The circular public toilet - A new approach to value our waste

AI Quick Summary

Following a growing interest in resource-efficient infrastructure, this project addresses two key issues: the inefficiency of current wastewater systems and the increasing demand for public toilets. We aim to rethink traditional wastewater management by developing a mobile, accessible toilet cabin that incorporates innovative urban sanitation technologies. Instead of wasting water for flushing, our system produces water and valuable fertilizer from urine on-site, eliminating the need for sewer connections. What fundamental problem are you addressing? What systemic problem hypotheses are the starting point for your mainstreaming approach?The current wastewater treatment practice leads to inefficient use of resources (water, nutrients) and instead allows a consecutive loss of biodiversity through environmental pollution. The causes are incomplete removal of nitrogen from wastewater in treatment plants and the production of greenhouse gases, such as methane and nitrous oxide in the sewers. Down the line microplastics from tyre abrasion and micropollutants like heavy metals from industry enter the wastewater. This increases the complexity of the wastewater and increases the effort to recover the actual resources from the water again. The treatment on site (behind the toilet) with our newly developed “Nutrient Harvester” offers the opportunity to cut of the downstream contamination and focus on the efficient recovery of water and nutrients present in wastewater. A stabilization avoids gas producing biological activity. By recovering water and nutrients in a fertilizer product, local circles can be closed again and the dependence of chemical fertilizer import can be reduced. By combining two problems of modern cities, we want to leverage and mainstream our new approach: Resource recovery and the provision of public toilets. Due to the on-site treatment approach the toilets not only become modern fertilizer production sites, but they also gain flexibility from the old sewer grid. The city of short distances thus benefits from a much larger coverage of public toilets. Especially much-frequented hotspots like parks, are otherwise difficult to serve as no sewer system is possible in to build. The system can even adapt to temporarily fluctuations in use.For us, social innovation means trying to change or redesign everyday habits that are shared by many people in a society (e.g. our usual ways of traveling, living, eating, etc.). Which habits do you want to change or mainstream through which approach?We want to change the way people perceive the waste they usually just leave and flush away in the toilet. Human excrements, especially urine is very rich in nutrients and a valuable source, available every where people live. Nowadays we have however forgotten about this, although the reuse of human output was common practice for long before our time. We want to bring back this knowledge by establishing new urban mining facilities (public toilets with resource recovery), that by their design inspire people to change the way they think about this topic.Who will benefit from mainstreaming and how?People moving and thriving in the public space will be the main beneficiaries of the our approach, as they can satisfy basic needs like going to the toilet. They will however also constantly learn and deepen their understanding of lived circularity. Cities and municipalities in their role as educators and pioneers in environmental education are the benefitting counterparts on the other side. Besides being enabled to provide more public toilets, they can further benefit from synergies within different departments, e.g. the produced fertilizer can directly be used in the greenery department. With one city creating a blueprint, this concept can easily be copied and implemented in other similar contexts. Which people/organizations are in your team and what is their role?Our team consists of researchers, environmental and mechanical engineers, architects, and designers. While the Nutrient Harvester resource recovery technology was developed at the Swiss Institute for aquatic Science and Technology Eawag, it will be implemented by its spin-off company Ogmo. With the help of FUS we can realize a pilot test in Q3/Q4 2025, where the Nutrient Harvester will be the core technology of a novel type of autonomous public toilet in Zurich. The communication design will be taken over by Cerca, a design office specialized in purpose projects. The construction and hosting of the public toilet will be covered by the association Labör, whose objective is, to establish a new hub for low barrier circularity promotion in Zurich-Örlikon. For certain parts of Cerca’s and Labör’s work complementary proposals were already submitted as well.Has the idea (or variants) already been tested? If so, with what findings?The technology of the Nutrient Harvester has be tested in the laboratory with promising results of high recovery levels of the nutrients nitrogen (97%), phosphorus and potassium (both 100%). First studies of a novel public toilet design have been conducted, but the really interesting part will be the interaction of the society with the project in the real world.What would you like to work on during the booster (e.g. test mainstreaming, feasibility study, developing a climate-friendly business model, building a first prototype, etc.)? What do you hope you will have achieved specifically at the end of the booster?During the booster we would like to prototype our idea of a novel type of resource recovering public toilet that actively communicates with its users by its design. Our aim is to developing a mobile, barrier-free toilet cubicle that integrates the pioneering technology of the Nutrient Harvester for urban sanitation. Instead of wasting water for flushing and transport, water is (re-) produced and a valuable fertilizer is made on site - from urine. As the wastewater streams are treated directly on site, no connection to the sewerage system is necessary. The entire pilot project shall not only be operational, but also function as a living information lab, showcasing the on-site resource recovery technology, but also the application potential of the reproduced water and fertilizer for local greenery.What do you hope for from the booster (e.g. search for specific partners (if so, who?), connection with the government/public sector, etc.)?One aim for the booster is to enable our prototype tests with the necessary funding of materials and development costs. Beside that we are specifically searching for more implementation partners like municipalities or manufacturers of public toilets to improve our network and be able to scale-up our solution in the future. Further connections to active entities in the public sector would be of interest to include our prototype tests into an embedding awareness campaign. Who do you need as an expert to further advance the idea?We would benefit from experts with knowledge in design for manufacturing and assembly and industrial manufacturing to enable the scale up of our core technology and spread the idea of resource-oriented sanitation.How much budget do you require from us for what (maximum CHF 22,500 including expert vouchers)? In total we ask a funding amount of 22’000 CHF.This breaks down into the following: Development costs including design optimization of the last laboratory treatment unit and the coordination with manufacturers sum up to 2’500 CHF. 10’000 CHF are necessary to cover the material costs of the Nutrient Harvester on-site wastewater treatment pilot reactor. To build the toilet cabin we will need 4’300 CHF. 1’500 CHF are needed for operational costs such as exchanging additives and collection of nutrient concentrate and service. Monitoring the system during the field operation will cost 3’700 CHF.

