Cranfield University is developing the Nano Membrane Toilet which will be able to treat human waste on-site without external energy or water. The Cranfield toilet is designed for single-household use (equivalent to 10 people) and will accept urine and faeces as a mixture. The Cranfield toilet is still under development; this is the vision of how it will work: The Cranfield toilet flush uses a unique rotating mechanism to transport the mixture into the Cranfield toilet without using any water whilst simultaneously blocking odour and the user’s view of the waste.
Solids separation (faeces) is principally accomplished through sedimentation. Loosely bound water (mostly from urine) is separated using low glass transition temperature hollow-fibre membranes. The unique nanostructured membrane wall facilitates water transport in the vapour state rather than as a liquid state which yields high rejection of pathogens and some odorous volatile compounds. The water will be collected for reuse at the household level in washing or irrigation applications.
Following release of unbound water, the residual solids are transported by mechanical screw into a gasifier which will convert them into ash and energy. The energy will power the membrane processes, and there may be extra energy for charging mobile phones or other low voltage items.
Developing the business model will be a key focus in the coming months of the project. One possibility is that the Nano Membrane Toilet will be rented by the households and maintenance will be undertaken with a trained operative responsible for the franchised area.