Ecological sanitation, often shortened to ecosan (also spelled eco-san or EcoSan), is also called circular sanitation because it uses ideas from the circular economy. This method focuses on safely reusing human waste in farming. It is not a specific tool or machine but a way of thinking that seeks to "close the loop" by safely returning nutrients and organic material from waste to the soil. A key goal is to reduce the use of non-renewable resources. When planned and managed correctly, ecosan systems create a safe process to turn human waste into nutrients for the soil and water for the land. Ecosan is also referred to as resource-oriented sanitation.

Definition

The meaning of ecosan has changed over time. In 2012, a widely accepted definition was created by experts from Sweden: "Ecological sanitation systems are systems that allow safe reuse of nutrients for growing crops in a way that uses as few non-renewable resources as possible. These systems can be sustainable if technical, organizational, social, and money-related factors are handled correctly."

Before 2012, ecosan was often linked to urine diversion, especially to urine-diverting dry toilets (UDDTs), a type of dry toilet. Because of this, the term "ecosan toilet" is often used to describe a UDDT. However, the ecosan idea should not be limited to just one type of toilet. Also, UDDTs can be used without reuse activities, which means they are not in line with the ecosan concept. An example is the 80,000 UDDTs built by eThekwini Municipality near Durban, South Africa, which were not part of a reuse plan.

The term "ecosan" was first used in 1995. The first project started in 1996 in Ethiopia, led by an organization called Sudea. A group of three people—Dr. Torsten Modig from Umeå University, Almaz Terrefe, the team leader, and Gunder Edström, a hygiene expert—chose a densely populated area as the starting point. They used urine-diverting dry toilets (UDDTs) along with reuse activities.

In the ecosan concept, human waste and wastewater are seen as potential resources. This is why the idea is also called "resource-oriented sanitation." The term "productive sanitation" has been used since about 2006.

The ecosan definition focuses on the health, environment, and resource aspects of sustainable sanitation. This means ecosan is not automatically sustainable, but ecosan systems can be made sustainable if technical, organizational, social, and money-related factors are managed well. Ecosan systems might not be sustainable if there is not enough user support or if the system costs are too high for the people who use it, making it financially unstable over time.

Overview

The main goals of ecological sanitation are to lower health dangers from poor sanitation, polluted water, and waste; to stop pollution of groundwater and surface water; and to reuse nutrients or energy found in waste.

The idea of "safely recycling" in ecosan includes making sure waste is clean, free from harmful germs, and safe from dangerous chemicals. Recycled human waste, whether solid or liquid, must be of high quality, with no harmful germs or chemicals. The phrase "use of non-renewable resources is minimized" means that the amount of resources saved by recycling must be greater than the resources used during recycling.

Ecosan is based on managing the movement of materials as part of a system that protects the environment and uses resources wisely. This system is designed to meet the needs of people and local conditions. It does not support any one type of sanitation technology but instead focuses on treating waste as valuable materials rather than waste to be thrown away.

The earliest supporters of ecosan systems focused on improving farming by reusing human waste as fertilizer, which also helped improve people's health. They aimed to reduce diseases caused by germs in feces and also to reduce malnutrition in children. The connection between clean water, sanitation, nutrition, a disease called environmental enteropathy, and slow child growth has become a major focus in the water, sanitation, and hygiene (WASH) field since around 2013.

Studies worldwide have shown that using treated human waste in farming helps crops grow better. This is especially true for urine, which has been used successfully on plants like spinach, maize, and fruit trees. A study in Finland found that using urine and wood ash could increase the growth of red beet roots by 27% and 10%, respectively. Urine is a useful fertilizer because it contains nitrogen, phosphorus, potassium, and important nutrients.

Ecosan systems also aim to address the possible shortage of phosphorus, a key ingredient for plant growth and fertilizer. Phosphorus is a limited resource, and known supplies are becoming harder to find and more expensive to extract. This is called the "peak phosphorus" crisis. One study found that collecting phosphorus from urine could meet 22% of the world's total need for phosphorus.

Benefits of ecosan systems include:
• Reducing harmful germs from human waste entering groundwater and surface water, such as pollution from pit latrines.
• Saving resources by using less water, replacing mineral fertilizers, and reducing water pollution.
• Using less mined phosphorus and other non-renewable materials for fertilizers.
• Saving energy in fertilizer production: Urine contains urea, a major component of fertilizers, which is made using fossil fuels. Properly managing urine can lower both treatment and fertilizer costs.

