Sustainable sanitation is a sanitation system designed to meet certain criteria and to work well over the long-term. Sustainable sanitation systems consider the entire "sanitation value chain", from the experience of the user, excreta and wastewater collection methods, transportation or conveyance of waste, treatment, and reuse or disposal. [2] The Sustainable Sanitation Alliance (SuSanA) includes five features (or criteria) in its definition of "sustainable sanitation": Systems need to be economically and socially acceptable, technically and institutionally appropriate and protect the environment and natural resources. [3]
The purpose of sustainable sanitation is the same as sanitation in general: to protect human health. However, "sustainable sanitation" attends to all processes of the system: This includes methods of collecting, transporting, treating and the disposal (or reuse) of waste. [2]
Increasingly, sustainable sanitation also involves the consideration of climate change related impacts on sanitation infrastructure and behaviour and the resilience of technologies and communities. [4]
The Joint Monitoring Programme for Water Supply and Sanitation (JMP) of the WHO (World Health Organization) and UNICEF (United Nations Children's Fund) was responsible for monitoring progress towards the Millennium Development Goal for drinking water and sanitation. For reasons of simplicity—being able to monitor the sanitation situation with household surveys—the JMP had to find a simple differentiation between "improved" sanitation (toilets that count towards the MDG goals) and "unimproved" sanitation (toilets that do not count towards the MDG goals).
According to the JMP definition, improved sanitation facilities include facilities which are: [5]
Unimproved sanitation facilities according to the JMP include: [5]
In some circumstances "improved" sanitation facilities can be regarded as not sustainable, whereas in other circumstances "unimproved" sanitation facilities can be regarded as sustainable. This is because it depends on the sanitation system, of which the toilet is only one part. For example, a pit latrine with a slab can become unsustainable sanitation if it is polluting the groundwater or if the waste sludge that is removed from the pit latrine is dumped into the environment. A bucket toilet can become sustainable if the collection, treatment and reuse or disposal of waste is taken care of in a safe manner, for example with the urine-diverting dry toilets that SOIL is employing in Haiti. [6]
Sustainable sanitation, defined with the five sustainability measures, may or may not have an focus on reuse of excreta, because the criterion of "protecting the natural resources" is only one of several that need to be aimed towards. In comparison, ecological sanitation (ecosan) has a strong focus on the reuse of waste.
The term is widely used since about 2009.
The main objective of a sanitation system is to protect and promote human health by providing a clean environment and breaking the cycle of disease. In order to be sustainable a sanitation system has to be not only economically viable, socially acceptable, and technically and institutionally appropriate, but it should also protect the environment and the natural resources. According to the Sustainable Sanitation Alliance, when improving an existing and/or designing a new sanitation system, sustainability criteria related to the following aspects should be considered: [3]
Health aspects include the risk of exposure to pathogens and hazardous substances that could affect public health at all points of the sanitation system from the toilet via the collection and treatment system to the point of reuse or disposal. The topic also covers aspects such as hygiene, nutrition and the improvement of livelihood achieved by the application of a certain sanitation system, as well as downstream effects.
Environment and natural resources aspects involve the required energy, water and other natural resources for construction, operation and maintenance of the system, as well as the potential emissions to the environment resulting from use. It also includes the degree of recycling and reuse of excreta practiced and the effects of these, for example reusing the wastewater, returning nutrients and organic material to agriculture, and the protecting of other non-renewable resources, for example through the production of renewable energy (e.g. biogas or fuel wood).
Technology and operation aspects incorporate the functionality and the ease with which the system can be constructed, operated and monitored using the available human resources (e.g. the local community, technical team of the local utility etc.). It also concerns the suitability to achieve an efficient substance flow management from a technical point of view. Furthermore, it evaluates the robustness of the system, its vulnerability towards disasters, and the flexibility and adaptability of its technical elements to the existing infrastructure, to demographic and socio-economic developments and climate change.
Financial and economic issues relate to the capacity of households and communities to pay for sanitation, including the construction, maintenance and depreciation of the system. Besides the evaluation of investment, operation and maintenance costs, the topic also takes into account the economic benefits that can be obtained in "productive" sanitation systems, including benefits from the production of the recyclables (soil conditioner, fertiliser, energy and reclaimed water), employment creation, increased productivity through improved health and the reduction of environmental and public health costs.
Socio-cultural and institutional aspects take into account the socio-cultural acceptance and appropriateness of the system, convenience, system perceptions, gender issues and impacts on human dignity, the contribution to subsistence economies and food security, and legal and institutional aspects.
Most sanitation systems have been designed with the five aspects in mind, but in practice they are failing far too often because some of the criteria are not met. Since there is no one-for-all sanitation solution which fulfils the sustainability criteria, evaluation will depend on the local framework and will have to take into consideration the existing environmental, technical, socio-cultural and economic conditions.
