A composting toilet is a type of
dry toilet
A dry toilet (or non-flush toilet, no flush toilet or toilet without a flush) 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 a ...
that treats
human waste by a biological process called
composting. This process leads to the
decomposition
Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...
of
organic matter and turns human waste into compost-like material. Composting is carried out by microorganisms (mainly
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
and
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
) under controlled
aerobic
Aerobic means "requiring air," in which "air" usually means oxygen.
Aerobic may also refer to
* Aerobic exercise, prolonged exercise of moderate intensity
* Aerobics, a form of aerobic exercise
* Aerobic respiration, the aerobic process of cel ...
conditions.
Most composting toilets use no water for flushing and are therefore called "
dry toilet
A dry toilet (or non-flush toilet, no flush toilet or toilet without a flush) 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 a ...
s".
In many composting toilet designs, a carbon additive such as
sawdust
Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sanding, milling, planing, and routing. It is composed of small chippings of wood. These operations can be performed by woodworking machine ...
,
coconut coir, or
peat moss
''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
is added after each use. This practice creates air pockets in the human waste to promote aerobic decomposition. This also improves the carbon-to-nitrogen ratio and reduces potential
odor. Most composting toilet systems rely on
mesophilic
A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, with an optimum growth range from . The optimum growth temperature for these organisms is 37°C. The term is mainly applied to microorganisms. Organi ...
composting. Longer retention time in the composting chamber also facilitates
pathogen
In biology, a pathogen ( el, πάθος, "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 ...
die-off. The end product can also be moved to a secondary system – usually another composting step – to allow more time for mesophilic composting to further reduce pathogens.
Composting toilets, together with the secondary composting step, produce a
humus-like end product that can be used to enrich soil if local regulations allow this. Some composting toilets have
urine diversion
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 ...
systems in the toilet bowl to collect the urine separately and control excess moisture. A
vermifilter toilet
Vermifilter toilet, also known as a primary vermifilter, vermidigester toilet, tiger toilet or tiger worm toilet, is an on-site sanitation system in which human excreta are delivered from a toilet (usually by flushing) onto a medium containing a wo ...
is a composting toilet with flushing water where
earthworm
An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. T ...
s are used to promote decomposition to compost.
Composting toilets do not require a connection to
septic tank
A septic tank is an underground chamber made of concrete, fiberglass, or plastic through which domestic wastewater ( sewage) flows for basic sewage treatment. Settling and anaerobic digestion processes reduce solids and organics, but the treatm ...
s or
sewer systems unlike
flush toilet
A flush toilet (also known as a flushing toilet, water closet (WC) – see also toilet names) is a toilet that disposes of human waste (principally urine and feces) by using the force of water to ''flush'' it through a drainpipe to another loca ...
s.
Common applications include
national parks
A national park is a natural park in use for conservation purposes, created and protected by national governments. Often it is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individua ...
, remote holiday cottages,
ecotourism
Ecotourism is a form of tourism involving responsible travel (using sustainable transport) to natural areas, conserving the environment, and improving the well-being of the local people. Its purpose may be to educate the traveler, to provide fund ...
resorts,
off-grid homes and rural areas in
developing countries
A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
.
Terminology
![Schematic of the composting chamber](https://upload.wikimedia.org/wikipedia/commons/9/9d/Schematic_of_the_composting_chamber.svg)
The term "composting toilet" is used quite loosely, and its meaning varies by country. For example, in Germany and Scandinavian countries, composting always refers to a predominantly aerobic process. This aerobic composting may take place with an increase in temperature due to microbial action, or without a temperature increase in the case of slow composting or cold composting. If earth worms are used (
vermicomposting
Vermicompost (vermi-compost) is the product of the decomposition process using various species of worms, usually red wigglers, white worms, and other earthworms, to create a mixture of decomposing vegetable or food waste, bedding materials, and ...
) then there is also no increase in temperature.
