Decentralised resource recovery from wastewater

The economical handling of resources is also becoming increasingly important in Switzerland. As has long been known from waste recycling, resources can also be efficiently recovered from wastewater. Eawag conducts interdisciplinary research into sustainable solutions that benefits both people and the environment.

Resource cycle using the example of a building: wastewater flows are separated at the source and the recovered resources are reused. (Infographic: Daniel Röttele/ infografik.ch) Click on graphic to enlarge
Resource cycle using the example of a building: wastewater flows are separated at the source and the recovered resources are reused. (Infographic: Daniel Röttele/ infografik.ch)
Click on graphic to enlarge


The construction of sewage systems and wastewater treatment plants (WWTPs) for the central treatment of wastewater has enabled decisive progress in the last century for human hygiene and health, but also for the protection of the environment around cities and villages. However, this system consumes large quantities of water and makes it difficult to recover the reusable materials contained in the wastewater. Climate change, the high input of nutrients into the environment, the growing population as well as the massive loss of biodiversity are urging us to rethink the existing system. As hot periods become more frequent and rainfall precipitation shifts, large amounts of water are needed in increasingly populous cities. Valuable substances contained in wastewater, such as phosphorus and nitrogen, become problematic substances when they enter natural waters. At the same time, phosphorus has to be mined under environmentally harmful conditions and imported because it is needed as fertiliser in agriculture.

In addition to the protection of human health and water bodies, the more efficient utilisation of resources from wastewater is therefore an objective in wastewater treatment. One approach is to close the cycles of water, nutrients and energy as locally as possible. New technologies based on the concept of separation at the source allow the decentralised treatment of wastewater on site in the smallest possible space.

News

News

Events

20.01.​2026
Practice-oriented course
Ressourcen-orientierte Sanitärsysteme: Technologien, Chancen und Herausforderungen
9.00 am
Eawag Dübendorf

Background

More detailed information on the topic.
 

Depending on the approach, wastewater can be treated in central treatment plants for entire communities or decentrally in buildings or neighbourhoods.
Wastewater treatment – centralised, decentralised, hybrid
Resources can be recovered more efficiently from wastewater if the various wastewater streams in the toilet are separated.
Resources from wastewater – separation at the source

News

The Global Science Film Festival has nominated the short film «Verhebets? A Resource-Oriented Apéro» by Eawag junior researchers in the category "Best Short Film 2023".

Verhebts? A ressource-oriented Apéro

The connection obligation is a killer argument against the implementation of decentralised and resource-oriented sanitation systems. Besides, there is no implementation knowledge for such systems in Switzerland. Young researchers from the Wings program asked themselves, "Is this really the case"? In their new video project, they dispel myths surrounding resource-based sanitation systems.
 

Knowledge transfer

How we put our knowledge into practice.

 
Water Hub

Development of decentralised water and wastewater management in the NEST building of Eawag and Empa.

 
Vuna

Former Eawag spin-off specialising in the recovery of nutrients from urine.

Publications for practice

2022
Decentralised resource recovery from wastewater
Eawag Newsletter Special
2022
Forschen mit Fäkalien
Comicreportage, Eawag
2022
Blackwater
Factsheet [pdf, 708.6 KB]
2021
Greywater
Factsheet [pdf, 253.3 KB]
2019
Urine Source Separation
Factsheet [pdf, 350.3 KB]
2018
Resource Recovery from Waste
Book, International Water Management Institute
2013
Source Separation and Decentralization for Wastewater Management
Book, IWA Publishing

Experts

Urine separation

Prof. Dr. Kai Udert
  • wastewater separation
  • decentralized technologies
  • nutrients
  • urine separation
  • resource recovery

Greywater treatment

Prof. Dr. Eberhard Morgenroth
  • wastewater
  • decentralized technologies
  • nutrients
  • urban water management
  • urban planning
  • urine separation
Dr. Frederik Hammes
  • biofilms
  • Flow cytometry
  • Legionella
  • Microbiology
  • sensors
Dr. Tim Julian
  • microbes
  • urban sanitation

Blackwater treatment

Dr. Linda Strande
  • urban sanitation
  • climate change
  • resource recovery
  • decentralized systems
  • microbial ecology

Wings

Dr. Sabine Hoffmann
  • sustainable water management
  • stakeholder participation
  • science-policy interface
  • transdisciplinary research

Research projects

We develop reactors for the separate treatment of urine, feces and water directly in the toilet.
Blue Diversion AUTARKY – Sewage Treatment off the Grid
By recovering nutrients from urine, we develop a sanitation system, which produces a valuable fertiliser
VUNA - Nutrient harvesting in South Africa
Communities across the world face water supply challenges due to increasing demand, drought, groundwater depletion and contamination,…
Greywater reuse at Eawag
Is a space research program, aiming to develop a bioregenerative life support system for long-term space missions and space habitations for…
Melissa «Micro Ecological Life Support System Alternative»
We are identifying the challenges of modular infrastructure systems for the Swiss economy and society using the example of urban water…
COMIX: Challenges and Opportunities of Modular water Infrastructures
Resource recovery, market based approaches, and business models, are key to sustainable management.
Resource recovery
An inter- and transdisciplinary strategic research program that strives to develop novel non-gridconnected water and sani- tation systems…
Water and sanitation innovations for non-grid solutions (Wings)