Some basic principles to be observed when planning and implementing a sustainable sanitation system were endorsed by the members of the Water Supply and Sanitation Collaborative Council (the "Bellagio Principles for Sustainable Sanitation") during its 5th Global Forum in November 2000:
These planning guidelines have been revised further and are now used in various training courses for urban planners. [7] [8]
Sustainable sanitation that allows for resource recovery has the potential to contribute to circular economies and green cities, sustainable food chains, renewable energy, and new business models for private sector involvement. [9]
Five recommendations were made in 2020 for the optimization of resource recovery: (i) prioritize short systems that close the loop at the lowest possible level; (ii) separate waste streams as much as possible, because this allows for higher recovery potentials; (iii) use storage and treatment technologies that contain the products as much as possible, avoid leaching technologies (e.g. single pits) and technologies with high risk of volatilization (e.g. drying beds); (iv) design sinks to optimize recovery and avoid disposal sinks; and (v) combine various reuse options for different side streams (e.g. urine diversion systems that combine reuse of urine and production of biofuel from feces). [9]
Some examples for improving present sanitation practices in the short-term, purely from a technology perspective, are listed below:
With respect to the other sustainability factors, key areas of attention include:
Sanitation refers to public health conditions related to clean drinking water and treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation systems aim to protect human health by providing a clean environment that will stop the transmission of disease, especially through the fecal–oral route. For example, diarrhea, a main cause of malnutrition and stunted growth in children, can be reduced through adequate sanitation. There are many other diseases which are easily transmitted in communities that have low levels of sanitation, such as ascariasis, cholera, hepatitis, polio, schistosomiasis, and trachoma, to name just a few.
Greywater refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater from toilets. Sources of greywater include sinks, showers, baths, washing machines or dishwashers. As greywater contains fewer pathogens than blackwater, it is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape or crop irrigation, and other non-potable uses. Greywater may still have some pathogen content from laundering soiled clothing or cleaning the anal area in the shower or bath.
A composting toilet is a type of dry toilet that treats human waste by a biological process called composting. This process leads to the decomposition of organic matter and turns human waste into compost-like material. Composting is carried out by microorganisms under controlled aerobic conditions. Most composting toilets use no water for flushing and are therefore called "dry toilets".
Human waste refers to the waste products of the human digestive system, menses, and human metabolism including urine and feces. As part of a sanitation system that is in place, human waste is collected, transported, treated and disposed of or reused by one method or another, depending on the type of toilet being used, ability by the users to pay for services and other factors. Fecal sludge management is used to deal with fecal matter collected in on-site sanitation systems such as pit latrines and septic tanks.
A pit latrine, also known as pit toilet, is a type of toilet that collects human waste in a hole in the ground. Urine and feces enter the pit through a drop hole in the floor, which might be connected to a toilet seat or squatting pan for user comfort. Pit latrines can be built to function without water or they can have a water seal. When properly built and maintained, pit latrines can decrease the spread of disease by reducing the amount of human feces in the environment from open defecation. This decreases the transfer of pathogens between feces and food by flies. These pathogens are major causes of infectious diarrhea and intestinal worm infections. Infectious diarrhea resulted in about 700,000 deaths in children under five years old in 2011 and 250 million lost school days. Pit latrines are a low-cost method of separating feces from people.
A bucket toilet is a basic form of a dry toilet whereby a bucket (pail) is used to collect excreta. Usually, feces and urine are collected together in the same bucket, leading to odor issues. The bucket may be situated inside a dwelling, or in a nearby small structure.
Ecological sanitation, commonly abbreviated as ecosan, is an approach to sanitation provision which aims to safely reuse excreta in agriculture. It 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. One of the aims is to minimise the use of non-renewable resources. When properly designed and operated, ecosan systems provide a hygienically safe system to convert human excreta into nutrients to be returned to the soil, and water to be returned to the land. Ecosan is also called resource-oriented sanitation.
Improved sanitation is a term used to categorize types of sanitation for monitoring purposes. It refers to the management of human feces at the household level. The term was coined by the Joint Monitoring Program (JMP) for Water Supply and Sanitation of UNICEF and WHO in 2002 to help monitor the progress towards Goal Number 7 of the Millennium Development Goals (MDGs). The opposite of "improved sanitation" has been termed "unimproved sanitation" in the JMP definitions. The same terms are used to monitor progress towards Sustainable Development Goal 6 from 2015 onwards. Here, they are a component of the definition for "safely managed sanitation service".
A toilet is a piece of sanitary hardware that collects human urine and feces, and sometimes toilet paper, usually for disposal. Flush toilets use water, while dry or non-flush toilets do not. They can be designed for a sitting position popular in Europe and North America with a toilet seat, with additional considerations for those with disabilities, or for a squatting posture more popular in Asia, known as a squat toilet. In urban areas, flush toilets are usually connected to a sewer system; in isolated areas, to a septic tank. The waste is known as blackwater and the combined effluent, including other sources, is sewage. Dry toilets are connected to a pit, removable container, composting chamber, or other storage and treatment device, including urine diversion with a urine-diverting toilet.
