Document Type

Thesis - Open Access

Award Date

2021

Degree Name

Master of Science (MS)

Department

Civil and Environmental Engineering

First Advisor

Guanghui Hua

Keywords

E. Coli., Filtration, Nutrient Removal, Steel Byproducts, Steel Chips, Steel Slag

Abstract

Stormwater runoff often carries a variety of pollutants and pathogens that can endanger public health and wildlife. One contaminant of concern often highlighted in stormwater quality is Escherichia Coli (E.Coli) because its presence indicates microbial contamination in water. Different types of media filtration are being studied to reduce contaminant concentrations in stormwater. In this study, steel byproducts were examined as a potential material to use in media filtration to remove E. Coli and other contaminants from stormwater. Batch scale studies were conducted in laboratory to evaluate the E. Coli removal potential of steel chips and steel slag over a 24-hour period. Steel chips were able to remove over 99% of initial E. Coli concentrations and steel slag removed between 46% and 73% of initial E. Coli concentrations. Laboratory column studies were conducted to evaluate the performance of steel chips and steel slag under an Empty Bed Contact Time (EBCT) of 15 minutes and fixed E. Coli concentrations. Column studies examining the steel slag showed an average E. Coli removal of 25% and 18% for aged and new material respectively. Column studies examining the steel chips showed an average E. Coli removal of 83% and 45% for new and aged material respectively. Based on these results, a third column study was performed to examine the impact of steel chips to slag ratio on E. Coli removal. Ratios of 5%, 10%, 20%, and 50% steel chips removed an average of 35%, 50%, 57%, and 62% of E. Coli respectively. A pilot filter was constructed at the inlet of a retention pond in Brookings, SD to examine the performance of steel byproducts under real conditions. In 2019 and 2020 the field filter was composed of 50% steel slag and 50% steel chips; this ratio was modified to 70% steel slag and 30% steel chips in 2021. Influent and effluent samples were collected from the filter in 2019, 2020, and 2021 to examine its effect on E. Coli, total phosphorus, orthophosphate, total nitrogen, nitrate, and iron. In 2019, the field filter removed an average of 53%, 45%, 53%, and 42% of E. Coli, total phosphorus, orthophosphate, and total nitrogen respectively. In 2020, the field filter removed average of 54%, 51%, 45%, 45%, and 8% of E. Coli, total phosphorus, orthophosphate, total nitrogen, and nitrate respectively. In 2021, the field filter removed an average of 29%, 31%, 65%, 41%, and 8% of E. Coli, total phosphorus, orthophosphate, total nitrogen, and nitrate respectively. During 2019 and 2020 the field filter increased dissolved iron concentrations in the effluent by an average of 0.27 mg/l. The 2021 field filter had a lower net average increase in dissolved iron concentration of 0.02 mg/l.

Number of Pages

96

Publisher

South Dakota State University

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Rights Statement

In Copyright