AWWA ACE61819

This study discusses the techniques for incorporating nanoscale materials intreatment systems (e.g., agglomerated media, embedded meshes, coated systems, etc).The second, main, part of the study focuses specifically on the use ofnanomaterials for arsenic removal. Conclusions include comments about the risk ofnanoparticles in drinking water.The new arsenic MCL means that water utilities have to install groundwater treatment atmany wells that previously had simply chlorination, if any treatment. A currentAwwaRF project is evaluating agglomerated nanoparticle media for arsenicremoval. A wide range of metal, metal oxide, ceramic and organic nanoparticles (<5 nmto ~ 60 nm) are commercially available. The research was focused on two mainobjectives: 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 inultrapure water and a GF/C filtered surface water adjusted to the same pH as the ultrapurewater and both spiked with sodium arsenate (pH 7, ~900 ugAs/L, 3 day contact time, 1g/L of nanoparticles). The surface water has a high TDS (~800 mg/L) and isrepresentative 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. Severalother nanoparticles removed arsenate nearly equivalently in the laboratory and surfacewaters, while others had lower removal in the surface water probably due to competitiveion 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 basednanoparticles had better removal surface water than laboratory water. Based upon theresults of the screening tests, isotherms experiments were conductedfor 8 nanoparticles. This work demonstrates the viability of titanium and zirconium basednanoparticle-based treatment systems. Our team has conducted kinetic and equilibriumexperiments, lab-scale rapid small scale column tests, and pilot-tests using onecommercially available agglomerated TiO2 media (MetSorbG), often in parallel studieswith other traditional adsorbents(E33,GFH). The agglomerated nanoparticle materialappears to have better kinetic properties, resulting in potentially shorter required contacttimes in treatment systems. Adsorption capacities for TiO2 agglomerated media can beon the same order as traditional metal (hydr)oxide medias for arsenate, but appear higher for arsenite. Includes 15 references, figure.

Product Details

Edition:

Vol. - No.

Published:

06/17/2005

Number of Pages:

4

File Size:

1 file , 510 KB