Department Process Engineering

Process Engineering

The research focus of the Process Engineering Department (ENG) ranges from current and future wastewater and drinking water treatment problems, as well as water pollution control and resource reuse. Our long-term goal is to develop sustainable concepts of the water and nutrient cycle in residential areas.

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News

In order to close nutrient cycles, many stakeholders must work together

May 5, 2022

Eawag researchers Sabine Hoffmann, Kai Udert and Lisa Deutsch are committed to a sanitation and nutrient transformation. They use an example to explain why a transformation is needed and why collaboration with politicians in particular is a challenge.

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Urine treatment: from trial and error to exciting innovation

May 4, 2022

What has been a purification process in wastewater treatment plants for decades can also be used decentrally or semi-centrally as a recycling process for nutrients. Early separation of "solid and liquid" plays a key role here. It allows for flexible solutions in terms of process technology, especially in the treatment of urine. New studies also show that the processes can be used not only for human urine, but also for that of cows or pigs.

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Success for the practice-oriented PEAK course «Activated carbon»

Geschäftsführer Klaus Alt, Hydro-Ingenieure GmbH, Düsseldorf: «Die GAK-Filtration in Kesselbausweise ist eine kostengünstige und vor allem sehr flexible Lösung zur Umsetzung der Spurenstoffelimination auf ARAn.» Foto: Marc Böhler

On June 22 and 23, the Eawag PEAK course « Activated carbon for the elimination of trace substances – Processes variants with PAC and GAC », in collaboration with the VSA, took place successfully.

The course received a great feedback from the practice, as shown by the high number of 92 participants from engineering offices, plant construction, administration and operators of wastewater treatment plants, who came to the Eawag/Empa Academy for two days to take part in the event.

Successful exchange of experiences and enriching discussions

In addition to the latest knowledge and developments in the field of the elimination of trace substances by adsorption on activated carbon, a larger scope was given to the exchange of experiences on these new treatment steps between operators of WWTPs. A panel discussion showed that there are still questions concerning the representativeness and the informative value of these measurements, especially when it comes to the sampling or monitoring of the treatment performance during rainwater inflow to wastewater treatment plants.

Another exciting subject of discussion was the high CO2 footprint of the use of powdered activated carbon, especially. There was unanimous agreement on the fact that biogenic products should be given priority over fossil activated carbon, when possible. It was also acknowledged that more efforts must be put into producing ideally “SWISS made” coal, both for the use as powdered carbon than granulated carbon.

Author: Marc Böhler

Water Hub: new movie!

Publications

Cross flow frequency determines the physical structure and cohesion of membrane biofilms developed during gravity-driven membrane ultrafiltration of river water: implication for hydraulic resistance

We evaluated how intermittent shear influences the physical structure, material properties and hydraulic resistance of membrane biofilms developed during gravity-driven ultrafiltration of river water, with the ultimate goal of increasing the filtration performances. Our results indicate intermittent shear helps slowing-down the flux decline but does not help to increase the level of stabilisation of the permeate flux. After several weeks, the biofilms exposed to different shear regimes were indeed characterised by similar hydraulic resistance. But the characteristic time to achieve a stable flux increased from 7 d to 25d when increasing the shear frequency. Also, most of the hydraulic resistance (up to 95%) was governed by the base layer that remained attached after erosion tests. With increasing exposure to shear conditions, the biofilms became more cohesive and more elastic, thus resisting better to cross flow conditions. Overall, our results demonstrate that engineering membrane biofilms with a desired permeability is not feasible using intermittent shear due to significant adaptability of the biofilms to their hydraulic environment.
Derlon, N.; Desmond, P.; Rühs, P. A.; Morgenroth, E. (2022) Cross flow frequency determines the physical structure and cohesion of membrane biofilms developed during gravity-driven membrane ultrafiltration of river water: implication for hydraulic resistance, Journal of Membrane Science, 643, 120079 (10 pp.), doi:10.1016/j.memsci.2021.120079, Institutional Repository

