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

Abstract

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.

Sulfide alters microbial functional potential in a methane and nitrogen cycling biofilm reactor

“…The reactor was operated to simulate treatment of an effluent from a mainstream anaerobic process. Synthetic influent (20 L) was prepared as described elsewhere (Bekele et al ., 2020) and in the Supporting Information. The synthetic influent was prepared approximately every 2 days using glassware that was autoclaved prior to influent preparation.…”

Integrated Modeling and Lab-Scale Investigations Demonstrate the Impact of Sulfide on a Membrane Aerated Biofilm Reactor

“…pH was controlled at a set point of 7.4 by sodium bicarbonate addition. Synthetic influent was meant to simulate mainstream anaerobic effluents and has been previously described , and contained 50 mg of NH 4 + -N/L, varying sulfide concentrations, and a target methane concentration at saturation.…”

“…Sulfide- and methane-rich wastewater would also result from anaerobic treatment processes because sulfate reducing bacteria convert the sulfate to sulfide, and there is residual dissolved methane in anaerobic effluents. − For these reasons, there is ongoing research on harnessing sulfide or methane as an electron donor for denitrification (e.g., − ). Several published studies have focused on one-stage nitrogen removal using either methane or sulfide as electron donors, ,− but to our knowledge, no studies have evaluated the application of both methane and sulfide for nitrogen removal in single-stage nitrogen removal reactors that support oxic and anoxic environments. ,, …”

Supervisory control configurations design for nitrogen and phosphorus removal in wastewater treatment plants

“…It showed the great performance to control the pilot WWTP (Baeza, Gabriel, & Lafuente, 1999). A sensor-mediated (coupled with residual ammonia controls and DO set-point) approach is implemented on a granular sludge reactor to remove nutrients in wastewater and showed that maintaining stable aerobic granular sludge will help to improve the performance (Bekele, Delgado Vela, Bott, & Love, 2020). Control options using the TSS controller with a high ratio of food to microbes in the reactor in the BSM2 framework reduced the risk and effect of bulking sludge (Flores-Alsina et al, 2009).…”