SCIENTISTS AT National Chemical Laboratory (NLC) in Pune, have come up
with a water filter that can remove microbes from drinking water.
The filter has pores small enough to exclude virus and bacteria and yet allows passage
of water on a slight tap pressure. Instead of electrical power, it runs on mechanical
power which makes it suitable for village environment.
Bugs that causes typhoid, dysentery, tuberculosis, cholera, giardiasis, polio,
hepatitis and encephalitis can be removed by the filter, according to B. D. Kulkarni of
NLC who along with his team developed and patented the filter.
The cost of the membrane-treated water would be around 83 paise per litre and if the
water is free from undissolved suspended particles, it can last upto three to four years,
he said, adding that the system is self- cleansing too.
It is based on a technique called ultrafiltration (UF) that allows formation of pores
smaller than the dimension of microbes.
The membrane was a successfully tested with Escherecha colibacteria and Picorniatype
virus as well as with small molecules like albumin, casein and polythylene glycol.
Chlorine treatment - the commonest water treatment method - requires harsher condition
and cannot remove spores and cysts completely.
Other methods such as ultra violet or ozone treatment, too have disadvantages as the
remants carrying residual toxins remain in water.
On the contrary, the new UF technique only needs membrane replacement after every three
to four years, he claimed.
The system consists of a mechanical pump that circulates water from the tank to the
membrane at a given pressure. The feed water is passed through the membrane in a
tangential direction so that large molecules do not block the pores. The technology is
already being used in France and Japan.