
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 (mainly nitrogen, phosphorus and potassium) 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
Water reclamation is the process of converting municipal wastewater or sewage and industrial wastewater into water that can be reused for a variety of purposes. It is also called wastewater reuse, water reuse or water recycling. There are many ty ...
from municipal
wastewater
Wastewater (or waste water) is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of do ...
. The intended reuse applications for the nutrient content may include:
soil conditioner
A soil conditioner is a product which is added to soil to improve the soil’s physical qualities, usually its fertility (ability to provide nutrition for plants) and sometimes its mechanics. In general usage, the term "soil conditioner" is often ...
or
fertilizer
A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
in
agriculture
Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...
or
horticultural
Horticulture (from ) is the art and science of growing fruits, vegetables, flowers, trees, shrubs and ornamental plants. Horticulture is commonly associated with the more professional and technical aspects of plant cultivation on a smaller and mo ...
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
Biogas is a gaseous renewable energy source produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, Wastewater treatment, wastewater, and food waste. Biogas is produced by anaerobic ...
.
There is a large and growing number of treatment options to make excreta safe and manageable for the intended reuse option.
Options include urine diversion and dehydration of feces (
urine-diverting dry toilet
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 ...
s), composting (
composting toilet
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 b ...
s or external
composting processes),
sewage sludge treatment technologies and a range of
fecal sludge treatment processes. They all achieve various degrees of pathogen removal and reduction in water content for easier handling. Pathogens of concern are enteric bacteria, virus, protozoa, and
helminth eggs in feces.
As the helminth eggs are the pathogens that are the most difficult to destroy with treatment processes, they are commonly used as an
indicator organism
Indicator organisms are used as a proxy to monitor conditions in a particular environment, ecosystem, area, habitat, or consumer product. Certain bacteria, fungi and helminth eggs are being used for various purposes.
Types Indicator bacteria ...
in reuse schemes. Other health risks and environmental pollution aspects that need to be considered include spreading
micropollutant Micropollutants are substances that even at very low concentrations have adverse effects on different environmental matrices. They are an inhomogeneous group of atroprogenic chemical compounds that is discharged by human to the environment. Commonly ...
s,
pharmaceutical residues and
nitrate
Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...
in the environment which could cause
groundwater pollution
Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwant ...
and thus potentially affect
drinking water quality.
There are several "human excreta derived fertilizers" which vary in their properties and fertilizing characteristics, for example: urine, dried feces, composted feces, fecal sludge,
sewage
Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewerage, sewer system. Sewage consists of wastewater discharged fro ...
,
sewage sludge
Sewage sludge is the residual, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. The term "septage" also refers to sludge from simple wastewater treatment but is connected to si ...
.
The nutrients and organic matter which are contained in human excreta or in domestic wastewater (sewage) have been used in agriculture in many countries for centuries. However, this practice is often carried out in an unregulated and unsafe manner in
developing countries
A developing country is a sovereign state with a less-developed Secondary sector of the economy, industrial base and a lower Human Development Index (HDI) relative to developed countries. However, this definition is not universally agreed upon. ...
.
World Health Organization
The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
Guidelines from 2006 have set up a framework describing how this reuse can be done safely by following a "multiple barrier approach".
Such barriers might be selecting a suitable crop, farming methods, methods of applying the fertilizer and education of the farmers.
Terminology
Human excreta, fecal sludge and wastewater are often referred to as wastes (see also
human waste
Human waste (or human excreta) refers to the waste products of the human digestive system, Menstruation, menses, and human metabolism including urine and Human feces, feces. As part of a sanitation system that is in place, human waste is collect ...
). Within the concept of a
circular economy
A circular economy (also referred to as circularity or CE) is a model of resource Production (economics), production and Resource consumption, consumption in any economy that involves sharing, leasing, Reuse, reusing, repairing, refurbishing, and ...
in sanitation, an alternative term that is being used is "resource flows".
The final outputs from the
sanitation
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 ...
treatment systems can be called "reuse products" or "other outputs".
These reuse products are general fertilizers,
soil conditioner
A soil conditioner is a product which is added to soil to improve the soil’s physical qualities, usually its fertility (ability to provide nutrition for plants) and sometimes its mechanics. In general usage, the term "soil conditioner" is often ...
s,
biomass
Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...
, water, or energy.
Reuse of human excreta focuses on the nutrient and organic matter content of human excreta unlike
reuse of wastewater which focuses on the water content. An alternative term is "use of human excreta" rather than "
reuse
Reuse is the action or practice of using an item, whether for its original purpose (conventional reuse) or to fulfill a different function (creative reuse or repurposing). It should be distinguished from recycling, which is the breaking down of ...
" as strictly speaking it is the ''first'' ''use'' of human excreta, not the second time that it is used.
Technologies and approaches

The resources available in wastewater and human excreta include water,
plant nutrients,
organic matter
Organic matter, organic material or natural organic matter is the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come fro ...
and energy content.
Sanitation
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 ...
systems that are designed for safe and effective
recovery of resources can play an important role in a community's overall
resource management
In organizational studies, resource management is the efficient and effective development of an organization's resources when they are needed. Such resources may include the financial resources, inventory, human skills, production resources, or ...
.
