A User-Friendly and Sustainable Toilet Based on Vermicomposting

Environmental awareness has sparked increasing interest in changing the way humans interact with their environment. This awareness includes the change in paradigm of considering human manure (humanure) not as a waste but as a valuable bioproduct instead. In this regard, composting is an age-old technique for nutrient recovery that has gained renewed interest, as it may be a sanitary and financially viable solution to closing the loop of human–nature interactions. This work investigates environmental solutions for toilet systems that are user-friendly and sustainable based on systems that filter nutrients via vermicomposting. The methodology is based on (1) reviewing several surveys across different continents to select the most appropriate interface of a targeted society, and (2) investigating the microbial dynamics of vermicomposting. The microbial activity was compared with the activity of the aerobic composting systems by measuring soil temperature, soil composition, decomposition rate, stabilization factor, and biological diversity. The microbial decomposition process in vermicomposting was faster due to the presence of earthworms, but the increase in temperature and volatile ammonia led to the earthworms burrowing into the soil. Overall, the flush toilet is still the most socially accepted toilet interface, and the connection of vermicomposting to this toilet interface poses challenges in managing high ammonia content and maintaining healthy conditions for the earthworm population.