Grantee Research Project Results
Final Report: Magnetic Nanocomposites for Water Remediation
EPA Grant Number: SU839449Title: Magnetic Nanocomposites for Water Remediation
Investigators: Colvin, Vicki L. , Mendoza-Garcia, Dr.Adriana , Ahmed, Zahra , Masterson, Caitlin , Rigby, Jennifer , Hu, Yue
Institution: Brown University
EPA Project Officer: Page, Angela
Phase: I
Project Period: December 1, 2018 through November 30, 2019
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2018) RFA Text | Recipients Lists
Research Category: P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards
Objective:
Arsenic is a pervasive and toxic species in drinking water that has remained at the top of the EPA priority contaminants list for more than a decade. There is a need for a more sustainable and more selective technology to remove trace levels of arsenic from drinking water. The overall objective of this project was to meet this need with a renewable treatment system that offered more sustainable and selective performance than current arsenic removal technologies. A central focus of this work was the demonstration that biological materials for arsenic removal could have removal efficiencies independent of interfering ions such as phosphate and silicate. Additionally, because the customers for arsenic treatment are rural households and small communities, a secondary goal was to design a remediation strategy that would be inexpensive, with minimal power requirements and no complicated equipment.
The technical strategy centered on using naturally occurring proteins found in bacteria for arsenic removal. Microbes have evolved these biomolecules to trap arsenic from water as a means of protecting against arsenic’s many toxic effects. These proteins not only have very strong interactions with the reduced forms of arsenic present in groundwater, but they are also highly selective for arsenic even in the presence of competition from phosphate, sulfate, and silicate. By overexpressing these proteins in bacteria, the effort created a living filter which bioaccumulated arsenic rapidly and with reasonable efficiency. To remove the bacteria from cleaned water, bacteria were rendered magnetic through labeling with iron oxide particles. As a result, the engineered bacteria, also referred to as a living filter, can be removed with handheld magnets once the removal process is complete.
Summary/Accomplishments (Outputs/Outcomes):
An output of this effort was the development of magnetically tagged microbes engineered to overexpress arsenic-binding proteins. These bacteria remain alive during the treatment of arsenic contaminated water. One gram of these organisms can bioaccumulate micrograms of arsenic within a few hours and can reduce arsenic levels in water samples to below the maximum recommended exposure level (e.g., 10 ppb). Their bioaccumulative properties do not change in the presence of interfering anions such as phosphate and silicate, or over wide ranges of pH or ionic strength. Another output was the generation of simple and relatively inexpensive processes for handling these bacteria in treatment systems. The performance of the microbes was enhanced through the inclusion of a fusion protein with enhanced arsenic binding capability. Additionally, freeze-drying methods to create stable powders of the arsenic sorbents were developed and optimized with little impact on subsequent performance. Several schemes for applying these living organisms in water treatment were evaluated. In a containment approach (e.g., teabag) microbes could be suspended in a porous polymer bag and immersed in contaminated water. The physical barrier slowed down the arsenic removal times and treatment could take a few days. However, the system was simple to apply and required no electrical power. In another approach, handheld magnets were used after arsenic removal to separate bacteria labeled with iron oxide particles. This separation was fast, on the order of seconds, and yielded efficient removal of arsenic-containing microbes.
Conclusions:
This work will form the basis of future proposals examining how synthetic biology may be used for broader challenges in water treatment. We have also identified partners at the USGS to work with arsenic contaminated well waters drawn from the Rhode Island and New Hampshire areas.
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
Water treatment, arsenic, groundwater, nanotechnology, biotechnologyP3 Phase II:
One in a Billion: Living Filters for Arsenic Removal | 2021 Progress Report | 2022 Progress Report | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.