In
France as in other European countries, lead pollution in drinking
water remains a public health problem, with known harmful effects
on children's neurological and behavioral development.
In
a CNRS partnership with industry its "Laboratoire des sciences
du génie chimique" (LSGC, Chemical Engineering Sciences
Laboratory) and "Laboratoire d'hygiène et de recherche
en santé publique"(LHRSP, Hygiene and Public Health Research
Laboratory) at Nancy and the company "Générale
des Eaux " have jointly devised a lead-adsorbent and filter unit
attachable directly to the domestic tap.
A
recent European Directive set stiffer standards reducing acceptable
threshold levels from 50 to 10 mg/l, following World Health Organization
recommendations. Drinking water released from the purification plant
contains less than 10 mg/l of lead. But flushing through lead piping
in older housing, it dissolves lead and picks it up as particles from
pipe walls or as precipitates. French government ministries subsequently
called for research on economical means to reduce lead levels in drinking
water.
The
challenge was to develop a device combining adsorbent and filter to
bring lead to under 10 mg/l in just a few seconds' contact time; and
to make the device small enough to connect to household taps. Researchers
first sought an adsorbent with a high lead-retaining capacity, effective
in extremely short contact times which would not alter water composition.
The LSGC used its expertise in porous-media separation processes and
selective trace-element removal from water. The LHRSP ensured the
analytical work and the end product's compliance with health and water
quality regulations. The second phase, prototype development, was
run by "Générale des Eaux". The result was
a two-element unit with stable adsorbent fixed on a compact granular
material and a mechanical filter for removing particles.
The
price per liter comes out to be less than the cost of bottled water.
Field trials currently under way will end in September 2001 and then
the final stage-marketing the product-can begin.
