Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
2000-01-20
2002-06-11
Fortuna, Ana (Department: 1723)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S651000, C210S652000, C210S321740, C210S321830, C210S641000, C210S433100, C210S435000
Reexamination Certificate
active
06402956
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a treatment system and a treatment method employing a spiral wound type membrane module.
2. Description of the Background Art
A reverse osmosis membrane (RO membrane) separation device is employed for desalinating seawater, producing ultrapure water or the like. Coagulation precipitation sand filtration is mainly performed as pretreatment for the reverse osmosis membrane separation device. In such coagulation precipitation sand filtration, the quality of treated water varies with the quality of raw water, and hence treated water having stable quality cannot be supplied to the reverse osmosis membrane separation device. Thus, the ability of the reverse osmosis membrane separation device is limited.
The membrane separation technique is recently applied as pretreatment for the reverse osmosis membrane separation device. A hollow fiber membrane element is mainly employed for such pretreatment.
FIG. 18
illustrates an exemplary conventional treatment system employing a reverse osmosis membrane separation device
406
.
Referring to
FIG. 18
, a reservoir
401
stores raw water such as river water. The raw water is supplied from the reservoir
401
to a supply pump
402
through a pipe
407
, and further supplied to a hollow fiber membrane element
403
by the supply pump
402
. The hollow fiber membrane element
403
separates the raw water into permeate and concentrate. The permeate obtained by the hollow fiber membrane element
403
is supplied to a reservoir
404
through a pipe
408
as pretreated water. The concentrate obtained by the hollow fiber membrane element
403
is returned to the reservoir
401
through a pipe
409
.
The pretreated water stored in the reservoir
404
is supplied to a pump
405
through a pipe
410
, and further supplied to the reverse osmosis membrane separation device
406
by the pump
405
. The reverse osmosis membrane separation device
406
separates the pretreated water into permeate and concentrate. The permeate obtained by the reverse osmosis membrane separation device
406
is taken out through a pipe
411
. The concentrate obtained by the reverse osmosis membrane separation device
406
is returned to the reservoir
401
through a pipe
412
.
In the aforementioned conventional treatment system, the pretreated water obtained by the hollow fiber membrane element
403
must be temporarily stored in the reservoir
404
, and the pretreated water must be supplied to the reverse osmosis membrane separation device
406
from the reservoir
404
by the pump
405
. Thus, the system cost as well as the size of the system are increased due to the necessity for the reservoir
404
and the pump
405
.
The hollow fiber membrane element
403
can attain a large membrane area (volumetric efficiency) per unit volume, but the membrane is disadvantageously easy to break. If the membrane of the hollow fiber membrane element
403
is broken, the quality of the pretreated water supplied to the reverse osmosis membrane separation device
406
is disadvantageously reduced.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a treatment system, which can be reduced in cost and miniaturized, having high reliability.
A treatment system according to an aspect of the present invention comprises a spiral wound type membrane module including a pressure vessel having a raw liquid inlet and one or a plurality of spiral wound type membrane elements stored in the pressure vessel, one or a plurality of reverse osmosis membrane separation devices, provided on a succeeding stage of the spiral wound type membrane module, including reverse osmosis membranes, and a first duct, the spiral wound type membrane element includes a spiral membrane component including a perforated hollow pipe, a plurality of independent or continuous envelope-like membranes wound around the outer peripheral surface of the perforated hollow pipe and a raw liquid passage forming member interposed between the plurality of envelope-like membranes, a liquid-permeable material covering the outer peripheral portion of the spiral membrane component, and an outer peripheral passage forming member entirely or partially covering the outer peripheral surface of the liquid-permeable material, the raw liquid passage forming member is arranged to supply a raw liquid, supplied into the pressure vessel through the raw liquid inlet, into the perforated hollow pipe from at least the outer peripheral side of the spiral wound type membrane element, and the first duct is provided to supply a permeated liquid taken out from at least one opening end of the perforated hollow pipe to the one or a plurality of reverse osmosis membrane separation devices.
In the treatment system, the raw liquid is supplied to the spiral wound type membrane module, and the permeated liquid taken out from the spiral wound type membrane module is supplied to the reverse osmosis membrane separation device.
In this case, the raw liquid is supplied from at least the outer peripheral side of the spiral wound type membrane element through the raw liquid inlet of the pressure vessel, for performing dead end filtration. Contaminants contained in the raw liquid are captured on at least the outer peripheral portion of the spiral wound type membrane element. The contaminants captured on the outer peripheral portion are readily removed in back wash reverse filtration.
As described above, dead end filtration is performed in the spiral wound type membrane element, whereby a pump for supplying the raw liquid to the spiral wound type membrane module may not have a large size. Further, the permeated liquid taken out from the spiral wound type membrane module can be directly fed to the reverse osmosis membrane separation device with pressure by the pump.
In this case, pressure is applied to the spiral wound type membrane element from all directions, whereby the spiral wound type membrane element is not deformed even if the raw liquid is supplied under high pressure, and high pressure resistance is attained. Thus, the raw liquid can be supplied with high pressure by the pump for supplying the raw liquid to the spiral wound type membrane module.
In the aforementioned treatment system, neither a pump nor a reservoir is required for supplying the permeated liquid taken out from the spiral wound type membrane module to the reverse osmosis membrane separation device, whereby the system cost is reduced and the system is miniaturized.
In pretreatment with the spiral wound type membrane module, the quality of the permeated liquid is not varied with the quality of the raw liquid dissimilarly to the coagulation precipitation.sand filtration method. Therefore, a pretreated liquid having stable quality can be regularly supplied to the reverse osmosis membrane separation device, not to reduce the ability of the reverse osmosis membrane separation device.
No dead space is defined in the clearance between the spiral wound type membrane element and the pressure vessel due to dead end filtration, to allow no residence of the fluid in the clearance between the spiral wound type membrane element and the pressure vessel. Also when employing the spiral wound type membrane for separating a fluid containing organic matter, therefore, high reliability is attained with no problems such as propagation of germs such as microorganisms, occurrence of a bad smell resulting from decomposition of the organic matter, decomposition of separation membranes and the like.
Further, the raw liquid is supplied from at least the outer peripheral side of the spiral wound type membrane element and pressure is applied to the spiral wound type membrane element from all directions with no pressure causing axial displacement, whereby the envelope-like membranes wound around the perforated hollow pipe are not deformed in the form of bamboo shoots. Thus, neither packing holders nor a protective sheath is required, whereby the component cost and the manufacturing cost are reduced.
In the treatment system, the one
Andou Masaaki
Hisada Hajimu
Kawada Ichirou
Akin Gump Strauss Hauer & Feld L.L.P.
Fortuna Ana
Nitto Denko Corporation
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