The disposal of human waste—arguably one of the oldest problems on Earth—continues as a serious challenge to municipalities and locales across the planet.
The World Toilet Organization is promoting international discussion and cooperation toward improving sanitation around the world, particularly in Asia and Africa, culminating in the World Toilet Summit (WTS).
Below is an overview of current sanitation systems in use, followed by highlights from the WTS 2022 and an innovative project by Georgia Institute of Technology.
Waste is Everyone’s Problem
Left untreated, human urine and feces present grave risks to human health and the environment, and so societies all over the world have developed sanitation systems to collect, transport, and treat this waste safely before disposal or reuse.
It follows that sanitation systems around the world differ widely in their design. Most people in developed countries use flush toilets. In this system, human waste is mixed with water and transported to sewage treatment plants via a sewage system consisting of sewage pipes and sewage mains.
Unfortunately, some societies have inadequate sanitation systems, while others have no systems at all, leaving their populations to void and defecate openly into the environment, thereby causing significant environmental and public health problems.
Risks from Untreated Human Waste
Human waste is considered a biowaste because it acts as a transmission conduit (“vector”) for pathogens or living organisms that can cause disease.
The risk to human health becomes especially acute if it enters sources of human drinking water. This is an everyday reality for many people around the world—according to the World Health Organization (WHO), approximately 2.2 million people die annually from diseases caused by contaminated water, such as cholera and diarrhea.
Sanitations Systems Around the World
Onsite sanitation systems typically include pit latrines, septic tanks, and container-based systems where toilets are contained in sealable containers that can be easily removed to treatment facilities. These facilities accumulate fecal sludge, which may include substances such as flushing water, cleaning materials, menstrual hygiene products, bathing or kitchen water (gray water, which can often also include fat, oil, and grease), and solid waste. This material is treated by an approach called fecal sludge management.
Recycling Human Waste
Human waste is potentially very valuable for agricultural purposes if it is properly treated. Urine, for example, contains a lot of nitrogen and phosphorus, both of which are key ingredients in fertilizer. Feces, meanwhile, contain organic matter and nutrients.
For these reasons, in some parts of the developing world, human waste is often recycled and used to irrigate and fertilize fields where there is a shortage of fresh water.
Raw human waste is potentially very dangerous, though. This is why sewage treatment systems work to kill off the bacterial contaminants, usually by running it through an anaerobic digester. The product of this anaerobic digestion is biosolids.
In the US, about half of the biosolids from the sewage treatment system are returned to farmland. This process is heavily regulated by the US Environmental Protection Agency, which introduced strict standards for biosolids in 1990, with a two-tier system. However, a National Academy of Sciences report in 2002 found that there are no studies that prove a link between biosolids and adverse health effects. In 2013, the US Geological Survey followed with an inconclusive investigation of what happens to plants when biosolids are applied to the soil.
With the help of scientists in 2015, South Asian countries, particularly India, Bangladesh, and Sri Lanka, developed composting policies and technology for their nations. For example, there were collaborative efforts between the World Bank’s Water and Sanitation Programme and the International Water Management Institute (IWMI), which helped to develop policy advice on the use of wastewater and septic tank sludge in India.
In that same year, US scientists concluded that it may be possible to recover valuable metals from biosolids. This could open up a source of metals such as gold, silver, platinum, and copper, as well as other metals regularly used by the electronics industry, such as palladium and vanadium.
It is not exactly clear how these metals enter the sewage system, but research by scientists at Arizona State University has indicated that an average American city with a population of about one million people is responsible for about $13 million worth of precious metals ending up in its sewage system each year. Research on potential avenues for recovery is still ongoing.
New Research on Using Human Waste in Plants
In 2021, Prof. Rebecca Nelson of Cornell University discussed human urine and plants in a presentation she gave in Salt Lake City, Utah, at the American Society of Agronomy (ASA), Crop Science Society of America (CSSA) and Soil Science Society of America (SSSA) Annual Meeting.
Nelson explained that plants at the Cornell study site are fertilized with human urine, which recycles its nitrogen and phosphorus content while diverting it from the sewage system. Cornell’s system also saves money as there is less need for conventional fertilizers.
Such an approach could be applied in countries where farmers have difficulty obtaining conventional fertilizer and could help to develop a more sustainable food production system.
Human feces can be used in those countries to improve the soil structure and absorb rainwater, thereby reducing the effects of drought on crops. Feces can also be converted into biochar which can act as a valuable source of carbon for soil improvement. Some US cities, including Tacoma, Washington; Brattleboro, Vermont; and Chicago, have already started using biosolids from wastewater systems in this manner.
Honey buckets (portable latrines) and sewage lagoons can be used in remote areas that do not have sewage or septic tank systems. The risk from disease tends to be low in these areas due to less dense populations. For instance, rural villages in Alaska do not try to build permanent conventional waste treatment systems because of the permafrost.
