Circular soap as an inclusive economic project

In times of corona, we wash our hands more than ever, resulting in a lot of hard soap scraps. Even in hotels and B&Bs, single-use hard soaps automatically end up in the trash. Being able to revalorise those waste streams into valuable products is key for a more sustainable future. 

With the RESOAP project, UC Leuven wanted to develop a circular soap from leftover hard soap with the addition of other food waste streams from the hotel sector, such as coffee grounds as a scrub and orange zest as a fragrance. 

The closure of hotels due to the corona crisis forced us to collect hard soap scraps through strategically placed boxes in Leuven. As there were concerns about the hygiene of those soap scraps, we conducted some tests to ensure that the soaps were safe for use. 

Furthermore, we made a manual on how to process soap scraps into circular soap. This was tested participatively together with vulnerable citizens via several workshops in Leuven's neighbourhood workplaces. Thus, we launched an inclusive circular economy project in Leuven and citizens were sensitised and trained in the basic principles of circular economy.


  1. Thanks to surveys of hotels, B&Bs and the general public, we gained insight into the hygiene products used before and during the corona crisis, the valuable waste streams in the hotel sector and the willingness to use circular soap. 
  2. We elaborated a ready-to-use manual with a roadmap for processing hard soap scraps into circular soap. We also succeeded in co-processing used frying oil. 
  3. We responded to consumer concerns and tested the soap for the presence of micro-organisms. This allowed us to guarantee that both the used soap scraps and the circular soap are pure and hygienic and thus safe for use. 
  4. We organised workshops with vulnerable citizens in community workplaces to test out the circular soap manual. Meanwhile, the workshop is already in the regular offer of a care institution, a neighbourhood operation and the UCLL Engineering and Science Academy.


  1. From our surveys and feedback from workshop participants, there were concerns about the purity of circular soap (especially in corona times). It was important to respond to this and test the soap for microorganisms to reassure consumers. 
  2. The soap scraps collected through public boxes have a different composition (multistream) with unknown ingredients. This makes proper certification to market the product almost impossible. A mono-flow from one hotel is therefore more interesting. 
  3. We notice that consumers are actively concerned with sustainability, and the demand for circular products is increasing. On social media, we received many positive reactions and, in particular, many questions about where circular soap can be bought. 
  4. It was very valuable to involve vulnerable citizens in the workshop. However, we had to adjust the initial objective of training them to conduct the workshop ourselves. After all, many of them carry too heavy a backpack to take on such engagement.
250 kg of hard soap scraps collected
8 workshops
88 workshop participants
149 respondents survey


Circular soap production continues through workshops and studios in various organisations. For example, the therapeutic activity centre of Zorggroep Sint-Kamillus in Bierbeek includes the workshop as an activity in the regular offer to their patients. Community work 't Lampeke vzw is also continuing to organise the workshop. They will donate the circular soap to people who need it or sell it to generate income for the community work. And the UCLL Engineering and Science Academy in Leuven and Limburg will also organise the workshop for primary school children during school holidays. 

In addition, discussions are ongoing with the City of Leuven and Leuven 2030 to include the RESOAP concept in a larger future project, namely an urban ecosystem with collection and processing of residual streams offered back as raw materials via local entrepreneurs. 

Finally, Visit Leuven is also showing interest in offering the circular soaps as gifts and wants to commit to collecting hard soap scraps from hotels and B&Bs.