The chlorine oxyanions perchlorate, chlorate, and chlorite present human health risks, and the primary exposure route is drinking water. For both ion exchange and biological methods for perchlorate removal, co-contamination with nitrate presents a problem. We have shown that the enzymes involved in perchlorate degradation are functional in the presence of nitrate and in real-world waters, suggesting potential for using them as biocatalysts in a cell-free system. Current work is focused on mining biological diversity to select the best enzymes, testing a variety of options for incorporating them in drinking water treatment, and performing life cycle analyses to assess the commercial potential and environmental impacts of such an approach.
Future work could include integrating this system with a mammalian transport protein inserted in a synthetic membrane, allowing concentration of perchlorate for degradation. Unlike aquaporins, this transport protein has a directionality, raising new fundamental questions and technical challenges for its insertion into synthetic polymers.
We view this project as proof of concept for a platform that has a wide range of applications for environmental engineering, allowing a mix-and-match approach without the constraint of maintaining viability or the risk of release and reproduction as in a biological process.
Funding: NSF CBET and US Army ERDC
Collaborators: Drs. Don Cropek & Irene MacAllister & D (ERDC-CERL, US Army)
Students: Justin Hutchison, Manish Kumar, Kellen Mobilia, & Sean Poust
Hutchison, J. M., and J. L. Zilles. 2015. Biocatalytic perchlorate reduction: kinetics and effects of groundwater characteristics. Environmental Science: Water Research and Technology. Advance Article available online 9 September 2015. DOI: 10.1039/C5EW00176E
Hutchison, J. M., S. K. Poust, M. Kumar, D. M. Cropek, I. E. MacAllister, C. M. Arnett, and J. L. Zilles. 2013. Perchlorate reduction using free and encapsulated Azospira oryzae enzymes. Environ. Sci. Technol. 47(17):9934-9941. doi: 10.1021/es402081b. Epub 2013 Aug 23.