Field testing of a prototype mechanical dry toilet flush

• Published in: The Science of the total environment 2019-06, Vol.668, p.419-431
• Main Authors: Hennigs, Jan, Ravndal, Kristin T., Blose, Thubelihle, Toolaram, Anju, Sindall, Rebecca C., Barrington, Dani, Collins, Matt, Engineer, Bhavin, Kolios, Athanasios J., McAdam, Ewan, Parker, Alison, Williams, Leon, Tyrrel, Sean
• Format: Article
• Language: English
• Subjects: Iterative design; Reinvent the toilet challenge; Science-design Interface; User testing; WASH
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.02.220

A prototype of a non-fluid based mechanical toilet flush was tested in a semi-public, institutional setting and in selected peri-urban households in eThekwini municipality, Republic of South Africa. The mechanism's functionality and users' perception of the flush were assessed. User perception varied depending on background: Users accustomed to porcelain water flush toilets were open to, yet reserved about the idea of using a waterless flush in their homes. Those who commonly use Urine Diversion Dehydration Toilets were far more receptive. The user-centred field trials were complemented by a controlled laboratory experiment, using synthetic urine, -faeces, and -menstrual blood, to systematically assess the efficiency of three swipe materials to clean the rotating bowl of the flush. A silicone rubber with oil-bleed-effect was found to be the best performing material for the swipe. Lubrication of the bowl prior to use further reduced fouling. A mechanical waterless flush that does not require consumables, like plastic wrappers, is a novelty and could – implemented in existing dry toilet systems – improve acceptance and thus the success of waterless sanitation. [Display omitted] •Prototype mechanical toilet flush successfully user-tested in households and lab•User feedback positive but dependent on toilet habit•Removal of fouling from soft faeces not satisfactory•Surface lubrication improves fouling removal.