Document Type

Thesis - University Access Only

Award Date

2004

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Delvin E. DeBoer

Abstract

Under the Interim Enhanced Surface Water Treatment Rule (IESWTR), water systems serving at least 10,000 people and using surface water or ground water under the direct influence of surface water must meet strengthened combined filter effluent turbidity performance standards. They must also carry out individual filter effluent turbidity monitoring. The goal of the IESWTR is to assist water systems with minimizing public exposure to waterborne pathogens by improving treatment plant performance. In particular, the rule focuses on the removal and inactivation of Giardia lamblia and Cryptosporidium. A strong correlation exists between the removal of turbidity and the removal of these and other pathogens. Thus, treatment facilities that consistently produce low-turbidity water greatly reduce the chance of an outbreak: caused by waterborne pathogens in the distribution system. The objectives of this study were to identify factors that affect filtered water turbidity levels and evaluate options for eliminating turbidity spikes. This was done using on-line turbidimeters to continuously monitor filter effluent turbidity levels. The Brookings East Water Treatment Plant and the Watertown Lake Water Treatment Plant were the two facilities where monitoring was conducted to identify factors affecting filter performance. The filter-to-waste process at the Sioux Falls Water Purification Plant was evaluated as an option for eliminating turbidity spikes. Several factors were identified that had an effect on filter effluent turbidity. The most significant increases in turbidity resulted when a filter was put into service following backwashing. Other causes of elevated turbidity included changes in flow, relatively higher flow rates, and filter influent turbidity. At the Brookings plant, backwashing one filter resulted in poorer performance of the other. In addition, one filter appeared to out-perform the other, possibly due in part to an uneven flow split. At the Sioux Falls plant, utilizing filter-to-waste eliminated spikes in combined filter effluent turbidity caused by backwashing.

Library of Congress Subject Headings

Water -- Purification -- Filtration -- South Dakota.
Turbidity.

Publisher

South Dakota State University

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Rights Statement

In Copyright