SUSTAINABLE SANITATIONDefinition and technical principles
...he same time incompatible with the technological, financial and social context of developing nations. Current state of things In the late 20th century the rush to sewer has created a widening gap in approach to adequate sanitation. Investments in environmental sanitation go to sewerage in urban areas, subsidizing services for the middle class and rich. United Nations statistics show that only 18 per cent of rural residents in developing countries have access to sanitation, compared with 63 per cent in cities. Nearly 3 billion people do not have access to any sanitary excreta disposal. [1] A pilot’s project director in Pakistan described to the UNICEF the grim facts of the current status of global sanitation: "On the brink of the 21st century, half the world's people are enduring a medieval level of sanitation. Almost 3 billion individuals do not have access to a decent toilet, and many of them are forced to defecate on the bare ground or queue up to pay for the use of a filthy latrine. This unconscionable degradation continues despite a fundamental truth: Access to safe water and adequate sanitation is the foundation of development. For when you have a medieval level of sanitation, you have a medieval level of disease, and no country can advance without a healthy population." [2]. Since then, almost eight years ago, world population growth has increased rapidly and the lump sum is more shocking. Access to safe water and adequate sanitation goes down as population goes up. The same association exists between access and international debt. As debt climbs in poor countries, spending on sanitation falls. The weightiest factors that are bringing in a sanitary crisis in the developing world are the fast growth of population and increasing urbanization of established cities. The disorganized and irregular foundation of shantytowns and slums also does not permit the setting up of large sewer networks. In addition to the exorbitant costs and inappropriate technologies that characterize these systems, other limitations have been identified as follows [3]: Modern sewerage systems use an unreasonable amount of water to transport human waste. This use of drinking-quality water to transport human excreta is a waste of precious and limited resource. Transporting and then discarding the organic residues of human waste is inefficient and wasteful of a valuable resource that –after proper composting- can be used to enrich soil in urban gardens and rural farms. Centralized western-style sanitation systems are planned and constructed without the feedback of the locals, i.e., the stakeholders who will ultimately be responsible for the financing and maintenance of such systems. The application of industrial sanitation methods to water- and resource-scarce developing nations is clearly inappropriate and unsustainable. The Sustainable Sanitation approach Small projects have demonstrated sanitation systems that are culturally appropriate, locally responsible, and functionally sustainable. Bringing these efforts to scale will require replacing the engineering and financial infrastructure that supports sewerage with one that supports ecological innovations in waste treatment. [1] Cancelling out practices that threaten to harm human health or the environment and rebuilding sanitation infrastructure from a sustainability orientation is the challenge. The mixing of the food and water cycles is one of the problems of conventional sewerage systems. These systems not only consume high amounts of freshwater but also dilute nutrients (phosphorus, nitrogen) and organic substances to such a degree that only a small part can be reclaimed for agricultural use. These nutrients and organic substances are washed away with the cleaned wastewater and are released to groundwater, rivers and the sea where they are extremely harmful. Exhaustion of fossil resources and high-energy demands are being caused by the increasing production of nutrients for agriculture. Sanitation that is sustainable spends the minimal amount of energy and resources with the least loss of useable matter to contain and convert it to its usable form in agriculture. The goal is to close the water and nutrients cycles, considering that the main task of sanitation is to assure highest hygienic standards in a cost- effective, environmental sustainable way, saving both water and energy and keeping soils fertile. This can be reached by separating diverse wastes from human communities like black-, brown-, yellow-, grey-, storm water, biodegradable and non- biodegradable wastes. Such sanitation reduces the freshwater consumption considerably and produces fertilizer for agriculture instead of waste. Maximum recycling of nutrients is the basis of sustainable food production and sanitation systems. [4] Conventional sanitation system Main negative aspects of the “end of pipe technology”: è High input of matter (resources) and energy for fertilizer production è High loss of nutrients (phosphorus, nitrogen) due to solution and washing out è Accumulation of nutrients in surface waters è High water consumption due to central sewerage systems è High costs and energy demand for construction, operation and maintenance of central sewerage systems è High energy demand for degradation of organic wastewater contents è High amount of non recyclable waste and therefore high demand for expensive treatment facilities (incineration plants and landfills) Sustainable sanitation system There are a variety of wastewaters with different properties and it makes no sense to m...