White Paper on the Application of Molecular, Spectroscopic, and Other Novel Methods to Monitor Pathogens for Potable Reuse

Direct potable reuse (DPR) is gaining interest in water-scarce and water-conscious regions of the world as a technology capable of treating domestic wastewater to potable water standards. Because wastewater is the source water of such treatment schemes, the removal of harmful biological and chemical contaminants present in wastewater is necessary. One of the primary challenges for water reuse applications is the effective removal of pathogens, including viruses and protozoa. A major limitation for the acceptance of DPR is the inability to actively monitor pathogen levels through potable reuse treatment trains. Although various methods to measure pathogen concentrations exist, the required reduction of these levels through treatment processes means pathogen quantification in finished water is not currently feasible in real-time. The lack of rapid, reliable, and inexpensive methods for monitoring through DPR has also hindered the ability of utilities to confirm sufficient pathogen removal through reuse. In this poster presentation, we will present findings from our collaborative project funded by the Water Environment and Reuse Foundation. WE&RF project 14-17 involves an extensive literature review on the current state of microbiological monitoring methods that have potential relevance in water reuse or application in the future. The white paper is intended to inform the DPR field on how to best monitor for pathogens through water reuse treatment trains. The presentation will present the major topics and conclusions from our collected research. In particular, we will discuss the challenges posed by extremely low pathogen concentrations in most of the DPR treatment train and the potential of concentration techniques coupled with detection methods to detect specific pathogens at various stages of DPR treatment trains. In addition, surrogate monitoring capabilities will be evaluated to determine methods for confirming adequate pathogen removal through treatment. Much of our white paper focuses on novel quantification, concentration, and surrogate monitoring methods that we find most promising for future water reuse applications. Specifically, recent developments in human norovirus (HuNoV) culture methods will surely aid in informing the ability of treatment trains to achieve adequate virus removal for the mitigation of public health risk. Of the many viral pathogens of interest in DPR, HuNoV is of principal concern because of its high concentration in raw wastewater and its large burden of disease. Flow cytometry (FCM) is another technique that will be highlighted in the poster presentation because of its real-time monitoring capabilities. FCM is a high-throughput technology that has been used effectively in real-time bacterial monitoring of environmental matrices. We believe FCM will become an important approach to near real-time virus monitoring in the future. New advances in quantitative PCR techniques also have promise in reuse applications to indicate pathogen contamination. Although not real-time, PCR-based methods are more rapid than culture-based methods. The potential ability of PCR-based methods to differentiate infective and non-infective microorganisms will also be reviewed. The poster presentation will conclude with a review of the most important research topics that are necessary to improve microbiological monitoring and pathogen credit maintenance in DPR applications.