Recovering the resources embedded in excreta and wastewater (like nutrients, water and energy) contributes to achieving
Sustainable Development Goal 6
Sustainable Development Goal 6 (SDG 6 or Global Goal 6) declares the importance of achieving "clean water and sanitation for all". It is one of the 17 Sustainable Development Goals established by the United Nations General Assembly to succeed the ...
and other
sustainable development goals
The ''2030 Agenda for Sustainable Development'', adopted by all United Nations (UN) members in 2015, created 17 world Sustainable Development Goals (SDGs). The aim of these global goals is "peace and prosperity for people and the planet" – wh ...
.
It can be efficient to combine wastewater and human excreta with other
organic waste
Biodegradable waste includes any organic matter in waste which can be broken down into carbon dioxide, water, methane, compost, humus, and simple organic molecules by micro-organisms and other living things by composting, aerobic digestion, ana ...
such as
manure
Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nut ...
, and food and crop waste for the purposes of resource recovery.
[Andersson, K., Rosemarin, A., Lamizana, B., Kvarnström, E., McConville, J., Seidu, R., Dickin, S. and Trimmer, C. (2016)]
Sanitation, Wastewater Management and Sustainability: from Waste Disposal to Resource Recovery
Nairobi and Stockholm: United Nations Environment Programme and Stockholm Environment Institute.
Treatment options
There is a large and growing number of treatment options to make excreta safe and manageable for the intended reuse option.
Various technologies and practices, ranging in scale from a single rural household to a city, can be used to capture potentially valuable resources and make them available for safe, productive uses that support human well-being and broader
sustainability
Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...
. Some treatment options are listed below but there are many more:
* Urine diversion and dehydration of feces (which is done with
urine-diverting dry toilet
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 ...
s)
* Composting (
composting toilet
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 b ...
s or external
composting processes)
*
Sewage sludge treatment technologies, which is installed downstream of various
wastewater treatment
Wastewater treatment is a process which removes and eliminates contaminants from wastewater. It thus converts it into an effluent that can be returned to the water cycle. Once back in the water cycle, the effluent creates an acceptable impact on ...
technologies
*
Fecal sludge treatment processes, such as sludge drying beds,
constructed wetland
A constructed wetland is an artificial wetland to treat sewage, greywater, stormwater runoff or Industrial wastewater treatment, industrial wastewater. It may also be designed for land reclamation after mining, or as a Flood mitigation, mitigatio ...
s.
*
Anaerobic digestion
Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to Waste management, manage waste or to produce fuels. Mu ...
with biogas production
*
Waste-to-energy
Waste-to-energy (WtE) or energy-from-waste (EfW) refers to a series of processes designed to convert waste materials into usable forms of energy, typically electricity or heat. As a form of energy recovery, WtE plays a crucial role in both wa ...
process
*
Omni processor
A guide by the
Swedish University of Agricultural Sciences provides a list of treatment technologies for sanitation resource recovery: Vermicomposting and
vermifiltration, black soldier fly composting,
algae
Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
cultivation,
microbial fuel cell, nitrification and distillation of urine,
struvite precipitation, incineration,
carbonization
Carbonization or carbonisation is the conversion of organic matters like plants and dead animal remains into carbon through destructive distillation.
Complexity in carbonization
Carbonization is a pyrolytic reaction, therefore, is considered a ...
, solar drying, membranes, filters, alkaline dehydration of urine, ammonia sanitization/urea treatment, and lime sanitization.
[McConville, J., Niwagaba, C., Nordin, A., Ahlström, M., Namboozo, V. and Kiffe, M. (2020)]
Guide to Sanitation Resource-Recovery Products & Technologies: A supplement to the Compendium of Sanitation Systems and Technologies
1st Edition. Swedish University of Agricultural Sciences (SLU), Department of Energy and Technology, Uppsala, Sweden. Further research involves UV advanced oxidation processes in order to degrade organic pollutants present in the urine before reuse or the dehydration of urine by using acids.
Reuse options
The most common reuse of excreta is as fertilizer and soil conditioner in agriculture. This is also called a "closing the loop" approach for sanitation with agriculture. It is a central aspect of the
ecological sanitation
Ecological sanitation, commonly abbreviated as ecosan (also spelled eco-san or 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 ch ...
approach.
Reuse options depend on the form of the excreta that is being reused: it can be either excreta on its own or mixed with some water (fecal sludge)
or mixed with much water (domestic wastewater or sewage).
The most common types of excreta reuse include:
*
Fertilizer
A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
and irrigation water in agriculture, and horticulture: for example using
recovered and treated water for irrigation; using composted excreta (and other organic waste) or appropriately treated
biosolids
Biosolids are solid organic matter recovered from a sewage treatment process and used as fertilizer. In the past, it was common for farmers to use animal manure to improve their soil fertility. In the 1920s, the farming community began also to us ...
as
fertilizer
A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
and soil conditioner; using treated source-separated urine as
fertilizer
A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
.
* Energy: for example digesting feces and other organic waste to produce
biogas
Biogas is a gaseous renewable energy source produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, Wastewater treatment, wastewater, and food waste. Biogas is produced by anaerobic ...
; or producing combustible fuels.