WASH and Sustainable Development Goals
Water, Sanitation and Hygiene (WASH) is a key topic in the international development sector, covered by the UN’s Sustainable Development Goal (SDG) 6. The policy document on this is entitled “Ensure availability and sustainable management of water and sanitation for all.”
SDG6 recognizes that access to safe water, sanitation, and hygiene is “the most basic human need for health and well-being.” Currently, billions of people lack access to these basic services and will continue to in 2030 unless current progress on these matters quadruples.
However, demand for water is rising due to population growth, urbanization, and increasing water needs from sectors such as agriculture, industry, and energy. This "water stress" is exacerbated by decades of poor management and over-extraction, pollution of groundwater and fresh water supplies, and water scarcity caused by climate change, underinvestment, and lack of cooperation across national boundaries.
6.1 By 2030, achieve universal and equitable access to safe and affordable drinking water for all.
6.2 By 2030, achieve access to adequate and equitable sanitation and hygiene for all and end open defecation, paying special attention to the needs of women and girls and those in vulnerable situations.
6.3 By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally.
6.4 By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity and substantially reduce the number of people suffering from water scarcity.
6.5 By 2030, implement integrated water resources management at all levels, including through transboundary cooperation as appropriate.
6.6 By 2020, protect and restore water-related ecosystems, including mountains, forests, wetlands, rivers, aquifers and lakes.
6.A By 2030, expand international cooperation and capacity-building support to developing countries in water- and sanitation-related activities and programs, including water harvesting, desalination, water efficiency, wastewater treatment, recycling and reuse technologies.
6.B Support and strengthen the participation of local communities in improving water and sanitation management.
World Toilet Organization
The World Toilet Organization was founded by Jack Sim on November 19, 2001, with an inaugural event called the World Toilet Summit. The aim of both the organization and the summit was to draw the world’s attention to the global sanitation crisis. Since the first summit, the event has attracted the support of NGOs, the private sector, civil society organizations, and the international community.
Sim’s founding of the World Toilet Organization was preceded by his establishment of the Restroom Association of Singapore (RAS) in 1998. In 2008, Sim founded SaniShop, which focuses on the entrepreneurship for toilet installation on a community level, and in 2013 he worked with the Singapore Ministry of Foreign Affairs to pass a resolution at the UN General Assembly titled "Sanitation for All," designating November 19 as official UN World Toilet Day.
Sim remains as the organization's founder and director, working alongside a team of eight directors. Originally, the World Toilet Organization had fifteen members, but this has grown to 151 current member organizations across fifty-three countries. It aims to continue building the global sanitation movement through collaborative action that provides innovative solutions with an ultimate aim of providing decent sanitation for everyone across the world. It does this through advocacy, education, and a market-based approach to providing solutions.
Its major ongoing project is the World Toilet College, which has facilities in Singapore and India, to address the education and training gap around sanitation.
The WTS 2022 was held on November 18 to 19 in Abuja, Nigeria, with the purpose of improving collaboration among stakeholders, increasing private sector participation regarding sanitation issues, mobilizing investment, and sharing knowledge on market-based approaches to sanitation solutions. Notably, representatives from eight states in Nigeria expressed their commitments to achieve a total of over thirty-five local government areas (LGAs) becoming open defecation free (ODF) between 2023 and 2025, with more details in the WTS 2022 report.
Generation II Reinvented Toilet (G2RT) Project
As part of the “Reinvent the Toilet Challenge” by the Gates Foundation, Dr. Shannon Yee, associate professor at Georgia Institute of Technology, is leading the G2RT team of seventy engineers, scientists, and industrial designers from around the world toward one goal—developing a plug-in toilet with minimal water input and no sewage output.
Its current experimental model has a front end (toilet) and a back end (waste-processing unit). The front end requires just 0.2 L of water to flush, and the urine and fecal matter are separated. The back end treats the urine and fecal matter to produce clean water and odorless “feces cake,” which can be reused. Details on its mechanism can be found here.
Current challenges include its size and cost, as G2RT is roughly the size of a washing machine with a target price of $450. It also requires a supply of electricity to run.
In a podcast with World Changing Ideas, Yee explains that the big issue here is that “[people need] to be able to treat waste without input water. So, no water coming into the toilet and no output sewage.”
If people had an appliance “where you just plug it in wherever you need a bathroom, and it treats your waste,” that would be such a big change, Yee says. “You wouldn’t need to have a dedicated plumbing area for where the bathroom is located. You could put a bathroom anywhere!”
*Robin Whitlock is an England-based freelance journalist specializing in environmental issues, climate change, and renewable energy, with a variety of other professional interests including green transportation.