A Preliminary Evaluation of the Effect of Dissolved Oxygen on Nitrification and Other Biological Process Parameters

Abstract

<p>This work examines the relationship between dissolved oxygen level and the nitrification process in municipal wastewaters. Carbon removal, chemical oxygen demand removal and sludge viability were also investigated. Parallel bench scale continuous activated sludge reactors operating at dissolved oxygen levels of approximately 2 mg/l and 8 mg/l were used.</p> <p>The high dissolved oxygen level sludge produced significantly more nitrate nitrogen and exhibited significantly greater nitrification rates overall. The nitrification rate differential increased with temperature. The nitrification rate appeared to be more sensitive to temperature and sludge age at the higher dissolved oxygen level.</p> <p>Significantly greater overall TOC reduction and TOC removal rates were observed at the high dissolved oxygen-level although no one set of experimental conditions exhibited a significant difference at the 99% confidence level. No significant difference in effluent COD quality or removal rate was observed.</p> <p>There was a significant difference at the 95% confidence level in unit ATP levels, indicating that the high dissolved oxygen level sludge may have been more viable.</p>