Browsing by Author "Hennigs, Jan"

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    Faeces - Urine separation via settling and displacement: Prototype tests for a novel non-sewered sanitation system
    (Elsevier, 2020-08-23) Hennigs, Jan; Ravndal, Kristin T.; Parker, Alison; Collins, Matt; Jiang, Ying; Kolios, Athanasios J.; McAdam, Ewan; Williams, Leon; Tyrrel, Sean F.
    The development of novel, non-sewered sanitation systems like the Nano Membrane Toilet requires thorough investigation of processes that may seem well-understood. For example, unlike the settling of primary sludge, the separation of solids from liquids in a small-volume container at the scale of a household toilet has not been studied before. In two sets of experiments, the settling of real faeces and toilet paper in settling columns and the settling of synthetic faeces in a conical tank are investigated to understand the factors affecting the liquid quality for downstream treatment processes. Toilet paper is found to be a major inhibitor to settling of solids. While a lower overflow point results in better phase separation through displacement of liquid, a higher overflow point and frequent removal of solids may be more advantageous for the liquid quality
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    Field testing of a prototype mechanical dry toilet flush
    (Elsevier, 2019-02-17) Hennigs, Jan; Ravndal, Kristin T.; Blose, Thubelihle; Toolaram, Anju; Sindall, Rebecca C.; Barrington, Dani J.; Collins, Matt; Engineer, Bhavin; Kolios, Athanasios J.; McAdam, Ewan; Parker, Alison; Williams, Leon; Tyrrel, Sean
    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.
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    Planning and communicating prototype tests for the Nano Membrane Toilet: A critical review and proposed strategy
    (Gates Open Research, 2019-08-30) Hennigs, Jan; Parker, Alison; Collins, Matt; Jiang, Ying; Kolios, Athanasios; McAdam, Ewan J.; Williams, Leon
    Urban sanitation in growing cities of the Global South presents particular challenges. This led to the Bill & Melinda Gates Foundation’s Reinvent The Toilet Challenge, which sparked the development of various non-sewered sanitation technologies like the Nano Membrane Toilet. Complex disruptive technologies like this entail an extensive product development process, including various types of prototype tests. While there is an abundance of literature discussing how to build prototypes, and the optimal number of tests, there has been little focus on how to plan and conduct tests, especially in a development endeavour of this complexity. Four approaches to testing are reviewed, and their strengths and weaknesses compared. A visualised testing strategy is proposed that encompasses the entire product development process and can be used to plan and communicate prototype tests for the Nano Membrane Toilet to ultimately achieve compliance with international standards.