Project Idea Metadata

• Project Idea Name: The circular public toilet - A new approach to value our waste
• Date: 5/25/2025 8:52:18 PM
• Administrators:

Project Idea Description

What fundamental problem are you addressing? What systemic problem hypotheses are the starting point for your mainstreaming approach?

The current wastewater treatment practice leads to inefficient use of resources (water, nutrients) and instead allows a consecutive loss of biodiversity through environmental pollution. The causes are incomplete removal of nitrogen from wastewater in treatment plants and the production of greenhouse gases, such as methane and nitrous oxide in the sewers. Down the line microplastics from tyre abrasion and micropollutants like heavy metals from industry enter the wastewater. This increases the complexity of the wastewater and increases the effort to recover the actual resources from the water again.

The treatment on site (behind the toilet) with our newly developed “Nutrient Harvester” offers the opportunity to cut of the downstream contamination and focus on the efficient recovery of water and nutrients present in wastewater. A stabilization avoids gas producing biological activity. By recovering water and nutrients in a fertilizer product, local circles can be closed again and the dependence of chemical fertilizer import can be reduced.

By combining two problems of modern cities, we want to leverage and mainstream our new approach: Resource recovery and the provision of public toilets. Due to the on-site treatment approach the toilets not only become modern fertilizer production sites, but they also gain flexibility from the old sewer grid. The city of short distances thus benefits from a much larger coverage of public toilets. Especially much-frequented hotspots like parks, are otherwise difficult to serve as no sewer system is possible in to build. The system can even adapt to temporarily fluctuations in use.

For us, social innovation means trying to change or redesign everyday habits that are shared by many people in a society (e.g. our usual ways of traveling, living, eating, etc.).

Which habits do you want to change or mainstream through which approach?

We want to change the way people perceive the waste they usually just leave and flush away in the toilet. Human excrements, especially urine is very rich in nutrients and a valuable source, available every where people live. Nowadays we have however forgotten about this, although the reuse of human output was common practice for long before our time. We want to bring back this knowledge by establishing new urban mining facilities (public toilets with resource recovery), that by their design inspire people to change the way they think about this topic.

