This study aimed to understand the effect of different dissolved oxygen (DO) concentrations on the abundance and performance of nitrifying bacteria in full-scale wastewater treatment bioreactors, particularly during the winter when nitrifying bacterial activity is often negligible. Biomass samples were collected from three parallel full-scale bioreactors with low DO concentrations (<1.3 mg/ L) and from two full-scale bioreactors with higher DO concentrations (~4.0 and ~2.3 mg/ L). The relative abundance of nitrifying bacteria was determined by sequencing of PCR-amplified 16S rRNA gene fragments. In the three bioreactors with low DO concentrations, effluent ammonia concentrations sharply increased with a decline in temperature below approximately 17 °C, while the bioreactors with high DO concentrations showed stable nitrification regardless of temperature. Even with the decline in nitrification during the winter in the three low DO bioreactors, the relative abundance of ammonia oxidizing bacteria (mostly Nitrosomonas spp.) was curiously maintained. The relative abundance of nitrite oxidizing bacteria was similarly maintained, although there were substantial seasonal fluctuations in the relative abundance values of Nitrospira spp. versus Nitrotoga spp. This research suggests that nitrification activity can be controlled during the winter via DO to produce better effluent quality with high DO concentrations or to reduce aeration costs with a concomitant decline in nitrification activity.
Bibliographical noteFunding Information:
This work was funded by the Metropolitan Council Environmental Services. We thank the analytical lab service division, especially Mallory Vanous, from the Metropolitan Council Environmental Services for collecting samples and for performing some of the experimental analyses described herein.
This work was funded by the Metropolitan Council Environmental Services . We thank the analytical lab service division, especially Mallory Vanous, from the Metropolitan Council Environmental Services for collecting samples and for performing some of the experimental analyses described herein.
© 2021 Elsevier B.V.
- Cold weather
- Dissolved oxygen concentrations
- Municipal wastewater treatment
- Nitrosomonas spp.
- Nitrospira spp. Nitrotoga spp.
- RNA, Ribosomal, 16S/genetics
- Water Purification
PubMed: MeSH publication types
- Journal Article