(ClO4-) has emerged as a significant new threat to
groundwater and drinking water supplies and the environment. The Oak Ridge
National laboratory recently developed a new class of bifunctional
anion exchange resins, which are highly selective for sorption of ClO4-
from contaminated groundwater or surface water.
A field experiment demonstrated that the bifunctional resin
was able to treat >100,000 bed volumes of groundwater before a 10%
breakthrough of ClO4- occurred (running at ~2 bed
volumes per minute with an initial ClO4- concentration of
The bifunctional resins are particularly effective in removing trace
quantities of ClO4- in groundwater to below the
detection limit (~1 mg/L).
Using pertechnetate (TcO4-)
as an analog (with similar chemical properties as ClO4-),
these bifunctional resins were able to remove TcO4-
from contaminated groundwater at below 0.001-ppb
levels. No pretreatment is needed to remove either dissolved organic matter or
other competing anions (such as Cl-, SO42-,
HCO3-, or NO3-), which may be
present at 3–5 orders of magnitude higher than that of ClO4-
in the groundwater or surface water. The
treatment process does not involve addition or removal of unwanted organic or
inorganic compounds or nutrients in the water because of the high selectivity
of the bifunctional resins.
a new resin regeneration technology was developed for regenerating the
bifunctional and other selective anion-exchange resins (e.g., Purolite
A-520E) using the ferric chloride-HCl displacement
patents: 6,448,299, 6,358,396).
Laboratory experiments indicated that a nearly 100% recovery of
ion-exchange sites was achieved by washing with as little as ~2 bed volumes of
the ferric chloride regenerant solution in a column flow-through system. There
was no significant deterioration of the resin’s performance with respect to
ClO4- removal after repeated loading and regeneration
innovative technology was recently developed for a complete destruction of
perchlorate in the ferric chloride regenerant solutions (US
patent pending, 10/157,407).
While perchlorate is destroyed, the treatment process does not alter the
properties of the regenerant solution so that it can be used repeatedly and no
waste regenerant is produced. This treatment process therefore has
enormous economic implications that not only a reduced volume of regenerant is
required but also the disposal of hazardous wastes containing perchlorate is
eliminated. The treatment process is efficient and cost-effective, while not
being subject to difficult–to–maintain operating conditions.