membrane filtration device), the power equipment is large and the membrane area per unit installation area is large, so the problem of the installation area is not solved. Will be installed on the ground.

  The present invention solves the above-mentioned conventional problems, and in a water purification treatment facility provided with a recovery system membrane filtration device for recovering permeate as raw water or purified water by subjecting the backwash wastewater of the water purification membrane filtration device to membrane filtration treatment An object of the present invention is to provide a water purification treatment facility capable of maintaining a high flux of the recovery system membrane filtration device and reducing the installation area and power cost, thereby reducing the size of the entire facility and saving energy.

  The water purification treatment facility of the present invention includes a water purification membrane filtration device that obtains purified water by subjecting raw water to membrane filtration, a recovery system membrane filtration device that performs membrane filtration treatment of backwash waste water of the water purification membrane filtration device, and the recovery system In a water purification treatment facility comprising means for collecting permeated water of a membrane filtration device as raw water or purified water, the recovery system membrane filtration device is a tank immersion type membrane filtration device in which an external pressure type membrane module is immersed in a backwash drainage tank. It is characterized by being.

  If it is a tank immersion type membrane filtration apparatus, even if SS (turbidity component) in backwash wastewater is high concentration, it can respond enough, and can maintain flux stably over a long period of time. Further, even when the organic matter concentration is high, it is possible to maintain stable operation with a high recovery rate. In addition, since it is a membrane filtration apparatus, protozoa such as Cryptosporidium and Giardia can be reliably removed.

  In addition, since it can be installed underground by receiving backwash wastewater in a groundwater tank, it can be a vertical arrangement instead of a planar arrangement for the main system water purification membrane filtration device. Space saving is possible. Furthermore, the flux can be set larger by selecting the pore diameter of the membrane, and it is possible to achieve downsizing and energy saving.

  In the present invention, by making the pore size of the membrane of the recovery system membrane filtration device larger than the pore size of the membrane of the water purification system membrane filtration device, the flux of the recovery system membrane filtration device is set to be large and the equipment is downsized, Energy saving can be achieved. Further, the water purification system membrane filtration device is preferably a casing storage type UF membrane filtration device or a casing storage type MF membrane filtration device capable of high pressure treatment and high flux compared to the submerged membrane. It is possible to reduce the number of membrane filtration devices necessary for water purification treatment. In particular, it is preferable that the water purification system membrane filtration device is a UF membrane filtration device and the recovery system membrane filtration device is an MF membrane filtration device.

  Moreover, it is preferable to provide a suction means for sucking the permeated water side of the tank-immersion type membrane filtration device of the recovery system membrane filtration device, whereby the membrane filtration treatment efficiency can be increased. The external pressure membrane module of the recovery membrane filtration device is preferably an external pressure hollow fiber membrane module that can secure a large membrane area per unit installation area and is advantageous for space saving.

  Moreover, the following effects can be acquired with the washing | cleaning effect of a membrane surface by providing an aeration means under the external pressure type | mold membrane module in a backwash drainage tank.

  That is, if iron or manganese is contained in the raw water of the water purification system, there arises a problem of flux reduction due to concentration of iron or manganese colloids in the recovery membrane filtration device. In order to prevent this problem, it is necessary to sufficiently oxidize iron and manganese in the backwash wastewater. However, by providing a diffuser below the membrane module of the recovery system, aeration from this diffuser However, it acts not only on the membrane cleaning but also on the oxidation of iron and manganese, and the clogging of the membrane by the colloid of iron and manganese can be suppressed. It is also possible to prevent clogging of the film due to iron or manganese colloid by adding an oxidizing agent such as sodium hypochlorite, but even in this case, aeration is used in combination. As a result, the required amount of the oxidizing agent can be reduced.

  Moreover, the backwash drainage tank of the recovery system membrane filtration device is provided below the water purification system membrane filtration device, for example, a two-story structure in which a backwash drainage tank is provided in the basement and a water purification system membrane filtration device is provided thereon. By doing, the installation area of the whole water purification processing equipment can be made small.

