TY - JOUR
T1 - Long-term nitrite-oxidizing bacteria suppression in a continuous activated sludge system exposed to frequent changes in pH and oxygen set-points
AU - Antileo, Christian
AU - Jaramillo, Francisco
AU - Candia, Oscar
AU - Osorio, Aahilyn
AU - Muñoz, Carlos
AU - Farías, Jorge
AU - Proal-Nájera, José B.
AU - Zhang, Qiqi
AU - Geissen, Sven Uwe
N1 - Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/9/15
Y1 - 2022/9/15
N2 - Research has proven the adaptation of nitrite-oxidizing bacteria to unfavorable environmental conditions, and this work presents a novel concept to prevent nitrite oxidation during partial nitrification in wastewater. The approach is based on the real-time updating of mathematical models of the process to search for optimal set-points of pH and oxygen concentration in a continuous activated sludge reactor with a high sludge age (20.3 days). A heuristic optimization technique by 13 optimum set-points simultaneously maximized the degree of ammonia oxidation (α) and nitrite accumulation (β), achieving an (α + β) = 190% per day. The activated sludge reactor was conducted for 780 days under three control schemes: open-loop control, fuzzy model supervisory control and phenomenological supervisory control. The phenomenological supervisory control system achieved the best results, simultaneously reaching 95% ammonium oxidation and 90% nitrite accumulation. The Haldane kinetics were analyzed using steady-state concentrations of all nitrogen species, concluding that the simultaneous maximization of α + β led to selecting set-points at the extreme values of the following ranges: pH = 7.5–8.5 and DO = 0.8–1.0 mg O2/L, which enabled the inhibition of one nitrifier species. At the same time, the other one was relieved from inhibition. The 16sRNA assays indicated that the nitrite-oxidizing bacteria presence (genera Nitrobacter and Nitrospira) shifted from 32% to less than 8% after 280 days of continuous operation with optimal pH and oxygen set-points.
AB - Research has proven the adaptation of nitrite-oxidizing bacteria to unfavorable environmental conditions, and this work presents a novel concept to prevent nitrite oxidation during partial nitrification in wastewater. The approach is based on the real-time updating of mathematical models of the process to search for optimal set-points of pH and oxygen concentration in a continuous activated sludge reactor with a high sludge age (20.3 days). A heuristic optimization technique by 13 optimum set-points simultaneously maximized the degree of ammonia oxidation (α) and nitrite accumulation (β), achieving an (α + β) = 190% per day. The activated sludge reactor was conducted for 780 days under three control schemes: open-loop control, fuzzy model supervisory control and phenomenological supervisory control. The phenomenological supervisory control system achieved the best results, simultaneously reaching 95% ammonium oxidation and 90% nitrite accumulation. The Haldane kinetics were analyzed using steady-state concentrations of all nitrogen species, concluding that the simultaneous maximization of α + β led to selecting set-points at the extreme values of the following ranges: pH = 7.5–8.5 and DO = 0.8–1.0 mg O2/L, which enabled the inhibition of one nitrifier species. At the same time, the other one was relieved from inhibition. The 16sRNA assays indicated that the nitrite-oxidizing bacteria presence (genera Nitrobacter and Nitrospira) shifted from 32% to less than 8% after 280 days of continuous operation with optimal pH and oxygen set-points.
KW - Continuous activated sludge reactor
KW - Intermittent kinetic inhibition
KW - Long-term partial nitrification
KW - Supervisory control
UR - http://www.scopus.com/inward/record.url?scp=85132523490&partnerID=8YFLogxK
U2 - 10.1016/j.jenvman.2022.115545
DO - 10.1016/j.jenvman.2022.115545
M3 - Artículo
C2 - 35752006
AN - SCOPUS:85132523490
SN - 0301-4797
VL - 318
JO - Journal of Environmental Management
JF - Journal of Environmental Management
M1 - 115545
ER -