JP2006167604A - Water treatment apparatus and water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment apparatus which is compact and has a high filtration capacity. <P>SOLUTION: In the water treatment apparatus, a treatment tank 11 is divided into two tanks 14, 15 by a partition plate 13 so that liquid can be circulated between the tanks, and an external pressure type filtration membrane 12 is immersed in the tank 15. A bubble generator 21 which generates bubbles having a diameter within the range of 1-20 mm is installed below the filtration membrane 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water treatment apparatus and a water treatment method particularly suitable for treatment of oil-containing wastewater.

Along with increasing interest in effective use of water resources, demand for water saving for washing water (150L or more per car) that consumes a large amount of tap water, and water quality for dripping down the drainage as it is Concerns about pollution are growing. In particular, the wastewater generated at the car wash station contains not only oil such as wax but also surfactant as well as earth and sand. Surfactants are not easily decomposed naturally, leading to environmental pollution of rivers and lakes. Then, the trial which tries to solve the said subject is made | formed by processing car wash wastewater and reusing treated water as car wash water.
JP 2003-170007 A JP 2003-326105 A JP 2003-327093 A

  When installing a water treatment device in a limited place such as a car wash, it is important that the water treatment device itself is small.

  Therefore, an object of the present invention is to provide a water treatment apparatus that can make the apparatus itself more compact and exhibit high water treatment capability, and a water treatment method using the same.

  As a means for solving the problems, the present invention provides a water treatment apparatus having a treatment tank having a coagulation function and a filtration function, and an external pressure filtration membrane that is immersed in the treatment tank and can be filtered by a suction means.

  As another means for solving the problem, the present invention provides an external pressure type filtration in which a treatment tank is divided into two or more parts capable of circulating liquids, one of which is a coagulation tank, and the filtration tank can be filtered by suction means. The water treatment device according to claim 1, wherein the membrane is immersed.

  The present invention provides a water treatment device according to claim 1 or 2, wherein a hollow fiber membrane made of cellulose acetate is used as an external pressure filtration membrane as another means for solving the problem.

  In another aspect of the present invention, there is provided a bubble generator or a bubble supply port capable of generating bubbles having a diameter in the range of 1 to 20 mm below the external pressure filtration membrane. The water treatment apparatus in any one of 1-3 is provided.

  This invention provides the water treatment apparatus of Claims 1-4 which uses what contains 90 mass% or more of inorganic compounds as a coagulant | flocculant as another solution means of a subject.

  In another aspect of the present invention, the flocculant contains 40-50 mass% bentonite, 40-50 mass% aluminum sulfate, 0-10 mass% sodium alginate, and 0-10 mass% cationic acrylamide. The water treatment apparatus according to claim 5 is provided.

  This invention provides the water treatment apparatus in any one of Claims 1-6 which processes a containing wastewater as another solution means of a subject.

  The present invention provides, as another means for solving the problems, the water treatment apparatus according to claim 7, wherein the waste water contains an amount of n-hexane extract that exceeds 1 mg / L.

  The present invention is a water treatment method using the water treatment apparatus according to any one of claims 1 to 8 as a means for solving other problems, and intermittently using an external pressure filtration membrane immersed in a treatment tank. A water treatment method is provided in which the sludge settled in the treatment tank is removed from the treatment tank when the filtration operation is stopped.

  The water treatment apparatus of the present invention can be made compact as a whole and has high filtration performance.

  The water treatment apparatus of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of the water treatment apparatus of the present invention.

  The water treatment apparatus 10 includes a treatment tank 11 having a coagulation function and a filtration function, and an external pressure filtration membrane 12 immersed in the treatment tank.

  The processing tank 11 is divided into two parts 14 and 15 by the partition plate 13 so that the liquids can flow with each other. The tank 15 is a filtration tank, and the external pressure filtration membrane 12 is immersed therein.

  The partition plate 13 is fixed to the side wall of the processing tank 11, the bottom surface is not in contact with the bottom surface of the processing tank 11, and the height of the top surface of the partition plate 13 is lower than the side wall in the processing tank 11. During the filtration operation, the water level is lower than the surface of the liquid to be treated. As a result, the liquid to be treated can freely circulate through the two tanks 14 and 15 from above and below the partition plate 13. Note that the size and installation position of the partition plate 13 can be freely adjusted according to the properties of the liquid to be treated and the type of the flocculant.

