Antimicrobial performance of microstructured metal materials in water and wastewater: proof-of-concept and scale-up

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Authors

Zhao, Jinghan

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Journal ISSN

Volume Title

Publisher

University of Guelph

Abstract

It is necessary to disinfect treated wastewater prior to discharge to reduce exposure risks to humans and the environment. The currently practiced wastewater disinfection technologies are challenged by toxic by-products, chemicals, and energy demand, a range of effectiveness limitations, among other concerns. An effective, eco-friendly, and energy-efficient alternative disinfection technique is desirable to modernize and enhance wastewater treatment operations. Copper and nickel micro-structured metal foams, and a conventional copper mesh, were evaluated as disinfecting surfaces for treating secondary-treated wastewater contaminated with coliform bacteria. The micro-structured copper foam was adopted for antiviral and scale-up study due to its stable and satisfactory antimicrobial performance obtained over a wide range of bacterial concentrations and metal-to-liquid ratios. Three scales of experiments, using two types of reactor designs, were performed using municipal wastewater to determine the optimal scale-up factors: small lab-scale batch reactor, intermediate lab-scale batch reactor, and pilot-scale continuous tubular reactor experiments. The performance was evaluated with the aim of minimizing metal material requirements with respect to bactericidal efficiency and leaching risks at all scales. Copper foam, at or above optimal conditions, consistently inactivated over 95 % of total coliforms, fecal coliforms, and E.coli in wastewater at various scales, and leachate copper concentrations were determined to be below Canadian guideline values for outfall. Furthermore, copper foam performed higher killing rates on the virus with the presence of host cells compared to in a virus-only water environment. The result demonstrated the contact-killing effect caused by the intensified structure of copper foam played an important role in its superior antimicrobial properties. This study successfully implemented the “structure” strategy of process intensification and opened up the possibility of applying micro-structured copper foam in a range of other water disinfection systems, from pre-treatment to point-of-use, and should thus become a topic of further research, which may help to resolve the water safety crisis and provide safe water supply to communities in need.

Description

Keywords

Wastewater disinfection, Bactericidal performance, Viricidal performance, Process scale-up, Metal foam, Process intensification, Coliform bacteria

Citation

Zhao, J., Yan, P., Snow, B., Santos, R. M., & Chiang, Y. W. (2020). Micro-structured copper and nickel metal foams for wastewater disinfection: proof-of-concept and scale-up. Process Safety and Environmental Protection, 142, 191-202. https://doi.org/10.1016/j.psep.2020.06.013