Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Civil Engineering

First Advisor

Dwayne A. Rollag


The city of Huron, South Dakota, draws its drinking water supply primarily from the James River, a stream of extremely variable water quality which is difficult to treat. In this research, ozone was applied to the raw water through use of a pilot plant to determine what effects ozonation has on odor and flocculation. Following a preliminary study based on trihalomethane reduction, ozone dosages of 0, 4, 8, 12, 16 and 24 mg/1 were applied to the raw water at a 20-minute contact time. Threshold Odor Tests were performed by an odor panel to obtain qualitative descriptions and quantitative measurements of odor intensity of raw and ozonated water samples. Odor tests were also performed on settled jar-test samples. The flocculation study also utilized jar tests. Constant dosages of chemicals used at the Huron plant were added to both raw and ozonated water samples in the jar-test procedure. The settled samples were analyzed for turbidity which was assumed to be a direct function of flocculation efficiency. In addition to turbidity values, visual observations of flocculation were also noted. Although aeration alone did not improve or reduce the odor, ozone consistently changed the odor of the raw water from one described as “fishy” to one described as “p1easant” or “sweet”. Odor intensity was also substantially reduced in most cases. Because of the characteristic odor change, ozone dosages of 4 or 8 mg/1 are probably adequate for most odor applications at Huron. Due to variability and inconsistency encountered in the flocculation study, a valid conclusion regarding the effectiveness of ozone in reducing turbidity could not be made. However, ozonated raw water, at the higher dosages, produced larger floc particles that formed more quickly and settled more readily than in corresponding samples of untreated water.

Library of Congress Subject Headings

Water -- Purification -- Ozonation
Water -- Purification -- Flocculation
Water -- Purification -- Taste and odor control
Water-supply -- South Dakota -- Huron



Number of Pages



South Dakota State University