Growth of Nitrosococcus-Related Ammonia Oxidizing Bacteria Coincides with Extremely Low pH Values in Wastewater with High Ammonia Content

Growth of Nitrosococcus-Related Ammonia Oxidizing Bacteria Coincides with Extremely Low pH Values in Wastewater with High Ammonia Content

Fumasoli, Alexandra (Swiss Federal Institute of Aquatic Science and Technology)
Bürgmann, Helmut (Swiss Federal Institute of Aquatic Science and Technology)
Weissbrodt, D.G. (TU Delft BT/Environmental Biotechnology; Swiss Federal Institute of Aquatic Science and Technology; ETH Zürich; Aalborg University)
Wells, G.N. (Swiss Federal Institute of Aquatic Science and Technology; Northwestern University)
Beck, Karin (Swiss Federal Institute of Aquatic Science and Technology)
Mohn, Joachim (Swiss Federal Laboratories for Materials Science and Technology (Empa))
Morgenroth, Eberhard (Swiss Federal Institute of Aquatic Science and Technology; ETH Zürich)
Udert, Kai M. (Swiss Federal Institute of Aquatic Science and Technology)

2017-06-20

Ammonia oxidation decreases the pH in wastewaters where alkalinity is limited relative to total ammonia. The activity of ammonia oxidizing bacteria (AOB), however, typically decreases with pH and often ceases completely in slightly acidic wastewaters. Nevertheless, nitrification at low pH has been reported in reactors treating human urine, but it has been unclear which organisms are involved. In this study, we followed the population dynamics of ammonia oxidizing organisms and reactor performance in synthetic fully hydrolyzed urine as the pH decreased over time in response to a decrease in the loading rate. Populations of the β-proteobacterial Nitrosomonas europaea lineage were abundant at the initial pH close to 6, but the growth of a possibly novel Nitrosococcus-related AOB genus decreased the pH to the new level of 2.2, challenging the perception that nitrification is inhibited entirely at low pH values, or governed exclusively by β-proteobacterial AOB or archaea. With the pH shift, nitrite oxidizing bacteria were not further detected, but nitrous acid (HNO₂) was still removed through chemical decomposition to nitric oxide (NO) and nitrate. The growth of acid-tolerant γ-proteobacterial AOB should be prevented, by keeping the pH above 5.4, which is a typical pH limit for the N. europaea lineage. Otherwise, the microbial community responsible for high-rate nitrification can be lost, and strong emissions of hazardous volatile nitrogen compounds such as NO are likely.

http://resolver.tudelft.nl/uuid:43179649-5354-41f9-b2da-027d40795544

https://doi.org/10.1021/acs.est.7b00392

0013-936X

Environmental Science & Technology (Washington), 51 (12), 6857-6866

Institutional Repository

journal article

© 2017 Alexandra Fumasoli, Helmut Bürgmann, D.G. Weissbrodt, G.N. Wells, Karin Beck, Joachim Mohn, Eberhard Morgenroth, Kai M. Udert