Composting toilets differ from
pit latrine
A pit latrine, also known as pit toilet, is a type of toilet that collects human feces 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 use ...
s and
arborloo
An arborloo is a simple type of composting toilet in which feces are collected in a shallow pit and a fruit tree is later planted in the fertile soil of the full pit. Arborloos have: a pit like a pit latrine but less deep; a concrete, ferroceme ...
s, which use less controlled decomposition and may not protect
groundwater
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated ...
from nutrient or
pathogen
In biology, a pathogen ( el, πάθος, "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 ...
contamination or provide optimal nutrient recycling. They also differ from
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 ma ...
s (UDDTs) where pathogen reduction is achieved through dehydration (also known by the more precise term "
desiccation") and where the feces collection vault is kept as dry as possible. Composting toilets aim to have a certain degree of moisture in the composting chamber.
Composting toilets can be used to implement an
ecological sanitation approach for
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. Reso ...
, and some people call their composting toilet designs "ecosan toilets" for that reason. However, this is not recommended as the two terms (i.e. composting and ecosan) are not identical.
[Rieck, C., von Münch, E., Hoffmann, H. (2012)]
Technology review of urine-diverting dry toilets (UDDTs) - Overview on design, management, maintenance and costs
Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
![SelfContainedCompostingToiletDesign](https://upload.wikimedia.org/wikipedia/commons/d/d5/SelfContainedCompostingToiletDesign.png)
Composting toilets have also been called "sawdust toilets", which can be appropriate if the amount of aerobic composting taking place in the toilet's container is very limited.
[Hill, B. G. (2013)]
An evaluation of waterless human waste management systems at North American public remote sites
PhD thesis, University of British Columbia (Vancouver), Canada The "
Clivus multrum
Clivus Multrum is a type of composting toilet and the name of a company that markets this brand name of composting toilets. " Clivus" is Latin for incline or slope; "multrum" is a Swedish composite word meaning "compost room", thus a "Clivus Mul ...
" is a type of composting toilet which has a large composting chamber below the toilet seat and also receives undigested organic material to increase the carbon to nitrogen ratio. Alternatives with smaller composting chambers are called "self-contained composting toilets" since the composting chamber is part of the toilet unit itself.
Applications
![Compostingtoilet](https://upload.wikimedia.org/wikipedia/commons/c/c8/Compostingtoilet.jpg)
Composting toilets can be suitable in areas such as a rural area or a park that lacks a suitable
water supply
Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Thes ...
,
sewers and
sewage treatment
Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding e ...
. They can also help increase the
resilience of existing
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 syste ...
systems in the face of possible natural disasters such as
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
,
earthquakes or
tsunami
A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...
. Composting toilets can reduce or perhaps eliminate the need for a
septic tank
A septic tank is an underground chamber made of concrete, fiberglass, or plastic through which domestic wastewater ( sewage) flows for basic sewage treatment. Settling and anaerobic digestion processes reduce solids and organics, but the treatm ...
system to reduce
environmental footprint
The ecological footprint is a method promoted by the Global Footprint Network to measure human demand on natural capital, i.e. the quantity of nature it takes to support people or an economy. It tracks this demand through an ecological accounti ...
(particularly when used in conjunction with an on-site
greywater treatment system
Greywater (or grey water, sullage, also spelled gray water in the United States) refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater fro ...
).
These types of toilets can be used for
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. Reso ...
by reusing sanitized feces and urine as fertilizer and soil conditioner for gardening or ornamental activities.
Basics
Components and use
A composting toilet consists of two elements: a place to sit or
squat and a collection/composting unit.
[Berger, W. (2011)]
Technology review of composting toilets - Basic overview of composting toilets (with or without urine diversion).
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany The composting unit consists of four main parts:
* storage or composting chamber
* a ventilation unit to ensure that the degradation process in the toilet is predominantly aerobic and to vent odorous gases
* a leachate collection or urine diversion system to remove excess liquid
* an access door for extracting the compost
Many composting toilets collect urine in the same chamber as feces, thus they do not
divert urine. Adding small amounts of water that is used for
anal cleansing
Anal hygiene or anal cleansing refers to hygienic practices that are performed on a person's anus, usually shortly after defecation. Post-defecation cleansing is rarely discussed academically, partly due to the social taboo. The scientific objec ...
is no problem for the composting toilet to handle.