* Other: other emerging excreta reuse options include producing protein feeds for livestock using
black soldier fly larvae, recovering organic matter for use as building materials or in paper production.
Resource recovery from fecal sludge can take many forms, including as a fuel, soil amendment, building material, protein, animal fodder, and water for irrigation.
Reuse products that can be recovered from sanitation systems include: Stored
urine
Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
, concentrated urine, sanitized
blackwater, digestate, nutrient solutions, dry urine, struvite, dried feces,
pit humus, dewatered sludge, compost, ash from sludge,
biochar
Biochar is a form of charcoal, sometimes modified, that is intended for organic use, as in soil. It is the lightweight black remnants remaining after the pyrolysis of biomass, consisting of carbon and ashes. Despite its name, biochar is steril ...
, nutrient-enriched filter material,
algae
Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
,
macrophytes, black soldier fly larvae, worms,
irrigation water,
aquaculture
Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...
, and biogas.
As fertilizer
Comparison to other fertilizers
There is an untapped fertilizer resource in human excreta. In Africa, for example, the theoretical quantities of nutrients that can be recovered from human excreta are comparable with all current fertilizer use on the continent.
Therefore, reuse can support increased food production and also provide an alternative to chemical fertilizers, which is often unaffordable to small-holder farmers. However, nutritional value of human excreta largely depends on dietary input.
Mineral fertilizers are made from mining activities and can contain heavy metals. Phosphate ores contain heavy metals such as cadmium and uranium, which can reach the food chain via mineral phosphate fertilizer. This does not apply to excreta-based fertilizers (unless the human's food was contaminated beyond safe limits to start with), which is an advantage.
Fertilizing elements of organic fertilizers are mostly bound in carbonaceous reduced compounds. If these are already partially oxidized as in the compost, the fertilizing minerals are adsorbed on the degradation products (
humic acids) etc. Thus, they exhibit a slow-release effect and are usually less rapidly leached compared to mineral fertilizers.
Urine
Urine
Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
contains large quantities of
nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
(mostly as
urea
Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two Amine, amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest am ...
), as well as reasonable quantities of dissolved
potassium
Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...
.
The nutrient concentrations in urine vary with diet.
[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 In particular, the nitrogen content in urine is related to quantity of protein in the diet: A
high protein diet results in high urea levels in urine. The nitrogen content in urine is proportional to the total food protein in the person's diet, and the phosphorus content is proportional to the sum of total food protein and vegetal food protein.
Urine's eight main ionic species (> 0.1 meq L−1) are
cation
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
s
Na,
K,
NH4,
Ca, and the
anions
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
,
Cl,
SO4,
PO4, and
HCO3.
Urine typically contains 70% of the nitrogen and more than half the potassium found in sewage, while making up less than 1% of the overall volume.
[ The amount of urine produced by an adult is around 0.8 to 1.5 L per day.]
Applying urine as fertilizer has been called "closing the cycle of agricultural nutrient flows" or ecological sanitation or ecosan. Urine fertilizer is usually applied diluted with water because undiluted urine can chemically burn the leaves or roots of some plants, causing plant injury, particularly if the soil moisture content is low. The dilution also helps to reduce odor development following application. When diluted with water (at a 1:5 ratio for container-grown annual crops with fresh growing medium each season or a 1:8 ratio for more general use), it can be applied directly to soil as a fertilizer. The fertilization effect of urine has been found to be comparable to that of commercial nitrogen fertilizers. Urine may contain pharmaceutical residues (environmental persistent pharmaceutical pollutant
The term environmental persistent pharmaceutical pollutants (EPPP) was first suggested in the nomination in 2010 of pharmaceuticals and environment as an emerging issue in a Strategic Approach to International Chemicals Management ( SAICM) by ...
s). Concentrations of heavy metals such as lead
Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
, mercury, and cadmium
Cadmium is a chemical element; it has chemical symbol, symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12 element, group 12, zinc and mercury (element), mercury. Like z ...
, commonly found in sewage sludge, are much lower in urine.
Typical design values for nutrients excreted with urine are: 4 kg nitrogen per person per year, 0.36 kg phosphorus per person per year and 1.0 kg potassium per person per year.[Jönsson, H., Richert Stintzing, A., Vinnerås, B. and Salomon, E. (2004]
Guidelines on the use of urine and faeces in crop production
EcoSanRes Publications Series, Report 2004-2, Sweden [This source seems to truncate the Jönsson & Vinnerås (2004) table by omitting the potassium row. The full version may be found at the original source a
RG#285858813
!-- -->] Based on the quantity of 1.5 L urine per day (or 550 L per year), the concentration values of macronutrients as follows: 7.3 g/L N; .67 g/L P; 1.8 g/L K. These are design values but the actual values vary with diet. Urine's nutrient content, when expressed with the international fertilizer convention of N:P2O5:K2O, is approximately 7:1.5:2.2. Since urine is rather diluted as a fertilizer compared to dry manufactured nitrogen fertilizers such as diammonium phosphate
Diammonium phosphate (DAP; IUPAC name diammonium hydrogen phosphate; chemical formula (NH4)2(HPO4)) is one of a series of water- soluble ammonium phosphate salts that can be produced when ammonia reacts with phosphoric acid.
Solid diammonium ph ...
