What is ECOSAN (Ecological Sanitation)?
The basic concept of collecting domestic liquid waste in water-borne sewer systems, treating the wastewater in centralised treatment plants and discharging the effluent to surface water bodies became the accepted, conventional approach to sanitation in urban areas in the last century. Although these conventional sewer systems have significantly improved the public health situation in those countries that can afford to install and operate them properly, the large number of people, particularly in the developing world, who still do not have adequate access to adequate sanitation is a clear indication that the conventional approach to sanitation is likely to be unable to meet needs universally.
The conventional sewer system was developed at a time, in regions, and under environmental conditions that made it in many cases an appropriate solution for removing liquid wastes from cities. Today with increased population pressure, changes in consumer habits and increasing pressure on freshwater and other resources, this human waste disposal system is no longer able to meet the pressing global needs and ideas of recycling have been developed.
A few decades ago it thus became a priority to:
? Identify appropriate simple, affordable decentralised sanitation systems and promote their adoption
? Implement appropriate technologies with the participation of the communities to be served, and
? Focus on health and hygiene education so that physical facilities would be properly used and maintained, and that hygienic behaviour would support the improvements brought about by the infrastructure.
Over the years, it became clear however that this health and hygiene driven paradigm shift was still incomplete: In practice faecal sludge management problems where often overlooked, as were negative downstream effects off effluents from sewer systems. Protection of the environment, resource conservation and waste reuse remained secondary concerns at best, or were neglected entirely, and operational problems reduced the health improvements expected of the technologies.
In the concept of ecological sanitation (ecosan) not only health issues but also conservation of water and other resources as well as the protection of aquatic ecosystems are taken into consideration. The ecosan approach places the emphasis on the hygenisation of the contaminated flow streams, and shifts the concept from waste disposal to resource conservation and safe reuse.
Limits of conventional water systems
Our conventional wastewater systems are largely linear, end-of-pipe systems where drinking water is misused to transport waste into the water cycle, causing environmental damage and hygienic hazards, and contributing to the water crisis. If we continue to promote these technologies in order to meet the Millennium Development Goals, the overall result could be disastrous as the hygienic situation of our waters would be further deteriorated and even more resources would be dissipated and introduced into water bodies.
While the above are serious disadvantages of both water-borne and dry conventional sanitation systems, a far more fundamental problem is that they do not facilitate the reuse of macro and micro nutrients present in excreta and wastewater. This lack of nutrient recovery and -use leads to a linear flow of nutrients from agriculture, via humans to recipient water bodies. The valuable nutrients and trace elements contained in human excrement are very rarely re-channelled back into agriculture in conventional systems. Even when sewage sludge is used in agriculture, only a very small fraction of the nutrients contained in the excrement are reintroduced into the living soil layer. Most are either destroyed in the treatment process (e.g. by nitrogen elimination) or enter the water cycle, where they pollute the environment, causing the eutrophication of lakes and rivers.
Not returning the nutrients to the soil has led to a situation where there is an increasing demand for chemical fertilisers, in response to the problem of decreasing soil fertility. To produce the required chemical fertilisers, large amounts of energy are needed, and finite mineral resources, such as phosphorous, must be exploited. Current estimates say that phosphorous reserves will be exhausted in between 60 and 130 years at the present rate of consumption (Rosemarin 2004). The relatively inexpensive phosphorous used today will almost certainly cease to exist in the next 50 years. Farmers around the world yearly require 135 Mio. tons of mineral fertiliser for their crops, while at the same time conventional sanitation dumps 50 Mio tons of fertiliser equivalents flows into our water bodies - nutrients with a market value of around 15 Billion US dollars. This illustration schematically illustrates the main limitations of conventional wastewater management systems.