Some composting toilets divert urine (and water used for anal washing) to prevent the creation of anaerobic conditions that can result from over saturation of the compost, which leads to odors and vector problems. This usually requires all users to use the toilet in a seated position. Offering a
waterless urinal
A urinal (, ) is a sanitary plumbing fixture for urination only. Urinals are often provided in public toilets for male users in Western countries (less so in Muslim countries). They are usually used in a standing position. Urinals can be wit ...
in addition to the toilet can help keep excess amounts of urine out of the composting chamber. Alternatively, in rural areas, men and boys may be encouraged just to find a tree.
Construction
The composting chamber can be constructed above or below ground level. It can be inside a structure or include a separate superstructure.
A drainage system removes
leachate. Otherwise, excess moisture can cause anaerobic conditions and impede decomposition. Urine diversion can improve
compost quality, since urine contains large amounts of
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
that inhibits microbiological activity.
Composting toilets greatly reduce human waste volumes through
psychrophilic
Psychrophiles or cryophiles (adj. ''psychrophilic'' or ''cryophilic'') are extremophilic organisms that are capable of growth and reproduction in low temperatures, ranging from to . They have an optimal growth temperature at . They are found in ...
,
thermophilic
A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...
or
mesophilic
A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, with an optimum growth range from . The optimum growth temperature for these organisms is 37°C. The term is mainly applied to microorganisms. Organi ...
composting. Keeping the composting chamber insulated and warm protects the composting process from slowing due to low temperatures.
Odorous gases
The following gases may be emitted during the composting process that takes place in composting toilets:
hydrogen sulfide (H
2S),
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
,
nitrous oxide
Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
(N
2O) and
volatile organic compound
Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, a ...
s (VOCs). These gases can potentially lead to complaints about odours. Some
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
may also be present, but it is not odorous.
Pathogen removal
Waste-derived compost recycles fecal nutrients, but it can carry and spread pathogens if the process of
reuse of waste is not done properly. Pathogen destruction rates in composting toilets are usually low, particularly of
helminth eggs (such as those from the genus ''
Ascaris
''Ascaris'' is a genus of parasitic nematode worms known as the "small intestinal roundworms", which is a type of parasitic worm. One species, '' Ascaris lumbricoides'', affects humans and causes the disease ascariasis. Another species, ''Asc ...
'').
This carries the risk of spreading disease if a proper system management is not in place. Compost from human waste processed under only mesophilic conditions or taken directly from the compost chamber is not safe for food production. High temperatures or long composting times are required to kill helminth eggs, the hardiest of all pathogens.
Helminth infections are common in many
developing countries
A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
.
In
thermophilic
A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...
composting
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
that thrive at temperatures of
oxidize
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
(break down) waste into its components, some of which are consumed in the process, reducing volume and eliminating potential
pathogen
In biology, a pathogen ( el, πάθος, "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 ...
s. To destroy pathogens, thermophilic composting must heat the compost pile sufficiently, or enough time (1–2 years) must elapse since fresh material was added that
biological activity has had the same pathogen removal effect.
One guideline claims that pathogen levels are reduced to a safe level by thermophilic composting at temperatures of 55 °C for at least two weeks or at 60 °C for one week.
An alternative guideline claims that complete pathogen destruction may be achieved already if the entire compost heap reaches a temperature of for one hour, for one day, for one week or for one month,
although others regard this as overly optimistic.
Design considerations
Environmental factors
Four main factors affect the decomposition process:
* Sufficient oxygen is necessary for aerobic composting
* Moisture content from 45 to 70 percent (heuristically, "the compost should feel damp to the touch, with only a drop or two of water expelled when tightly squeezed in the hand".
)
* Temperature between and , which is achieved through proper chamber dimensioning and possibly active mixing
*
Carbon-to-nitrogen ratio
A carbon-to-nitrogen ratio (C/N ratio or C:N ratio) is a ratio of the mass of carbon to the mass of nitrogen in organic residues. It can, amongst other things, be used in analysing sediments and soil including soil organic matter and soil amendm ...
