Ecological sanitation

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Ecosan concept showing a separation of flow streams, treatment and reuse

Ecological sanitation, which is commonly abbreviated to ecosan (also spelled eco-san or EcoSan), is an approach, rather than a technology or a device which is characterized by a desire to "close the loop" (mainly for the nutrients and organic matter) between sanitation and agriculture in a safe manner. Put in other words: "Ecosan systems safely recycle excreta resources (plant nutrients and organic matter) to crop production in such a way that the use of non-renewable resources is minimised". When properly designed and operated, ecosan systems provide a hygienically safe, economical, and closed-loop system to convert human excreta into nutrients to be returned to the soil, and water to be returned to the land.

The main objectives of ecological sanitation are:[1]

  • To reuse nutrients or energy contained within wastes.

Traditionally, ecosan has often been associated with urine diversion and in particular with urine-diverting dry toilets (UDDTs), a form of dry toilet. For this reason, the term "ecosan toilet" is widely used in various languages and people using this term are usually referring to a UDDT.[2] However, as stated above, the ecosan concept should not be limited to one particular type of toilet. Also, UDDTs can be used without having any reuse activities in which case they are not in line with the ecosan concept (example: 80,000 UDDTs implemented by eThekwini Municipality near Durban, South Africa).[3]

Concepts[edit]

Poster by EcoSanRes program: Closing the loop on Sanitation (2005)
Ecosan closing the loop poster (in French), by the NGO CREPA in 2005, UDDTs are used in this example

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 minimised" means that the gain in resources by recycling shall be larger than the cost of resources by recycling.

Ecosan is based on an overall view 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 favour 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]

Right from the start, the first proponents of ecosan systems had a strong focus on increasing agricultural productivity (via the excreta-based fertilisers) and thus improving the nutritional status of the people at the same time as providing them with safe sanitation.[4] Disease reduction was meant to be achieved not only by reducing faecally transmitted infections but also by reducing malnutrition, particularly in children. This link between WASH, nutrition and a disease called environmental enteropathy (or tropical enteropathy)[5] as well as stunting (or stunted growth) of children is still very relevant to this day and has recently risen to the top of the agenda of the WASH sector.

Another aspect that ecosan systems are trying to address is to prepare ourselves for an upcoming shortage of phosphorus which is a limited resource and is needed in fertiliser production.[6] Phosphorus has an important role in fertiliser production and for plant growth but is a limited mineral resource.[7] The situation is similar for potassium. Known mineral phosphate rock reserves, in particular, are becoming scarce and increasingly costly to extract - this is also called the "peak phosphorus" crisis. One day, recycling of excreta will be required to meet future demands, and ecosan systems can play an important contribution for this.

Many studies have shown that human excreta based fertiliser has the same or even better fertilising properties as commercially manufactured fertilisers, for example in reuse trials in Zimbabwe.[8] In another example, a 2010 study in Finland showed 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 fertiliser, containing nitrogen, phosphorus, potassium and important micro-nutrients.[10]

History[edit]

Excreta reuse in dry sanitation systems[edit]

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.[11]

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.[12] 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.[11]

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.[13]

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.

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.[11] This practice was also called gong farmer in England but carried many health risks for those involved with transporting the excreta and faecal sludge.

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.[11]

Decline in recovery of nutrients from human excreta in dry systems[edit]

Recovery of nutrients and organic matter from excreta and greywater in non-sewered sanitation systems was addressing the sanitation problems in settlements in Europe and elsewhere and was contributing to securing agricultural productivity.[14] 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:[11]

  • Growth of urban settlements and increasing distance from agricultural fields: urban settlements had grown dramatically over the centuries. The logistical challenge of removing the faeces of a booming population from densely packed city centres to bring to agricultural areas many miles away proved too great.[14]
  • 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.[14]
  • Production of cheap synthetic fertilisers: The nutrient demand of farmers was eventually met by cheap chemical fertilisers, making any efforts to recover and reuse the nutrients and organic material from the large volumes of sewage completely obsolete.[14]
  • 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 off because inhaling bad smells was thought to lead to illness. The miasma theory did contribute to containing disease in urban settlements, but did not allow for a suitable approach to safe excreta reuse to be adopted.[14]

Interestingly, the use of (odorous) animal manure in agriculture continued through to this day, probably because the odour of manure was not thought to contribute to human illnesses and because the vast amount of manure could not be "flushed away" like human excreta can.

Even in situations where dry sanitation systems have been replaced by sewer-based sanitation systems, the recovery of nutrients from wastewater may continue 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 industrialised countries due to the risks of polluting soils with heavy metals and micropollutants if not managed properly.