Challenges

The ecosan approach has been criticized for focusing too much on reusing waste in farming while not considering other important parts of sustainable sanitation. Ecosan systems may not be sustainable if people do not accept them or if the system costs too much for the people who need it, making it hard to keep the system running over time.

Some people who support ecosan have been criticized for being too strict, placing too much importance on protecting the environment instead of focusing on keeping people healthy and providing affordable sanitation. For example, some ecosan toilets, like UDDTs, can cost more to build than simple pit latrines, even though they may be cheaper to maintain later.

The safety of ecosan systems depends on how well they destroy harmful germs during the treatment process. This is a topic that people who support and oppose ecosan systems often debate. However, the WHO Guidelines on Reuse, which include a plan with many safety steps, have helped create a shared standard for safely reusing waste. Still, questions remain about whether ecosan systems can be used by millions of people and how to make them safe enough to operate. The excitement about ecosan in the early 2000s has turned into a realization that changing people’s habits and attitudes about sanitation requires time and effort.

Peter Morgan, a pioneer of handpumps and ventilated pit latrines (VIPs), was awarded the Stockholm Water Prize in 2013 for his work on ecosan-type toilets, including the Arborloo, the Skyloo, and the Fossa alterna. He is known as one of the main creators of ecological sanitation solutions that allow safe reuse of human waste to improve soil and grow crops. His ecosan toilets are now used in many countries worldwide, turning a sanitation problem into a useful resource.

Since about 2011, the Bill and Melinda Gates Foundation has funded many research projects focused on recovering resources from waste. These projects may be influenced by the ecosan concept, even though researchers do not always use the term "ecosan."

Technologies used in ecosan systems

Ecosan is a system that can be adapted to different situations by combining various methods. It includes both systems that handle waste in one central location and those that handle waste in different places. It also combines methods that use water with those that do not, and methods that use advanced technology with those that use simpler technology. By considering many different options, solutions that work best for each situation can be created. Many Ecosan systems separate waste at the source, meaning different types of waste are kept apart. This makes it easier to treat waste and reuse it safely. The most common type of technology used in Ecosan systems is the urine-diverting dry toilet. However, other technologies may also be used, such as vacuum toilets connected to biogas plants, constructed wetlands, composting toilets, and others. Examples of Ecosan projects around the world are listed in a report published by GIZ in 2012. Additional examples can be found in case studies published by the Sustainable Sanitation Alliance, which focus on projects that reuse waste materials.

History

The reuse of urine and feces in "dry sanitation systems," which do not use sewers or mix large amounts of water with waste, has been practiced by nearly all cultures. This practice was not limited to farming. For example, the Romans knew that urine could whiten clothes because of the ammonia it contained.

Many traditional farming societies recognized the value of human waste for soil fertility and collected it without using water. This allowed them to return nutrients and organic matter from waste to the soil. Although historical records about these practices are limited, it is known that reuse of human waste was common in Asia (such as in China, Japan, Vietnam, Cambodia, and Korea) and also in Central and South America. The most well-known example of organized reuse of human waste for farming was in China. The Chinese valued "night soil" as fertilizer and had systems to collect waste from cities and transport it to fields. Over 2,500 years ago, the Chinese understood the benefits of using waste in farming, which helped them support larger populations in smaller areas.

In Mexico, the Aztec culture collected human waste for farming. In the city of Tenochtitlan, which was built in 1325 and conquered by the Spanish in 1521, people placed waste in special boats near the city. Mixtures of waste and other materials were used to fertilize chinampas (floating gardens) or strengthen the edges of lakes. Urine was collected in containers in homes, then mixed with mud to make fabric dye. The Aztecs understood the importance of recycling nutrients from waste.

In Peru, the Incas stored, dried, and crushed human waste to use as fertilizer for planting maize.

During the Middle Ages, the use of human waste and greywater (wastewater from sinks and baths) in farming was common. European cities were growing quickly, and sanitation became a serious problem. At the same time, cities became important sources of nutrients for farming. Farmers used waste and wastewater for agriculture until the middle of the 19th century. This practice was called "gong farmer" in England but carried health risks for those who transported waste.

In addition to direct use, waste was sometimes processed to create chemicals. Using methods like nitraries and nitre beds, nitrogen was extracted as potassium nitrate (KNO₃), a key ingredient in gunpowder. KNO₃ also helped scientists discover nitric acid in the 17th century.

Traditional sanitation and waste reuse continued in many parts of the world for centuries and were still common when the Industrial Revolution began. Even as cities grew, waste collected from sanitation systems without water was used in many societies to maintain soil fertility, despite increasing population density.

