Date of Award

Spring 2001

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Civil and Environmental Engineering


This project involved the investigation of the dissolved oxygen requirements for nitrification and a means to monitor the nitrifier activity. The nitrifiers were monitored with a respirometer. This equipment was used to determine if the ambient temperatures at the plant had an effect on the nitrification rate. The investigation into finding a way to monitor the nitrifiers continuously was accomplished with the installation of two online analyzers. These analyzers were installed at the South Shore Wastewater Treatment Plant (SSWTP) and their results were compared to laboratory data. The dissolved oxygen requirements for the nitrifiers were investigated with a laboratory experiment, performed on SSWTP mixed liquor using a continuously mixed, dissolved oxygen controlled, batch reactor to monitor ammonia, nitrate and COD removal. The data collected from the online analyzer were also studied to understand the dissolved oxygen trends and the ammonia, nitrate and COD removals in the aeration basins at the plant. Each portion of the investigation provided useful data. The nitrifiers at the plant experienced a lagging increase and decrease with the ambient temperature. In the aeration tank, the nitrifiers tended to remove all ammonia within the first quarter of the plug flow tank, where the dissolved oxygen was low and the substrate was high. In the laboratory, this same phenomenon was encountered, but simultaneous nitrate and ammonia removal occurred at dissolved oxygen concentrations as low as 0.5 mg/L. Finally, of the two online analyzers, the ISCO STIP Process Buoy proved to be the most accurate.



Restricted Access Item

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