Research in the 1990s[edit]

Research into how to make reuse of urine and faeces 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 Faeces in Crop Production"[15] was a milestone which was later incorporated into the WHO "Guidelines on Safe Reuse of Wastewater, Excreta and Greywater" from 2006.[16] 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.

The term "ecosan"[edit]

The term "ecosan" was first used in about the 1990s (or perhaps even late 1980s) by an NGO in Ethiopia called Sudea. They used it for urine-diverting dry toilets coupled with reuse activities. It was further used and defined by Swedish experts, many of whom worked at Stockholm Environment Institute which had a program, called EcosanRes, running from 2001-2011 where they did research on ecosan. Important publications about the safety of reuse where published from that group which were also taken up in the WHO Guidelines from 2006. GIZ also had a large "ecosan program" from 2001 to 2012 which was led by Christine Werner during the period 2001 to 2008 who has authored or co-authored many publications on this topic.

In the early days 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 "establishment" defended deep pit latrines, and waterborne systems and they felt offended. Ecosan supporters criticised conventional sanitation for killing children, contaminating waterways with nutrients and pathogens and making helminth worms a global pandemic with upwards of 2 billion cases. Since then, the two opposing sides have slowly found ways of dealing with each other, and the formation of the Sustainable Sanitation Alliance has further helped to provide a space for all sanitation actors to meet and push into the same direction of sustainable sanitation.

Initially, there were dedicated "ecosan conferences": One in Bonn, Germany in 2000 followed by the "first" ecosan conference in Nanning, China in 2001, the "second" ecosan conference in Lübeck Germany in 2003 and the third one in Durban, South Africa in 2005. Since then the ecosan theme has been integrated into other WASH conferences, and separate large ecosan conferences have no longer been organised.

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 used since about 2006.[17]

Advantages[edit]

Advantages of ecosan systems are:

  • Minimising the introduction of pathogens from human excreta into the water cycle (groundwater and surface water) - a major consideration in low-lying geographies is pollution of groundwater by pit latrines. In many areas where the water table is high, pit latrines directly pollute the water table, potentially affecting the large numbers of people.
  • Promotion of safe, hygienic recovery and use of nutrients (nitrogen and phosphorus), organics, trace elements, water and energy
  • Preservation of soil fertility, improvement of agricultural productivity and food security
  • Contribution to the conservation of resources through lower water consumption, substitution of mineral fertiliser and minimisation of water pollution
  • Less reliance on mined phosphorus for fertiliser production
  • Energy reduction in fertiliser production: Urea is the 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. Feces also contains recognized nutrients, and could be used for modern agriculture, as micronutrient deficiency is a significant problem.

Is sustainable sanitation the same as ecosan?[edit]

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.

Technologies used in ecosan systems[edit]

Possible technology components for sustainable sanitation, of which ecosan is a sub-set focussing on the reuse possibilities

Ecosan offers a flexible framework, where centralised elements can be combined with decentralised ones, waterborne with dry sanitation, high-tech with low-tech, etc. By considering a much larger range of options, optimal and economic solutions can be developed for each particular situation.[18] Technologies used in ecosan systems often - but not always - include elements of source separation, i.e. keeping different waste streams separate, as this can make treatment and safe reuse easier.

The most common technology used in ecosan systems is the urine-diverting dry toilet, but ecosan systems can also use other technologies, such as vacuum toilets coupled with biogas plants, constructed wetlands, composting toilets and so forth.

Examples of ecosan projects worldwie can be found in a list published by GIZ in 2012 [19] as well as in those case studies published by the Sustainable Sanitation Alliance that are focused on reuse activities.[20]

Criticisms[edit]

The ecosan approach has been criticised for being overly focussed on reuse in agriculture, whilst neglecting some of the other criteria for sustainable sanitation. In fact, 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.

Some proponents of ecosan have been criticised for being too dogmatic, which an over-emphasis on environmental resource protection rather than a focus on public health protection and provision of sanitation at a very low cost (for example UDDTs, which some people call "ecosan toilets" may be more expensive to build than pit latrines, even if in the longer term they are cheaper to maintain).

The safety of ecosan systems in terms of pathogen destruction during the various treatment processes is a continuous topic of debate between proponents and opponents of ecosan systems. However, the publication of the WHO Guidelines on Reuse,[16] with its multiple barrier concept, has gone a long way in establishing a common framework for safe reuse.

Whether ecosan is the same as sustaianable sanitation or not, whether it is "better" or "worse" than sustainable sanitation, whether ecosan systems can ever be scaled up to reach millions of people, whether they are sufficiently safe to operate - all these issues are regularly being debated amongst the experts.[21] The initial excitement in the early 2000s by the ecosan pioneers has changed into a realisation that changing attitudes and behaviours in sanitation takes a very long time and a lot of patience.

