Upcycling human excreta-derived products through sustainable seedling production: Feasibility studies

Managing human excreta and organic waste from municipal solid waste is important for a cleaner environment. The recent circular bioeconomy paradigm brought the idea of sustainable resource recovery and reuse through valorising organic waste streams and wastewater reuse. Many studies have been done on human excreta valorisation, but the adoption of bio-fertilisers by farmers is poor due to unclear policies and the absence of viable business models. This study investigated the feasibility of upcycling domestic wastewater and human excreta-derived co-compost through seedling production. A greenhouse experiment was done using a randomised complete design to assess the effects of domestic wastewater and co-compost on parameters for best practices in seedling production. Three vegetables (onion, tomato and Swiss chard) were used as test crops. Data was collected on growing media characterisation, seedling vigour and E. coli contamination. Economic analyses used water usage data to assess the financial viability of seedling production. Using wastewater and co-compost on seedling production was comparable to conventional practices. The significant benefits are saving water and fertiliser costs, creating employment, ensuring food and nutrition security, combating social ills such as crime, minimising the carbon footprint in local food production systems and mitigating environmental pollution. The major limitation is marketing the seedlings to niche markets due to prohibitions on Good Agricultural Practices certifications. Depending on local regulations farmers may produce seedlings for use on their farms or market them in their food production networks. Policymakers should review the use of human excreta fertilisers, and active participation of regulatory authorities is needed to allow bio-certification of eco-innovations such as seedlings. This will provide opportunities for seedling producers to penetrate the niche market.