, the relative transport costs for urine are high as a lot of water needs to be transported.
The general limitations to using urine as fertilizer depend mainly on the potential for buildup of excess nitrogen (due to the high ratio of that macronutrient), and inorganic salt
In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...
s such as sodium chloride
Sodium chloride , commonly known as Salt#Edible salt, edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs a ...
, which are also part of the wastes excreted by the renal system
The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressu ...
. Over-fertilization with urine or other nitrogen fertilizers can result in too much ammonia for plants to absorb, acidic conditions, or other phytotoxicity
Phytotoxicity describes any adverse effects on plant growth, physiology, or metabolism caused by a chemical substance, such as high levels of fertilizers, herbicides, heavy metals, or nanoparticles. General phytotoxic effects include altered plan ...
. Important parameters to consider while fertilizing with urine include salinity tolerance of the plant, soil composition, addition of other fertilizing compounds, and quantity of rainfall or other irrigation. It was reported in 1995 that urine nitrogen gaseous losses were relatively high and plant uptake lower than with labelled ammonium nitrate
Ammonium nitrate is a chemical compound with the formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, but does not form hydrates. It is predominantly us ...
. In contrast, phosphorus
Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
was utilized at a higher rate than soluble phosphate. Urine can also be used safely as a source of nitrogen in carbon-rich compost.
Human urine can be collected with sanitation systems that utilize urinal
A urinal (, ) is a sanitary plumbing fixture similar to a toilet, but for urination only. Urinals are often provided in men's public restrooms in Western countries (less so in Muslim countries). They are usually used in a standing position. ...
s or urine diversion toilets. If urine is to be separated and collected for use as a fertilizer in agriculture, then this can be done with sanitation systems that utilize waterless urinals, urine-diverting dry toilets (UDDTs) or urine diversion flush toilets. During storage, the urea in urine is rapidly hydrolyzed by urease
Ureases (), functionally, belong to the superfamily of amidohydrolases and phosphotriesterases. Ureases are found in numerous Bacteria, Archaea, fungi, algae, plants, and some invertebrates. Ureases are nickel-containing metalloenzymes of high ...
, creating ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
. Further treatment can be done with collected urine to stabilize the nitrogen and concentrate the fertilizer. One low-tech solution to odor is to add citric acid
Citric acid is an organic compound with the formula . It is a Transparency and translucency, colorless Weak acid, weak organic acid. It occurs naturally in Citrus, citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, ...
or vinegar
Vinegar () is an aqueous solution of diluted acetic acid and trace compounds that may include flavorings. Vinegar typically contains from 5% to 18% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting ...
to the urine collection container, so that the urease is inactivated and any ammonia that do form are less volatile. Besides concentration, simple chemical processes can be used to extract pure substances: nitrogen as nitrates (similar to medieval nitre beds) and phosphorus as struvite.
The health risks of using urine as a source of fertilizer are generally regarded as negligible, especially when dispersed in soil rather than on the part of a plant that is consumed. Urine can be distributed via perforated hoses buried ~10 cm under the surface of the soil
Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...
among crop plants, thus minimizing risk of odors, loss of nutrients due to votalization, or transmission of pathogen
In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
s. There are potentially more environmental problems (such as eutrophication
Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...
resulting from the influx of nutrient rich effluent into aquatic or marine ecosystems) and a higher energy consumption when urine is treated as part of sewage in sewage treatment plants
Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water ...
compared with when it is used directly as a fertilizer resource.
In developing countries, the use of raw sewage or fecal sludge has been common throughout history, yet the application of pure urine to crops is still quite rare in 2021. This is despite many publications that advocate the use of urine as a fertilizer since at least 2001. Since about 2011, the Bill and Melinda Gates Foundation
The Gates Foundation is an American private foundation founded by Bill Gates and Melinda French Gates. Based in Seattle, Washington, it was launched in 2000 and is reported to be List of wealthiest charitable foundations, the third largest char ...
is providing funding for research involving sanitation systems that recover the nutrients in urine.
Feces
According to the 2004 "proposed Swedish default values", an average Swedish adult excretes 0.55 kg nitrogen, 0.18 kg phosphorus, and 0.36 kg potassium as feces per year. The yearly mass is 51 kg wet and 11 kg dried, so that wet feces would have a NPK% value of 1.1:0.8:0.9.
Dried feces
Reuse of dried feces
Feces (also known as faeces American and British English spelling differences#ae and oe, or fæces; : faex) are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the ...
from urine-diverting dry toilets after post-treatment can result in increased crop production through fertilizing effects of nitrogen, phosphorus, potassium and improved soil fertility
Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality. through organic carbon.[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 GmbH, Eschborn, Germany
Composted feces
Compost derived from composting toilets (where organic kitchen waste is in some cases also added to the composting toilet) has, in principle, the same uses as compost derived from other organic waste products, such as sewage sludge
Sewage sludge is the residual, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. The term "septage" also refers to sludge from simple wastewater treatment but is connected to si ...
or municipal organic waste. One limiting factor may be legal restrictions due to the possibility that pathogens remain in the compost. In any case, the use of compost from composting toilets in one's own garden can be regarded as safe and is the main method of use for compost from composting toilets. Hygienic measures for handling of the compost must be applied by all those people who are exposed to it, e.g. wearing gloves and boots.