A sanitation worker is a person responsible for cleaning, maintaining, operating, or emptying the equipment or technology at any step of the sanitation chain. This is the definition used in the narrower sense within the WASH sector. More broadly speaking, sanitation workers may also be involved in cleaning streets, parks, public spaces, sewers, stormwater drains, and public toilets. Another definition is: "The moment an individual’s waste is outsourced to another, it becomes sanitation work." Some organizations use the term specifically for municipal solid waste collectors, whereas others exclude the workers involved in management of solid waste sector from its definition.
Sewage is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residences and from commercial, institutional and public facilities that exist in the locality. Sub-types of sewage are greywater and blackwater. Sewage also contains soaps and detergents. Food waste may be present from dishwashing, and food quantities may be increased where garbage disposal units are used. In regions where toilet paper is used rather than bidets, that paper is also added to the sewage. Sewage contains macro-pollutants and micro-pollutants, and may also incorporate some municipal solid waste and pollutants from industrial wastewater.
Urine diversion, also called urine separation or source separation, refers to the separate collection of human urine and feces at the point of their production, i.e. at the toilet or urinal. Separation of urine from feces allows human waste to be treated separately and used as a potential resource. Applications are typically found where connection to a sewer-based sanitation system is not available or areas where water supplies are limited.
A dry toilet is a toilet which, unlike a flush toilet, does not use flush water. Dry toilets do not use water to move excreta along or block odors. They do not produce sewage, and are not connected to a sewer system or septic tank. Instead, excreta falls through a drop hole.
Resource recovery is using wastes as an input material to create valuable products as new outputs. The aim is to reduce the amount of waste generated, thereby reducing the need for landfill space, and optimising the values created from waste. Resource recovery delays the need to use raw materials in the manufacturing process. Materials found in municipal solid waste, construction and demolition waste, commercial waste and industrial wastes can be used to recover resources for the manufacturing of new materials and products. Plastic, paper, aluminium, glass and metal are examples of where value can be found in waste.
A urine-diverting dry toilet (UDDT) is a type of dry toilet with urine diversion that can be used to provide safe, affordable sanitation in a variety of contexts worldwide. The separate collection of feces and urine without any flush water has many advantages, such as odor-free operation and pathogen reduction by drying. While dried feces and urine harvested from UDDTs can be and routinely are used in agriculture, many UDDT installations do not apply any sort of recovery scheme. The UDDT is an example of a technology that can be used to achieve a sustainable sanitation system. This dry excreta management system is an alternative to pit latrines and flush toilets, especially where water is scarce, a connection to a sewer system and centralized wastewater treatment plant is not feasible or desired, fertilizer and soil conditioner are needed for agriculture, or groundwater pollution should be minimized.
Reuse of human excreta is the safe, beneficial use of treated human excreta after applying suitable treatment steps and risk management approaches that are customized for the intended reuse application. Beneficial uses of the treated excreta may focus on using the plant-available nutrients that are contained in the treated excreta. They may also make use of the organic matter and energy contained in the excreta. To a lesser extent, reuse of the excreta's water content might also take place, although this is better known as water reclamation from municipal wastewater. The intended reuse applications for the nutrient content may include: soil conditioner or fertilizer in agriculture or horticultural activities. Other reuse applications, which focus more on the organic matter content of the excreta, include use as a fuel source or as an energy source in the form of biogas.
Omni processor is a term coined in 2012 by staff of the Water, Sanitation, Hygiene Program of the Bill & Melinda Gates Foundation to describe a range of physical, biological or chemical treatments to remove pathogens from human-generated fecal sludge, while simultaneously creating commercially valuable byproducts. An omni processor mitigates unsafe methods in developing countries of capturing and treating human waste, which annually result in the spread of disease and the deaths of more than 1.5 million children.
Container-based sanitation refers to a sanitation system where toilets collect human excreta in sealable, removable containers that are transported to treatment facilities. This type of sanitation involves a commercial service which provides certain types of portable toilets, and delivers empty containers when picking up full ones. The service transports and safely disposes of or reuses collected excreta. The cost of collection of excreta is usually borne by the users. With suitable development, support and functioning partnerships, CBS can be used to provide low-income urban populations with safe collection, transport and treatment of excrement at a lower cost than installing and maintaining sewers. In most cases, CBS is based on the use of urine-diverting dry toilets.
Emergency sanitation is the management and technical processes required to provide sanitation in emergency situations. Emergency sanitation is required during humanitarian relief operations for refugees, people affected by natural disasters and internally displaced persons. There are three phases of emergency response: Immediate, short term and long term. In the immediate phase, the focus is on managing open defecation, and toilet technologies might include very basic latrines, pit latrines, bucket toilets, container-based toilets, chemical toilets. The short term phase might also involve technologies such as urine-diverting dry toilets, septic tanks, decentralized wastewater systems. Providing handwashing facilities and management of fecal sludge are also part of emergency sanitation.