Document Type

Thesis - Open Access

Award Date

2019

Degree Name

Master of Science (MS)

Department

Civil and Environmental Engineering

First Advisor

Guanghui Hua

Keywords

adsorption, Escherichia Coli, microbial removal, steel byproducts, stormwater runoff, stormwater treatment

Abstract

Microbial pathogens are considered one of the most important pollutants in regards to surface waters such as coastal waters, rivers and urban estuaries. Escherichia Coli (E. coli) is a bacterial microorganism found in the guts of humans and some animals that if ingested can cause diarrhea, severe stomach cramps, and vomiting. E. coli carried by stormwater runoff can deteriorate water quality of receiving bodies of water. It is necessary to develop technologies to remove E. coli from stormwater runoff to protect surface waters and public health. The use of steel byproducts as an adsorption technology is an emerging stormwater treatment method. The objective of this study was to evaluate the efficiency of recycled steel byproducts for E. Coli removal from stormwater runoff using a pilot scale filter installed at the inlet to a stormwater retention pond. Laboratory batch tests were also performed to compare the ability of different steel byproducts to remove E. coli from water. The steel byproducts used in this study included recycled steel chips and steel slag. These byproducts were sieved into two different size ranges of 2-4 mm and 4-9.4 mm. Batch tests were conducted to evaluate the impact of contact times and initial concentrations of E. coli adsorption by the selected steel byproducts. The results showed that steel chips exhibited higher E. coli adsorption capacities than steel slag. Steel chips in the size range of 2-4 mm achieved greater than 90% E. coli removal within the first two hours. A stormwater retention pond located in Brookings, South Dakota, was selected as the site for pilot scale testing of the steel byproduct filtration for E. coli removal. The filter structure’s dimensions were 5 ft. wide, 6 ft. long, and 8 in. deep with 2 in. of free board. The mixed media used in the filter was composed of 25% 4-9.4 mm steel slag, 12.5% 2-4 mm steel slag, 50% 4-9.4 mm steel chips, and 12.5% 2-4 mm steel chips. Filter influent and effluent were sampled over a three-month testing period in which four different storm runoff events were tested. E. coli, total phosphorus, dissolved orthophosphate, and dissolved nitrate were analyzed for each sample. The results of the pilot scale steel byproduct filter experiments showed that the filter media removed an average of 50% of the E. coli, an average of 29% total phosphorus, and an average of 42% dissolved orthophosphate from the stormwater runoff. The filter was not effective at nitrate removal. The results of the bench and pilot scale studies suggest that recycled steel byproducts are efficient and promising low-cost filter materials for E. Coli removal from stormwater runoff.

Format

application/pdf

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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