Human user testing of the Nano Membrane Toilet

Cranfield University is developing the Nano Membrane Toilet as part of the Bill and Melinda Gates Foundation’s Reinvent the Toilet Challenge. The Nano Membrane Toilet is developed for single-household use. it is an innovative self-contained toilet designed to treat human waste on-site without the need for external energy and water supply. The Frontend of the toilet consists of a unique waterless rotating flush, followed by post-flush source separation of urine and faeces. It is designed to require little or no change in user behaviour compared to conventional flush toilets. Here we report on initial human user testing of the toilet Frontend. Human user testing has been performed both in university settings and in households in a peri-urban area. Testing in a university allowed for a regular footfall of users, simulating our design specification of ten users per day, and testing at the households simulated the expected operating environment for the final product. To evaluate the design of the Frontend, a range of different tests were conducted, including social surveys and interviews, technical functionality and performance tests. Social surveys focused on how user behaviour compared to a conventional toilet, and on how users perceived the cleanliness and odour of the toilet. This was combined with quantitative measurements of cleanliness and odour. In addition the performance of the post-flush source separation in an early stage prototype was evaluated. Such a combination of social, technological and scientific testing is necessary to not only understand how the technology works, but to also gain feedback from potential users, ensuring the toilet will be attractive to users. A holistic testing approach on early prototypes was valuable in gaining information needed to redesign the toilet Frontend for incorporation with the toilet Backend where post-separation treatment occurs.