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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Christopher Schmit


The objective of this study was to further evaluate feasibility of using on-off aeration in the activated sludge basins at the City of Sioux Falls Wastewater Reclamation Facility (SFWRF) to achieve denitrification during winter weather conditions. Previous research performed by Jennifer Nelson (2011) concluded that complete denitrification was achievable utilizing the SFWRF wastewater at 20° C. For this project, a total of six test runs were completed to determine the feasibility of on-off aeration at various aeration scenarios. It was determined that one hour aeration on and three hours aeration off was the most effective time scenario to achieve total nitrogen concentrations below 14 mg/L at 10° C and to conserve alkalinity. The bioreactor was fed with 100% primary clarifier effluent collected from the SFWRF. The alkalinity in the system was shown to be consumed during the nitrification process and was reclaimed during the denitrification cycle. The replenishment of alkalinity kept the system from experiencing large swings in pH. Additionally, denitrification would allow the SFWRF to discontinue the addition of supplemental alkalinity. To be able to better calibrate BioWin® a biological modelling program, detailed waste characterization was performed in order to better calibrate the application of the BioWin® model to the SFWRF that was originally modelled by Nelson (2011). The xv calibrated model will allow the SFWRF to predict effluent constituents of ON-OFF aeration scenarios. The laboratory scale reactor results confirmed that ON-OFF aeration could effectively remove nitrogen in the Sioux Falls Water Reclamation Facility in cold temperatures. The most effective time scenario during cold weather conditions was found to be one hour ON-three hours OFF in the reactor. The lab-scale reactor found that primary clarifier effluent would be required to successfully remove nitrogen from the wastewater. Significant cost savings can be incurred by implementing ON-OFF aeration due to savings in energy costs.

Library of Congress Subject Headings

Sewage disposal plants--South Dakota--Sioux Falls--Management.
Sewage--Purification--Nitrogen removal
Sewage--Purification--Activated sludge process


Includes bibliographical references (pages 76-77)



Number of Pages



South Dakota State University



Rights Statement

In Copyright