This study discusses the techniques for incorporating nanoscale materials in
treatment systems (e.g., agglomerated media, embedded meshes, coated systems, etc).
The second, main, part of the study focuses specifically on the use of
nanomaterials for arsenic removal. Conclusions include comments about the risk of
nanoparticles in drinking water.
The new arsenic MCL means that water utilities have to install groundwater treatment at
many wells that previously had simply chlorination, if any treatment. A current
AwwaRF project is evaluating agglomerated nanoparticle media for arsenic
removal. A wide range of metal, metal oxide, ceramic and organic nanoparticles (<5 nm
to ~ 60 nm) are commercially available. The research was focused on two main
objectives: screening different nanoparticles for use as arsenic adsorbents; and,
investigation of commercially available agglomerated TiO2 nanoparticle media.
One set of experiments evaluated arsenate removal using 15 different nanoparticles in
ultrapure water and a GF/C filtered surface water adjusted to the same pH as the ultrapure
water and both spiked with sodium arsenate (pH 7, ~900 ugAs/L, 3 day contact time, 1
g/L of nanoparticles). The surface water has a high TDS (~800 mg/L) and is
representative of many groundwaters in the area, except that the surface water contains ~
4 mg/L of DOC. Some nanoparticles (TungsO, La2O2) did not remove arsenate. Several
other nanoparticles removed arsenate nearly equivalently in the laboratory and surface
waters, while others had lower removal in the surface water probably due to competitive
ion adsorption. The ZnO removed arsenate from 890 ug/L to <1 ug/L in laboratory water,
but had significantly less effectiveness in the surface water. Some titanium based
nanoparticles had better removal surface water than laboratory water. Based upon the
results of the screening tests, isotherms experiments were conducted
for 8 nanoparticles. This work demonstrates the viability of titanium and zirconium based
nanoparticle-based treatment systems. Our team has conducted kinetic and equilibrium
experiments, lab-scale rapid small scale column tests, and pilot-tests using one
commercially available agglomerated TiO2 media (MetSorbG), often in parallel studies
with other traditional adsorbents(E33,GFH). The agglomerated nanoparticle material
appears to have better kinetic properties, resulting in potentially shorter required contact
times in treatment systems. Adsorption capacities for TiO2 agglomerated media can be
on the same order as traditional metal (hydr)oxide medias for arsenate, but appear higher for arsenite. Includes 15 references, figure.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 510 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 4 |
| Published : | 06/17/2005 |