Some of the urine
Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
will be part of the compost although some urine will be lost via leachate and evaporation. Urine
Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
can contain up to 90 percent of the nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
, up to 50 percent of the phosphorus
Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
, and up to 70 percent of the potassium present in human excreta.
The nutrients in compost from a composting toilet have a higher plant availability than dried feces from a typical urine-diverting dry toilet. The two processes are not mutually exclusive, however: some composting toilets do divert urine (to avoid over-saturation of water and nitrogen) and dried feces can still be composted.[Berger, W. (2011)]
Technology review of composting toilets - Basic overview of composting toilets (with or without urine diversion).
Deutsche Gesellschaft für Internationale Zusammenarbeit GmbH, Eschborn, Germany
Fecal sludge
Fecal sludge is defined as "coming from onsite sanitation technologies, and has not been transported through a sewer." Examples of onsite technologies include pit latrines, unsewered public ablution blocks, septic tanks and dry toilets. Fecal sludge can be treated by a variety of methods to render it suitable for reuse in agriculture. These include (usually carried out in combination) dewatering, thickening, drying (in sludge drying beds), composting
Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...
, pelletization, and anaerobic digestion
Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to Waste management, manage waste or to produce fuels. Mu ...
.
Municipal wastewater
Reclaimed water can be reused for irrigation, industrial uses, replenishing natural water courses, water bodies, aquifer
An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...
s, and other potable and non-potable uses. These applications, however, focus usually on the water aspect, not on the nutrients and organic matter reuse aspect, which is the focus of "reuse of excreta".
When wastewater is reused in agriculture, its nutrient (nitrogen and phosphorus) content may be useful for additional fertilizer application. Work by the International Water Management Institute
The International Water Management Institute (IWMI) is a non-profit international water management research organisation under the One CGIAR with its headquarters in Colombo, Sri Lanka, and offices across Africa and Asia. One CGIAR is a reformulat ...
and others has led to guidelines on how reuse of municipal wastewater in agriculture for irrigation and fertilizer application can be safely implemented in low income countries.
Sewage sludge
The use of treated sewage sludge (after treatment also called "biosolids
Biosolids are solid organic matter recovered from a sewage treatment process and used as fertilizer. In the past, it was common for farmers to use animal manure to improve their soil fertility. In the 1920s, the farming community began also to us ...
") as a soil conditioner or fertilizer is possible but is a controversial topic in some countries (such as USA, some countries in Europe) due to the chemical pollutants it may contain, such as heavy metals and environmental persistent pharmaceutical pollutants.
Northumbrian Water in the United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
uses two biogas plants to produce what the company calls "poo power"—using sewage sludge to produce energy to generate income. Biogas production has reduced its pre-1996 electricity
Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...
expenditure of 20 million GBP
Sterling (symbol: £; currency code: GBP) is the currency of the United Kingdom and nine of its associated territories. The pound is the main unit of sterling, and the word '' pound'' is also used to refer to the British currency general ...
by about 20%. Severn Trent and Wessex Water also have similar projects.
Sludge treatment liquids
Sludge treatment liquids (after anaerobic digestion) can be used as an input source for a process to recover phosphorus in the form of struvite for use as fertilizer. For example, the Canadian company Ostara Nutrient Recovery Technologies is marketing a process based on controlled chemical precipitation of phosphorus in a fluidized bed reactor that recovers struvite in the form of crystalline pellets from sludge dewatering streams. The resulting crystalline product is sold to the agriculture
Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...
, turf
Sod is the upper layer of turf that is harvested for transplanting. Turf consists of a variable thickness of a soil medium that supports a community of turfgrasses.
In British and Australian English, sod is more commonly known as ''turf'', ...
, and ornamental plant
Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...
s sectors as fertilizer under the registered trade name "Crystal Green".
Peak phosphorus
In the case of phosphorus in particular, reuse of excreta is one known method to recover phosphorus to mitigate the potential shortage (also known as " peak phosphorus") of economical mined phosphorus. Mined phosphorus is a limited resource that is used up by fertilizer production, a shortage of which would threaten worldwide food security
Food security is the state of having reliable access to a sufficient quantity of affordable, healthy Human food, food. The availability of food for people of any class, gender, ethnicity, or religion is another element of food protection. Simila ...
. Therefore, phosphorus from excreta-based fertilizers is an interesting alternative to fertilizers containing mined phosphate ore.
Health and environmental aspects of agricultural use
Pathogens
Multiple barrier concept for safe use in agriculture
Research into how to make reuse of urine and feces safe in agriculture has been carried out in Sweden since the 1990s. In 2006 the World Health Organization
The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
(WHO) provided guidelines on safe reuse of wastewater, excreta, and greywater. The multiple barrier concept to reuse, which is the key cornerstone of this publication, has led to a clear understanding of how excreta reuse can be done safely. The concept is also used in water supply and food production, and is generally understood as a series of treatment steps and other safety precautions to prevent the spread of pathogens.
