Grantee Research Project Results

Final Report: Water purification using a graphene bead filter

EPA Grant Number: SU839293
Title: Water purification using a graphene bead filter
Investigators: Joo, Sung Hee , Suph, Albani , Garvey, Andrew , Michel, Carlos , Bravo, Isabel , Helm, Madeline , Baek, Soyoung , Zeineddine, Tamin
Institution: University of Miami
EPA Project Officer: Page, Angela
Phase: I
Project Period: February 1, 2018 through January 31, 2019
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2017) RFA Text |  Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources , Sustainable and Healthy Communities

Objective:

According to a recent news report (CNN, 4/3/2018 "Unusual forms of 'nightmare' antibiotic-resistant bacteria detected in 27 states"), superbugs (antibiotic-resistant bacteria) have been detected even in drinking water across the nation. The growing demand for clean drinking water is urgently rising, especially in local communities where there is a lack of access to clean water resources and people cannot afford drinking water. The overall objective of the stage I project was to develop and advance applications of nanotechnology using cost-effective, nanomaterial-coated bead filtration, specifically to integrate recently studied methods regarding the various types of nanomaterials as coating materials and how to optimize treatment parameters for removal of difficult-to-treat contaminants (i.e. target contaminants: E. coli, P. aeruginosa, nitrates, and perchlorate). Thus, a novel nanocomposite-coated bead filtration system was used to efficiently treat water containing antibiotic-resistant bacteria and other drinking-water contaminants of concern (e.g., chlorate, perchlorate), thereby reducing the extensive treatment that is required by conventional treatment technologies.

The specific objectives are to efficiently treat water containing the contaminants of concern (antibiotic-resistant bacteria) and reduce the extensive treatment required by conventional treatment technologies; to generate economic benefits, along with the benefits of less waste generated from the system, less energy consumption, and increased simplicity of use; and to create a sustainable approach for purifying contaminated water using the novel filtration system to meet the nation's clean-water needs. The beads will allow the bacteria or chemical contaminants to either adhere to the bead membrane or be absorbed into the bead. Since small quantities of nanomaterials can contain significant concentrations of contaminants, the materials' use can be widely regarded as a possible solution to small-scale water treatment applications. The innovative aspects of the proposed project include (a) immobilization of nanocomposites by coating them onto alginate gel beads so that no leaching occurs, (b) removal of contaminants as influent water makes contact with nanoparticle-coated beads in the designed filtration system, (c) a strong adsorbent for the removal of toxic contaminants, and (d) feasible and cost effective filtration for a decentralized water supply. The benefits in the perspectives of supporting people, planet and prosperity include (a) improving public health through awareness of the need for clean drinking water and education of the public on emerging contaminants of concern, (b) saving on extensive treatments and reducing long-term treatment costs, (c) finding sustainable approaches to meeting clean-water needs. The stage I project also includes collaboration with an industry partner (JACOBS environmental consulting firm) and University of Alaska Fairbanks on activities including assessment of the treatment-efficacy educational activities that make the community aware of this sustainable approach to purifying contaminated water using the novel filtration system.

Summary/Accomplishments (Outputs/Outcomes):

Preliminary results indicate that ZnO-coated beads effectively eliminated significant amounts of antibiotic-resistant bacteria (e.g., P. aeruginosa) and E. coli (108 CFU/mL), with 99.5% and 100% removal, respectively, within 6 hours (tested amounts of entrapped ZnO nanoparticles: 0.2, 1, and 2 g). As the amount of nanocomposites increased, the cloudiness of contaminated water decreased, indicating a decrease of bacteria due to a more active site and surface area for better interaction with the bacteria. When the nanocomposite amount increased to 1 g, bacteria inactivation was almost achieved, and inactivation was further improved at the mass of 2 g. Two different sizes of beads were fabricated and tested. Among the two methods, method-B beads that had smaller sizes were more effective due to their higher adsorption capacity, thus offering an active surface site of nanoparticles.

Conclusions:

It was observed that even with increased amounts of nanocomposites, bacteria were inactivated without the issue of nanoparticles leaching into the water. Currently, nanocomposite-coated beads including ZnO and graphene-coated beads are tested to treat other contaminants of concern, especially nitrates, perchlorate, and chlorates. The treatment optimization in water purification systems will be carried out with column reactors, along with characterization studies and detailed mechanisms of nanoparticle-coated beads.

Proposed Phase II Objectives and Strategies: Further from the promising outcomes achieved in Phase I, we will implement three objectives, focused on technology deployment and application in local communities, process optimization, as well as educational and outreach activities. Phase 2 is also aimed at a strategy of identifying the mechanisms of contaminant removal and optimum conditions that maximize treatment performance in a cost-effective manner. In addition, the proposed study could be used to investigate other types of deadly bacteria such as flesh-eating bacteria in floodwaters, which are a significant concern, especially when a hurricane hits. Strategies of successfully implementing our project are to a) maximize treatment performance of the target contaminants in an environmentally sound and cost-effective manner; (b) optimize the fabrication and quantities of nanocomposite-coated beads; (c) successfully deploy and apply our developed technology in local communities for decentralized water supplies; and (d) conduct outreach education comprising workshops, an exhibition, a community forum, an annual summer camp at which students have hands-on activities, and publications in peer-reviewed journals.

Supplemental Keywords:

Antibiotic-resistant bacteria, Decentralized water supply, Bead filtration, Zinc oxide, Graphene, Nanomaterials, Sustainability

Relevant Websites:

Environmental Nanotechnology Laboratory Exit