Ecological sanitation

The term "ecosan" was first used in 1995 and the first project started in 1996 in Ethiopia, by an NGO called Sudea. A trio, Dr Torsten Modig, Umeå University, Almaz Terrefe, teamleader, and Gunder Edström, hygiene expert, chose an area in a dense urban area as a starting point. They used urine diverting dry toilets (UDDTs) coupled with reuse activities.

In the ecosan concept, human excreta and wastewater is regarded as a potential resource – which is why it has also been called "resource oriented sanitation". The term "productive sanitation" has also been in use since about 2006.

The definition of ecosan is focusing on the health, environment and resource aspect of sustainable sanitation. Thus ecosan is not, per se, sustainable sanitation, but ecosan systems can be implemented in a sustainable way and have a strong potential for sustainable sanitation, if technical, institutional, social and economical aspects are cared for appropriately. Ecosan systems can be "unsustainable" for example if there is too little user acceptance or if the costs of the system are too high for a given target group of users, making the system financially unsustainable in the longer term.

The statement in the definition of ecosan to "safely recycle" includes hygienic, microbial and chemical aspects. Thus, the recycled human excreta product, in solid or liquid form, shall be of high quality both concerning pathogens and all kind of hazardous chemical components. The statement "use of non-renewable resources is minimized" means that the gain in resources by recycling shall be larger than the cost of resources by recycling.

Ecosan is based on an overall concept of material flows as part of an ecologically and economically sustainable wastewater management system tailored to the needs of the users and to the respective local conditions. It does not favor a specific sanitation technology, but is rather a certain philosophy in handling substances that have so far been seen simply as wastewater and water-carried waste for disposal.[1]

The first proponents of ecosan systems had a strong focus on increasing agricultural productivity (via the reuse of excreta as fertilizers) and thus improving the nutritional status of the people at the same time as providing them with safe sanitation.[5] Disease reduction was meant to be achieved not only by reducing infections transmitted via the fecal–oral route but also by reducing malnutrition in children. This link between WASH, nutrition, a disease called environmental enteropathy (or tropical enteropathy)[6] as well as stunted growth of children has risen to the top of the agenda of the WASH sector since about 2013.

Agricultural trials around the world have shown measurable benefits of using treated excreta in agriculture as a fertilizer and soil conditioner. This applies in particular to the use of urine. Reuse trials in Zimbabwe showed positive results for using urine on green, leafy plants such as spinach or maize as well as fruit trees.[7][8] Another study in Finland indicated that the use of urine and the use of urine and wood ash "could produce 27% and 10% more red beet root biomass".[9] Urine has been proven in many studies to be a valuable, relatively easy to handle fertilizer, containing nitrogen, phosphorus, potassium and important micro-nutrients.[10]

Another aspect that ecosan systems are trying to address is the possible upcoming shortage of phosphorus.[11] Phosphorus has an important role for plant growth, and therefore in fertilizer production, but is a limited mineral resource.[12] The situation is similar for potassium. Known mineral phosphate rock reserves are becoming scarce and increasingly costly to extract – this is also called the "peak phosphorus" crisis. One review of global phosphate supply suggested that if collected, phosphate in urine could supply 22% of the total demand.[13]

Benefits of ecosan systems include:[1]

• Minimizing the introduction of pathogens from human excreta into the water cycle (groundwater and surface water) - for example groundwater pollution by pit latrines.
• Conservation of resources through lower water consumption, substitution of mineral fertilizer and minimization of water pollution.
• Less reliance on mined phosphorus and other non-renewable resources for fertilizer production.
• Reduced consumption of energy in fertilizer production: Urea is a major component of urine, yet we produce vast quantities of urea by using fossil fuels. By properly managing urine, treatment costs as well as fertilizer costs can be reduced.

The recovery and use of urine and feces in "dry sanitation systems", i.e. without sewers or without mixing substantial amounts of water with the excreta, has been practiced by almost all cultures. The reuse was not limited to agricultural production. The Romans, for example, were aware of the bleaching attribute of the ammonia within urine and used it to whiten clothing.[21]

Many traditional agricultural societies recognized the value of human waste for soil fertility and practised the "dry" collection and reuse of excreta. This enabled them to live in communities in which nutrients and organic matter contained in excreta were returned to the soil. Historical descriptions about these practices are sparse, but it is known that excreta reuse was practiced widely in Asia (for example in China, Japan, Vietnam, Cambodia, Korea) but also in Central and South America. However, the most renowned example of the organised collection and use of human excreta to support food production is that of China.[22] The value of "night soil" as a fertilizer was recognized with well-developed systems in place to enable the collection of excreta from cities and its transportation to fields. The Chinese were aware of the benefits of using excreta in crop production more than 2500 years ago, enabling them to sustain more people at a higher density than any other system of agriculture.[21]

In Mexico the Aztec culture collected human excreta for agricultural use. One example of this practice has been documented for the Aztec city of Tenochtitlan which was founded in 1325 and was one of the last cities of pre-Hispanic Mexico (conquered in 1521 by the Spanish): The population placed the sweepings in special boats moored at docks around the city. Mixtures of sweepings and excreta were used to fertilize the chinampas (agricultural fields) or to bolster the banks bordering the lake. Urine was collected in containers in all houses, then mixed with mud and used as a fabric dye. The Aztecs recognized the importance of recycling nutrients and compounds contained in wastewater.[23]

In Peru, the Incas had a high regard for excreta as a fertilizer, which was stored, dried and pulverized to be utilized when planting maize.[24]

In the Middle Ages, the use of excreta and greywater in agricultural production was the norm. European cities were rapidly urbanizing and sanitation was becoming an increasingly serious problem, whilst at the same time the cities themselves were becoming an increasingly important source of agricultural nutrients. The practice of directly using the nutrients in excreta and wastewater for agriculture therefore continued in Europe into the middle of the 19th century. Farmers, recognizing the value of excreta, were eager to get these fertilizers to increase production and urban sanitation benefited.[21] This practice was also called gong farmer in England but carried many health risks for those involved with transporting the excreta and fecal sludge.

