Terra Preta sanitation: re-discovered from an ancient Amazonian civilisation – integrating sanitation, bio-waste management and agriculture
The recent discovery of the bio-waste and excreta treatment of a former civilisation in the Amazon reveals the possibility of a highly efficient and simple sanitation system. With the end product that was black soil they converted 10% of former infertile soil of the region: Terra Preta do Indio (black soil of the Indians). These soils are still very fertile 500 years after this civilisation had disappeared. Deriving from these concepts, Terra Preta Sanitation (TPS) has been re-developed and adopted. TPS includes urine diversion, addition of a charcoal mixture and is based on lactic-acid-fermentation with subsequent vermicomposting. No water, ventilation or external energy is required. Natural formation processes are employed to transform excreta into lasting fertile soil that can be utilised in urban agriculture. The authors studied the lacto-fermentation of faecal matter with a minimum of 4 weeks followed by vermicomposting. The results showed that lactic-acid fermentation with addition of a charcoal mixture is a suitable option for dry toilets as the container can be closed after usage. Hardly any odour occured even after periods of several weeks. Lactic-acid fermentation alone without addition of bulking agents such as paper and sliced-cut wood to raise the C/N ratio is creating a substrate that is not accepted by worms.
Keywords: bio-waste treatment, nutrient recovery, Terra Preta sanitation, urban agriculture