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Pedrouso, A., Correa-Galeote, D., Maza-Marquez, P., Juarez-Jimenez, B., Gonzalez-Lopez, J., Rodelas, B., et al. (2021). Understanding the microbial trends in a nitritation reactor fed with primary settled municipal wastewater. Sep. Purif. Technol., 256, 117828.
Abstract: Partial nitritation was pointed out as the key step to implement the autotrophic nitrogen removal processes at low temperature. This study investigated the initiation and maintenance of a nitritation process with simultaneous COD removal in a sequencing batch reactor (SBR) run at 15 degrees C and fed with primary settled urban wastewater characterized by 42 +/- 10 mg TOC/L and 45 +/- 4 mg NH4+-N/L. A nitrite accumulation ratio of nearly 100% was observed and the long-term (354 days) process stability was successfully maintained despite the municipal wastewater composition fluctuations. The absence of nitrite oxidizing bacteria (NOB) activity was attributed to the free nitrous acid (FNA) in-situ accumulated at high levels (0.02-0.20 mg HNO2-N/L). Despite nitrate production was not observed, the quantification of bacterial groups indicated that NOB were present in the SBR sludge throughout the entire operational period. Ammonium oxidizing bacteria (AOB) abundance and community structure were significantly influenced by the organic matter present in the feeding. Average organic matter removal efficiencies of 80% were obtained without observing any detrimental effect over the nitritation process performance, due to the functional redundancy within both the chemoheterotrophic and AOB communities.
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Pedrouso, A., del Rio, A. V., Morales, N., Vazquez-Padin, J. R., Campos, J. L., & Mosquera-Corral, A. (2021). Mainstream anammox reactor performance treating municipal wastewater and batch study of temperature, pH and organic matter concentration cross-effects. Process Saf. Environ. Protect., 145, 195–202.
Abstract: The anammox process is an energy efficient promising alternative to biologically remove the nitrogen. Thus, a 5-L anammox granular reactor was inoculated with sludge coming from a sidestream partial nitritation and anammox reactor (>200 mg TN/L and 30 degrees C) and it was directly subjected to 15 +/- 1 degrees C treating mimicked municipal wastewater (50 mg TN/L). Results indicated that an acclimation period (commonly used) to progressive reach the mainstream conditions is not needed, shortening the start-up periods. The long-term anammox process stability was proved to treat synthetic wastewater with decreasing alkalinities and nitritified primary settled municipal wastewater. The low pH values (6.2 +/- 0.1) of the municipal wastewater fed did not affect the process stability. Residual organic matter concentrations augmented the nitrogen removal efficiency from 80 % (with the synthetic medium) to 92 % achieving effluent concentrations below 10 mg TN/L. Finally, the effect of pH (6-8), temperature (15-30 degrees C) and organic matter concentration (0-75 mg TOC/L) over the specific anammox activity (SA(Amx)) was evaluated at short-term. pH and temperature and their interactions exerted significant influence on the SAAmx value while the TOC concentrations itself did not significantly change the SA(AMX). (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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