Selection of screw characteristics and operational boundary conditions to facilitate post-flush urine and faeces separation within single household sanitation systems

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dc.contributor.authorMercer, Edwina
dc.contributor.authorCruddas, Peter
dc.contributor.authorWilliams, Leon
dc.contributor.authorKolios, Athanasios
dc.contributor.authorParker, Alison
dc.contributor.authorTyrrel, Sean
dc.contributor.authorCartmell, Elise
dc.contributor.authorPidou, Marc
dc.contributor.authorMcAdam, Ewan J.
dc.date.accessioned2016-10-06T18:21:33Z
dc.date.available2016-10-06T18:21:33Z
dc.date.issued2016-09-15
dc.description.abstractTo ensure adequate access to sanitation in developing economies, off-grid single household sanitation has been proposed which obviates the need for significant infrastructure capital investment. Whilst treatment at this scale is most efficient when coupled to source separation (i.e. urine from faeces), existing source separation solutions have proved difficult to implement in this context. In this study, screw extrusion is therefore investigated to provide ‘post-flush’ source separation. Both screw characteristics and operational boundary conditions were evaluated. Preferential screw characteristics included tapering of the shaft and progressive pitch reduction, linked to a small extrusion aperture, the combination of which enhanced solids extrusion efficiency and promoted higher solids concentration in the extruded fraction. Whilst maximum extrusion efficiency was observed at high rotational speeds (over 400 rpm), this also promoted free water transport. Operating below 300 rpm instead introduced selectivity for transport of faecal sludge over urine, enabling phase separation. Constraining the volumetric ratio of urine to faeces also enhanced the extrusion rate of faecal sludge by increasing feed viscosity sufficient to overcome backpressure imposed by unmasticated food particles that would otherwise restrict separation. Importantly, this study demonstrates the feasibility of screw extrusion for ‘post flush’ separation of urine and faeces which constitutes a significant advancement towards realising sanitation at a single household scale.en_UK
dc.identifier.citationE. Mercer, P. Cruddas, L. Williams, A. Kolios, A. Parker, S. Tyrrel, E. Cartmell, M. Pidou and E. J. McAdam. Selection of screw characteristics and operational boundary conditions to facilitate post-flush urine and faeces separation within single household sanitation systems. Environmental Science: Water Research and Technology, 2016, Volume 2, Issue 6, pp953-964en_UK
dc.identifier.issn2053-1400
dc.identifier.urihttp://dx.doi.org/10.1039/C6EW00170J
dc.identifier.urihttp://dspace.lib.cranfield.ac.uk/handle/1826/10683
dc.language.isoenen_UK
dc.publisherRoyal Society of Chemistryen_UK
dc.rightsAttribution-NonCommercial 4.0 International
dc.rights.urihttp://creativecommons.org/licenses/by-nc/4.0/
dc.subjectscrewen_UK
dc.subjectfaecesen_UK
dc.subjecturineen_UK
dc.subjectseparationen_UK
dc.subjectsolids concentrationen_UK
dc.subjectextrusionen_UK
dc.titleSelection of screw characteristics and operational boundary conditions to facilitate post-flush urine and faeces separation within single household sanitation systemsen_UK
dc.typeArticleen_UK

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