Acknowledgement for ecosan came with the awarding of the Stockholm Water Prize in 2013 to Peter Morgan, a pioneer of handpumps and ventilated pit latrines (VIPs) in addition to ecosan-type toilets[8][22] (the Arborloo, the Skyloo and the Fossa alterna). Dr. Morgan is renowned as one of the leading creators and proponents of ecological sanitation solutions, which enable the safe reuse of human waste to enhance soil quality and crop production. His ecosan-type toilets are now in use in countries across the globe, centred on converting a sanitary problem into a productive resource.[23]

Also many of the research projects that the Bill and Melinda Gates Foundation have been funding since about 2011 in sanitation are dealing with resource recovery - this might well be a legacy of the ecosan concept, even if the term "ecosan" is not used by these researchers.

Examples[edit]

  • Sweden is the leader in Europe to put ecosan into practice at a larger scale. For example, Tanum Municipality in Sweden has introduced urine separation toilets to recover phosphorus. Sweden has also made it possible in 2003 to certify safe and sanitized blackwater urine and human waste from latrines and for further use as a recognized fertilizer. The criteria for the certification have been developed by the Swedish Institute for Agricultural and Environmental Engineering and may pave the way for farmers to use human waste for agricultural production. The Federation of Swedish Farmers have been active in this development. Furthermore, the Swedish EPA in their last proposal[24] in 2014 has downgraded the hygiene risk associated with urine. Previously the normal storage requirement for hygenic quality for large scale use of urine was 6 months. Now they propose decreasing this to one month.
  • Stockholm Environment Institute (SEI) ran a large worldwide ecosan research programme called "Ecosanres" from 2001 to 2011. One of the ecosan pilot projects of this programme was a large scale implementation of urine-diverting dry toilets (UDDTs) in multi-story buildings together with other technologies to allow resource recovery from excreta.[25] This project was called the Erdos Eco-Town Project in a town called Erdos in the Inner Mongolia Autonomous Region of China. It was a collaboration between the Dongsheng District government in Erdos and the Stockholm Environment Institute and aimed to save water and provide sanitation services in this drought-stricken and rapidly urbanizing area of northern China. For a variety of technical, social and institutional reasons, the UDDTs were removed after only a few years and the project failed to deliver in the area of nutrient recovery. This project is now well documented and has raised more awareness of the challenges and disadvantages of "urban ecosan".[26][27]
  • SOIL in Haiti built what they call "ecosan toilets" (UDDTs) as part of the emergency relief effort following the 2010 Haiti earthquake. More than 20,000 Haitians are currently using SOIL ecological sanitation toilets and SOIL has produced over 400,000 liters of compost as a result.[28] The compost is used for agricultural and reforestation projects.[29]
  • Wherever the Need, an NGO in the UK[30] build ecosan facilities (UDDTs) in various parts of the developing world. They predominantly work in Tamil Nadu (India), where the Tamil Nadu State Government provides subsidies for their work. Wherever the Need have also constructed ecosan in other parts of rural India, Kenya and Sierra Leone. According to their website, heir ecosan projects have positively affected 50,000 people in the developing world.
  • The NGO CREPA which was operating in the French-speaking West Africa region (now bi-lingual and called WSA - Water and Sanitation in Africa) was very active in ecosan promotion during the years of 2002 - 2010 (?) with a strong focus on UDDTs coupled with reuse in agriculture, especially in Burkina Faso.

References[edit]