The degree of treatment required for excreta-based fertilizers before they can safely be used in agriculture depends on a number of factors. It mainly depends on which other barriers will be put in place according to the multiple barrier concept. Such barriers might be selecting a suitable crop, farming methods, methods of applying the fertilizer, education of the farmers, and so forth.[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
For example, in the case of urine-diverting dry toilets secondary treatment of dried feces can be performed at community level rather than at household level and can include thermophilic composting where fecal material is composted at over 50 °C, prolonged storage with a duration of 1.5 to two years, chemical treatment with ammonia from urine to inactivate the pathogens, solar sanitation for further drying or heat treatment to eliminate pathogens.
Exposure of farm workers to untreated excreta constitutes a significant health risk due to its pathogen
In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
content. There can be a large amount of enteric bacteria, virus, protozoa, and helminth eggs in feces. This risk also extends to consumers of crops fertilized with untreated excreta. Therefore, excreta needs to be appropriately treated before reuse, and health aspects need to be managed for all reuse applications as the excreta can contain pathogens even after treatment.
Treatment of excreta for pathogen removal
Temperature is a treatment parameter with an established relation to pathogen inactivation for all pathogen groups: Temperatures above have the potential to inactivate most pathogens. Therefore, thermal sanitization is utilized in several technologies, such as thermophilic composting and thermophilic anaerobic digestion and potentially in sun drying. Alkaline conditions (pH value above 10) can also deactivate pathogens. This can be achieved with ammonia sanitization or lime treatment.
The treatment of excreta and wastewater for pathogen removal can take place:
* at the toilet itself (for example, urine collected from urine-diverting dry toilets is often treated by simple storage at the household level); or
* at a semi-centralized level (for example, by composting
Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...
); or
* at a fully centralized level at sewage treatment plants
Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water ...
and sewage sludge treatment plants.
Indicator organisms
As an indicator organism
Indicator organisms are used as a proxy to monitor conditions in a particular environment, ecosystem, area, habitat, or consumer product. Certain bacteria, fungi and helminth eggs are being used for various purposes.
Types Indicator bacteria ...
in reuse schemes, helminth eggs are commonly used as these organisms are the most difficult to destroy in most treatment processes. The multiple barrier approach is recommended where e.g. lower levels of treatment may be acceptable when combined with other post-treatment barriers along the sanitation chain.
Pharmaceutical residues
Excreta from humans contains hormone
A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...
s and pharmaceutical drug
Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the ...
residues which could in theory enter the food chain via fertilized crops but are currently not fully removed by conventional wastewater treatment plants anyway and can enter drinking water sources via household wastewater (sewage).[von Münch, E., Winker, M. (2011)]
Technology review of urine diversion components - Overview on urine diversion components such as waterless urinals, urine diversion toilets, and urine storage and reuse systems.
Gesellschaft für Internationale Zusammenarbeit GmbH In fact, the pharmaceutical residues in the excreta are degraded better in terrestrial systems (soil) than in aquatic systems.
Nitrate pollution
Only a fraction of the nitrogen-based fertilizers is converted to produce plant matter. The remainder accumulates in the soil or is lost as run-off. This also applies to excreta-based fertilizer since it also contains nitrogen. Excessive nitrogen which is not taken up by plants is transformed into nitrate which is easily leached. High application rates combined with the high water-solubility of nitrate leads to increased runoff into surface water
Surface water is water located on top of land, forming terrestrial (surrounding by land on all sides) waterbodies, and may also be referred to as ''blue water'', opposed to the seawater and waterbodies like the ocean.
The vast majority of surfac ...
as well as leaching into groundwater
Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...
. Nitrate levels above 10 mg/L (10 ppm) in groundwater can cause ' blue baby syndrome' (acquired methemoglobinemia
Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). Complications ma ...
). The nutrients, especially nitrates, in fertilizers can cause problems for ecosystem
An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...
s and for human health if they are washed off into surface water
Surface water is water located on top of land, forming terrestrial (surrounding by land on all sides) waterbodies, and may also be referred to as ''blue water'', opposed to the seawater and waterbodies like the ocean.
The vast majority of surfac ...
or leached through the soil into groundwater.
Other uses
Apart from use in agriculture, there are other possible uses of excreta. For example, in the case of fecal sludge, it can be treated and then serve as protein ( black soldier fly process), fodder
Fodder (), also called provender (), is any agriculture, agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, domestic rabbit, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food ...
, fish food, building materials, and biofuel
Biofuel is a fuel that is produced over a short time span from Biomass (energy), biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricu ...
s (biogas from anaerobic digestion, incineration or co-combustion of dried sludge, pyrolysis of fecal sludge, and biodiesel from fecal sludge).
Fuel
Solid fuel, heat, electricity
Pilot scale research in Uganda and Senegal has shown that it is viable to use dry feces as for combustion in industry, provided it has been dried to a minimum of 28% dry solids.
Dried sewage sludge can be burned in sludge incineration plants and generate heat and electricity (the waste-to-energy
Waste-to-energy (WtE) or energy-from-waste (EfW) refers to a series of processes designed to convert waste materials into usable forms of energy, typically electricity or heat. As a form of energy recovery, WtE plays a crucial role in both wa ...
process is one example).
Resource recovery of fecal sludge as a solid fuel has been found to have high market potential in Sub-Saharan Africa
Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...
.
