Author ORCID Identifier
Date Available
1-3-2025
Year of Publication
2023
Document Type
Master's Thesis
Degree Name
Master of Science in Civil Engineering (MSCE)
College
Engineering
Department/School/Program
Civil Engineering
Advisor
Dr. Diana M. Byrne
Abstract
Bioretention, also referred to as a stormwater biofilter, is an extensively used low-impact development technology for both stormwater management and water quality gains. However, little attention has been paid to the acceptability and uncertainty of human health risks associated with the treatment performance of bioretention filter media, and non-potable water reuse scenarios to guide decision-making and system design. This study uses bioretention mechanistic modeling paired with quantitative microbial risk assessment (QMRA) under uncertainty to evaluate human health risks from two reference pathogens – Campylobacter jejuni and Cryptosporidium. Consumption of irrigated green salad, consumption of raw green salad washed with effluent, accidental ingestion during urban farming irrigation, and ingestion during recreational swimming were the investigated exposure scenarios. The influence of filter media configurations of sand (35-70%), compost (10-20%), woodchips (10-20%), and loam (10-25%) on health risk was investigated. A median outflow of 92 liters per day per storm event and equivalent hydraulic conductivity of 0.2 m/day were obtained for a modeled 1-year, 1-hour storm. Sand-dominated media configurations mimicked slow sand filtration and achieved high removal rates of up to 4.85 log removal for both pathogens, and lowest annual risks of 2.22 x 10-11 and 8.01 x 10-12 for C. jejuni and Cryptosporidium, respectively in all exposure scenarios. Media composition had minimal influence on the modeled annual risks. A moderate influence of influent concentrations on annual risks was reported. For both C. jejuni and Cryptosporidium, the washed salad scenario had the highest median annual risk (4.6 x 10-4 and 1.72 x 10-3), while recreational swimming had the lowest median annual risk (1.99 x 10-9 and 7.62 x 10-9), respectively. The risk from C. jejuni in the irrigated salad scenario was influenced by microbial growth in the salad during production. The major limitation of this study was the precision of influent pathogen-specific data and exposure parameters. In the future, the findings from this study will be combined with life cycle assessment (LCA) and life cycle costing (LCC) to comprehensively guide multi-criteria decision-making in the design and development of sustainable water infrastructure for stormwater reuse.
Digital Object Identifier (DOI)
https://doi.org/10.13023/etd.2023.012
Recommended Citation
OLUK, ISAAC, "Quantitative Microbial Risk Assessment (QMRA) For Urban Stormwater Reuse After Treatment Through A Bioretention System" (2023). Theses and Dissertations--Civil Engineering. 130.
https://uknowledge.uky.edu/ce_etds/130