Besides direct use, excreta was also processed to produce pure chemicals. Using nitraries and nitre beds, one extract the nitrogen within as potassium nitrate (KNO₃), a key ingredient in gunpowder.[25] KNO₃ was also responsible for the discovery of nitric acid in the 17th century.[26]

Traditional forms of sanitation and excreta reuse have continued in various parts of the world for centuries and were still common practice at the advent of the Industrial Revolution. Even as the world became increasingly more urbanised, the nutrients in excreta collected from urban sanitation systems without mixing with water were still used in many societies as a resource to maintain soil fertility, despite rising population densities.[21]

Recovery of nutrients from excreta in non-sewered sanitation systems was addressing the sanitation problems in settlements in Europe and elsewhere and was contributing to securing agricultural productivity.[21] However, the practice did not become the dominant approach to urban sanitation in the 20th century and was gradually replaced with sewer-based sanitation systems without nutrient recovery (apart from agricultural reuse of sewage sludge in some cases) – at least for cities that can afford it.

There were four main driving factors that led to the demise in the recovery and use of excreta and greywater from European cities in the 19th century:[21]

• Growth of urban settlements and increasing distance from agricultural fields.
• Increasing water consumption and use of flush toilet: Water flushing greatly increased the volume of sewage, at the same time diluting the nutrients, making it virtually impossible for them to be recovered and reused as they previously were.
• Production of cheap synthetic fertilizers, making any efforts to recover and reuse the nutrients and organic material from the large volumes of sewage obsolete.
• Political intervention as a consequence of the perceived need for a change with regards to how to deal with odorous substances: Up until the end of the nineteenth century the dominant theory on the spread of illness was the miasma theory. This theory stated that everything that smelled had to be gotten rid of because inhaling bad smells was thought to lead to illness.

The use of (odorous) animal manure in agriculture has continued through to this day, probably because the odor of manure was not thought to contribute to human illnesses.

The recovery of nutrients from wastewater still continues in two forms:

• Wastewater reuse or resource recovery: Use of raw, treated or partially treated wastewater for irrigation in agriculture (with the associated health risks if it is done in an improper way which is often the case in developing countries); and
• Application of sewage sludge to agricultural lands which is not without controversy in many industrialized countries due to the risks of polluting soils with heavy metals and micropollutants if not managed properly (see biosolids).

The Swedish International Development Cooperation Agency (Sida) funded the "SanRes R&D programme" during 1993 to 2001 which lay the foundation for the subsequent "EcoSanRes programme" carried out by Stockholm Environment Institute (2002–2011).[27][28] A publication by Sida called "Ecological sanitation" in 1998 compiled the knowledge generated to date about ecosan in a popular book which was published as a second edition in 2004.[29] The book has also been translated into Chinese,[30] French[31] and Spanish.[32]

The German government enterprise GIZ also had a large "ecosan program" from 2001 to 2012. Whilst the term "ecosan" was preferred in the initial stages of this program, it was from 2007 onwards more and more replaced by the broader term "sustainable sanitation". In fact, the Sustainable Sanitation Alliance was founded in 2007 in an attempt to broaden the ecosan concept and to bring together various actors under one umbrella.

Research into how to make reuse of urine and feces safe in agriculture was carried out by Swedish researchers, for example Hakan Jönsson and his team, whose publication on "Guidelines on the Use of Urine and feces in Crop Production"[33] was a milestone which was later incorporated into the WHO "Guidelines on Safe Reuse of Wastewater, Excreta and Greywater" from 2006.[14] The multiple barrier concept to reuse, which is the key cornerstone of this publication, has led to a clear understanding on how excreta reuse can be done safely.

Initially, there were dedicated "ecosan conferences" to present and discuss research on ecosan projects:

• A first workshop on ecological sanitation was held in Balingsholm, Sweden in 1997, where all the then established ecosan experts, such as Håkan Jönsson, Peter Morgan (winner of the 2013 Stockholm Water Prize),[17] Ron Sawyer, George Anna Clark and Gunder Edström participated.
• Workshop in Mexico in 1999 with the title "Closing the Loop - Ecological sanitation for food security"[34]
• Ecosan conference in Bonn, Germany in 2000
• First international ecosan conference in Nanning, China in 2001
• Second ecosan conference in Lübeck Germany in 2003[35]
• Third ecosan conference in Durban, South Africa in 2005
• Ecosan conference in Fortaleza, Brazil called "International Conference on Sustainable Sanitation - Water and Food Security for Latin America" in 2007[36]

Since then the ecosan theme has been integrated into other WASH conferences, and separate large ecosan conferences have no longer been organised.

During the 1990s, when the term ecosan was something new, discussions were heated and confrontational. Supporters of ecosan claimed the corner on containment, treatment and reuse. The proponents of conventional sanitation systems on the other side defended pit latrines and waterborne sewage systems. Ecosan supporters criticized conventional sanitation for contaminating waterways with nutrients and pathogens. Since about 2007, the two opposing sides have slowly found ways of dealing with each other, and the formation of the Sustainable Sanitation Alliance in that year has further helped to provide a space for all sanitation actors to meet and push into the same direction of sustainable sanitation.