Stoichiometric evaluation of partial nitritation, anammox and denitrification processes in a sequencing batch reactor and interpretation of online monitoring parameters.
A laboratory-scale sequencing batch reactor (SBR) performing partial nitritation - anammox and denitrification was used to treat anaerobic digester effluents. The SBR cycle consisted of a short mixing filling phase followed by oxic and anoxic reaction phases. Working at 25 °C, an ammonium conversion efficiency of 96.5%, a total nitrogen removal efficiency of 88.6%, and an organic carbon removal efficiency of 63.5% were obtained at a nitrogen loading rate of 0.15 kg N m-3d-1, and a biodegradable organic carbon to nitrogen ratio of 0.37. The potential contribution of each biological process was evaluated by using a stoichiometric model. The nitritation contribution decreased as the temperature decreased, while the contribution from anammox depended on the wastewater type and soluble carbon to nitrogen ratio. Denitrification improved the total nitrogen removal efficiency, and it was influenced by the biodegradable organic carbon to nitrogen ratio. The characteristic patterns of conductivity, oxidation-reduction potential (ORP) and pH in the SBR cycle were well related to biological processes. Conductivity profiles were found to be directly related to the decreasing profiles of ammonium. Positive ORP values at the end of the anoxic phases were detected for total nitrogen removal efficiency of lower than 85%, and the occurrence of bending points on the ORP curves during the anoxic phases was associated with nitrite depletion by the anammox process.
Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123, Trento, Italy. Electronic address: michela.langone@unitn.it.
Michela
M
Langone
Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123, Trento, Italy. Electronic address: roberta.ferrentino@unitn.it.
Roberta
R
Ferrentino
Agenzia per la Depurazione, Provincia Autonoma di Trento, via Gilli 3, 38121, Trento, Italy. Electronic address: maria.cadonna@provincia.tn.it.
Maria
M
Cadonna
Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123, Trento, Italy. Electronic address: gianni.andreottola@unitn.it.
Gianni
G
Andreottola
D064751:Ammonium Compounds / Q000032:analysis* / Q000302:isolation & purification; D019149:Bioreactors; D058440:Denitrification; D004784:Environmental Monitoring / Q000379:methods; D009573:Nitrites / Q000032:analysis* / Q000302:isolation & purification; D009584:Nitrogen / Q000032:analysis* / Q000302:isolation & purification; D009862:Online Systems; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods
D064751:Ammonium Compounds; D009573:Nitrites; D009584:Nitrogen; D062065:Wastewater; D014874:Water Pollutants, Chemical
Conductivity; Correlation; Cyclic bio-reactor; Nutrient removal; Oxidation-reduction potential; pH