Screw Dewatering of Faecal Sludge

A significant inhibitor for faecal sludge management are the high emptying and transport cost attributed to rheologically difficult sludge types and volumes consisting of over 95% water (Basamykina et al., 2020; Gold et al., 2016). Onsite solid/liquid separation, which removes water before transport, could be the critical step in making faecal sludge management economically feasible. Thickening and dewatering processes represent the initial water removal stages to minimise sludge volume. They play a key role in preparing faecal solids for downstream processes which facilitate safe environmental disposal through drying or pasteurisation (Brockmann, 1973; Naidoo et al., 2020; Septien et al., 2018), or sustainable sanitation opportunities such as the provision of energy or fertiliser product from an organic and nutrient rich solid phase (Eshetu Moges et al., 2018; Forbis- Stokes et al., 2016; Harder et al., 2019; Onabanjo et al., 2016). As such, localised solid/liquid separation could enable a community accepted shift towards sustainable faecal sludge management (Mikhael et al., 2014). However, there is limited understanding of the material properties of faecal solids which ultimately govern how to design and manage solid/liquid separation processes. This project contributes to the transformative technologies portfolio by providing the required fundamental scientific knowledge of fresh faeces rheology and dewaterability to design and implement effective solids/liquid separation for non-sewered sanitation. This was achieved in collaboration with Shane Usher from Melbourne University, who leads research on the rheology and dewaterability of particulate matrices. We have adapted these methods for the characterisation of faeces.