If the above mentioned ecological sanitation can fulfil furthermore as well social en ecological m requirements it is called “sustainable sanitation�. Such a sanitation is also form the hygienic point of view desirable, due to the fact, that it includes also other aspects, which save health in order to a risk management. Some further aspects of sustainable sanitation are (see also figure 6):

• Closing and separating the cycles of water and nutrients; avoidance of hygienic problems due to the separation of faeces from the water cycle

• Reclamation of nutrients (phosphorus and nitrogen) for agricultural use and hence saving of resources and energy (for the production of artificial fertilizer)

• Considerable savings of freshwater through the use of water saving toilet systems (vacuum, separating or dry toilets)

• Energy production (biogas) instead of energy consumption (for carbon degradation in sewage plants)

• Savings of construction, operation and maintenance costs compared to the conventional central sewerage systems

• Sophisticated modular system, which can be adapted perfectly to local social, economical and environmental conditions

• Easier operation and maintenance compared to centralized technology; local job creation

Figure 6: Sustainable Sanitation System (source Otterwasser GmbH)