Cranfield Univeristy’s Nano Membrane Toilet treats waste without water or electricity, producing recycled water for household use along with energy and ash. The system uses the membrane to separate water from the waste and gasifies solids. The energy produced can be used to sustain the membrane process and any extra energy could be used to charge electronic devices.
The toilet structure is made entirely of composite material and can therefore be manufactured entirely using a 3-D printer and a laser cutter.
Intellectural Property Type
User Provision Model
The proposed user provision model is for toilets to be rented by households.
Distributions to Date Status
No distributions to date; the product is still in its testing phase.
Time until emptying
The toilet rotates the solid and liquid waste mixture to empty it from the toilet, and then sedimentation separates solids from the mixture. Pathogens and odors are removed as water is transported through the membrane walls in the vapor state, and then recycled for household use. The partly-dry solids are then transported via mechanical screw to a gasifier, which converts the waste to ash and energy. The energy produced continues to power the membrane process, and extra energy can be used to charge devices.
Support is proposed to be provided every six months by a franchised maintenance company.
The technicians would replace the membrane cartridge, bead cartridge, and the polymer.
Manufacturer Specified Performance Parameters
Designer specified performance targets include the daily operation cost being 0.05 USD/user/day, the energy recovered being 90 kW/user/day, and the water recovered being 1.5 L/user/day.
Vetted Performance Status
Field testing of a prototype was conducted in both a semi-public institutional setting and in peri-urban households in the Republic of South Africa. Additionally, laboratory experiments were conducted to determine that the best cleaning material for wiping the toilet bowl was a silicone rubber with oil-bleed-effect. The following study explains a new method for quantifying liquid fecal odors, which is an important aspect in promoting user acceptance of the Nano Membrane Toilet. The study also examines various membranes considered for use in the Nano Membrane Toilet. The following study highlights the potential of slow progressive burning and fuel blending to promote combustion of human feces - an important pre-treatment step for converting feces into energy. A performance assessment determined that a Sterling Engine within the toilet could potentially provide a net power output while simultaneously reducing harmful gas emissions.
In the unlikely event that the toilet breaks, the hydrophobic beads pose a potential choking hazard to children.
Complementary Technical Systems
Academic Research and References
Hennigs, J., Ravndal, K. T., Blose, T., Toolaram, A., Sindall, R. C., Barrington, D., Collins, M., Engineer, B., Kolios, A. J., McAdam, E., Parker, A., Williams, L., & Tyrrel, S., 2019, Field testing of a prototype mechanical dry toilet flush, Science of The Total Environment, 668, pp. 419–431.
Mercer, E., Davey, C. J., Campo, P., Fowler, D., Williams, L., Kolios, A., Parker, A., Tyrrel, S., Walton, C., Cartmell, E., Pidou, M., & McAdam, E. J., 2018, Quantification of liquid phase faecal odourants to evaluate membrane technology for wastewater reuse from decentralised sanitation facilities, Environmental Science: Water Research & Technology, 5(1), pp. 161–171.
Parker, A., 2014, Membrane technology plays key role in waterless hygienic toilet, Membrane Technology.
Perez Lopez, E., 2014, Design and testing of a novel human-powered generator device as a backup solution to power Cranfield’s Nano-membrane Toilet, Cranfield University.
Lieu Le, Ngoc and Nunes, Suzana P., 2016, Materials and membrane technologies for water and energy sustainability, Sustainable Materials and Technologies.
Hanak, Dawid P. et al., 2016, Conceptual energy and water recovery system for self-sustained nano membrane toilet, Energy Conversion and Management.
Kolios, Athanasios et al., 2018, Probabilistic performance assessment of complex energy process systems – The case of a self-sustained sanitation system, Energy Conversion and Management.
Compliance with regulations
Cranfield University produced a video to explain how their toilet works. Winner of the CleanEquity Monaco 2015 award.