Mitigation of viruses of concern and bacteriophage surrogates via common unit processes for water reuse: a meta-analysis

Authors: Heffron, Joseph; SAMSAMI, MARYAM - Marquette University; JUEDEMANN, SAMANTHA - Marquette University; LAVIN, JENNIFER - Marquette University; TAVAKOLI NICK, SHADI - Marquette University; KIEKE, BURNEY - Marshfield Clinic Research; MAYER, BROOKE - Marquette University

Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2024
Publication Date: 2/25/2024
Citation: Heffron, J.A., Samsami, M., Juedemann, S., Lavin, J., Tavakoli Nick, S., Kieke, B.A., Mayer, B.K. 2024. Mitigation of viruses of concern and bacteriophage surrogates via common unit processes for water reuse: a meta-analysis. Water Research. https://doi.org/10.1016/j.watres.2024.121242.
DOI: https://doi.org/10.1016/j.watres.2024.121242

Interpretive Summary: Potable and nonpotable reuse of wastewater is a growing necessity for water-scarce communities. In the US, recycled water production is expected to reach 6.6 billion gallons per day by 2027. Emerging regulations and guidelines emphasize pathogens, and viruses in particular, as top health risks for water reuse. Bacteriophages are viruses that are safe and convenient to use as surrogates for human viruses in water treatment process testing. However, the treatability of bacteriophage surrogates throughout the multiple barrier treatment trains required for water reuse has not been properly evaluated. This meta-analysis extracted data from the literature to develop regression models for virus and bacteriophage reduction by the five common treatment processes common to water reuse treatment trains: advanced oxidation, chlorination, membrane filtration, ozonation, and ultraviolet disinfection. We demonstrated that no one bacteriophage was a representative surrogate for all five treatment processes. Instead, we recommended a core suite of three bacteriophages that are appropriate to represent a range of virus treatability across the entire treatment train. Researchers and water treatment managers can use these three bacteriophages in developing and monitoring water reuse treatment trains and thereby avoid a non-protective or overly conservative estimate of virus reduction.

Technical Abstract: Water reuse is a growing global reality. In regulating water reuse, viruses have come to the fore as key pathogens due to high shedding rates, low infectious doses, and resilience to traditional wastewater treatments. To demonstrate the high log reductions required by emerging water reuse regulations, cost and practicality necessitate surrogates for viruses for use as challenge organisms in unit process evaluation and monitoring. Bacteriophage surrogates that are mitigated to the same or lesser extent than viruses of concern are routinely used for individual unit process testing. However, the behavior of these surrogates over a multi-barrier treatment train typical of water reuse has not been well-established. Toward this aim, we performed a meta-analysis of log reductions of common bacteriophage surrogates for five treatment processes typical of water reuse treatment trains: advanced oxidation processes, chlorination, membrane filtration, ozonation, and ultraviolet (UV) disinfection. Robust linear regression was applied to identify a range of doses consistent with a given log reduction of bacteriophages and viruses of concern for each treatment process. The results were used to determine relative conservatism of surrogates. We found that no one bacteriophage was a representative or conservative surrogate for viruses of concern across all multi-barrier treatments (encompassing multiple mechanisms of virus mitigation). Rather, a suite of bacteriophage surrogates provides both a representative range of inactivation and information about the effectiveness of individual processes within a treatment train. Based on the abundance of available data and diversity of virus treatability using these five key water reuse treatment processes, bacteriophages MS2, phiX174, and Qbeta were recommended as a core suite of surrogates for virus challenge testing.