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Pilot Plant Demonstration of Stable and Efficient High Rate Biological Nutrient Removal with Low Dissolved Oxygen Conditions
Citation:
Keene, N., S. Reusser, M. Scarborough, A. Grooms, M. Seib, J. Santodomingo, AND D. Noguera. Pilot Plant Demonstration of Stable and Efficient High Rate Biological Nutrient Removal with Low Dissolved Oxygen Conditions. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 121:72-85, (2017). https://doi.org/10.1016/j.watres.2017.05.029
Impact/Purpose:
Although nitrification at low-DO has been well documented, there is lack of information on how reducing aeration affects enhanced biological phosphorus removal (EBPR) processes. To address this knowledge gap, we studied the effect of steady reductions in aeration in a pilot-plant that simulated the University of Cape Town (UCT)-type configuration used at the Nine Springs Wastewater treatment plant (WWTP) (Madison, WI). The target audience is WWTP designers and operators.
Description:
Aeration in biological nutrient removal (BNR) processes accounts for nearly half of the total electricity costs at many wastewater treatment plants. Even though conventional BNR processes are usually operated to have aerated zones with high dissolved oxygen (DO) concentrations, recent research has shown that nitrification can be maintained using very low-DO concentrations (e.g., below 0.2 mg O2/L), and therefore, it may be possible to reduce energy use and costs in BNR facilities by decreasing aeration. However, the effect of reduced aeration on enhanced biological phosphorus removal (EBPR) is not understood. In this study, we investigated, at the pilot-scale level, the effect of using minimal aeration on the performance of an EBPR process. Over a 16-month operational period, we performed stepwise decreases in aeration, reaching an average DO concentration of 0.33 mg O2/L with stable operation and nearly 90% phosphorus removal. Under these low-DO conditions, nitrification efficiency was maintained, and nearly 70% of the nitrogen was denitrified, without the need for internal recycling of high nitrate aeration basin effluent to the anoxic zone. At the lowest DO conditions used, we estimate a 25% reduction in energy use for aeration compared to conventional BNR operation. Our improved understanding of the efficiency of low-DO BNR contributes to the global goal of reducing energy consumption during wastewater treatment operations.
URLs/Downloads:
DOI: Pilot Plant Demonstration of Stable and Efficient High Rate Biological Nutrient Removal with Low Dissolved Oxygen Conditions
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