Abluftmessungen in der biologischen Abwasserreinigung

Neue Leistungsanforderungen an Abwasserreinigungsanlagen hinsichtlich Ablaufqualität, Energieeffizienz und Treibhausgasemission werden immer bedeutender. Um dabei Zielkonflikte zu vermeiden, ist bei der Optimierung die genaue Überwachung der Prozesse erforderlich. So ist die Messung von Gaskonzentrationen in der Abluft aus biologischen Reinigungsstufen ein nützliches Werkzeug, um verschiedene Zielsetzungen einer ARA hochaufgelöst und wartungsarm zu überwachen.
Gruber, W.; Joss, A.; von Känel, L.; Biolley, L.; Braun, D.; Morgenroth, E. (2022) Abluftmessungen in der biologischen Abwasserreinigung, Aqua & Gas, 102(1), 24-25, Institutional Repository

Lachgasemissionen aus ARA. Reduktionsmassnahmen zeichnen sich ab

Lachgas (N2O) ist ein starkes Treibhausgas und die wichtigste ozonzerstörende Substanz in der Stratosphäre. Auf Abwasserreinigungsanlagen wird N2O während des biologischen Stickstoffabbaus gebildet, der somit die grösste Treibhausgasquelle während des Reinigungsprozesses darstellt. Reduktionsmassnahmen sind deshalb von grosser Bedeutung und gemäss neuen Erkenntnissen durch eine Optimierung der Nitrifikation und Denitrifikation auch erreichbar.
Gruber, W.; Niederdorfer, R.; Bürgmann, H.; Joss, A.; von Känel, L.; Braun, D.; Mohn, J.; Morgenroth, E. (2022) Lachgasemissionen aus ARA. Reduktionsmassnahmen zeichnen sich ab, Aqua & Gas, 102(1), 14-22, Institutional Repository

Performance and dynamics of active greywater heat recovery in buildings

In the effort to de-carbonize the building stock, heat pumps are increasingly utilized in Switzerland, with 70% of the fast-growing heat pump market using ambient air as heat source. Inexpensive and easy to implement, these heat pumps are, however, less efficient than their ground- or water-source counterparts. In this modeling study, we aim at increasing the efficiency of air-source heat pumps using domestic greywater-contained heat. We assess the performance improvement relative to standard heat pump configurations across various climates, seasons, building envelopes, and domestic hot water consumption patterns. The results show that the annually-averaged coefficient of performance improves by 4.1% on average - ranging from 0.6% to 7.5%. This efficiency gain translates on average to 1.8 kWh/week of compressor electricity savings. Although attractive due to its simplicity, the proposed open-loop configuration - preheating of an external heat source - only leads to moderate performance improvement of air-source heat pumps. Based on these results, we extensively discuss and compare alternative system configurations and identify several fundamental differences in the heat recovery dynamics of each configuration. We show that closed-loop systems - using greywater as direct heat source - show the largest performance improvement potential, although being more expensive and complex to implement.
Hadengue, B.; Morgenroth, E.; Larsen, T. A.; Baldini, L. (2022) Performance and dynamics of active greywater heat recovery in buildings, Applied Energy, 305, 117677 (13 pp.), doi:10.1016/j.apenergy.2021.117677, Institutional Repository
To the library

Research Projects

By recovering nutrients from urine, we develop a sanitation system, which produces a valuable fertiliser

VUNA - Nutrient harvesting in South Africa
We develop reactors for the separate treatment of urine, feces and water directly in the toilet.

Blue Diversion AUTARKY – Sewage Treatment off the Grid
Inadequate access to microbiologically safe drinking water continuously threatens the health and well-being of more than a billion people, primarily in developing countries

GDM Gravity-Driven Membrane technology

Nitrations- / Anammox process

Micro-sieving of municipal wastewater

Aerobic Granular Sludge
Modelling of aerobic granular sludge (AGS) reactors

Eawag Aerobic Granular Sludge (AGS) Model

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