Hydrogen fuel
Urine has also been investigated as a potential source of hydrogen fuel. Urine was found to be a suitable wastewater for high rate hydrogen production
Hydrogen gas is produced by several industrial methods. Nearly all of the world's current supply of hydrogen is created from fossil fuels. Article in press. Most hydrogen is ''gray hydrogen'' made through steam methane reforming. In this process, ...
in a microbial electrolysis cell (MEC).[
]
Biogas
Small-scale biogas plants are being utilized in many countries, including Ghana, Vietnam and many others. Larger centralized systems are being planned that mix animal and human feces to produce biogas. Biogas is also produced during sewage sludge treatment processes with anaerobic digestion. Here, it can be used for heating the digesters and for generating electricity.
Biogas is an important waste-to-energy resource which plays a huge role in reducing environmental pollution and most importantly in reducing greenhouse gases effect caused by the waste. Utilization of raw material such as human waste for biogas generation is considered beneficial because it does not require additional starters such as microorganism seeds for methane production, and a supply of microorganisms occurs continuously during the feeding of raw materials.
Food source for livestock
Combination outhouses/feeding troughs were used in several countries since ancient times.[ They are generally being phased out.
]
Food source to produce protein for animal feed
Pilot facilities are being developed for feeding black soldier fly larvae with feces. The mature flies would then be a source of protein to be included in the production of feed for chickens in South Africa.
Black soldier fly (BSF) bio-waste processing is a relatively new treatment technology that has received increasing attention over the last decades. Larvae grown on bio-waste can be a necessary raw material for animal feed production, and can therefore provide revenues for financially applicable waste management systems. In addition, when produced on bio-waste, insect-based feeds can be more sustainable than conventional feeds.
Building materials
It is known that additions of fecal matter up to 20% by dried weight in clay bricks does not make a significant functional difference to bricks.
Precious metals recovery
A Japanese sewage treatment facility extracts precious metal
Precious metals are rare, naturally occurring metallic chemical elements of high Value (economics), economic value. Precious metals, particularly the noble metals, are more corrosion resistant and less reactivity (chemistry), chemically reac ...
s from sewage sludge, "high percentage of gold found at the Suwa facility was probably due to the large number of precision equipment manufacturers in the vicinity that use old The facility recently recorded finding 1,890 grammes of gold per tonne of ash from incinerated sludge. That is a far higher gold content than Japan’s Hishikari Mine, one of the world’s top gold mines, ..which contains 20–40 grammes of the precious metal per tonne of ore." This idea was also tested by the US Geological Survey (USGS) which found that the yearly sewage sludge generated by 1 million people contained 13 million dollars worth of precious metals.
Other materials
With pyrolysis, urine is turned into a pre-doped, highly porous, carbon material termed "urine carbon" (URC). URC is cheaper than current fuel cell
A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen fuel, hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most bat ...
catalysts while performing better.
History
The reuse of excreta as a fertilizer for growing crops has been practiced in many countries for a long time.
Society and culture
Economics
Debate is ongoing about whether reuse of excreta is cost effective.[ The terms "sanitation economy" and "toilet resources" have been introduced to describe the potential for selling products made from ]human feces
Human feces (American English) or faeces (British English), commonly and in medical literature more often called stool, are the solid or semisolid remains of food that could not be digested or absorbed in the small intestine of humans, but has b ...
or urine
Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
.
Sale of compost
The NGO SOIL in Haiti
Haiti, officially the Republic of Haiti, is a country on the island of Hispaniola in the Caribbean Sea, east of Cuba and Jamaica, and south of the Bahamas. It occupies the western three-eighths of the island, which it shares with the Dominican ...
began building urine-diverting dry toilets and composting the waste produced for agricultural use in 2006. SOIL's two composting waste treatment facilities currently transform over of human excreta into organic, agricultural-grade compost every month. The compost produced at these facilities is sold to farmers, organizations, businesses, and institutions around the country to help finance SOIL's waste treatment operations. Crops grown with this soil amendment include spinach, peppers, sorghum, maize, and more. Each batch of compost produced is tested for the indicator organism '' E. coli'' to ensure that complete pathogen kill has taken place during the thermophilic
A thermophile is a type of extremophile that thrives at relatively high temperatures, between . Many thermophiles are archaea, though some of them are bacteria and fungi. Thermophilic eubacteria are suggested to have been among the earliest bact ...
composting process.
Policies
There is still a lack of examples of implemented policy where the reuse aspect is fully integrated in policy and advocacy.[SEI (2009)]
Sanitation policies and regulatory frameworks for reuse of nutrients in wastewater, human excreta and greywater
- Proceedings from SEI/EcoSanRes2 Workshop in Sweden. Stockholm Environment Institute, Sweden When considering drivers for policy change in this respect, the following lessons learned should be taken into consideration: Revising legislation does not necessarily lead to functioning reuse systems; it is important to describe the “institutional landscape” and involve all actors; parallel processes should be initiated at all levels of government (i.e. national, regional and local level); country specific strategies and approaches are needed; and strategies supporting newly developed policies need to be developed).
