Evaluating Fecal Indicator and Pathogen Relationships in Sewage Impacted Surface Waters to Blend with Reclaimed Water for Potable Reuse in North Carolina.

Emily S Bailey,Lisa Casanova,Mark D Sobsey,Margret Hopkins

doi:10.3390/pathogens10121603

Emily S Bailey, Lisa Casanova + Show 2 more

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https://doi.org/10.3390/pathogens10121603

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Abstract

Surface waters used for drinking water supply often receive upstream wastewater effluent inputs, resulting in de facto wastewater reuse for drinking water and recreation. As populations grow, demands on water supplies increase. As this trend continues, it creates the need to understand the risks associated with such reuse. In North Carolina, potable reuse has been proposed as a combination of at least 80% surface water with up to 20% tertiary-treated, dual-disinfected, reclaimed wastewater, which is then stored for 5 days and further treated using conventional drinking water treatment methods. The state of North Carolina has set standards for both intake surface water and for the reclaimed water produced by wastewater utilities, using indicator microorganisms to measure compliance. The goal of this study was to quantify fecal indicator microorganisms, specifically E. coli, coliphages, and C. perfringens as well as key pathogens, specifically Salmonella spp. bacteria, adenoviruses, noroviruses, and the protozoan parasites Cryptosporidium and Giardia, in two types of water representing potential candidates for potable reuse in North Carolina, (1) run of river surface water and (2) sewage-impacted surface waters, with the purpose of determining if there are predictive relationships between these two microorganism groups that support microbial indicator reliability.

Highlights

E. coli and enterococci bacteria were detected on average at levels of 1.12 MPN per 100 mL and 0 MPN per 100 mL, while in surface waters these bacteria were detected at levels of 2.12 × 102 MPN per mL and 1.98 × MPN
The binary logistic regression analysis showed that indicator presence or absence was not consistently predictive of pathogen presence, and the results indicated a high number of false-negative or false-positive values for one of the indicator pathogen combinations, the adenovirus/F+ coliphage relationship
Presence by binary logistic regression, but Salmonella spp. was statistically significantly correlated with the concentrations of total coliform by Spearman’s correlation analysis. These results suggest that there may not be one “ideal” indicator for the prediction of survival or presence of pathogens in surface water even when there is evidence that log10 concentrations of indicator organisms are often correlated with pathogen concentrations

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Surface waters used for drinking water supply often receive upstream wastewater effluent inputs, resulting in de facto wastewater reuse for drinking water and recreation. This trend will probably continue, creating a need to quantify the microbial health risks associated with such de facto reuse [1,2,3]

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