Sensor-mediated granular sludge reactor for nitrogen removal and reduced aeration demand using a dilute wastewater.

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A sensor-mediated strategy was applied to a laboratory-scale granular sludge reactor (GSR) to demonstrate that energy-efficient inorganic nitrogen removal is possible with a dilute mainstream wastewater. The GSR was fed a dilute wastewater designed to simulate an A-stage mainstream anaerobic treatment process. DO, pH, and ammonia/nitrate sensors measured water quality as part of a real-time control strategy that resulted in low-energy nitrogen removal. At a low COD (0.2 kg m-3  day-1 ) and ammonia (0.1 kg-N m-3  day-1 ) load, the average degree of ammonia oxidation was 86.2 ± 3.2% and total inorganic nitrogen removal was 56.7 ± 2.9% over the entire reactor operation. Aeration was controlled using a DO setpoint, with and without residual ammonia control. Under both strategies, maintaining a low bulk oxygen level (0.5 mg/L) and alternating aerobic/anoxic cycles resulted in a higher level of nitrite accumulation and supported shortcut inorganic nitrogen removal by suppressing nitrite oxidizing bacteria. Furthermore, coupling a DO setpoint aeration strategy with residual ammonia control resulted in more stable nitritation and improved aeration efficiency. The results show that sensor-mediated controls, especially coupled with a DO setpoint and residual ammonia controls, are beneficial for maintaining stable aerobic granular sludge. PRACTITIONER POINTS: Tight sensor-mediated aeration control is need for better PN/A. Low DO intermittent aeration with minimum ammonium residual results in a stable N removal. Low DO aeration results in a stable NOB suppression. Using sensor-mediated aeration control in a granular sludge reactor reduces aeration cost.





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Bekele, Zerihun A, Jeseth Delgado Vela, Charles B Bott and Nancy G Love (2020). Sensor-mediated granular sludge reactor for nitrogen removal and reduced aeration demand using a dilute wastewater. Water environment research : a research publication of the Water Environment Federation, 92(7). pp. 1006–1016. 10.1002/wer.1296 Retrieved from

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Delgado Vela

Jeseth Delgado Vela

Assistant Professor of Civil and Environmental Engineering

Dr. Jeseth Delgado Vela joined Duke University as an Assistant Professor in August 2023. Her work focuses on leveraging environmental biotechnology to improve urban water infrastructure. She integrates molecular tools and modeling to understand how microbial community interactions and dynamics affect engineered water treatment systems. Dr. Delgado Vela earned a Ph.D. and M.S. in Environmental Engineering and M.S. at the University of Michigan, and a B.S. in Civil Engineering from the University of Texas at Austin. Prior to joining Duke, she was an Assistant Professor in the Department of Civil and Environmental Engineering at Howard University. She was a recipient of the Ford Foundation Dissertation Award (2016), was named an Early Career Research Fellow by the Gulf Research Program (2022), and was awarded an NSF CAREER Award (2022).

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