What about the reuse?
The plant nutrients, organic material, water and energy from the human excreta and waste water streams should preferably be reused. Reuse of these resources often increases sustainability as it decreases the need for limited, and often expensive, global resources. Furthermore, safe reuse also decreases the risk of these flows spreading diseases and/or degrading surface or ground water. After proper treatment, the sanitation products can be used to improve soil fertility and food production without transmitting diseases. Where food supply is limited, improved food production can give substantial health gains. Deficient nutritional status contributes far more to the burden of disease to a much larger extent than unsafe sanitation. Organic material can improve the water and nutrient holding capacities which are important for restoring and for preserving soil fertility. Where water is scarce, reuse of wastewater by irrigation can give substantially increased productivity and enable crop production where cultivation is not possible without irrigation. The use of sanitation nutrient products in agriculture, horticulture or wasteland greening can support a productive economy at both household and community level. Production of energy in the form of biogas can be very beneficial e.g. in locations where the energy supply is absent or unreliable.
The fertilizer value of the sanitation nutrient products, as well as application rates depends on the type of sanitation system. Most of the plant nutrients in house-hold waste water are contributed by the human excreta and especially the urine. Primary treatment (e.g. storage/dehydration in a vault with ash) and secondary treatment (e.g. composting) to stabilise and sanitise the material may cause nutrient losses and often affect the plant availability of the nutrients, especially nitrogen.
Recycling of sanitation nutrient products is an essential part of many sustainable sanitation systems and the recycling system should be described clearly when planning and describing the sanitation system as a whole. Inclusion of this aspect in the planning and involvement of the intended users of the nutrient products, e.g. farmers and/or the households themselves, in the planning is crucial for a good performance of the system.
Characteristics
| Characteristic | Faeces | Urine | Grey water |
| Hygienically critical | High | Low | Low |
| Most important components | Organics, plant nutrients, micro nutrients | Plant nutrients, micro nutrients, water | Water, nutrients, organics |
| Most important contaminants | Pharmaceutical residues and hormones, but importance seems low | Pharmaceutical residues and hormones, but importance seems low | Chemicals used – may contain a vast range of substances |
| Average production (/person and year) | 50-100 kg | About 500 l | 7–100 m3 |
| Nutrient concentration | High | High | Very low |
| Stabilisation and sanitation | Contains degradable organics. Can contain high concentrations of pathogens. Requires a safe handling, treatment and reuse system, including e.g. composting, storage/drying, chemical treatment. | Low in organics and pathogens. Secondary treatment (separate storage) only needed in large systems. Storage time depends on temperature and crop. | If anal cleansing water is included, the risk of pathogens can be high.Contains easily degradable organics that in anaerobic conditions quickly produces malodour. Irrigation should be matched by suitable treatment of the water. |
Benefits, concerns and advice
| Ecosan product | Benefit | Concern | Advice |
| Faeces | Concentrated soil improver and fertilizer high in Phosphorus and micronutrients. Slow release Nitrogen fertilizer. | Hygiene - handling and treatment system must be safe | Apply sub-soil, preferably before seeding or planting. Do not use for crops eaten raw. |
| Urine | Liquid fertilizer, especially strong in Nitrogen, but also in Phosphorus, Potassium and Sulphur. Contains some micronutrients | Large volumes in large systems | Nutrients best preserved and odour prevented when air contact is minimized, i.e. store in closed containers and cover with soil or water down after application. Do not apply on leaves. |
| Greywater | Water for plant growth (irrigation). Phosphorus and Potassium from detergents and liquid soaps. | Hygiene, if anal cleansing water included. Sodium chloride and other pollutants from detergents and chemicals used. | Handle anal cleansing water separately. Minimize use of environmentally hazardous chemicals and of sodium chloride. Avoid stagnant water constituting breeding place for mosquitoes. |
Further information about reuse (in French version)
Further information about reuse (in English version)
- Schlick, J. & Werner, C. (2002). Ecosan, Introduction of close-loop aproaches...
- WP (2006). Smart sanitation solutions
- Werner, C. (2005). Ecological sanitation: principles
- Jönsson, H., Salomon, E., Stintzing, A. & Vinneras, B. (2004). Guidelines on the use of urine and faeces in crop production
- Schönning, C. & Stenström, T. (2004). Guidelines on the safe use of urine and faeces in ecological sanitation system
- NETSSAF (2008). Safe disposal of excreta using an ecological sanitation toilet
- SuSanA (2008). Food security and productive sanitation systems. Version 1.3 (May 2008).
- EcoSanRes. Mal nutrition ecosan.