  According to the present invention, in a water purification treatment facility provided with a recovery system membrane filtration device for performing membrane filtration treatment of backwash wastewater of a water purification system membrane filtration device and recovering permeate as raw water or purified water, a recovery system membrane filtration device In addition to maintaining a high flux, the installation area and power cost can be reduced, and the entire equipment can be reduced in size and energy can be saved.

  Embodiments of the water purification treatment facility of the present invention will be described in detail below with reference to the drawings.

  FIG. 1 is a system diagram showing an embodiment of the water purification treatment facility of the present invention.

  Raw water obtained by subjecting river water, spring water, etc. to pretreatment such as sand filtration is introduced into the water purification system membrane filtration device 2 through the pipe 11, the receiving well 1 and the pipe 12, and the permeate is purified. As shown in FIG. Note that a chlorine agent is added to the pipe 12 as necessary.

  In this water purification system membrane filtration apparatus 2, a cross-flow type or a dead end type membrane filtration process is performed according to the quality of raw water. Generally, when the raw water is sufficiently clean water that has undergone, for example, coagulation sedimentation treatment and sand filtration treatment, a dead end type is adopted, and when the raw water is not sufficiently clean water, a cross flow type is adopted. .

  As described above, the water purification system membrane filtration device 2 is preferably a casing storage type membrane filtration device from the viewpoint that high-pressure treatment is possible, and a membrane type is particularly preferably a UF membrane.

  The water purification system membrane filtration device 2 is backwashed by allowing permeate (purified water) to flow backward at a predetermined interval, and the backwash wastewater is fed from the pipe 15 to the recovery system membrane filtration device 3 for membrane filtration treatment. Then, the permeated water of the recovery system membrane filtration device 3 is returned as recovered water from the pipe 16 to the raw water introduction side, and the concentrated water is discharged out of the system as drainage from the pipe 17. The recovered water may be used as purified water from the pipe 18.

  In the present invention, as the recovery system membrane filtration device 3, a bath immersion type membrane filtration device in which an external pressure membrane module 5 is immersed in a backwash drainage receiving tank 4 is used.

  The membrane of the membrane module 5 of the recovery system membrane filtration device 3 is preferably an MF membrane that can be subjected to membrane filtration at a low pressure. The pore size of the membrane of the water purification system membrane filtration device 2 is larger than the pore size of the membrane of the water purification system membrane filtration device 2. This is preferable in that the flux of the apparatus 5 can be set large to reduce the size and energy of the equipment. For example, it is preferable that the water purification system membrane filtration apparatus 2 is an MF membrane filtration apparatus having a pore diameter of about 0.01 μm, and the recovery system membrane filtration apparatus 5 is an MF membrane filtration apparatus having a pore diameter of about 0.02 μm. However, the membrane of the recovery membrane filtration device 5 is preferably one that can sufficiently remove protozoa such as Cryptosporidium. The material of the membrane is not particularly limited, but a physically and chemically stable polysulfone or PVDF (polyvinylidene fluoride) membrane is preferable.

  Although not shown, this membrane module 5 is preferably provided with a suction means for sucking the permeate side. For example, by providing a suction pump in the pipe 16 (or the pipe 18), the membrane filtration processing efficiency is increased. Can be preferred. The membrane module 5 is preferably an external pressure type hollow fiber membrane module that can secure a large membrane area per unit installation area.

  In this recovery system membrane filtration device 5, a diffuser tube 6 is provided below the membrane module 5 in the backwash waste water receiving tank 4, whereby the membrane cleaning effect by aeration and the aforementioned membrane of iron and manganese colloids are provided. Can be suppressed.

  In particular, in the present invention, the backwash wastewater receiving tank 4 of the recovery system membrane filtration device 3 is provided below the water purification system membrane filtration device 2, for example, the backwash drainage receiving tank 4 is provided in the basement, and the water purification system is provided thereon. By setting it as the two-story structure which provided the membrane filtration apparatus 2, the installation area of the whole water purification processing equipment can be made small, and it is preferable.