  The tank 14 is connected to a medicine supply device 20 with a quantitative feeder, and a stirring device can be attached if necessary. The medicine supply device 20 may be attached to the tank 15. A drug injection unit 23 can be connected to the line 31 leading to the tank 15.

  As the flocculant, a mixture of an inorganic flocculant and an organic flocculant is preferable. As the inorganic flocculant, bentonite, polyaluminum chloride, aluminum sulfate, polyiron chloride and the like are preferable, and as the organic flocculant, water-soluble polymers such as polyacrylamide, poly (meth) acrylic acid and polysaccharides are preferable. The flocculant preferably contains 90% by mass or more of an inorganic flocculant, and the remainder can be an organic flocculant.

  More preferable flocculants include bentonite 40 to 50% by mass, aluminum sulfate 40 to 50% by mass, sodium alginate 0 to 10% by mass, and cationic acrylamide 0 to 10% by mass (however, the sum of bentonite and aluminum sulfate) Is 90% by mass or more).

  When the chemical supply device 20 is attached to the tank 14, the liquid to be treated is mixed and stirred with the flocculant in the tank 14, and is subjected to agglomeration treatment while circulating and circulating in the tank 14 and the tank 15. Then, the tank 15 is filtered by the external pressure filtration membrane 12.

  A known separation membrane can be used as the external pressure filtration membrane 12 that can be filtered by a suction means immersed in the tank 15, but a hollow fiber membrane made of cellulose acetate is preferable. In addition, as long as it can be filtered, it is not limited to the suction means (pump 26 in FIG. 1), and may exhibit an equivalent function, for example, a system that sends pressure opposite to suction.

  A bubble generating device 21 is installed below the filtration membrane 12 in the tank 15. The bubble generating device 21 may be installed outside the processing tank 11 and only the bubble supply port may be installed in the device. The bubble generating device 21 is preferably capable of generating bubbles having a diameter in the range of 1 to 20 mm.

  The water treatment apparatus 10 of the present invention is suitable for the treatment of oil-containing wastewater containing an amount of n-hexane extract of more than 1 mg / L, and further the amount of n-hexane extract of more than 1 mg / L and the COD concentration. It is suitable for the treatment of oil-containing wastewater with numerical values exceeding 10 mg / L and SS (turbidity) concentration exceeding 10 mg / L, especially for the treatment of oil-containing wastewater containing oils and surfactants generated at car wash stations, etc. Is suitable.

  Next, the operation method of the water treatment apparatus 10 will be described with reference to FIG. The pump 25 is operated to supply raw water or primary treated water into the coagulation tank 14 from the liquid supply line 30 to be treated.

  If the water to be treated is car wash wastewater generated at a car wash, etc., it may contain sand, pebbles, and dust along with oil and surfactants. It can be.

  In the tank 14, after a predetermined amount of the flocculant is added from the medicine supply device 20, it is preferably sufficiently stirred to form and settle a flock so that the liquid circulates in the tanks 14 and 15.

  In the tank 15, the suction pump 26 is operated to perform filtration with the external pressure filtration membrane 12, and sent from the line 31 to the next processing unit (for example, activated carbon processing unit) or a water storage tank. In addition, when the pore diameter of the membrane is large and the filtration resistance is sufficiently small, filtration is possible only by the difference in gravity.

  Filtration operation conditions are not particularly limited. In this filtration process, bubbles are generated from the bubble generator 21 constantly or intermittently so that the liquid to be treated in the tank is in a homogeneous state and cake (sludge) adhered to the surface of the external pressure filtration membrane 12. To prevent the filtration performance from deteriorating.

  In addition, after a certain filtration operation, the operation is stopped, and the washing water (treated water or tap water) sent from the line 31 is filtered by a chemical solution supplied with a sodium hypochlorite aqueous solution from the drug injection unit 23. The membrane 12 can also be back-pressure cleaned.

  The filtration operation is stopped after about 10 to 60 minutes, and sludge settled at the bottom of the tank 14 and the tank 15 is extracted from the respective drawing lines 32 and 33 until the operation is restarted or during back pressure washing. .

  The water treatment apparatus of the present invention can be applied to the waste water treatment apparatus shown in FIG. 1 of Patent Document 1 as a collection of the coagulation sedimentation section 2 and the membrane separation section 3. In the car wash wastewater treatment apparatus and the car wash wastewater treatment system shown in FIG. 1, the aggregation tank provided in the oil / water separation tank 1 and the membrane separation unit 4 can be applied as a single unit. In the car wash wastewater recycling apparatus shown in FIG. 1, the coagulation sedimentation processing unit 2 and the membrane separation processing unit 3 can be applied as a single unit.