Reusing nutrients from waste in non-sewered systems helped solve sanitation problems in Europe and other regions while supporting farming. However, this practice was not the main way cities handled waste in the 20th century and was replaced by sewer systems that did not recover nutrients (except for some reuse of sewage sludge in agriculture).

Four main reasons led to the decline of waste and greywater reuse in European cities during the 19th century:

• Growth of cities and greater distance from farmland.
• Increased use of water-flushing toilets, which diluted waste and made it harder to reuse nutrients.
• The production of cheap synthetic fertilizers made recovering nutrients from waste unnecessary.
• Political changes due to concerns about bad smells, which were linked to illness under the miasma theory (the belief that bad smells caused disease).

The use of animal manure in farming continues today, possibly because its smell is not thought to cause illness.

Nutrient recovery from wastewater still happens in two ways:

• Reusing wastewater for irrigation in farming, which can carry health risks if not done safely.
• Applying treated sewage sludge to farmland, which is controversial in some countries due to risks of soil pollution from heavy metals and other chemicals.

The Swedish International Development Cooperation Agency (Sida) funded the "SanRes R&D programme" from 1993 to 2001, which led to the later "EcoSanRes programme" by the Stockholm Environment Institute (2002–2011). A 1998 Sida publication called "Ecological sanitation" summarized knowledge about ecosan and was later translated into Chinese, French, and Spanish.

The German government's GIZ organization ran an "ecosan program" from 2001 to 2012. Initially, the term "ecosan" was used, but it was later replaced by the broader term "sustainable sanitation." The Sustainable Sanitation Alliance was created in 2007 to expand the ecosan concept and unite different groups.

Research on safely reusing urine and feces in farming was led by Swedish scientists like Hakan Jönsson. His work on "Guidelines on the Use of Urine and Feces in Crop Production" influenced the World Health Organization's 2006 guidelines on safe reuse. These guidelines introduced the "multiple barrier concept," which outlines steps to ensure safe reuse of waste.

Early ecosan conferences included:

• A 1997 workshop in Sweden with experts like Håkan Jönsson and Peter Morgan.
• A 1999 workshop in Mexico titled "Closing the Loop – Ecological Sanitation for Food Security."
• An ecosan conference in Germany in 2000.
• The first international ecosan conference in China in 2001.
• The second international ecosan conference in 2002.

Examples

• Sweden leads Europe in using ecosan on a large scale. For example, Tanum Municipality in Sweden introduced urine separation toilets because of difficult terrain at first, and later to recycle phosphorus.
• In 2013, Sweden allowed certification of safe and clean blackwater (urine and human waste) from systems like vacuum toilets or septic tanks. This certification, developed by the Swedish Institute for Agricultural and Environmental Engineering, helps farmers use human waste as fertilizer. The Federation of Swedish Farmers supported this effort. Additionally, the Swedish EPA reduced the hygiene risk linked to urine in 2014.
• The Stockholm Environment Institute (SEI) led a global ecosan research program called "Ecosanres" from 2001 to 2011. One project tested "dry ecosan" (using dry toilets) in multi-story buildings in Erdos, China, to recover nutrients from waste. This project, called the Erdos Eco-Town Project, aimed to save water and improve sanitation in a drought-prone area. However, the system was removed after a few years due to technical, social, and institutional challenges, and the project did not achieve its goal of nutrient recovery. This failure has highlighted the difficulties of using ecosan in urban areas.
• The Rich Earth Institute in Brattleboro, Vermont, USA, is an organization that focuses on using human urine as fertilizer. It runs the only community-scale program in the U.S. to collect and treat urine for reuse in agriculture.
• In Haiti, an organization called SOIL built "ecosan toilets" (UDDTs) as part of aid efforts after the 2010 earthquake. Over 20,000 people now use these toilets, and more than 400,000 liters of compost have been made from waste. This compost is used for farming and reforestation. SOIL’s composting process effectively kills harmful parasite eggs in waste within 16 weeks. Their methods may help other countries improve sanitation.
• Sanitation First, a UK-based organization, builds ecosan facilities (UDDTs) in developing regions. They work mainly in Tamil Nadu, India, where the government provides financial support. They have also built ecosan toilets in other parts of India, Kenya, and Sierra Leone. As of 2021, 58,000 people worldwide use their ecosan toilets.
• The NGO CREPA, which operated in French-speaking West Africa from 2002 to 2010, promoted ecosan, especially UDDTs, with a focus on using waste in agriculture. Their work was concentrated in Burkina Faso.