(C:N) of 25:1
Additives and bulking material
Human waste and food waste do not provide optimum conditions for composting. Usually the water and nitrogen content is too high, particularly when urine is mixed with feces. Additives or "bulking material", such as wood chips, bark chips, sawdust, shredded dry leaves, ash and pieces of paper can absorb moisture. The additives improve pile aeration and increase the carbon to nitrogen ratio.
Bulking material also covers feces and reduces insect access. Absent sufficient bulking material, the material may become too compact and form impermeable layers, which leads to anaerobic conditions and odour.
Leachate management
Leachate removal controls moisture levels, which is necessary to ensure rapid, aerobic composting. Some commercial units include a urine-separator or
urine-diverting system and/or a drain at the bottom of the composter for this purpose.
Aeration and mixing
Microbial action also requires oxygen, typically from the air. Commercial systems provide ventilation that moves air from the bathroom, through the waste container, and out a vertical pipe, venting above the roof. This air movement (via
convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the conve ...
or fan forced) passes carbon dioxide and odors.
Some units require manual methods for periodic aeration of the solid mass such as rotating the composting chamber or pulling an "aerator rake" through the mass.
Comparisons with other types of toilets
Pit latrines
Composting toilets convert feces into a dry, odorless material which is very different to the wet fecal sludge produced in
pit latrines
A pit latrine, also known as pit toilet, is a type of toilet that collects human feces 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 ...
which has to be taken care of through a
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 ...
system. Composting toilets do not 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 unwante ...
due to their safe containment of feces in above-ground vaults compared to pit latrines, allowing composting toilets to be sited in locations where pit-based systems are not appropriate.
Composting toilets have higher capital costs than pit latrines, but lower lifecycle costs. They require more involvement by the user than the "drop and forget" approach of pit latrines.
Flush toilets
Unlike
flush toilet
A flush toilet (also known as a flushing toilet, water closet (WC) – see also toilet names) is a toilet that disposes of human waste (principally urine and feces) by using the force of water to ''flush'' it through a drainpipe to another loca ...
s, composting toilets do not require a
sewerage system and do not mix flushing water with urine and feces. They require more involvement by the user than the "flush and forget" approach of flush toilets connected to
sewage treatment plants
Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding en ...
.
Urine-diverting dry toilets
Composting toilets, although similar to and sharing many advantages and disadvantages with
urine-diverting dry toilets
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 ma ...
(UDDT), are more complex and require more maintenance to keep a consistent and relatively high moisture content. Some composting toilets are designed with
urine diversion
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 ...
.
Types
![Local de compostage - composting unit (6150163178)](https://upload.wikimedia.org/wikipedia/commons/0/02/Local_de_compostage_-_composting_unit_%286150163178%29.jpg)
Commercial units and construct-it-yourself systems are available. Variations include number of composting vaults, removable vault,
urine diversion
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 ...
and active mixing/aeration.
Slow composting (or moldering) toilets
Most composting toilets use slow composting which is also called "cold composting". The compost heap is built up step by step over time.
The finished end product from "slow" composting toilets ("moldering toilets" or "moldering privies" in the US), is generally not free of pathogens.
World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
Guidelines from 2006 offer a framework for safe
reuse of waste, using a multiple barrier approach.
[WHO (2006)]
WHO Guidelines for the Safe Use of Wastewater, Excreta and Greywater - Volume IV: Excreta and greywater use in agriculture
World Health Organization (WHO), Geneva, Switzerland
Slow composting toilets employ a passive approach. Common applications involve modest and often seasonal use, such as remote trail networks. They are typically designed such that the materials deposited can be isolated from the operational part. The toilet can also be closed to allow further mesophilic composting.
[Appalachian Trail Conservancy (2014)]
Backcountry Sanitation Manual, 2nd Edition
Appalachian Trail Conservancy, Green Mountain Club, USDA Forest Service, National Park Service, USA Slow composting toilets rely on long retention times for pathogen reduction and for decomposition of waste or on the combination of time and/or the addition of
red wriggler worms for vermi-composting. Worms can be introduced to accelerate composting. Some jurisdictions of the US consider these worms as
invasive species.
