Staff

Valentin Faust

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About Me

I am an ETH environmental engineer and former PhD student in the Process Engineering department of Eawag under the supervision of Prof. Kai Udert. In my PhD project, I focused on optimizing nutrient recovery from urine for Space Missions. I am interested in modelling, decentralized waste water treatment, source separation, nutrient recovery and closed-loop systems.

Projects

Is a space research program, aiming to develop a bioregenerative life support system for long-term space missions and space habitations for example on Mars.

PhD Project

The project is part of MELiSSA (Micro Ecological Life Support System Alternative), a project of the European Space Agency for the development of a biological life support system (closed-loop) for long-term space missions (ex. Mars mission). In the MELiSSA loop, urine is the main target for nitrogen recovery. However, urine has to be converted into a biologically stable solution, before it can be used as a fertilizer.

In this project, we aim to increase the stability of the urine treatment process in general and the nitrification in particular to allow the use for Space missions. A urine treatment chain for space application is proposed based on Eawag’s technology and MELiSSA’s experience. The treatment chain consists of five treatment units: (1) In the storage tank the urea, which is the main Nitrogen source, is hydrolysed. (2) The removal of the organics takes place in a membrane aerated biofilm reactor (MABR). (3) In a second MABR the urine is nitrified. No base is added, therefore only half of the ammonia is nitrified due to the limited amount of alkalinity. (4) Micropollutants are adsorbed in a granular active carbon column. (5) In the final step, the urine is disinfected and can be used for the plant compartment of the MELiSSA loop.

The alkalinity-limited urine nitrification is of advantage compart to full nitrification, because no base has to be added and less oxygen is consumed, but it makes the process also susceptible for process failures: Nitrite accumulation resulting in the washout of nitrite oxidizing bacteria (NOB), complete cessation of nitrification at high pH and low influent rate resulting in a low pH and the growth of acid-tolerant ammonium oxidizing bacteria (AOB) have been observed in the past. For space application, a robust, controlled and reliable operation as well as high level of predictability is required. Therefore the main goal of this thesis is to increase the process stability of alkalinity-limited urine nitrification. In the first work package the nitrification process is modelled to predict the process failures qualitatively. With the model, no-go regions are anticipated, where the complete cessation of nitrification and the growth of acid-tolerant AOB are very likely. In order to avoid irreversible nitrite accumulation two different approaches are tested: In the second work package stable nitrification should be achieved with model based operating strategies optimization. In the third work package the accumulation of nitrite should be prevented by introducing an electrochemical nitrite oxidation unit to remove excess nitrate turning the positive feedback loop of nitrite concentration into a negative feedback loop. The more promising approach or a combination of both should be applied to the pilot-scale reactor.

Curriculum Vitae

2024 - Researcher at University of Applied Science in Rapperswil-Jona (OST) in the field of applied chemistry
2023 Post-Doc at Eawag in the department of process engineering.
2018 - 2023

PhD student at ETH and Eawag in the department of process engineering. Supervised by Prof. Kai Udert

2016 - 2017 Research Assistant at Eawag working for the VUNA and AUTARKY project
2010 - 2016 Bachelor and Master of Science in Environmental Engineering at ETH Zurich. Majors in urban water management and water resource management. Master's thesis at Polytechnique Montreal

Publications

Faust, V.; Gruber, W.; Ganigué, R.; Vlaeminck, S. E.; Udert, K. M. (2022) Nitrous oxide emissions and carbon footprint of decentralized urine fertilizer production by nitrification and distillation, ACS ES&T Engineering, 2(9), 1745-1755, doi:10.1021/acsestengg.2c00082, Institutional Repository
Faust, V.; van Alen, T. A.; Op den Camp, H. J. M.; Vlaeminck, S. E.; Ganigué, R.; Boon, N.; Udert, K. M. (2022) Ammonia oxidation by novel "Candidatus Nitrosacidococcus urinae" is sensitive to process disturbances at low pH and to iron limitation at neutral pH, Water Research X, 17, 100157 (11 pp.), doi:10.1016/j.wroa.2022.100157, Institutional Repository
Faust, V.; Vlaeminck, S. E.; Ganigué, R.; Udert, K. M. (2024) Influence of pH on urine nitrification: community shifts of ammonia-oxidizing bacteria and inhibition of nitrite-oxidizing bacteria, ACS ES&T Engineering, 4(2), 342-353, doi:10.1021/acsestengg.3c00320, Institutional Repository
Faust, V.; Boon, N.; Ganigué, R.; Vlaeminck, S. E.; Udert, K. M. (2023) Optimizing control strategies for urine nitrification: narrow pH control band enhances process stability and reduces nitrous oxide emissions, Frontiers in Environmental Science, 11, 1275152 (14 pp.), doi:10.3389/fenvs.2023.1275152, Institutional Repository
Faust, V. (2023) Effects of pH on urine nitrification: from microbial selection to process performance, 250 p, doi:10.3929/ethz-b-000648527, Institutional Repository

This member of staff no longer works at Eawag. Please contact info@eawag.ch for further information.

Focalpoints

  • Decentralized wastewater treatment and source separation
  • Nutrient recovery
  • Closed-loop system
  • Modelling
  • Optimization and process control