Ammonia-oxidizing bacteria (AOB) are very sensitive to environmental conditions and wastewater treatment plant operational parameters. One of the most important factors affecting their activity is pH. Its effect is associated with: NH3/NH4+ and HNO2/NO2− chemical equilibriums and biological reaction rates. The aim of this study was to quantify and model the effect of pH and free nitrous acid (FNA) concentration on the activity of AOB present in a lab-scale partial nitritation reactor. For this purpose, two sets of batch experiments were carried out using biomass from this reactor. Fluorescent in situ hybridization analysis showed that Nitrosomona eutropha and Nitrosomona europaea species were dominant in the partial nitritation reactor (>94%). The experimental results showed that FNA inhibits the AOB activity. This inhibition was properly modelled by the non-competitive inhibition function and the half inhibition constant value was determined as 1.32 mg HNO2-N L−1. The optimal pH for these AOB was found to be in the range 7.4–7.8. The pH inhibitory effect was stronger at high pH values than at low pH values. Therefore, an asymmetric inhibition function was proposed to represent the pH effect on these bacteria. A combination of two sigmoidal functions was able to reproduce the experimental results obtained.
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Research Article|
June 01 2013
Effect of pH and HNO2 concentration on the activity of ammonia-oxidizing bacteria in a partial nitritation reactor
J. Claros;
J. Claros
1Institut Universitari d'Investigació d'Enginyeria de l'Aigua i Medi Ambient, IIAMA, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain
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E. Jiménez;
2Departament d'Enginyeria Química, Escola Tècnica Superior d'Enginyeria, Universitat de València, Avinguda de la Universitat s/n, Burjassot, 46100 Valencia, Spain
E-mail: Emerita.Jimenez@uv.es
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D. Aguado;
D. Aguado
1Institut Universitari d'Investigació d'Enginyeria de l'Aigua i Medi Ambient, IIAMA, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain
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J. Ferrer;
J. Ferrer
1Institut Universitari d'Investigació d'Enginyeria de l'Aigua i Medi Ambient, IIAMA, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain
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A. Seco;
A. Seco
2Departament d'Enginyeria Química, Escola Tècnica Superior d'Enginyeria, Universitat de València, Avinguda de la Universitat s/n, Burjassot, 46100 Valencia, Spain
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J. Serralta
J. Serralta
1Institut Universitari d'Investigació d'Enginyeria de l'Aigua i Medi Ambient, IIAMA, Universitat Politècnica de València, Camí de Vera s/n, 46022 Valencia, Spain
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Water Sci Technol (2013) 67 (11): 2587–2594.
Article history
Received:
November 20 2012
Accepted:
January 28 2013
Citation
J. Claros, E. Jiménez, D. Aguado, J. Ferrer, A. Seco, J. Serralta; Effect of pH and HNO2 concentration on the activity of ammonia-oxidizing bacteria in a partial nitritation reactor. Water Sci Technol 1 June 2013; 67 (11): 2587–2594. doi: https://doi.org/10.2166/wst.2013.132
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