Active composters (self-contained)
"Self-contained" composting toilets compost in a container within the toilet unit. They are slightly larger than a
flush toilet
A flush toilet (also known as a flushing toilet, water closet (WC) – see also toilet names) is a toilet that disposes of human waste (principally urine and feces) by using the force of water to ''flush'' it through a drainpipe to another loca ...
, but use roughly the same floor space. Some units use fans for aeration, and optionally, heating elements to maintain optimum temperatures to hasten the composting process and to evaporate urine and other moisture. Operators of composting toilets commonly add a small amount of absorbent carbon material (such as untreated
sawdust
Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sanding, milling, planing, and routing. It is composed of small chippings of wood. These operations can be performed by woodworking machine ...
, coconut
coir
Coir (), also called coconut fibre, is a natural fibre extracted from the outer husk of coconut and used in products such as floor mats, doormats, brushes, and mattresses. Coir is the fibrous material found between the hard, internal shell an ...
, or
peat moss
''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
) after each use to create air pockets to encourage aerobic processing, to absorb liquid and to create an odor barrier. This additive is sometimes referred to as "bulking agent". Some owner-operators use microbial "starter" cultures to ensure composting bacteria are in the process, although this is not critical.
Vermifilter toilet
A
vermifilter toilet
Vermifilter toilet, also known as a primary vermifilter, vermidigester toilet, tiger toilet or tiger worm toilet, is an on-site sanitation system in which human excreta are delivered from a toilet (usually by flushing) onto a medium containing a wo ...
is a composting toilet with flushing water where
earthworm
An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. T ...
s are used to promote decomposition to compost. It can be connected to a
low-flush or a micro-flush toilet which uses about per use. Solids accumulate on the surface of the filter bed while liquid drains through the filter medium and is discharged from the reactor. The solids (feces and toilet paper) are aerobically digested by aerobic bacteria and
composting earthworms into castings (humus), thereby significantly reducing the volume of organic material.
[C. Furlong, W. T. Gibson, M. R. Templeton, M. Taillade, F. Kassam, G. Crabb, R. Goodsell, J. McQuilkin, A. Oak, G. Thakar, M. Kodgire, R. Patankar]
The development of an onsite sanitation system based on vermifiltration: the "Tiger Toilet"
Journal of Water, Sanitation and Hygiene for Development, January 2015
Other
Some units employ roll-away containers fitted with aerators, while others use sloped-bottom tanks.
Maintenance
Maintenance is critical to ensure proper operation, including odor prevention. Maintenance tasks include: cleaning, servicing technical components such as fans and removal of compost, leachate and urine. Urine removal is only required for those types of composting toilets using urine diversion.
Once composting is complete (or earlier), the compost must be removed from the unit. How often this occurs is a function of container size, usage and composting conditions, such as temperature.
Active, hot composting may require months, while passive, cold composting may require years. Properly managed units yield output volumes of about 10% of inputs.
Uses of compost
![Kiel-Hassee Erde mit Schubkarre (5708339858)](https://upload.wikimedia.org/wikipedia/commons/5/56/Kiel-Hassee_Erde_mit_Schubkarre_%285708339858%29.jpg)
The material from composting toilets is a
humus-like material, which can be suitable as a
soil amendment for agriculture. Compost from residential composting toilets can be used in domestic gardens, and this is the main such use.
Enriching soil with compost adds substantial nitrogen, phosphorus, potassium, carbon and calcium. In this regard compost is equivalent to many
fertilizers
A fertilizer (American English) or fertiliser (British English; see spelling differences) 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 ...
and
manures
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 nutrie ...
purchased in garden stores. Compost from composting toilets has a higher nutrient availability than the dried feces that result from a
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 ma ...
.
Urine is typically present, although some is lost via leaching and evaporation. Urine can contain up to 90 percent of the residual
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, up to 50 percent of the
phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
, and up to 70 percent of the
potassium
Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosph ...
.
Compost derived from these toilets 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 s ...
or municipal organic waste. However, users of waste-derived compost must consider the risk of pathogens.
