Microbial risk associated with CSOs upstream of drinking water sources in a transboundary river using hydrodynamic and water quality modeling

Milad Taghipour; Ahmad Shakibaeinia; Émile Sylvestre; Samira Tolouei; Sarah Dorner

doi:10.1016/j.scitotenv.2019.05.130

Microbial risk associated with CSOs upstream of drinking water sources in a transboundary river using hydrodynamic and water quality modeling

Sci Total Environ. 2019 Sep 15:683:547-558. doi: 10.1016/j.scitotenv.2019.05.130. Epub 2019 May 15.

Authors

Milad Taghipour¹, Ahmad Shakibaeinia², Émile Sylvestre³, Samira Tolouei³, Sarah Dorner²

Affiliations

¹ Civil, Geological and Mining Engineering, Polytechnique Montréal, C.P.6079, Station Centre-ville, Montréal, Québec H3C 3A7, Canada. Electronic address: milad.taghipour@polymtl.ca.
² Civil, Geological and Mining Engineering, Polytechnique Montréal, C.P.6079, Station Centre-ville, Montréal, Québec H3C 3A7, Canada.
³ Civil, Geological and Mining Engineering, Polytechnique Montréal, C.P.6079, Station Centre-ville, Montréal, Québec H3C 3A7, Canada; NSERC Industrial Chair on Drinking Water, Polytechnique Montréal, P.O. Box 6079, Station Centre-ville, Montréal, Québec H3C 3A7, Canada.

PMID: 31146060
DOI: 10.1016/j.scitotenv.2019.05.130

Abstract

Urban source water protection planning requires the characterization of sources of contamination upstream of drinking water intakes. Elevated pathogen concentrations following Combined Sewer Overflows (CSOs) represent a threat to human health. Quantifying peak pathogen concentrations at the intakes of drinking water plants is a challenge due to the variability of CSO occurrences and uncertainties with regards to the fate and transport mechanisms from discharge points to source water supplies. Here, a two-dimensional deterministic hydrodynamic and water quality model is used to study the fluvial contaminant transport and the impacts of the upstream CSO discharges on the downstream concentrations of Escherichia coli in the raw water supply of two drinking water plants, located on a large river. CSO dynamic loading characteristics were considered for a variety of discharges. As a result of limited Cryptosporidium data, a probability distribution of the ratio of E. coli to Cryptosporidium based on historical data was used to estimate microbial risk from simulated CSO-induced E. coli concentrations. During optimal operational performance of the plants, the daily risk target was met (based on the mean concentration during the peak) for 80% to 90% of CSO events. For suboptimal performance of the plants, these values dropped to 40% to 55%. Mean annual microbial risk following CSO discharge events was more dependent on treatment performance rather than the number of CSO occurrences. The effect of CSO-associated short term risk on the mean annual risk is largely dependent on the treatment performance as well as representativeness of the baseline condition at the intakes, demonstrating the need for assessment of treatment efficacy. The results of this study will enable water utilities and managers with a tool to investigate the potential alternatives in reducing the microbial risk associated with CSOs.

Keywords: Cryptosporidium; Dynamic CSO loading; Event-based QMRA; Source water protection.

MeSH terms

Drinking Water*
Environmental Monitoring / methods*
Hydrodynamics*
Rivers / chemistry*
Water Microbiology*
Water Quality

Substances

Drinking Water