Document Type

Thesis - Open Access

Award Date

2017

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Guanghui Hua

Abstract

Stormwater runoff from agricultural and urban areas carries a wide range of pollutants and pathogens that can negatively affect surface water bodies and cause significant risks to the ecosystem and public health. Bacteria is one of the pollutants carried by stormwater, and Escherichia coli (E. coli) is commonly used as a microbial pollution indicator of surface water. The aim of this research was to investigate the removal of E. coli from stormwater using low-cost filter materials. Two industrial byproducts (steel slag and steel chips) and two natural minerals (zeolite and limestone) with three different sizes (0.5-1 mm, 1-2 mm, and 2-4 mm) were chosen to investigate the potential of these materials as filter media for E. coli removal from stormwater. Batch experiments were conducted to investigate the impact of initial E. coli concentration, temperature, pH, particles size and mass, salt, natural organic matter (NOM), and contact time on the removal of E. coli. Column adsorption experiments were also performed to obtain the E. coli adsorption characteristics of steel chips, steel slag, limestone, and zeolite under continuous flow conditions. In addition, the E. coli release potential of these materials were determined. Using a desorption test, the batch adsorption results demonstrated that the maximum E. coli removal efficiencies of 100%, 99.5%, 86.5%, and 80.2% were achieved using steel byproducts, steel slag, limestone, and zeolite, respectively, using E.coli concentrations of 107 MPN/mL for steel chips and 104 MPN/mL for steel slag, limestone, and zeolite, in the synthetic stormwater. Increasing pH from 5 to 9 resulted in a reduction in E. coli adsorption by 33.5% and 19.0% for steel chips and steel slag, respectively. As temperature increased steel chips and steel slag adsorption capacities increased. The effect of the addition of NOM on E. coli removal efficiencies was determined. The results indicated that E. coli removal efficiency were reduced by 19.77% and 41.77% for steel chips and 6.86% and 11.56% for steel slag in the presence of 20 and 50 mg/L of NOM. Moreover, E. coli release from steel chips was negligible in comparison with other absorbents. Finally, adding high salt concentrations in E. coli solution showed a significant impact in natural minerals adsorption capacities. As the salinity increased the E. coli adsorption capacity of limestone and zeolite were improved by 23.5%, and 35.5%, respectively.

Library of Congress Subject Headings

Runoff -- Health aspects.
Escherichia coli.
Water quality management.
Water -- Purification -- Microbial removal.

Description

Includes bibliographical references (pages 44-53)

Format

application/pdf

Number of Pages

66

Publisher

South Dakota State University

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Rights Statement

In Copyright