Nitrite oxidizing bacteria suppression based on in-situ free nitrous acid production at mainstream conditions

Alba Pedrouso, Ángeles Val del Río, Nicolás Morales, Jose R. Vázquez-Padín, Jose L. Campos, Ramón Méndez, Anuska Mosquera-Corral

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

The application of autotrophic nitrogen removal processes in the main line of wastewater treatment plants will contribute to achieve its self-energy-sufficiency. However, the effective suppression of nitrite oxidizing bacteria (NOB) activity at the conditions of low temperature and low ammonium concentration (mainstream conditions) was identified as one of the main bottlenecks. In this study, stable partial nitritation at 16 °C and 50 mg NH4+-N/L was achieved maintaining inside the reactor free nitrous acid (FNA) concentrations inhibitory for NOB (>0.02 mg HNO2-N/L), without dissolved oxygen concentration control. The FNA inhibitory concentration was generated by the partial nitritation process, and its stimulation was studied with two different inhibitors: sodium azide and nitrite. The microbiological analysis revealed that, throughout the operational period with inhibitory FNA levels, the NOB populations (dominated by Nitrospira) were effectively washed out from the reactor. This is an advantage that allowed maintaining a good stability of the process, even when the FNA concentration was not enough to inhibit the NOB, taking about 40 days to develop significant activity. The observed delay on the NOB development is expected to enable the establishment of corrective actions to avoid the partial nitritation destabilization. The use of the FNA to achieve a stable partial nitritation process is recommended to profit from the natural pH decrease associated to the nitritation process and from its favoured accumulation at low temperatures as those from the mainstream. In this research study an analysis about the influence of ammonium and alkalinity concentrations was also performed to know in which scenarios the FNA inhibitory concentration can be achieved.

Original languageEnglish
Pages (from-to)55-62
Number of pages8
JournalSeparation and Purification Technology
Volume186
DOIs
StatePublished - 2017
Externally publishedYes

Keywords

  • Ammonium oxidizing bacteria
  • Flocculent sludge
  • Free nitrous acid
  • Mainstream
  • Nitrite oxidizing bacteria
  • Partial nitritation

Fingerprint

Dive into the research topics of 'Nitrite oxidizing bacteria suppression based on in-situ free nitrous acid production at mainstream conditions'. Together they form a unique fingerprint.

Cite this