Scientific publications

In-building heat recovery mitigates adverse temperature effects on biological wastewater treatment: a network-scale analysis of thermal-hydraulics in sewers

Heat recovery from wastewater is a robust and straightforward strategy to reduce water-related energy consumption. Its implementation, though, requires a careful assessment of its impacts across the entire wastewater system as adverse effects on the water and resource recovery facility and competition among heat recovery strategies may arise. A model-based assessment of heat recovery from wastewater therefore implies extending the modeling spatial scope, with the aim of enabling thermal-hydraulic simulations from the household tap along its entire flow path down to the wastewater resource recovery facility. With this aim in mind, we propose a new modeling framework interfacing thermal-hydraulic simulations of (i) households, (ii) private lateral connections, and (iii) the main public sewer network. Applying this framework to analyze the fate of wastewater heat budgets in a Swiss catchment, we find that heat losses in lateral connections are large and cannot be overlooked in any thermal-hydraulic analysis, due to the high-temperature, low-flow wastewater characteristics maximizing heat losses to the environment. Further, we find that implementing shower drain heat recovery devices in 50% of the catchment's households lower the wastewater temperature at the recovery facility significantly less – only 0.3 K – than centralized in-sewer heat recovery, due to a significant thermal damping effect induced by lateral connections and secondary sewer lines. In-building technologies are thus less likely to adversely affect biological wastewater treatment processes. The proposed open-source modeling framework can be applied to any other catchment. We thereby hope to enable more efficient heat recovery strategies, maximizing energy harvesting while minimising impacts on biological wastewater treatment.
Hadengue, B.; Joshi, P.; Figueroa, A.; Larsen, T. A.; Blumensaat, F. (2021) In-building heat recovery mitigates adverse temperature effects on biological wastewater treatment: a network-scale analysis of thermal-hydraulics in sewers, Water Research, 204, 117552 (11 pp.), doi:10.1016/j.watres.2021.117552, Institutional Repository

The potential contribution of urine source separation to the SDG agenda - a review of the progress so far and future development options

Sanitation and wastewater management are highly relevant for reaching a number of interconnected sustainable development goals (SDGs), especially SDG 6, the provision of safe drinking water and adequate sanitation for all as well as protection of water resources against pollution, and SDG 14.1, reducing nutrient emissions to the marine environment. Recent evidence increasingly shows that conventional sewer-based wastewater management will not be able to reach these targets. Rather than further optimizing and diffusing this ageing infrastructure paradigm, radical innovations like urine source separation technologies could help to leapfrog towards faster achievement of the SDGs. The technology would simplify on-site sanitation and develop a closed-loop nutrient cycle, thereby allowing for exceptionally high nutrient removal from wastewater and direct reuse in agriculture from the first day of implementation. Radical innovations, however, need decades to materialize. Based on a review of relevant academic and grey literature, we show how the past three decades of development of urine source separation have brought breakthroughs in toilet design and treatment processes, enabling the technology's value chain to reach the brink of maturity. In a short outlook, we discuss how the technology may reach global diffusion over the next decade, with the main remaining challenges relating to the creation of mass-markets for urine-diverting toilets, automation and mass-production of treatment systems, and the legitimation of fertilizer produced from urine in the agricultural sector.
Larsen, T. A.; Gruendl, H.; Binz, C. (2021) The potential contribution of urine source separation to the SDG agenda - a review of the progress so far and future development options, Environmental Science: Water Research and Technology, 7(7), 1161-1176, doi:10.1039/D0EW01064B, Institutional Repository

State of the art of urine treatment technologies: a critical review.

Over the last 15 years, urine treatment technologies have developed from lab studies of a few pioneers to an interesting innovation, attracting attention from a growing number of process engineers. In this broad review, we present literature from more than a decade on biological, physical-chemical and electrochemical urine treatment processes. Like in the first review on urine treatment from 2006, we categorize the technologies according to the following objectives: stabilization, volume reduction, targeted N-recovery, targeted P-recovery, nutrient removal, sanitization, and handling of organic micropollutants. We add energy recovery as a new objective, because extensive work has been done on electrochemical energy harvesting, especially with bio-electrochemical systems. Our review reveals that biological processes are a good choice for urine stabilization. They have the advantage of little demand for chemicals and energy. Due to instabilities, however, they are not suited for bathroom applications and they cannot provide the desired volume reduction on their own. A number of physical-chemical treatment technologies are applicable at bathroom scale and can provide the necessary volume reduction, but only with a steady supply of chemicals and often with high demand for energy and maintenance. Electrochemical processes is a recent, but rapidly growing field, which could give rise to exciting technologies at bathroom scale, although energy production might only be interesting for niche applications. The review includes a qualitative assessment of all unit processes. A quantitative comparison of treatment performance was not the goal of the study and could anyway only be done for complete treatment trains. An important next step in urine technology research and development will be the combination of unit processes to set up and test robust treatment trains. We hope that the present review will help guide these efforts to accelerate the development towards a mature technology with pilot scale and eventually full-scale implementations.
Larsen, T. A.; Riechmann, M. E.; Udert, K. M. (2021) State of the art of urine treatment technologies: a critical review., Water Research X, 13, 100114 (20 pp.), doi:10.1016/j.wroa.2021.100114, Institutional Repository

