Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering


The Indian Health Service and the Crow Creek Sioux Tribe are concerned that the new surface water treatment plants along the Missouri River will not be able to meet the United States Environmental Protection Agency's (USEPA) new Surface Water Treatment Rule Regulations Stage 1 for Disinfectants/Disinfection Byproducts (D/DBPs). This new rule is expected to become effective for small plants serving populations of less than 10,000 people by January 2004 (US EPA 1998a). The objective of this pilot study was to look at water treatment plant process enhancements for removal of disinfection byproduct precursors (total organic carbon) by evaluating the recently installed microfiltration plant at Fort Thompson, South Dakota. The Indian Health Service acquired and installed, in parallel to the existing U.S. Filter (Memcor) 48-module microfiltration plant, a three-module pilot plant provided by Memcor. The pilot plant was used to evaluate the enhancement potential of adding aluminum chlorohydrate (ACH) as a coagulant aid ahead of the filter system at varying dosages. ACH was used in this pilot study because it is not a carbon based coagulant and causes negligible filter media fouling and/or deterioration. Total organic carbon (TOC) remaining in the filtered water reacts with chlorine in the disinfection process at the water treatment plant forming disinfection byproducts (DBPs). This study suggested that ACH could be used as a coagulant aid ahead of the filter media to remove a portion of the TOC with the filter media. There would then be less TOC to react with the chlorine in the disinfection process. The result of this pilot study reflected TOC reduction was achieved during filtration thus reducing the amount of TOC reacting with chlorine disinfection at the water treatment plant and in the distribution system. This reduced the amount of DBPs measured as trihalomethane concentrations (THMs). This study showed mixed results for the removal of haloacetic acid concentrations (HAA5s) produced after the disinfection process. THMs and HAA5s are to be regulated by the USEP A for small systems like the Fort Thompson water system. This pilot study also evaluated the effects of DBP production at the end consumer in the Fort Thompson water system utilizing a Simulated Distribution System (SDS) test (USEPA, November 1997). The results of the SDS testing showed that without process enhancements of the existing system, the production of THMs during warmer summer months exceeded the new anticipated DBP rules. The reduction of TOC using Sumalchlor 50 % ahead of the filter media correlated well with the reduction of THMs at the end consumer on the system. HAA5 production was inconclusive throughout the study period because the test results were below detection limits.

Library of Congress Subject Headings

Water -- Purification -- Filtration Water -- Purification -- Coagulation Water -- Purification -- Disinfection Water treatment plants -- South Dakota -- Fort Thompson



Number of Pages



South Dakota State University