NSF-GACR: Reactive Interfaces for Degrading Contaminants of Emerging Concern and Pathogenic Viruses in Constructed Wetlands

Constructed wetlands (CWs) have emerged as promising and cost-effective nature-based systems for the treatment of wastewater due to their low-cost, efficiency, and benefits to the environment. Current CWs have been primarily designed to remove suspended solids, bulk organics, and nutrients including nitrogen and phosphorus. However, they are not effective at removing and degrading contaminants of emerging concern (CECs) or potentially harmful viral pathogens (VPs).

As CECs and VPs have become global threats to human and ecosystem health, their efficient and rapid removal would be critical if a CW system is to be installed in an urban, suburban, or a rural area to treat contaminated wastewater. The overarching goal of this NSF-Czech Science Foundation (GAC) project is to investigate the design, development, and evaluation of a new CW treatment system designed to remove CECs and VPs.

To advance this goal, the Principal Investigator (PIs) propose to explore the design and integration of reactive interfaces into CWs, including solid-water interfaces generated by iron and manganese oxides and air-water interfaces generated by air bubbles, to promote the simultaneous removal and destruction of CECs and VPs. The successful completion of this project will benefit society through the generation of fundamental knowledge to advance the design and implementation of more efficient and cost-effective constructed wetland systems for wastewater treatment.

The joint implementation of this project in the United States (US) and the Czech Republic will broaden the impact of the research with the potential to improve global water management. Additional benefits to society will be achieved through student education and training including the mentoring of one graduate student and one undergraduate student at the University of Tennessee Knoxville.

Constructed wetlands (CWs) are promising pollution control and environmental remediation systems as they offer cost-effective, nature-based systems for wastewater treatment. However, existing CWs are primarily designed for the removal of nutrients but not for retention and degradation of compounds of emerging concern (CECs) or viral pathogens (VPs).

The goals of this NSF-GAC collaborative project are to investigate, understand, and quantify how solid-water interfaces generated by functionalized metal oxides (e.g., iron and manganese oxides) and air-water interfaces created by air bubbles increase the microbial/chemical degradation of CECs and removal of VPs under aerobic-anaerobic conditions in constructed wetlands (CWs). The specific objectives of the research are to (1) synthesize and/or functionalize iron and manganese oxide particles to promote binding and degradation of CECs; (2) optimize reaction conditions for virus binding and removal at solid-water interfaces; (3) optimize environmental conditions to maximize the removal of CECs and viruses under varying flow conditions; and (4) validate the CEC degradation and virus inactivation mechanisms under pilot scale CW conditions.

The US team will systematically assess the capacity of solid, water, and air interfaces to remove viruses from wastewater in model CW columns. The Czech team will focus on the chemical and biological reactions and mechanisms controlling the persistence of CECs in model soil columns, microcosms, and pilot-scale mesocosms designed to simulate CWs. The successful completion of this research will advance the fundamental understanding of the synergistic roles of air bubbles and metal oxides in removing CECs and VPs under varying environmental conditions in model laboratory and pilot CWs.

To implement the education and training goals of the project, the Principal Investigators propose to leverage an existing NSF REU site award at the University of Tennessee Knoxville to recruit and engage undergraduate students from underrepresented and underserved groups in Appalachia to work on the project. In addition, the PIs plan to develop activities for local K-12 science teachers as well as training of undergraduate and graduate students in the US and the Czech Republic.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.