Sustainability 2022, 14, 14983. https://doi.org/10.3390/su142214983 www.mdpi.com/journal/sustainability Article Fortifying Social Acceptance When Designing Circular Economy Business Models on Biowaste Related Products Tuomo Eskelinen 1, *, Oswald Sydd 1,2 , Miika Kajanus 1 , David Fernández Gutiérrez 3 , Miguel Mitsou 3 , José M. Soriano Disla 3 , Manuel Vals Sevilla 4 and Johan Ib Hansen 5 1 Department for Multi-Disciplinary RDI, Savonia University of Applied Sciences, Microkatu 1, 70201 Kuopio, Finland 2 Department of History and Geography, University of Eastern Finland, 80101 Joensuu, Finland 3 Centro Tecnológico de la Energía y el Medio Ambiente (CETENMA), P.I. Cabezo Beaza, C/Sofía 6-13, 30353 Cartagena, Spain 4 Murcia City Council, 30100 Murcia, Spain 5 Department for Sustainable Development, Kalundborg Municipality, Holbaekvej 141B, 4400 Kalundborg, Denmark * Correspondence: tuomo.eskelinen@savonia.fi; Tel.: +358-447856613 Abstract: (1) Background: VALUEWASTE, a European Commission Horizon 2020 project, is at- tempting to find new and sustainable sources of protein and fertiliser products using biowaste as a resource. Introducing these products to the market is essential to understand the social acceptance, behavioural changes and socioeconomic impacts related to products and value chains. (2) Methods: The applied framework provides insights from market, socioeconomic, and community acceptance points of view. Initially, we designed the context and targets of the study. The acceptance levels were tested in two study regions: the cities of Murcia (Spain) and Kalundborg (Denmark). Secondly, we established a survey questionnaire (N = 523) combining social acceptance and life-cycle assess- ment methodology questions. Lastly, we performed a scenario-based workshop discussing behav- ioural changes related to the introduction of new bio-products to customers. (3) Results: Our study of developing new bio-products (food, feed, fertiliser) from biowaste produced forceful compara- tive results from the two regions regarding three aspects of social acceptance: market, socioeco- nomic, and community. (4) Conclusions: The present study, engaging citizens, consumers, produc- ers, and policy makers, provides insights into what is important for the social acceptance of new protein sources for food, feed, and recycled fertilisers from bio-waste in the Murcia and Kalundborg city regions. Our observations, based on analyses applying three dimensions of social acceptance, can be directly applied elsewhere, guiding decision makers on how to fortify social acceptance re- garding new circular economy business models and the bioeconomy in Europe. Keywords: social acceptance; biowaste; business models; insect/bacteria proteins; circular economy; bioeconomy; valorisation; fortification; behavioural change 1. Introduction The worldwide population increases exponentially every year and is forecasted to reach over 9 billion by 2050, posing causing great challenges to human sustainability [1,2]. For example, food production will need to increase by 70% to support such a population [3]. Yet, even today, the food system is under pressure. Two key challenges are the in- crease in demand for food and nutrients and the increase waste output [4], with as much as one third of food being wasted [3]. European challenges are the overuse of natural re- sources resulting in the loss of bio-diversity, meaning that our food chains are not sus- tainable [5–7]. To overcome these challenges, circular economy policies provide sustaina- ble solutions and opportunities for companies, customers, and society [8]. The European Citation: Eskelinen, T.; Sydd, O.; Kajanus, M.; Fernández Gutiérrez, D.; Mitsou, M.; Soriano Disla, J.M.; Vals Sevilla, M.; Ib Hansen, J. Fortifying Social Acceptance When Designing Circular Economy Business Models on Biowaste Related Products. Sustainability 2022, 14, 14983. https://doi.org/10.3390/ su142214983 Academic Editors: Antonis A. Zorpas, Irene Voukkali and Iliana Papamichael Received: 6 October 2022 Accepted: 9 November 2022 Published: 13 November 2022 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional claims in published maps and institu- tional affiliations. Copyright: © 2022 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https://cre- ativecommons.org/licenses/by/4.0/).