Urine diversion terra preta toilets are a low cost, dry terra preta sanitation (TPS) systems based on urine diversion and the addition of charcoal producing lasting and highly fertile soils with properties similar to the recently discovered pre-Columbian man-made terra preta soils. The terra preta toilets are based on a three-step process of collection (including urine diversion), lactic acid fermentation (lacto-fermentation) and vermicomposting. Any urine diversion or composting toilet can thus been adapted for TPS. The main advantage of lacto-fermentation is that no gas (e.g. methane) and no odour is produced what makes it particularly interesting for in-house systems even in urban areas. Vermicomposting transforms the carbon and nutrients into the deep black, fertile and stable soil, which also has the potential as a long-term carbon sink. (compiled by: Dorothee Spuhler (seecon international gmbh), Robert Gensch (Xavier University))
None of the options were relevant for Terra Preta Toilet.