Browse Prior Art Database

Publication Date: 2012-Jul-24
Document File: 4 page(s) / 68K

Publishing Venue

The Prior Art Database


Embodiments of the present invention provide a method for detecting leaks in an ultrafiltration membrane filtration system that decreases the time and manual labor required to detect leaks, wherein the method comprises closing all isolation valves of a cassette while it is still submerged in a membrane tank. The cassette may then be removed from the membrane tank and a permeate cap for each module in the cassette may be inspected for bubbles. If there are bubbles found in the permeate cap, the rate of water being drained and the visible bubble stream may be used to pinpoint the leaking module and the specific leaking fiber.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 48% of the total text.

Page 01 of 4


    Embodiments of the present invention relate generally to water purification and more particularly to detecting leaks in ultrafiltration membranes.

    Water is one of the most abundant natural resources on earth yet, paradoxically, one of the scarcest natural resources. While nearly seventy-five percent of the surface of the planet is water, very little of it is available for use by man without further treatment since most of it is saline or brackish. Furthermore, the distribution of water, especially potable water, on the planet is such that many inhabited areas do not have an abundance of potable water. Thus, there is a need for purifying saline or brackish water to obtain potable water in many parts of the world.

    The principles of water purification through ultrafiltration (UF) have been known for many years. UF is a type of membrane filtration in which a drop in hydrostatic pressure forces water against a semipermeable membrane which blocks the passage of suspended solids, bacteria, pathogens and viruses that are larger than the pore size of the membrane, but allows the water to pass through. In at least one known UF system, membranes are formed in the shape of hollow fibers, wherein a vacuum is applied to the interior of the fiber providing the necessary hydrostatic pressure differential to pull water through the membrane wall of the fiber, to the interior, and out of the filtration system as a permeate stream. A filter module is comprised of thousands of horizontally strung membrane fibers that have millions of microscopic pores in
each strand. A number of modules are joined together to form cassettes. A module is further comprised of a clear plastic permeate cap which collects the filtered water prior to the permeate stream being connected to the cassette. Multiple cassettes are joined to form a process train. The process train is a production unit containing a number of cassettes immersed in a membrane tank. Feed water flows into the membrane tank and treated water is drawn through the membranes during production by applying a vacuum to the inside of the membrane fibers. The water removed by permeation is replaced with feed water to maintain a constant level in the tank. Multiple process trains form a water treatment plant.



Page 02 of 4


    Over the life of the membrane, it is possible for leaks to develop where suspended solids are able to circumvent the membrane altogether by passing through the leak into the permeate stream. Thus, an efficient method is required to check for leaks periodically to ensure the UF process is working properly, but in a manner that minimizes down time of the system. Traditionally, a method for detecting leaks comprises removing a cassette from service, removing a module from the cassette, placing the module into a repair tank, attaching a vacuum source to the permeate cavity of the module, and locating bubble streams wi...