When Are Anaerobic Digestion and Black Soldier Fly Bioconversion Solutions Sustainable in Humanitarian Waste Management? A Life Cycle and Feasibility Assessment

Humanitarian operations generate significant quantities of biowaste, the biodegradable fraction of organic solid waste (OFMSW), in contexts where collection, segregation, and controlled end-of-life treatment are often limited. In such settings, biological waste valorisation technologies may contribute to reducing environmental impacts while supporting local resource recovery. However, their performance depends strongly on operational and socio-economic conditions. This study assesses anaerobic digestion (AD), black soldier fly (BSF) bioconversion, and composting as organic-waste treatment options for humanitarian settings through a context-sensitive life cycle and feasibility framework. The analysis builds on evidence generated in the EU-funded Bio4HUMAN project for the Democratic Republic of the Congo (DRC) and South Sudan (SSD) and on life cycle assessment (LCA) principles applied to the treatment of biowaste. AD, BSF, composting, and uncontrolled open dumping disposal are considered as alternative end-of-life routes. A feasibility layer is subsequently incorporated to account for key contextual factors, including waste segregation practices, contamination risk, infrastructure availability, technical capacity, output valorisation, market access, governance readiness, and health and biosafety constraints. The results indicate that neither AD nor BSF bioconversion can be considered universally preferable across humanitarian contexts. AD is most suitable where segregated organic waste, local biogas demand, operational capacity, and safe digestate valorisation are available. In contrast, BSF bioconversion showed potential for resource recovery, but its sustainability was highly sensitive to the existence of safe and locally validated outlets for larvae biomass and frass. When larvae-feed credits were reduced or removed, BSF performance declined, confirming that recovered-product credits should not be assumed in the absence of documented local valorization pathways. Under the current mixed-waste baseline and the balanced weighting case, the contextual sustainability score ranked composting as the most favourable option in both DRC and SSD, followed by modular renewable micro-AD, micro-AD, and BSF bioconversion, while open dumping was used as the current unmanaged benchmark. However, this ranking does not imply direct deployment readiness under mixed or contaminated waste conditions, since all biological routes require source-separation, contamination control, and safe output valorisation. The source-separated scenario reduced feasibility penalties for all biological options but did not automatically reverse the ranking because composting also benefits from improved waste-stream quality. Overall, the results support a context-sensitive framework combining LCA-derived environmental burdens, recovered-product credits, and feasibility penalties, rather than universal rankings, for selecting organic-waste technologies in humanitarian settings.