Comparative life cycle assessment of on-site sanitation systems using lagoons or drying beds for fecal sludge treatment in low-income tropical countries.

Environmental challenges in low-income countries, such as Haiti, persist due to inadequate sanitation infrastructure. This study assesses the environmental impacts of nine on-site sanitation systems to identify those with the least environmental impacts and explore improvement options. Nine scenarios were developed, each representing different systems for managing 1 ton of fecal sludge over 1 year. The 'Impact World + ' and 'IPCC 2013 GWP 100a' methods evaluated impacts on ecosystems, human health, and climate change. Data sources included interviews, weighing records, and scientific publications. Results show that Scenario 8 (Flush Toilet - Evacuation - Planted Drying Beds) is most impactful on health (1.17 × 10^-2 DALY), while Scenario 1 (Composting Toilet - Evacuation - Unplanted Drying Beds) is least impactful (1.77 × 10^-3 DALY). For ecosystem impacts, Scenario 2 (Container-based Toilet - Evacuation - Planted Drying Beds) is most impactful (3.81 × 10³ PDF·m²·year), while Scenario 6 (VIP latrine - Evacuation - Lagoons) is least impactful (3.52 × 10³ PDF·m²·year). Key hotspots include toilet paper, wood shavings, GHG emissions, and water use. The study recommends an integrated approach combining environmental life cycle assessment (LCA) with life cycle cost assessment and social LCA for sustainable decision-making on sanitation systems in low-income countries.