(Processing apparatus and processing method)
A partition plate installed in the central portion of the processing tank having an inner volume of 0.76 m ^3, diffusing pipe to the bottom of the filtration tank (Parukon: Daisen Membrane Systems Inc., PMD-T06) were placed two, directly above A casing-free submerged membrane element 3 m ² filled with a cellulose acetate hollow fiber membrane having an outer diameter of 2 mm and an inner diameter of 0.9 mm was immersed in a 6-unit filtration tank at intervals of 90 mm.

Car wash wastewater (average n-hexane extract amount 16 mg / L, average COD concentration 42 mg / L, turbidity (SS) concentration 48 mg / L) was introduced from the oil / water separation tank to the treatment tank. The flocculant was added at 50 mg / L, and the agglomeration reaction and suction filtration were simultaneously performed while air aeration was constantly or intermittently performed from the air diffuser. The initial processing speed was set to 1.0 m ³ / Hr.

  The filtrate was stored in a filtrate tank, a part was used as backwash water, and the remainder was passed through activated carbon as car wash wastewater reuse water and returned to the car wash machine. Every 30 minutes of filtration, backwashing with an aqueous sodium hypochlorite solution with an effective chlorine concentration of 5 mg / L was performed for 1 minute.

Example 1
As flocculants, bentonite 48 wt%, aluminum sulfate 48 mass% sodium alginate 2% by weight, with Memufurokku (manufactured by Daicel Chemical Industries, Ltd.) 2% by weight cationic polyacrylamide, the air quantity always 4m ³ / Hr And filtered with aeration. Moreover, the coagulated sludge was automatically extracted from the bottom of the tank during backwashing.

When operated for half a year, the average processing speed was 0.8 m ³ / Hr. In addition, the quality of recycled water is average n-hexane extract amount <0.5 mg / L, average COD concentration 10 mg / L, and turbidity (SS) concentration <0.5 mg / L. did it.

Example 2
The same flocculant as in Example 1 was used as the flocculant, and filtration was performed while aeration was always performed with an air amount of 4 m ³ / Hr. During the filtration and backwash operation, air aeration was stopped for 1 minute, during which time the aggregated sludge was automatically extracted from the bottom of the tank.

When operated for half a year, the average treatment speed was 0.9 m ³ / Hr. In addition, the quality of recycled water is average n-hexane extract amount <0.5 mg / L, average COD concentration 8 mg / L, and turbidity (SS) concentration <0.5 mg / L. did it.

The schematic sectional drawing of the water treatment apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Water treatment apparatus 11 Processing tank 12 External pressure type filtration membrane 13 Partition plate 14 Tank 15 Tank (filtration tank)

Claims (9)

  A water treatment apparatus having a treatment tank having a coagulation function and a filtration function, and an external pressure filtration membrane immersed in the treatment tank and capable of being filtered by a suction means.   The processing tank is divided into two or more parts capable of flowing liquid to each other, one of which is a coagulation tank, and an external pressure filtration membrane that can be filtered by a suction means is immersed in the filtration tank. Water treatment equipment.   The water treatment apparatus according to claim 1 or 2, wherein a hollow fiber membrane made of cellulose acetate is used as the external pressure filtration membrane.   The water treatment apparatus according to any one of claims 1 to 3, wherein a bubble generator or a bubble supply port capable of generating bubbles having a diameter in the range of 1 to 20 mm is installed below the external pressure filtration membrane. .   The water treatment apparatus of Claims 1-4 using what contains 90 mass% or more of inorganic flocculants as a flocculant.   The water treatment apparatus according to claim 5, wherein the flocculant contains 40-50 mass% bentonite, 40-50 mass% aluminum sulfate, 0-10 mass% sodium alginate, and 0-10 mass% cationic acrylamide.   The water treatment apparatus in any one of Claims 1-6 which processes oil-containing wastewater.   The water treatment apparatus according to claim 7, wherein the oil-containing wastewater contains n-hexane extract in an amount exceeding 1 mg / L. It is the water treatment method using the water treatment apparatus in any one of Claims 1-8, performs a filtration operation intermittently using the external pressure type | mold filtration membrane immersed in the processing tank, and processes at the time of a filtration operation stop A water treatment method in which sludge settled in the tank is extracted out of the treatment tank.

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