  In such a water purification treatment facility of the present invention, the membrane specifications of the water purification system membrane filtration device and the recovery system membrane filtration device, the pore diameter, the water recovery rate, the backwash frequency of the water purification system membrane filtration device, other operating conditions, etc. Although there is no restriction | limiting in particular, For example, the following conditions are employable.

<Water purification system membrane filtration device: casing storage type UF membrane filtration device>
Membrane type: Polysulfone UF membrane (chlorine resistance)
Molecular weight cut off = 13 to 150 kDa
Membrane flux: 0.5 to 8.0 m ³ / m ² / day
Water recovery rate: 90-99%
Backwash interval: 30 to 180 minutes Backwash flux: 5 to 16 m / day
Backwash drainage: 0.02-0.2 times the amount of permeate

<Recovery system membrane filtration device: Submerged MF membrane filtration device>
Membrane type: PVDF or polysulfone MF membrane (chlorine resistance)
Pore diameter = 0.02 to 0.1 μm
Water recovery rate: 90-95%
Membrane flux: 0.3 to 2.0 m ³ / m ² / day
Concentrated wastewater amount: 0.05 to 0.1 times the amount of raw water (backwash wastewater) When water purification treatment is performed under the above conditions, the water recovery rate of the whole water purification treatment facility is:
Minimum 90 + 10 × 0.9 = 99%
99 + 1 × 0.95 = 99.95%
It becomes.

The water recovery rate is preferably set appropriately depending on the raw water quality, particularly the raw water turbidity. For example, when the raw water turbidity is 1 degree, the recovery rate is set to 99.95%, and when the raw water turbidity is 10 degrees, the recovery rate is set. Set to 99%. Drainage turbidity at this time is as follows, but if it is a tank immersion type membrane separator, even if the turbidity is 2000 degrees, it can sufficiently cope, and even under the above conditions, it is sufficiently stable operation. Is possible.
When the raw water turbidity is 1 degree (operation at a recovery rate of 99.95%)
Wastewater turbidity = 1 x 2000 = 2000 degrees When the raw water turbidity is 10 degrees (operation at a recovery rate of 99%)
Wastewater turbidity = 10 x 100 = 1000 degrees

It is a systematic diagram showing an embodiment of the water purification treatment facility of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Landing well 2 Water purification system membrane filtration apparatus 3 Recovery system membrane filtration apparatus 4 Backwash drainage tank 5 Membrane module 6 Aeration pipe

Claims (9)

A purified water membrane filtration device that obtains purified water by subjecting raw water to membrane filtration,
A recovery membrane filtration device for membrane filtration treatment of the backwash waste water of the water purification membrane filtration device;
In the purified water treatment facility provided with means for collecting the permeated water of the recovery system membrane filtration device as raw water or purified water,
A water purification treatment facility, wherein the recovery system membrane filtration apparatus is a tank immersion type membrane filtration apparatus in which an external pressure type membrane module is immersed in a backwash drainage receiving tank.   The water purification treatment facility according to claim 1, wherein the pore diameter of the membrane of the recovery system membrane filtration device is larger than the pore diameter of the membrane of the water purification system membrane filtration device.   The water purification treatment facility according to claim 1 or 2, wherein the water purification system membrane filtration device is a casing storage type UF membrane filtration device or a casing storage type MF membrane filtration device.   The water purification treatment facility according to any one of claims 1 to 3, wherein the water purification system membrane filtration device is a UF membrane filtration device, and the recovery system membrane filtration device is an MF membrane filtration device.   The water purification treatment facility according to any one of claims 1 to 4, further comprising suction means for sucking a permeate side of the tank submerged membrane filtration device.   The water purification treatment facility according to any one of claims 1 to 5, wherein the external pressure membrane module is an external pressure hollow fiber membrane module.   The water purification treatment facility according to any one of claims 1 to 6, further comprising a diffuser means below the external pressure membrane module in the backwash drainage tank.   The water purification treatment facility according to any one of claims 1 to 7, wherein the backwash drainage tank is provided below the water purification membrane filtration device.   The water purification treatment facility according to any one of claims 1 to 8, wherein the backwash drainage tank is provided in the basement.

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