The new sanitation paradigm: ecological sanitation
In order to reach the MDGs and achieve sustainability in the field of wastewater management and sanitation, a new paradigm is clearly needed. This was the unanimous conclusion of a group of experts from a wide range of international organisations involved in environmental sanitation that met in February 2000 in Bellagio, Italy. The group called for a radical rethinking of conventional sanitation policies and practices world-wide. This group formulated the four ?Bellagio Principles? the basis for a new paradigm and approach in environmental sanitation (SANDEC/WSSCC 2000a).
The Bellagio Principles (2000)
(1) Human dignity, quality of life and environmental security at household level should be at the centre of the new approach, which should be responsive and accountable to needs and demands in the local and national setting.
? solutions should be tailored to the full spectrum of social, economic, health and environmental concerns
? the household and community environment should be protected
? the economic opportunities of waste recovery and use should be harnessed
(2) In line with good governance principles, decision making should involve participation of all stakeholders, especially the consumers and providers of services.
? decision making at all levels should be based on informed choices
? incentives for provision and consumption of services and facilities should be consistent with the overall goal and objective
? rights of consumer and providers should be balanced by responsibilities to the wider human community and environment
(3) Waste should be considered a resource, and its management should be holistic and form part of integrated water resources, nutrient flow and sanitation.
? inputs should be reduced so as to promote efficiency and water and environmental security
? exports of waste should be minimised to promote efficiency and reduce the spread of pollution
? wastewater should be recycled and added to the water budget
(4) The domain in which environmental sanitation problems are resolved should be kept to the minimum practical size (household, community, town, district, catchment, city) and wastes diluted as little as possible.
? waste should be managed as close as possible to the source
? water should be minimally used to transport waste
? additional technologies for waste sanitisation (sic) and reuse should be developed
These principles were endorsed by the members of the WSSCC during its 5th Global Forum in November 2000 in Iguacu, Brazil (SANDEC/WSSCC 2000b).
Ecosan - the new paradigm
The new paradigm in sanitation must be based on ecosystem approaches and the closure of material flow cycles rather than on linear, expensive and energy intensive end-of-pipe technologies. Sanitation systems are part of several cycles, of which the most important cycles are the pathogen-, water-, nutrient- and energy cycle. In order to ensure public health, sanitation approaches primarily aim at interrupting the life cycle of pathogens. In addition, the new approach is recognising human excreta and water from households not as a waste but as a resource that could be made available for reuse, especially considering that human excreta and manure from husbandry play an essential role in building healthy soils and are providing valuable nutrients for plants. While conventional sanitation restricts health security to the in-house environment and sometimes leads to a disastrous situation in the neighbourhood or the receiving water body, the new approach is aiming at sanitizing the products instead of exporting problems and apply a health oriented multi-barrier concept of treatment, croprestriction and exposure control.
This approach, mostly addressed as ?ecological sanitation? or ecosan offers an alternative to conventional sanitation. It is based on an overall view of material flows as part of an ecologically and economically sustainable sanitation system tailored to the needs of the users and to specific local conditions. It does not favour or promote a specific sanitation technology, but is rather a new philosophy in handling substances that have so far been seen merely as wastewater and watercarried waste for disposal. It carries with it a new approach to sanitation education, a new discourse, and a new way of managing knowledge.
Ecosan systems restore a remarkable natural balance between the quantity of nutrients excreted by one person in one year and that required to produce their food (7.5 kg nitrate, phosphorous and potassium to produce 250 kg of grain) and therefore can greatly help in saving limited resources. This is particularly urgent with regard to fresh water and mineral resources ? for example current estimates for phosphorus state that economically extractable reserves risk to be exhausted in the foreseeable future. Ecosan does not favour a particular technology but is rather a philosophy in recycling oriented resource management and offers modern, convenient, gender friendly and desirable solutions, in accordance with the Bellagio Principles as formulated by the WSSCC (Water Supply and Sanitation Collaborative Council) (SANDEC/WSSCC 2000a).
The core principle of ecosan is to close the loop between sanitation and agriculture, enabling and bringing about ?agricultural reuse?, along with other means of closing flow cycles.