FROM A MEDICAL GRADE DEVICE
USED FOR HEMODIALYSIS
The scope of hemodialysis is to substitute the blood purification effect of the best filter in world – the human kidneys – with artificial extra-physical means. The hemodialysis task is to extract from the blood all the "impurities" which are characterized by a low molecular weight (i.e potassium, creatine, urea, etc.), while keeping in the blood essential components (i.e albumin, which has a molecular weight of approximately 66 kD – equivalent to a relative size of approximately 40 nm). In the hemodialysis process, blood is purified by means of an artificial kidney, named "dialyzer", which is basically a hollow-fiber membrane. "Polluted" blood flows through the dialyzer in the inner side of the fibers through the blood ports, which have an absolute porosity lower than 30 nm (= 0.03 µ), while a saline solution ("dialysate") is circulated on the outer part of the fibers through the dialysate ports. Thanks to the accurate and absolute porosity of the fiber, all the low-molecular weight "impurities" in the blood are attracted by diffusion outside the fiber, while the blood is recycled to the human body with no alteration in the concentration of its essential high-molecular components which could not exit the 30 nm barrier. Dialyzers are therefore manufactured according to the strictest medical standards, with excellent materials and quality-test procedures.
Approved medical procedures allows for the reprocessing of used dialyzers under AAMI/ANSI standards, by means of a thorough and accurate sterilization after the usage. However, due to the logistic difficulties to implement the rule which approves re-use of the dialyzer for the same patient only, most dialysis centers are discarding and disposing one-time used dialyzers to the waste. Hundreds of millions of dialyzers are disposed to the environment every year
INSIDE-OUT DEAD END FILTRATION MODE
TO AN ABSOLUTE WATER ULTRA FILTER
The NUF technology is based on a worldwide granted patent – basic, simple and genial at the same time - invented by Prof. Yoram Lass, Professor Emeritus at the University of Tel Aviv's Faculty of Medicine. The patent provides for the re-use of dialyzers, after the same accurate sterilization procedure under medical standards,
as a…water treatment device. The result of the field application of the patent is the NUF membrane, which is therefore a water purifier with the efficiency, accuracy and quality of an artificial kidney.
However, the flow in the water purification process differs from hemodialysis. In order to take advantage of the membrane characteristics raw water flows from both blood ports into the fiber. All the components bigger than 0.03 µ nm are retained into the fiber itself due to the absolute barrier effect, the ones between 0.003 µ (the nominal filtration rate of the membrane) are retained at lower efficiency, and all the low-molecular weight materials (mainly aqueous salts) are permeating with the purified water and collected at both "dialysate ports" – in a classical "inside-out dead-end" filtration mode.
For high pollutant load cases, a "cross-flow" configuration – where a concentrate is discharged back to the process from the inside of the fiber through the second "blood port" – can be implemented.
NUF IN THE FILTRATION SPECTRUM
The NUF membrane is an absolute 30 nm barrier to a very broad range of water pollutants, and an efficient high-rejection mean for small relative size materials (0.003 µ to 0.03 µ) as well.
The performances of the NUF membranes are almost unbeatable in the water and waste water treatment field, mainly within the range of Ultrafiltration ("UF") membranes produced by the main suppliers in the field.
After the medical grade sterilization, the NUF membrane is basically a new, robust and highly efficient water filtration element with unique characteristics:
Originally designed, built, proofed and quality tested as a medical device
ABSOLUTE filtration rate of 30 nm => nominal filtration rate of 3.3 nm
Smooth membrane surface => low fouling and extremely easy to clean
Simple to operate: filtration, backwash (at 1-1.5 filtration velocity rate only) and CEB
Robust: more than 3 years of continuous operation (and going on)
Built-in mechanical filter – 200 µ
In line steam sterilized => resistant to high temperature
Easy scalability: 1 unit = 50-200 lt/hr; 10,000 units in parallel = 500-2,000 m3/hr
Together with top of the line UF quality, NUF provides for extremely affordable investment and operational costs – making UF at last an approachable technology also for applications which are economically unthinkable to be accessed with commercial UF membranes.