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Droplet Digital PCR Quantification of Norovirus and Adenovirus in Decentralized Wastewater and Graywater Collections: Implications for Onsite Reuse
Citation:
Jahne, M., N. Brinkman, S. Keely, B. Zimmerman, E. Wheaton, AND J. Garland. Droplet Digital PCR Quantification of Norovirus and Adenovirus in Decentralized Wastewater and Graywater Collections: Implications for Onsite Reuse. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 169:115213, (2020). https://doi.org/10.1016/j.watres.2019.115213
Impact/Purpose:
Decentralized water reuse can provide economic and environmental benefits; however, expansion of its application has been hindered by uncertain treatment and management requirements. A fundamental barrier to the development of treatment guidance for decentralized reuse systems has been lack of pathogen characterization data for onsite or locally-collected wastewaters. To improve upon previous detection methods for low-level pathogen densites in wastewaters, this study presents a droplet digital polymerase chain reaction (ddPCR) protocol to quantify viral enteric pathogens (norovirus genogroups GI and GII and adenovirus) in untreated graywater and combined wastewater. Measurement results from three different building-scale decentralized collection systems are compared to the epidemiology-based pathogen simulation used to model log-reduction targets (LRTs) for non-potable onsite wastewater reuse, and to traditional quantitative PCR (qPCR) analysis methods. To our knowledge, this is the first quantitative report of norovirus concentrations in graywater or in onsite-collected combined wastewater. Results will support future quantitative microbial risk assessments (QMRAs) evaluating the safety of decentralized water systems and the continued development of risk-based treatment guidance for decentralized water reuse by State agencies and industry stakeholder groups.
Description:
Risk-based treatment of onsite wastewaters for decentralized reuse requires information on the occurrence and density of pathogens in source waters, which differ from municipal wastewater due to scaling and dilution effects in addition to variable source contributions. In this first quantitative report of viral enteric pathogens in onsite-collected graywater and wastewater, untreated graywater (n = 50 samples) and combined wastewater (i.e., including blackwater; n = 28) from three decentralized collection systems were analyzed for two norovirus genogroups (GI/GII) and human adenoviruses using droplet digital polymerase chain reaction (ddPCR). Compared to traditional quantitative PCR (qPCR), which had insufficient sensitivity to quantify viruses in graywater, ddPCR allowed quantification of norovirus GII and adenovirus in 4% and 14% of graywater samples, respectively (none quantifiable for norovirus GI). Norovirus GII was routinely quantifiable in combined wastewater by either PCR method (96% of samples), with well-correlated results between the analyses (R2 = 0.96) indicating a density range of 5.2–7.9 log10 genome copies/L. These concentrations are greater than typically reported in centralized municipal wastewater, yet agree well with an epidemiology-based model previously used to develop pathogen log-reduction targets (LRTs) for decentralized non-potable water systems. Results emphasize the unique quality of onsite wastewaters, supporting the previous LRTs and further quantitative microbial risk assessment (QMRA) of decentralized water reuse.
URLs/Downloads:
DOI: Droplet Digital PCR Quantification of Norovirus and Adenovirus in Decentralized Wastewater and Graywater Collections: Implications for Onsite Reuse
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