Influence of Temperature on the Spatial Distribution of Macro-Organisms in the GSAP† Microflush Toilet Digester and On Extended Applications of the Technology


Stephen Mecca, Cayla Stifler and Catherine Beley


Review I Published January,2017


Journal of Physical Science and Environmental Studies Vol. 3 (1), pp. 1-7


Composting macro-organisms such as those found in the GSAP (Global Sustainable Aid Project) Microflush toilet prefer habitats based on a number of factors including temperature, pH, soil moisture, oxygen, C/N ratio in the waste, light intensity, propagule pressure and competition from other detritus feeders. One such organism, e-fetida (Eisenia-fetida), is especially important in composting human feces in the filter-digester. Casual observations of several installed systems find a high density of this macro-organism in the perimeter area of the bed. Even though the measured temperatures across the bed are rather constant and within the range of acceptable habitats for this composting worm, among the possible factors, temperature was thought to be the likely cause. The heat conduction (Poisson) equation in 3-dimensions was solved for the geometry, structural elements and installed depth of the digester with boundary conditions typical of the tropical regions where the toilet is used. Results show temperature gradients in the narrow region near the perimeter of the bed supporting the hypothesis. The role of digester construction material in impacting transient temperatures, temperature gradients and hence performance of the system has also been explored and the potential for application of the technology in colder climates has been studied.  

Key words: E-fetida habitat, Temperature gradients, GSAP-Microflush, Sustainable sanitation.

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