Human excreta recycling in Sweden: a PESTEL-SWOT framework analysis – Review

Source-separating sanitation systems can maximise resource recovery from wastewater and mitigate the environmental impacts of conventional wastewater treatment plants, including eutrophication and climate change. This study conducts a comprehensive review of the literature on source-separating sanitation systems in Sweden, aiming to identify the challenges hindering their diffusion and potential expansion opportunities. Employing a rapid evidence synthesis approach, we extracted data from the Web of Science and supplemented findings through hand-searches in additional electronic databases. Of the 713 studies initially identified, 24 met our stringent inclusion criteria. The analysis was structured around a combined PESTEL (Political, Economic, Technical, Social, Environmental, Legal) and SWOT (Strengths, Weaknesses, Opportunities, Threats) framework to synthesise the existing body of work and discern main patterns. The findings underscore the untapped strengths in these technologies' potential in enhancing nutrient recovery and food security, in addition to reducing eutrophication and greenhouse gas emissions. The studies analysed reported Sweden's strengths in source separation, highlighting organisational diversity, market benefits, social acceptance, technological readiness, and nutrient recovery, all contributing to the SDGs and addressing challenges such as eutrophication and limited sanitation access. The primary challenges were identified as social and cultural taboos towards the recycling of human excreta, disbelief in its quality as a fertiliser, concerns about hazardous substances like pharmaceuticals, and a preference for using it to grow non-food crops. Our article main contribution lies in proposing 12 structured upscaling strategies addressing these barriers and leveraging the opportunities identified including policy measures to incentivise circular practices, building support through stakeholder engagement, updating building codes to require double piping, and enhancing municipal-utility cooperation. While grounded in Sweden, our study contributes to research on the broader shift towards sustainable food systems by leveraging internal strengths and external opportunities in circular wastewater systems.