Pharmaceutical residues
Waste-derived compost may contain
prescription pharmaceuticals. Such residues are also present in conventional
sewage treatment
Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding e ...
effluent. This could
contaminate groundwater. Among the medications that have been found in groundwater in recent years are
antibiotics,
antidepressants,
blood thinner
Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where th ...
s,
ACE inhibitors,
calcium-channel blockers,
digoxin,
estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
,
progesterone,
testosterone
Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
,
Ibuprofen,
caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine to ...
,
carbamazepine
Carbamazepine (CBZ), sold under the trade name Tegretol among others, is an anticonvulsant medication used primarily in the treatment of epilepsy and neuropathic pain. It is used as an adjunctive treatment in schizophrenia along with other m ...
,
fibrate
In pharmacology, the fibrates are a class of amphipathic carboxylic acids and esters. They are derivatives of fibric acid (phenoxyisobutyric acid). They are used for a range of metabolic disorders, mainly hypercholesterolemia (high cholesterol), ...
s and
cholesterol
Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
-reducing medications. Between 30% and 95% of pharmaceuticals medications are excreted by the human body. Medications that are
lipophilic
Lipophilicity (from Greek λίπος "fat" and φίλος "friendly"), refers to the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such non-polar solvents are themselves lipo ...
(dissolved in fats) are more likely to reach groundwater by leaching from fecal wastes. Sewage treatment plants remove an average of 60% of these medications. The percentage of medications degraded during composting of waste has not yet been reported.
History
In the late 19th century in developed countries, some inventors, scientists and
public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...
officials supported the use of "dry earth closets", a type of
dry toilet
A dry toilet (or non-flush toilet, no flush toilet or toilet without a flush) 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 a ...
with similarities to composting toilets, although the collection vessel for the
human waste was not designed to compost.
Society and culture
Regulations
International Organization for Standardization (ISO)
In 2016, the
International Organization for Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...
(
ISO
ISO is the most common abbreviation for the International Organization for Standardization.
ISO or Iso may also refer to: Business and finance
* Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007
* Iso ...
) published the standard "Activities relating to drinking water and wastewater services — Guidelines for the management of basic on-site domestic wastewater services". The standard is meant to be used in conjunction with ISO 24511. It deals with toilets (including composting toilets) and toilet waste. The guidelines are applicable to basic wastewater systems and include the complete domestic wastewater cycle, such as planning, usability, operation and maintenance, disposal, reuse and health.
International Association of Plumbing and Mechanical Officials
The
International Association of Plumbing and Mechanical Officials
The International Association of Plumbing and Mechanical Officials (IAPMO) coordinates the development and adaptation of plumbing, mechanical, swimming pool and solar energy codes to meet the specific needs of individual jurisdictions both in the ...
(IAPMO) is a plumbing and mechanical code structure adopted by many developed countries. It recently proposed an addition to its "Green Plumbing Mechanical Code Supplement" that, "...outlines performance criteria for site built composting toilets with and without urine diversion and manufactured composting toilets." If adopted, this composting and urine diversion toilet code (the first of its kind in the United States) will appear in the 2015 edition of the Green Supplement to the Uniform Plumbing Code.
United States
No performance standards for composting toilets are universally accepted in the US. Seven jurisdictions in North America use ''American National Standard/NSF International Standard ANSI/NSF 41-1998: Non-Liquid Saturated Treatment Systems''. An updated version was published in 2011. Systems might also be listed with the Canadian Standards Association, cETL-US, and other standards programs.
Regarding byproduct regulation, several US states permit disposal of solids from composting toilets (usually a distinction between different types of dry toilets is not made) by burial, with varying or no minimum depth mandates (as little as 6 inches). For instance:
* Massachusetts: "Residuals from the composting toilet system must be buried on-site and covered with a minimum of six inches of clean compacted soil.
Massachusetts requires that any liquids produced but, "not recycled through the toilet
tself beeither discharged through a greywater system on the property that includes a septic tank and soil absorption system, or removed by a licensed septage hauler."
* Oregon: "Humus from composting toilets may be used around ornamental shrubs, flowers, trees, or fruit trees and shall be buried under at least twelve inches of soil cover."
* Rhode Island: "Solids produced by alternative toilets may be buried on site," while, "residuals shall not be applied to food crops."
* Virginia: "All materials removed from a composting privy shall be buried," and "compost material shall not be placed in vegetable gardens or on the ground surface."