Who will benefit from mainstreaming and how?

People moving and thriving in the public space will be the main beneficiaries of the our approach, as they can satisfy basic needs like going to the toilet. They will however also constantly learn and deepen their understanding of lived circularity. Cities and municipalities in their role as educators and pioneers in environmental education are the benefitting counterparts on the other side. Besides being enabled to provide more public toilets, they can further benefit from synergies within different departments, e.g. the produced fertilizer can directly be used in the greenery department. With one city creating a blueprint, this concept can easily be copied and implemented in other similar contexts.

Which people/organizations are in your team and what is their role?

Our team consists of researchers, environmental and mechanical engineers, architects, and designers. While the Nutrient Harvester resource recovery technology was developed at the Swiss Institute for aquatic Science and Technology Eawag, it will be implemented by its spin-off company Ogmo. With the help of FUS we can realize a pilot test in Q3/Q4 2025, where the Nutrient Harvester will be the core technology of a novel type of autonomous public toilet in Zurich. The communication design will be taken over by Cerca, a design office specialized in purpose projects. The construction and hosting of the public toilet will be covered by the association Labör, whose objective is, to establish a new hub for low barrier circularity promotion in Zurich-Örlikon. For certain parts of Cerca’s and Labör’s work complementary proposals were already submitted as well.

Has the idea (or variants) already been tested? If so, with what findings?

The technology of the Nutrient Harvester has be tested in the laboratory with promising results of high recovery levels of the nutrients nitrogen (97%), phosphorus and potassium (both 100%). First studies of a novel public toilet design have been conducted, but the really interesting part will be the interaction of the society with the project in the real world.

What would you like to work on during the booster (e.g. test mainstreaming, feasibility study, developing a climate-friendly business model, building a first prototype, etc.)? What do you hope you will have achieved specifically at the end of the booster?

During the booster we would like to prototype our idea of a novel type of resource recovering public toilet that actively communicates with its users by its design. Our aim is to developing a mobile, barrier-free toilet cubicle that integrates the pioneering technology of the Nutrient Harvester for urban sanitation. Instead of wasting water for flushing and transport, water is (re-) produced and a valuable fertilizer is made on site - from urine. As the wastewater streams are treated directly on site, no connection to the sewerage system is necessary. The entire pilot project shall not only be operational, but also function as a living information lab, showcasing the on-site resource recovery technology, but also the application potential of the reproduced water and fertilizer for local greenery.

What do you hope for from the booster (e.g. search for specific partners (if so, who?), connection with the government/public sector, etc.)?

One aim for the booster is to enable our prototype tests with the necessary funding of materials and development costs. Beside that we are specifically searching for more implementation partners like municipalities or manufacturers of public toilets to improve our network and be able to scale-up our solution in the future. Further connections to active entities in the public sector would be of interest to include our prototype tests into an embedding awareness campaign.

Who do you need as an expert to further advance the idea?

We would benefit from experts with knowledge in design for manufacturing and assembly and industrial manufacturing to enable the scale up of our core technology and spread the idea of resource-oriented sanitation.

How much budget do you require from us for what (maximum CHF 22,500 including expert vouchers)?

In total we ask a funding amount of 22’000 CHF.

This breaks down into the following:

Development costs including design optimization of the last laboratory treatment unit and the coordination with manufacturers sum up to 2’500 CHF. 10’000 CHF are necessary to cover the material costs of the Nutrient Harvester on-site wastewater treatment pilot reactor. To build the toilet cabin we will need 4’300 CHF. 1’500 CHF are needed for operational costs such as exchanging additives and collection of nutrient concentrate and service. Monitoring the system during the field operation will cost 3’700 CHF.

Following a growing interest in resource-efficient infrastructure, this project addresses two key issues: the inefficiency of current wastewater systems and the increasing demand for public toilets. We aim to rethink traditional wastewater management by developing a mobile, accessible toilet cabin that incorporates innovative urban sanitation technologies. Instead of wasting water for flushing, our system produces water and valuable fertilizer from urine on-site, eliminating the need for sewer connections.