Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Civil Engineering

First Advisor

Dr. Dwayne A. Rollag


The City of Sioux Falls, South Dakota obtains its water supply from the Big Sioux aquifer which is located below and adjacent to the Big Sioux River. An extensive well field consisting of 34 wells has been developed to the north of the city. In addition to the well field, two surface water supply intakes in the Big Sioux River diversion channel are available for use during peak demand times of the year. Because the raw water generally has iron concentrations in the range of 3.0 to 6.0 milligrams per liter (mg/1) and manganese concentrations in the range of 2.0 to 2.6 mg/1, the Sioux Falls treatment process has been designed primarily to remove iron and manganese. The Sioux Falls Water Purification Plant treatment process presently employs prechlorination, lime softening, flocculation, recarbonation, chlorination, fluoridation, and filtration. A detailed description of the treatment process is presented in the "Methods and Materials" section. Based upon plant operations records, the finished water which is delivered to the Sioux Falls general public conforms to the United States Public Health Service (USPHS) recommended standards. Preliminary analyses conducted by the plant staff in 1980 revealed that the Sioux Falls water distribution system TTHM levels ranged from 50 to 115 ug/1 while raw well water samples revealed undetectable TTHM levels. Therefore, it appears that the trihalomethanes were formed as a result of the water treatment process utilized at the Sioux Falls Water Purification Plant. The purpose of this investigation was to determine the feasibility of using ozone prior to chlorine addition for preventing trihalomethane formation, for reducing chlorine demand, and for disinfection. Pilot-scale ozone and filter units were utilized in this investigation to avoid any disruption in the treatment plant operation. The filter media employed during the pilot studies was identical to that utilized at the Sioux Falls Water Purification Plant. Further studies were conducted to determine the effects on trihalomethane formation in the distribution system by altering the point of chlorine addition in the Sioux Falls Water Purification Plant treatment process.

Library of Congress Subject Headings


Water -- Purification -- Ozonization

Water quality

Water treatment plants -- South Dakota

South Dakota State University Theses



Number of Pages



South Dakota State University