* Vermont: "Byproducts may be disposed via "...shallow burial in a location approved by the Agency that meets the minimum site conditions
equired for an onsite septic tank-based sanitation system"
* Washington: models its extensive regulations for what it refers to as "waterless toilets" on the federal regulations that govern
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 s ...
.
The
Environmental Protection Agency has no jurisdiction over the byproducts of a dry toilet as long as waste are not referred to as "fertilizer" (but instead simply a material that is being disposed of). Federal rule 503, known colloquially as the "EPA Biosolids rule" or the "EPA sludge rule" applies only to fertilizer. Thus, individual states regulate composting toilets.
Germany
The regulations for composting toilets and other forms of dry toilets in Germany vary from state to state and from one application to another (e.g. use in allotment gardens or use in family homes and settlements). In the different states of Germany, it is the "Landesbauordnung" (translates to "state civil engineering regulations") of the respective state that regulates the use of such alternative toilets.
Most of them stipulate the use of
flush toilet
A flush toilet (also known as a flushing toilet, water closet (WC) – see also toilet names) is a toilet that disposes of human waste (principally urine and feces) by using the force of water to ''flush'' it through a drainpipe to another loca ...
s, however there are many exceptions, for example in the states of
Hamburg
(male), (female) en, Hamburger(s),
Hamburgian(s)
, timezone1 = Central (CET)
, utc_offset1 = +1
, timezone1_DST = Central (CEST)
, utc_offset1_DST = +2
, postal ...
,
Lower Saxony
Lower Saxony (german: Niedersachsen ; nds, Neddersassen; stq, Läichsaksen) is a German state (') in northwestern Germany. It is the second-largest state by land area, with , and fourth-largest in population (8 million in 2021) among the 16 ...
,
Bavaria
Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...
,
Mecklenburg-Western Pomerania
Mecklenburg-Vorpommern (MV; ; nds, Mäkelborg-Vörpommern), also known by its anglicized name Mecklenburg–Western Pomerania, is a state in the north-east of Germany. Of the country's sixteen states, Mecklenburg-Vorpommern ranks 14th in po ...
,
Rhineland-Palatinate
Rhineland-Palatinate ( , ; german: link=no, Rheinland-Pfalz ; lb, Rheinland-Pfalz ; pfl, Rhoilond-Palz) is a western state of Germany. It covers and has about 4.05 million residents. It is the ninth largest and sixth most populous of the ...
,
Saxony-Anhalt
Saxony-Anhalt (german: Sachsen-Anhalt ; nds, Sassen-Anholt) is a state of Germany, bordering the states of Brandenburg, Saxony, Thuringia and Lower Saxony. It covers an area of
and has a population of 2.18 million inhabitants, making it th ...
and
Thuringia
Thuringia (; german: Thüringen ), officially the Free State of Thuringia ( ), is a state of central Germany, covering , the sixth smallest of the sixteen German states. It has a population of about 2.1 million.
Erfurt is the capital and lar ...
.
These generally make exceptions for the use of composting toilets in homes provided that there are no concerns for public health.
Regulations governing the use of compost and urine from composting toilets is less clear in Germany but it seems generally allowed provided it is used on one's own property and not sold to third parties.
Examples
Finland
Numerous sparsely settled villages in rural areas in Finland are not connected to municipal
water supply
Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Thes ...
or sewer networks, requiring homeowners to operate their own systems. Individual private wells, i.e. shallow dug wells or boreholes in the bedrock, are often used for water supply, and many homeowners have opted for composting toilets. In addition, these toilets are common at holiday homes, often located near sensitive water bodies. For these reasons, many manufacturers of composting toilets are based in Finland, including Biolan, Ekolet, Kekkilä, Pikkuvihreä and Raita Environment.
Estimates made by leading Finnish composting toilet manufacturers and the Global Dry Toilet Association of Finland provided the following 2014 figures for composting toilet use in Finland:
* About 4% of single-family homes not connected to a public sewer network are equipped with a composting toilet.
