From inocula to biological reactors: molecular characterization of N-cycle bacterial assemblages in a PANAMMOX process

Nowadays, the combination of the autotrophic nitrification together with heterotrophic denitrification is the most common process for N-removal in the WWTPs. However, when the C:N ratio is low, this two-step process does not properly work and an external C source must be added. The anammox bacteria are the target of this thesis, capable to oxidize ammonium under chemolithotrophic and anaerobic conditions. The main aim of this doctoral thesis is the search and enrichment of the anammox bacteria for a long time period, in order to be used as inocula for an anammox bioreactor. Once identified, several molecular techniques were used to optimize their detection and made it faster, to characterize their bacterial ecological partners and to study the composition of the ammonium-oxidizing bacteria and nitrite-oxidizing bacteria populations, required to obtain a suitable ammonium concentration in the influent of the anammox reactor.