Field testing of a prototype mechanical dry toilet flush

Hennigs, Jan and Ravndal, Kristin T. and Blose, Thubelihle and Toolaram, Anju and Sindall, Rebecca C. and Barrington, Dani and Collins, Matt and Engineer, Bhavin and Kolios, Athanasios J. and McAdam, Ewan and Parker, Alison and Williams, Leon and Tyrrel, Sean (2019) Field testing of a prototype mechanical dry toilet flush. Science of the Total Environment, 668. pp. 419-431. ISSN 1879-1026 (

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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.