Regulatory considerations
Regulations such as Global Good Agricultural Practices may hinder export and import of agricultural products that have been grown with the application of human excreta-derived fertilisers.[Elisabeth Kvarnström, Linus Dagerskog, Anna Norström and Mats Johansson (2012]
Nutrient reuse as a solution multiplier
(SIANI policy brief 1.1), A policy brief by the SIANI Agriculture-Sanitation Expert Group, Sweden
Urine use in organic farming in Europe
The European Union
The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...
allows the use of source separated urine only in conventional farming within the EU, but not yet in organic farming. This is a situation that many agricultural experts, especially in Sweden, would like to see changed. This ban may also reduce the options to use urine as a fertilizer in other countries if they wish to export their products to the EU.
Dried feces from urine-diverting dry toilets in the U.S.
In the United States, the EPA regulation governs the management of sewage sludge
Sewage sludge is the residual, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. The term "septage" also refers to sludge from simple wastewater treatment but is connected to si ...
but has no jurisdiction over the byproducts of a urine-diverting dry toilet. Oversight of these materials falls to the states.
Country examples
China
Treatment disposal of human excreta can be categorized into three types: fertilizer use, discharge and biogas use. Discharge is the disposal of human excreta to soil, septic tank or water body. In China, with the impact of the long tradition, human excreta is often used as fertilizer for crops. The main application methods are direct usage for crops and fruits as basal or top application after fermentation in a ditch for a certain period, compost with crop stalk for basal application and direct usage as feed for fish in ponds. On the other hand, as much as many people rely on human waste as an agricultural fertilizer, if the waste is not properly treated, the use of night soil may promote the spread of infectious diseases.
India
Urine is used as organic manure in India. It is also used for making an alcohol-based bio-pesticide: the ammonia within breaks down lignin, allowing plant materials like straw
Straw is an agricultural byproduct consisting of the dry wikt:stalk, stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the crop yield, yield by weight of cereal crops such as barley, oats, rice, ry ...
to be more easily fermented into alcohol.
Kenya
In Mukuru, Kenya, the slum dwellers are worst hit by the sanitation challenge due to a high population density and a lack of supporting infrastructure. Makeshift pit latrines, illegal toilet connections to the main sewer systems and lack of running water to support the flushable toilets present a sanitation nightmare in all Kenyan slums. The NGO Sanergy seeks to provide decent toilet facilities to Mukuru residents and uses the feces and urine from the toilets to provide fertilizer and energy for the market.
Uganda
Reuse of wastewater in agriculture is a common practice in the developing world. In a study in Kampala
Kampala (, ) is the Capital city, capital and largest city of Uganda. The city proper has a population of 1,875,834 (2024) and is divided into the five political divisions of Kampala Central Division, Kampala, Kawempe Division, Kawempe, Makindy ...
, although famers were not using fecal sludge, 8% of farmers were using wastewater sludge as a soil amendment. Compost from animal manure and composted household waste are applied by many farmers as soil conditioners. On the other hand, farmers are already mixing their own feed because of limited trust in the feed industry and the quality of products.
Electricity demand is significantly more than the electricity generation and only a small margin of the population nationally has access to electricity. The pellets produced from fecal sludge are being used in gasification for electricity production. Converting fecal sludge for energy could contribute toward meeting present and future energy needs.
In Tororo District in eastern Uganda—a region with severe land degradation
Land degradation is a process where land becomes less healthy and productive due to a combination of Human impact on the environment, human activities or natural conditions. The causes for land degradation are numerous and complex. Human activitie ...
problems— smallholder farmers appreciated urine fertilization as a low-cost, low-risk practice. They found that it could contribute to significant yield increases. The importance of social norms and cultural perceptions needs to be recognized but these are not absolute barriers to adoption of the practice.
Ghana
In Ghana, the only wide scale implementation is small scale rural digesters, with about 200 biogas plants using human excreta and animal dung as feedstock. Linking up of public toilets with biogas digesters as a way of improving communal hygiene and combating hygiene-related communicable diseases including cholera and dysentery is also a notable solution within Ghana.
See also
*Compost
Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...
*Ecological sanitation
Ecological sanitation, commonly abbreviated as ecosan (also spelled eco-san or 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 ch ...
*Fecal sludge management
Fecal sludge management (FSM) (or faecal sludge management in British English) is the storage, collection, transport, treatment and safe end use or disposal of fecal sludge. Together, the collection, transport, treatment and end use of fecal slud ...
*Manure
Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nut ...
*Night soil
Night soil is a historical euphemism for Human waste, human excreta collected from cesspit, cesspools, privies, pail closets, pit latrines, privy middens, septic tanks, etc. This material was removed from the immediate area, usually at night, by ...
*Resource recovery
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. Resou ...
* Vermifilter toilet
Notes
References
External links
Documents on reuse of excreta
in the library of the Sustainable Sanitation Alliance
The Sustainable Sanitation Alliance (SuSanA) is a loose network of organizations who are "working along the same lines towards achieving sustainable sanitation". It began its work in 2007, one year before the United Nations International Year o ...
Photos on reuse of excreta
in photo database of the Sustainable Sanitation Alliance
The Sustainable Sanitation Alliance (SuSanA) is a loose network of organizations who are "working along the same lines towards achieving sustainable sanitation". It began its work in 2007, one year before the United Nations International Year o ...
{{Recycling
Agriculture
Excretion
Feces
Repurposing
Sanitation