Preservation and reactivation of Candidatus Jettenia asiatica and Anammoxoglobus propionicus using different preservative agents.

Anaerobic ammonium oxidation (anammox) bacteria have peculiar characteristics that make them difficult to cultivate. The conservation of these microorganisms in culture collections or laboratories requires successful preservation and reactivation techniques. Furthermore, studies have shown that successful reactivation may be preservative dependent. Considering this, the present study aimed to evaluate the preservation and reactivation of anammox consortia enriched from swine manure treatment lagoons, by using different preservative agents at different temperatures: KNO3 (at 4 °C), glycerol (-20 °C, -80 °C), and skimmed cow milk (-20 °C, -80 °C, -200 °C). After 4 months, the biomass was thawed (except for KNO3), and the reestablishment of anammox activity was evaluated by stoichiometric coefficients. Microbial community transformation during the reactivation process was also studied by 16S rDNA sequence analysis. The results showed that the anammox biomass preserved with glycerol or skimmed cow milk at -80 °C recovered activity, while the biomass preserved with other methodologies did not reestablish activity during the studied time (90 days). The bacterial community from the biomass with anammox activity was characterized and showed the presence of Candidatus Brocadia anammoxidans, Candidatus Jettenia asiatica, and Candidatus Anammoxoglobus propionicus. Preservation with skimmed cow milk at -80 °C favored the selection of Candidatus Anammoxoglobus propionicus, while preservation with glycerol at -80 °C was successful for Candidatus Jettenia asiatica. The present study was effective on anammox sludge preservation and reactivation using low-cost processes for anammox cultures preservation, which is important for biomass transport and deammonification reactor start up.

High nitrogen removal rate using ANAMMOX process at short hydraulic retention time.

The anaerobic ammonium oxidation (ANAMMOX) is a chemolithoautotrophic process, which converts NH(4)(+) to N(2) using nitrite (NO(2)(-)) as the electron acceptor. This process has very high nitrogen removal rates (NRRs) and is an alternative to classical nitrification/denitrification wastewater treatment. In the present work, a strategy for nitrogen removal using ANAMMOX process was tested evaluating their performance when submitted to high loading rates and very short hydraulic retention times (HRTs). An up-flow ANAMMOX column reactor was inoculated with 30% biomass (v v(-1)) fed from 100 to 200 mg L(-1) of total N (NO(2)(-)-N + NH(4)(+)-N) at 35 °C. After start-up and process stability the maximum NRR in the up-flow anaerobic sludge blanket (UASB) reactor was 18.3 g-N L(-1) d(-1) operated at 0.2 h of HRT. FISH (fluorescence in situ hybridization) analysis and process stoichiometry confirmed that ANAMMOX was the prevalent process for nitrogen removal during the experiments. The results point out that high NRRs can be obtained at very short HRTs using up-flow ANAMMOX column reactor configuration.