Making waves: why water reuse frameworks need to co-evolve with emerging small-scale technologies

Novel technologies allow to reuse or recycle water for on-site applications such as toilet flushing, showering, or hand washing at the household- or building-scale. Many of these technologies have now reached technology readiness levels that require for verification and validation testing in the field. Results from such field tests of decentralized water reuse systems have been published over the past few years, and observed performance is often compared to quality targets from water reuse frameworks (WRFs). An inspection of ten recent journal publications reveals that targets from WRFs are often misinterpreted, and the emphasis of these publications is too often on demonstrating successful aspects of the technologies rather than critically evaluating the quality of the produced water. We hypothesize that some of these misinterpretations are due to ambiguous definition of scopes of WRFs (e.g., "unrestricted urban reuse") and unclear applicability for novel recycling systems that treat the water for applications that go beyond the reuse scopes defined in current WRFs. Additional challenges are linked to the verification of WRF quality targets in small-scale and decentralized systems under economic and organizational constraints. Current WRFs are not suitable for all possible reuse cases, and there is need for a critical discussion of quality targets and associated monitoring methods. As the scope of water reuse has expanded greatly over the past years, WRFs need to address new applications and advances in technology, including in monitoring capacities.
Reynaert, E.; Hess, A.; Morgenroth, E. (2021) Making waves: why water reuse frameworks need to co-evolve with emerging small-scale technologies, Water Research X, 11, 100094 (5 pp.), doi:10.1016/j.wroa.2021.100094, Institutional Repository

Emerging solutions to the water challenges of an urbanizing world

The top priorities for urban water sustainability include the provision of safe drinking water, wastewater handling for public health, and protection against flooding. However, rapidly aging infrastructure, population growth, and increasing urbanization call into question current urban water management strategies, especially in the fast-growing urban areas in Asia and Africa. We review innovative approaches in urban water management with the potential to provide locally adapted, resource-efficient alternative solutions. Promising examples include new concepts for stormwater drainage, increased water productivity, distributed or on-site treatment of wastewater, source separation of human waste, and institutional and organizational reforms. We conclude that there is an urgent need for major transdisciplinary efforts in research, policy, and practice to develop alternatives with implications for cities and aquatic ecosystems alike.
Larsen, T. A.; Hoffmann, S.; Lüthi, C.; Truffer, B.; Maurer, M. (2016) Emerging solutions to the water challenges of an urbanizing world, Science, 352(6288), 928-933, doi:10.1126/science.aad8641, Institutional Repository

A research agenda for the future of urban water management: exploring the potential of non-grid, small-grid, and hybrid solutions

Recent developments in high- and middle-income countries have exhibited a shift from conventional urban water systems to alternative solutions that are more diverse in source separation, decentralization, and modularization. These solutions include non-grid, small-grid, and hybrid systems to address such pressing global challenges as climate change, eutrophication, and rapid urbanization. They close loops, recover valuable resources, and adapt quickly to changing boundary conditions such as population size. Moving to such alternative solutions requires both technical and social innovations to co-evolve over time into integrated socio-technical urban water systems. Current implementations of alternative systems in high- and middle-income countries are promising, but they also underline the need for research questions to be addressed from technical, social, and transformative perspectives. Future research should apply a transdisciplinary research approach through socio-technical "lighthouse" projects that apply alternative urban water systems at scale. Such research should leverage experience from lighthouse projects in a range of socio-economic contexts, identify their potentials and limitations from an integrated perspective, and share their successes and failures across the urban water sector.
Hoffmann, S.; Feldmann, U.; Bach, P. M.; Binz, C.; Farrelly, M.; Frantzeskaki, N.; Hiessl, H.; Inauen, J.; Larsen, T. A.; Lienert, J.; Londong, J.; Lüthi, C.; Maurer, M.; Mitchell, C.; Morgenroth, E.; Nelson, K. L.; Scholten, L.; Truffer, B.; Udert, K. M. (2020) A research agenda for the future of urban water management: exploring the potential of non-grid, small-grid, and hybrid solutions, Environmental Science and Technology, 54(9), 5312-5322, doi:10.1021/acs.est.9b05222, Institutional Repository

Cover picture: Daniel Röttele/infografik.ch