Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
1999-06-22
2001-02-06
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S321690, C210S321870, C210S490000, C210S650000, C216S056000
Reexamination Certificate
active
06183647
ABSTRACT:
This Application is a 371 of International Application PCT/FI97/00776, filed on Dec. 11, 1997
FIELD OF THE INVENTION
The invention relates to a method for treatment of liquid, that is meant particularly for filtering of pressurized liquid, such as water led from a water distribution system or like, by means of an apparatus, which has an essentially closed body, in connection with which there has been arranged at least filtering means for purifying of liquid and flow means, such as feed-flow and/or exhaust-flow arrangements for leading of liquid. The filtering means are made of thin filtering film, preferably made of plastic based material, such as PTM (Particle Track Membrane), TeM (Track-etch Membrane) or like, the thickness of which is preferably 7-25 &mgr;m and the size of pores of which is 0.05-10 &mgr;m, whereby in connection with the body there has been arranged preferably a support arrangement to support the filtering film. The filtering means are purified by means of purification means.
BACKGROUND OF THE INVENTION
Finnish patent application 944287 discloses the type of water purification device described above comprising a membrane-structured filtering part. The solution in question is meant to operate by so called syphon principle, thanks to which the structure of the same is very simple. The water purification device in question is very safe and easy to use in practice, because the quality of the water flowing to the collecting point thanks to the syphon phenomenon being self-powered is continually homogeneous regardless of the operating time of the device. This is first of all based on the fact that a water purification device equipped with a thin PTM- or TeM-filtering film does not at any stage let through material parts exceeding a certain particle size, in which case, when the filtering film gets dirty, only the penetration speed of the filter decreases and may even totally be interrupted, in case the filtering film is not cleaned every now and then.
The device described above is very useful in most heterogeneous connections, e.g. in terrain for filtering of lake water or under other circumstances as well, wherein actual tap water may not be used. One disadvantage of the device is mainly the slowness of the filtering speed and on the other hand also the fact, that e.g. in ordinary household use the device requires use of separate vessels, so that functioning of the syphon phenomen could be brought out. In practice, cleaning of the filtering film of the device in question is disadvantageous to a certain extent as well, because it must be carried out first of all manually as a totally separate stage of operation. Manual cleaning of the filtering film is on the other hand disadvantageous in such respect as well, that during mechanical rubbing by too “heavy-handed” treatment the pores in the filtering film may get enlarged unintentionally or on the other hand they may get stuffed up by impurities. This is why, functioning of the filtering film of a device being used under particularly dirty circumstances, may weaken too much immediately after the first cleaning measure due to decreased penetration ability. A crucial disadvantage involved with the type of apparatus in question may be in practice, however, the fact, that it is not possible to exploit the same as such very simply, e.g. for filtering of water being led directly from a water distribution system, but instead separate water vessels must be used because of the syphon principle.
On the other hand from e.g. Japanese application 5-177 185 it is known to exploit a membrane-structured filtering device, that is placed to a basin comprising liquid to be treated. The solution in question is thus meant for large-scale use, but in principle a corresponding type of solution may be placed e.g. directly at the end of a supply pipe as well. In the solution in question the filtering means are brought out by a so called bag filter principle in a way, that liquid to be treated goes through the walls of the elongated membrane pipes to the secondary side of the filter keeping clean water and furthermore for some utility purpose through a flow-way being connected to this side. The solution in question is advantageous in such respect, that for purifying of the filtering means there has been exploited an inverse flushing flow, in which case at the secondary side of the filter there has been placed a supplementary container keeping filtered water. In this case, when running of water is interrupted, a pump is being used, which feeds the filtered water from the supplementary container as an inverse flow through the filtering pipes, whereby the same get purified.
The arrangement in question is advantageous in such respect, that the porous structures of the filtering pipework may be flushed by means of an inverse flow. In practice, the type of elongated, flexible pipe structures as described above collect, however, impurities particularly to the outer surfaces of the same, that is why e.g. bacteria growth may get collected to the same, that may not be, however, influenced directly by means of the type of inverse flow described above. This is why the flushing principle in question operates only partly. In addition to that, the type of solution has such a disadvantage as well, that the filtering pipework is a very confused entirety, that is why it is not possible to get any kind of sight inside the same, in which case e.g. fungus or some other corresponding undesired bacteria formulation being generated therewith may not be noticed. The solution in question is on the other hand disadvantageous in such respect as well, that a separate pump must be used for the purification flushing, which requires a very complicated control and adjustment automation and instrumentation. This for its part makes use of the device more difficult and decreases efficiency of the same decisively in practice as well.
Thus, nowadays there are not any water purifiers or like on the market, that would be profitable enough by the acquisition or functional costs and that would be technically easy to utilize e.g. for household use and, that would operate effectively enough and eliminate particularly bacteria under all kinds of circumstances reliably enough.
SUMMARY OF THE INVENTION
It is an aim of the method according to the invention to achieve a decisive improvement in the problems presented above and thus to raise substantially the level of prior techniques. To achieve this aim, the method is primarily characterized in, that the filtering film belonging to the filtering means are being purified essentially self-powered, such as by means of purification means exploiting the pressure, the movement and/or like of the liquid to be treated and/or the liquid that has been treated.
As the most important advantages of the method according to the invention may be mentioned the simplify and reliability of the construction and use of the same, which matters are crucial requirements for achievement of reliable purifying result particularly when the aim is to produce e.g. drinking water under most heterogeneous circumstances. Thanks to the simple principle of the method, manufacturing of the apparatus to be exploited therewith is advantageous as well, in addition to which the method is also profitable thanks to continuous functioning of the same, because the filtering film belonging to the same may be purified extremely simply, fast and reliably. In addition to that one crucial advantage of the method is also the fact, that manual purification measures are not needed any more, so that no direct mechanical rubbing of the filtering film may not occur. Thanks to the method, the filtering film may get effectively flushed first of all throughout the entire outer surface of the same by exploiting a by-pass flow of not yet treated water and on the other hand also as an advantageous embodiment due to the inverse flow of the treated liquid, that is e.g. filtered water, that takes place through the perforation. Thanks to the method, the quality of the produced liquid is always homogene
Aalto Kari
Antipov Valery
Melnikov Alexander
Sotov Michail Ivanovich
Drodge Joseph W.
Pollock Vande Sande & Amernick
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