Crop failures and the hot summers we have experienced in the recent past have shown that water shortages are also increasingly becoming an issue in Switzerland due to climate change. In most cases, wastewater from households, toilets and industrial facilities still makes its way to sewage treatment plants, where it is cleaned meticulously in various stages. The resulting sludge, which contains both valuable nutrients and toxic substances, also ultimately has to be disposed of in an equally complex manner. This isn’t the case, however, in the ZHAW laundromat based in the MODO (Mobile Ecotechnology Demonstration Object) demo unit: In this prototype, the water is cleaned separately. Following the wash cycle, the water is filtered in an ecological purification process, biologically cleaned and then directly reused for the next washing load. Any water that is lost in the wet clothes removed from the washing machine and during the cleaning process is replenished using rainwater. The electricity required for the washing machine pumps is provided by a photovoltaic system on the roof. Using this concept, it has been possible to develop a closed-loop washing machine that is completely independent of the central water and power supply.

Dry toilet with the separate treatment of urine and faeces

The dry separation toilet integrated in the demo unit also works according to the closed-loop principle. Urine and faeces are collected separately, with the urine going directly into a tank situated under the unit. It can subsequently be processed and used as fertiliser. The faeces are transported to a separate area via a conveyor belt operated using a foot pedal. As the faeces dry very quickly in the air flow, any unpleasant odours are kept within limits. The faeces is later used to produce so-called biochar to improve soil quality. It is this last step, in particular, that is of interest to the ZHAW researchers, who want to use these valuable nutrients as fertilisers in an effective and safe manner. Those who use the toilet wash their hands using purified water from the washing machines. This wastewater is also treated again.

Project in South Africa with further developed prototype

The concept of a completely self-sufficient laundromat is already being developed further as part of the “LaundReCycle” project in South Africa with the objective of creating a marketable solution. “Water shortages are a major issue there. And many people do not have access to a washing machine, in part also due to an insufficient water and power supply,” explains project manager Devi Bühler. “The pilot project in Cape Town aims to provide access to washing facilities, on the one hand, and to promote the sustainable user of water and energy resources, on the other.”

Public to become part of the research project

In order to bring to life the closed-loop principle in ecotechnological research and gain insights into its suitability for everyday use, the Institute of Natural Resource Sciences will launch regular public washing days at the ZHAW Grüental campus in Wädenswil from 7 May (see information box). Interested individuals are invited to bring their laundry to be washed in the demo unit. Visitors can also give the integrated dry toilet a try. Users will thus become part of the research project investigating the used of closed-loop technology.

New app provides insights into research

Together with the self-sufficient laundromat, the new “1001 Kreislauf” app (Android and iOS), which invites you to take a (partly virtual) ecotechnology tour in the gardens of the Grüental campus, is also being launched. Using augmented reality, the free app allows users to gain direct insights into these and other research topics from the field of ecotechnology. With the help of their smartphone, visitors get to see what is going on behind the laboratory doors and gain background information from the researchers involved. And all of this is supplemented by narrative elements about how the research being performed could change the world.