On the compressional rheology of fresh faeces: Evidence for improving community scale sanitation through localised dewatering

Non-sewered sanitation is currently dependant upon pit latrine emptying, the safety of which compromised by high costs faecal sludge transport to centralised treatment facilities. Transport in turn hindered complex rheology sludge. This study therefore characterised compressional fresh faeces and modelled implications for passive (gravity) or mechanical (forced) solid/liquid separation. informs on viability decentralising dewatering more efficient volume reduction improving economics transportation. The gel point (ϕg) solids concentration where material has a networked structure signifies when intervention required further solid-liquid For faeces, ϕg ranged between 6.3 15.6% total (TS) concentration. significantly higher than observed wastewater at facilities, it implies that gravity driven processes can suffice improve localised dewatering. kinetics sedimentation were illustrate thickening from 3 10% TS <0.5 h. highlights early thicken while separation efficiency. Filtration was lengthy cake filtration times comparably short compression times, similar mineral slurries Consequently, presented improved characteristics, supporting final concentrations kinetics. By complementing with 300 kPa filtration, 1.4 cm thick 25% product could be achieved <24 Investigation matrix properties highlighted increased conductivity (e.g. exposure urine) negatively influenced dewaterability, an effect mitigated introducing earlier. thermodynamically favourable identified focussing radically management, primarily through reducing costs.