* Some 200,000 manufactured composting toilets are thought to serve holiday homes, matched by the number of other dry toilets. The simplest ones are sited in an
outhouse
An outhouse is a small structure, separate from a main building, which covers a toilet. This is typically either a pit latrine or a bucket toilet, but other forms of dry (non-flushing) toilets may be encountered. The term may also be used ...
.
Germany
![Composting container](https://upload.wikimedia.org/wikipedia/commons/0/05/Composting_container_%22TerraNova%22%2C_showing_open_removal_chamber_%286210814073%29.jpg)
Composting toilets have been successfully installed in houses with up to four floors.
An estimate from 2008 put the number of composting toilets in households in Germany at 500.
Most of these residences are also connected to a sewer system; the composting toilet was not installed due to a lack of sewer system but for other reasons, mainly because of an "ecological mindset" of the owners.
In Germany and Austria, composting toilets and other types of
dry toilet
A dry toilet (or non-flush toilet, no flush toilet or toilet without a flush) 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 a ...
s have been installed in single and multi-family houses (e.g. Hamburg, Freiburg, Berlin), ecological settlements (e.g. Hamburg-Allermöhe, Hamburg-Braamwisch, Kiel-Hassee, Bielefeld-Waldquelle, Wien-Gänserndorf) and in public buildings (e.g. Ökohaus Rostock, VHS-Ökostation Stuttgart-Wartberg, public toilets in recreational areas, restaurants and huts in the Alps, house boats and forest Kindergartens).
The ecological settlement in Hamburg-Allermöhe has had composting toilets since 1982. The settlement of 36 single-family houses with approximately 140 inhabitants uses composting toilets,
rainwater harvesting
Rainwater harvesting (RWH) is the collection and storage of rain, rather than allowing it to run off. Rainwater is collected from a roof-like surface and redirected to a tank, cistern, deep pit (well, shaft, or borehole), aquifer, or a reservoir ...
and
constructed wetlands
A constructed wetland is an artificial wetland to treat sewage, greywater, stormwater runoff or industrial wastewater. It may also be designed for land reclamation after mining, or as a mitigation step for natural areas lost to land developmen ...
. Composting toilets save about 40 litres of water per capita per day compared to a conventional flush toilet (10 liter per flush), which adds up to 2,044 m³ water savings per year for the whole settlement.
United States
Slow composting toilets have been installed by the
Green Mountain Club
The Green Mountain Club is a non-profit membership organization dedicated to preserving and protecting Vermont's Long Trail. The Long Trail is the oldest long-distance hiking trail in America and stretches from the Massachusetts state line to the ...
in
Vermont
Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to ...
's woodlands. They employ multiple vaults (called cribs) and a movable building. When one of the vaults fills, the building is moved over an empty vault. The full vault is left untouched for as long as possible (up to three years) before it is emptied. The large surface area and exposure to air currents can cause the pile to dry out. To counteract this, signs instruct users to urinate in the toilet. The club also uses
pit latrine
A pit latrine, also known as pit toilet, is a type of toilet that collects human feces 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 use ...
s and simple
bucket toilet
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 i ...
s with woodchips and external composting and directs users to urinate in the forest to prevent odiferous anaerobic conditions.
Worldwide
Composting toilets with a large composting container (of the type
Clivus Multrum
Clivus Multrum is a type of composting toilet and the name of a company that markets this brand name of composting toilets. " Clivus" is Latin for incline or slope; "multrum" is a Swedish composite word meaning "compost room", thus a "Clivus Mul ...
and derivations of it) are popular in US, Canada, Australia, New Zealand and Sweden. They can be bought and installed as commercial products, as designs for self builders or as "design derivatives" which are marketed under various names. It has been estimated that approximately 10,000 such toilets might be in use worldwide.
See also
*
Reuse of human excreta
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 ...
*
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 syste ...
*
Sustainable sanitation
References
External links
Composting toilet description(Sustainable Sanitation and Water Management Toolbox)
Composting systems(documents in library of
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 ...
)
More photos of composting toiletsin Flickr photo database of
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 ...
{{DEFAULTSORT:Composting Toilet
Permaculture
Sustainable building
Appropriate technology
Toilet types
Composting
Home composting
Water conservation
Sanitation