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Resource-oriented or ecological sanitation concepts Print E-mail

Resource-oriented systems are an alternative approach to avoid the disadvantages of conventional wastewater systems. The ecological sanitation paradigm in sanitation is based on ecosystem approaches and the closure of material flow cycles (Figure 2). Human excreta and water from households are recognised as a resource (not as a waste), which should be made available for re-use. According to Niemczynowicz (2001), the basic motivation behind the need to reshape the management of nutrients and streams of organic residuals may be found in the socalled "basic system conditions for sustainable development" for water and sanitation management, formulated in the Agenda 21 (UN, 1992):

• The withdrawal of finite natural resources        should be minimised.

• The release of non-biodegradable substances to the environment must be stopped.

• Physical conditions for circular flows of matter should be maintained.


• The withdrawal of renewable resources should not exceed the pace of their regeneration.

 

 

 

Figure 2: Resource-oriented or ecological sanitation system (Langergraber and Müllegger, 2005)

 Ecological sanitation represents a holistic approach towards ecologically and economically sound sanitation. It is a systemic approach where single technologies are only means to an end and are not ecological per se but only in relation to the observed environment. The applied technologies may range from natural wastewater treatment techniques to compost toilets, simple household installations to complex, mainly decentralized systems (Otterpohl, 2004).
 According to Werner et al. (2004), resource-oriented sanitation systems:
• reduce the health risks related to sanitation, contaminated water and waste,
• prevent the pollution of surface and groundwater,
• prevent the degradation of soil fertility, and
• optimise the management of nutrients and water resources.
 The principles underlying ecological sanitation are not novel. In different cultures, sanitation systems based on ecological principles have been used for hundreds of years. EcoSan systems are still widely used in parts of East and Southeast Asia. In Western countries, this option was largely abandoned as "flush and discharge" became the norm. Only in recent years, there has been a revival of interest in these techniques (Esrey et al., 1998). Resource-oriented sanitation systems are based on collecting and treating the different wastewater flows separate to optimise the potential for reuse (e.g. Esrey et al., 1998; Wilderer, 2001). The different fractions include:
 
• blackwater (wastewater from the toilets, a mixture of urine and faeces), and
• greywater (wastewater without excreta respectively from kitchen, bathroom and laundry),
• separately collected urine (also called yellowwater), and
• separately collected faeces are called faecal sludge or faecal matter, respectively, depending on if flush water is used or not.
 Recommendations how to sanitise human excreta before use have been developed and are continuously extended and updated (e.g., Schönning, 2004; Jönsson et al., 2004). The characteristics of the different streams of wastewater, the possibilities for reuse and the hygienic hazards can be summarised as follows (Langergraber and Müllegger, 2005):
 • Most of the soluble nutrients are found in urine. If urine is separated and converted to
agricultural usage, the biggest step towards nutrient reuse and highly efficient water protection will be taken.
• The hygienic hazards of wastewater originate mainly from faecal matter. Separation opens the way to hygienisation and finally to an excellent end-product.
• Wastewater that is not mixed with faeces and urine is a great resource for high quality reuse of water.
• Source control should include evaluating all products that end up in the water. High quality reuse will be far easier when household chemicals are not only degradable but can be mineralised with the available technology.
 The advantages of the proposed resource-oriented sanitation concepts can be summarized as follows:
 Resource-oriented sanitation concepts are a way towards a more ecological sound sanitation. The concepts are based on source separation and reuse. Hygienic hazards are well known and guidelines for the treatment and save use of urine and faeces are available. There are many technological options so that most social and economic conditions can be met. Creativity is needed to find the appropriate technology and the best way of implementing, operating and financing.
 A number of case studies exist for rural areas (e.g. Werner et al., 2004; Austin, 2005). However, there is a lack in implementing these concepts for larger settlements, i.e. more densely populated areas, particularly in African countries. The ROSA project tackles this gap.
Last Updated ( Monday, 21 September 2009 )
 
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