  1. ^ a b GTZ, IWA (2003). Ecosan - closing the loop - Proceedings of the 2nd international symposium, 7th –11th April 2003, Lübeck, Germany. Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH and International Water Association (IWA)
  2. ^ Rieck, C., von Münch, E., Hoffmann, H. (2012). Technology review of urine-diverting dry toilets (UDDTs) - Overview on design, management, maintenance and costs. Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
  3. ^ Roma, E., Holzwarth, S., Buckley, C. (2011). Large-scale peri-urban and rural sanitation with UDDTs, eThekwini Municipality (Durban), South Africa - Case study of sustainable sanitation projects. Sustainable Sanitation Alliance (SuSanA)
  4. ^ Esrey, S., Andersson, I., Hillers, A., Sawyer, R. (2001). Closing the Loop - Ecological sanitation for food security. Swedish International Development Cooperation Agency, 2000.
  5. ^ Humphrey, J. H. (2009). Child undernutrition, tropical enteropathy, toilets, and handwashing. The Lancet, Volume 374, Issue 9694, pages 1032 - 1035
  6. ^ Schröder, J., Cordell, D., Smit, A., Rosemarin, A. (2010). Sustainable use of phosphorus. Plant Research International, Wageningen, The Netherlands
  7. ^ Soil Association (2010). A rock and hard place - Peak phosphorus and the threat to our food security. Soil Association, Bristol, UK
  8. ^ a b Morgan, P. (2010). Ecological toilets - Start simple and upgrade from arborloo to VIP. Harare, Zimbabwe
  9. ^ Pradhan, Surendra K. "Human Urine and Wood Ash as Plant Nutrients for Red Beet (Beta vulgaris) Cultivation: Impacts on Yield Quality". Journal of Agricultural and Food Chemistry. Retrieved 10 February 2014. 
  10. ^ Richert, A., Gensch, R., Jönsson, H., Stenström, T., Dagerskog, L. (2010). Practical guidance on the use of urine in crop production. Stockholm Environment Institute (SEI), Sweden
  11. ^ a b c d e Lüthi, C., Panesar, A., Schütze, T., Norström, A., McConville, J., Parkinson, J., Saywell, D., Ingle, R. (2011). Sustainable sanitation in cities: a framework for action. Sustainable Sanitation Alliance (SuSanA), International Forum on Urbanism (IFoU), Papiroz Publishing House
  12. ^ Brown, AD (2003). Feed or feedback: agriculture, population dynamics and the state the planet. International Books. Utrecht, The Netherlands. ISBN 90 5727 048X
  13. ^ Becerril, J. E. and Jiménez, B. (2007) Potable water and sanitation in Tenochtitlan: Aztec culture, Water Science & Technology: Water Supply Vol 7 No 1 pp 147–154, doi:10.2166/ws.2007.017
  14. ^ a b c d e Bracken, P., Wachtler, A., Panesar, A.R., Lange, J. (2007) The road not taken: how traditional excreta and greywater management may point the way to a sustainable future, Water Science & Technology: Water Supply Vol 7 No 1 pp 219–227, doi:10.2166/ws.2007.025
  15. ^ Joensson, H., Richert Stintzing, A., Vinneras, B., Salomon, E. (2004). Guidelines on the Use of Urine and Faeces in Crop Production. Stockholm Environment Institute, Sweden
  16. ^ a b WHO (2006). WHO Guidelines for the Safe Use of Wastewater, Excreta and Greywater - Volume IV: Excreta and greywater use in agriculture. World Health Organization (WHO), Geneva, Switzerland
  17. ^ "Conversation on SuSanA Discussion Forum". March 2012. Retrieved 18 October 2014. 
  18. ^ Jenssen, P., Heeb, J., Huba-Mang, E., Gnanakan, K., Warner, W., Refsgaard, K., Stenström, T., Guterstam, B., Alsen, K. (2004). Ecological Sanitation and Reuse of Wastewater - A thinkpiece on ecological sanitation. The Agricultural University of Norway
  19. ^ GIZ (2012). Worldwide list of 324 documented ecosan projects by various organisations. Gesellschaft für internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
  20. ^ "Case studies of sustainable sanitation projects". Sustainable Sanitation Alliance. 2013. Retrieved 18 October 2014. 
  21. ^ "Discussion about ecosan on SuSanA Discussion Forum". 1 September 2014. Retrieved 18 October 2014. 
  22. ^ Morgan, P. (2007). Toilets That Make Compost - Low-cost, sanitary toilets that produce valuable compost for crops in an African context. Stockholm Environment Institute, ISBN 978-9-197-60222-8
  23. ^ "SIWI website". 2013. Retrieved 17 October 2014. 
  24. ^ "Swedish EPA". Retrieved 18 October 2014. 
  25. ^ McConville, J., Rosemarin, A. (2012). Urine diversion dry toilets and greywater system, Erdos City, Inner Mongolia Autonomous Region, China - Case study of sustainable sanitation projects. Sustainable Sanitation Alliance (SuSanA)
  26. ^ Flores, A. (2010). Towards sustainable sanitation: evaluating the sustainability of resource-oriented sanitation. PhD Thesis, University of Cambridge, UK
  27. ^ Rosemarin, Arno; McConville, Jennifer; Flores, Amparo; Qiang, Zhu (2012). The challenges of urban ecological sanitation : lessons from the Erdos eco-town project. Practical Action Publishers. p. 116. ISBN 1853397687. 
  28. ^ SOIL (2011). The SOIL guide to ecological sanitation. Sustainable Organic Integrated Livelihoods (SOIL), Sherburne NY, USA
  29. ^ "Human Waste to Revive Haitian Farmland?", The National Geographic, Christine Dell'Amore, October 26, 2011
  30. ^ "wherevertheneed.org.uk". wherevertheneed.org.uk. Retrieved 2013-06-29. 

External links[edit]