PhD: Understanding the Seasonal Variation of Greenhouse Gas Production in Wastewater Treatment Plants

Overview

Open Positions

Time Span

01 Oct 2026 for 4 years

Application Deadline

01 Oct 2025

Financing

yes

Type of Position

Full PhD

Working Language

English

Required Degree

Master

Areas of study

Geoecology, Bioinformatics, Environmental Science, Sustainability Sciences (Ecological), Environmental Protection Technology, Microbiology, Ecology, Environmental Engineering

Description

Wastewater treatment plants (WWTPs) are estimated to contribute 8 – 11% of the methane and 2.7% of the nitrous oxide global gas emissions. Methane and nitrous oxide are greenhouse gases (GHG) and are 27 and 273 times more potent than CO2, respectively (Intergovernmental Panel On Climate Change (IPCC), 2023). Additionally, nitrous oxide is considered to be the major anthropogenic contributor to the depletion of atmospheric ozone (Gruber, Von Känel, et al., 2021). These GHG are produced in the WWTPs by the action of methanogenic, nitrifying, and denitrifying microorganisms with the latter two being integral parts of the wastewater treatment process. For example, previous studies have shown that a decrease in the number of nitrite-oxidizing bacteria could lead to an accumulation of nitrite in the system (Gruber, Niederdorfer, et al., 2021). Nitrite accumulation coupled with suboptimal aeration rates can induce the denitrification activity of ammonia-oxidizing bacteria, leading to higher production of nitrous oxide (Chen et al., 2018). There is also seasonal and diurnal variations in nitrous oxide emissions which are correlated with the accumulation of nitrite or suboptimal oxygen concentrations in the system, respectively (Daelman et al., 2013, 2015; Gruber, Von Känel, et al., 2021). Seasonal variations in methane emission rates also occur and appear to be positively correlated with seasonal changes in water temperature (Masuda et al., 2015). Understanding how changes in the composition and flow rates of incoming wastewater can affect microbial community dynamics in WWTP is of the utmost importance. This will allow us find potential solutions that could lead to the reduction of GHG emissions from the wastewater treatment process.

References:

Chen, X., Yuan, Z., & Ni, B.-J. (2018). Nitrite accumulation inside sludge flocs significantly influencing nitrous oxide production by ammonium-oxidizing bacteria. Water Research, 143, 99–108. https://doi.org/10.1016/j.watres.2018.06.025

Daelman, M. R. J., Van Voorthuizen, E. M., Van Dongen, L. G. J. M., Volcke, E. I. P., & Van Loosdrecht, M. C. M. (2013). Methane and nitrous oxide emissions from municipal wastewater treatment – results from a long-term study. Water Science and Technology, 67(10), 2350–2355. https://doi.org/10.2166/wst.2013.109

Daelman, M. R. J., van Voorthuizen, E. M., van Dongen, U. G. J. M., Volcke, E. I. P., & van Loosdrecht, M. C. M. (2015). Seasonal and diurnal variability of N2O emissions from a full-scale municipal wastewater treatment plant. Science of The Total Environment, 536, 1–11. https://doi.org/10.1016/j.scitotenv.2015.06.122

Gruber, W., Niederdorfer, R., Ringwald, J., Morgenroth, E., Bürgmann, H., & Joss, A. (2021). Linking seasonal N2O emissions and nitrification failures to microbial dynamics in a SBR wastewater treatment plant. Water Research X, 11, 100098. https://doi.org/10.1016/j.wroa.2021.100098

Gruber, W., Von Känel, L., Vogt, L., Luck, M., Biolley, L., Feller, K., Moosmann, A., Krähenbühl, N., Kipf, M., Loosli, R., Vogel, M., Morgenroth, E., Braun, D., & Joss, A. (2021). Estimation of countrywide N2O emissions from wastewater treatment in Switzerland using long-term monitoring data. Water Research X, 13, 100122. https://doi.org/10.1016/j.wroa.2021.100122

Intergovernmental Panel On Climate Change (IPCC). (2023). Climate Change 2021 – The Physical Science Basis: Working Group I Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (1st ed.). Cambridge University Press. https://doi.org/10.1017/9781009157896

Masuda, S., Suzuki, S., Sano, I., Li, Y.-Y., & Nishimura, O. (2015). The seasonal variation of emission of greenhouse gases from a full-scale sewage treatment plant. Chemosphere, 140, 167–173. https://doi.org/10.1016/j.chemosphere.2014.09.042