Process development studies on the biological utilization of nitrogen in a domestic wastewater treatment system

This research document presents the results of a study of a full- scale advanced wastewater treatment facility which included a suspended growth nitrification reactor and attached growth denitrification reactors. A literature review is made of nitrification and denitrification phenomena and of the design criteria developed for utilizing these phenomena in laboratory and pilot plant studies of nitrogen removal from wastewater. Conclusions reached as a result of this study included the following: 1. The addition of the suspended growth nitrification reactor resulted in almost complete conversion of ammonia nitrogen to nitrates. 2. Attached growth denitrification reactors utilizing either granular or plastic media provide a feasible means of removing nitrate nitrogen from domestic wastewater. 3. Plastic media with higher porosity required less operator attention and gave better denitrification results. Evaluation of the full-scale facility led to recommendations that methanol dose rate should be more carefully controlled and that additional studies be conducted to optimize denitrification, to delineate the role of the filtration phenomenon in removal of suspended solids by the granular media denitrification reactor, and to determine the influence of temperature and influent concentration gradients on each unit process.