Grantee Research Project Results
2021 Progress Report: One in a Billion: Living Filters for Arsenic Removal
EPA Grant Number: SV840018Title: One in a Billion: Living Filters for Arsenic Removal
Investigators: Colvin, Vicki L.
Institution: Brown University
EPA Project Officer: Aja, Hayley
Phase: II
Project Period: July 1, 2020 through June 30, 2022 (Extended to June 30, 2023)
Project Period Covered by this Report: July 1, 2020 through June 30,2021
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2020) Recipients Lists
Research Category: 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 ot 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. In the Phase I research, the project team developed engineered bacteria, also referred to as a living filter, to selectively bioaccumulate trace levels of arsenic from drinking water. The primary goal for Phase II research is to adapt the living filters to an inexpensive, simple treatment system with minimal power requirements and enable this technology to provide arsenic-free drinking water for rural households and small communities.
Progress Summary:
In our previous research, we engineered the native arsenic-binding protein in E. coli and achieved improved arsenic bioaccumulation performance. To systematically promote the accumulation capacity based on protein structure modification, we eliminated the effects of non-specific binding and native protein upregulation resulting from the background strain. We identified that an extra pair of As(III) binding sites could enhance the sorption capacity by 50%.
In parallel with improving the As(III) bioaccumulation mechanism of the engineered biosorbents, we iteratively designed several schemes to enable these living sorbents for point of- use applications. We evaluate the design base on their arsenic removal efficiency, treatment volume capacity, treatment speed, and the potential of eliminating the risk of secondary contamination. We first used a “tea-bag” model and confined the microbes in a porous polymer bag for contaminated water remediation. However, we realized the physical barrier slowed down the treatment process. Inspired by the bioreactors in the wastewater treatment industry, we switched to a combination of free dispersed sorbents and pressure or vacuum-driven membrane filtration system. According to batch experiment results, this system fulfills our criteria for water treatment at a low sorbent dose. However, when a high sorbent dose was needed to meet the demand for high-level arsenic removal, the treatment capacity and speed were limited due to membrane blockage. Previously, we labeled the engineered bacteria with magnetic nanoparticles and achieved 90% sorbent removal with a handheld magnet. To meet the stringent drinking water regulation criteria and to prevent secondary contamination, we will adapt the magnetically engineered biosorbents to serve as a prefilter to alleviate the membrane fouling issue and design a small magnetic-membrane dual filtration system.
Future Activities:
In the next reporting period, we plan to (1) design a magnetic-membrane dual filtration system suitable for point-of-use drinking water arsenic removal; (2) to conduct a user survey on the New England rural residents' demand on the household water treatment system.
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
Water treatment, arsenic, groundwater, nanotechnology, biotechnologyProgress and Final Reports:
Original AbstractP3 Phase I:
Magnetic Nanocomposites for Water Remediation | 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.