Composting Chamber

Composting refers to the process by which biodegradable components are biologically decomposed by microorganisms (mainly bacteria and fungi) under aerobic conditions. A composting chamber is designed to convert excreta and organics into compost. Compost is a stable, inoffensive product that can be safely handled and used as a soil conditioner.

This technology usually requires four main parts: (1) a reactor (storage chamber); (2) a ventilation unit to provide oxygen and allow gases (CO2, water vapour) to escape; (3) a leachate collection system and (4) an access door to remove the mature product.

Excreta, food waste and bulking material (such as wood chips, sawdust, ash or paper) are mixed in the chamber. There are four factors that ensure the good functioning of the system: (a) sufficient oxygen, provided by active or passive aeration; (b) proper moisture (ideally 45 to 70% moisture content); (c) internal (heap) temperature of 40 to 50 °C (achieved by proper chamber dimensioning); and (d) a 25:1 C:N ratio (theoretically) which can be adjusted by adding bulking material as a carbon source.

In practice, these optimal conditions are difficult to maintain. As a result, the output product is often not sufficiently stabilized and sanitized, and requires further treatment.

Design Considerations

A composting chamber can be designed in various configurations and constructed above or below ground, indoors or with a separate superstructure.  

A design value of 300 L/person/year can be used to calculate the required chamber volume. 

Ventilation channels (air ducts) under the heap can be beneficial for aeration. More complex designs can include a small ventilation fan, a mechanical mixer or multiple compartments to allow for increased storage and degradation time. A sloped bottom and a chamber for compost withdrawal facilitate access to the final product. A drainage system is important to ensure the removal of leachate.

Excessive ammonia from urine inhibits the microbial processes in the chamber. The use of a Urine-Diverting Dry Toilet UDDT or Urinal can, therefore, improve the quality of the compost (see also urine diversion components).

Appropriateness

Since this technology is compact and waterless, it is especially suited in areas where land and water are limited, or when there is a need for compost. It can also be installed in rocky areas, or where the groundwater table is high. In cold climates, a composting chamber should be indoors to ensure that low temperatures do not impede the microbial processes. This technology cannot be used for the collection of anal cleansing water or greywater; if the reactor becomes too wet, anaerobic conditions will cause odour problems and improper degradation.

Health Aspects/Acceptance 

If the composting chamber is well designed, the users will not have to handle the material during the first year.

A well-functioning composting chamber should not produce odours. If there is ample bulking material and good ventilation, there should be no problems with flies or other insects. When removing the final product, it is advisable to wear protective clothing to prevent contact with (partially) composted material.

Operation & Maintenance

Although simple in theory, composting chambers are not that easy to operate. The moisture must be controlled, the C:N ratio must be well balanced and the volume of the unit must be such that the temperature of the compost pile remains high to achieve pathogen reduction. After each defecation, a small amount of bulking material is added to absorb excess liquid, improve the aeration of the pile and balance the carbon availability. Turning the material from time to time will boost the oxygen supply. 

A squeeze test can be made to check the moisture level within the chamber. When squeezing a handful of compost, it should not crumble or feel dry, nor should it feel like a wet sponge. Rather, the compost should leave only a few drops of water in one’s hand. If the material in the chamber becomes too compact and humid, additional bulking material should be added. If a UDDT is used, some water should be added to obtain the required humidity.

Depending on the design, the composting chamber should be emptied every 2 to 10 years. Only the mature compost should be removed. The material may require further treatment to become hygienically safe (e.g., Co Composting).

With time, salt or other solids may build up in the tank or drainage system. These can be dissolved with hot water and/or scraped out.

References

Further Readings

  • Cover image of a reference book or miscellany.

    BERGER, W. (2011): Technology Review of Composting Toilets. Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ). URL [Accessed: 06.02.2012]. PDF

    This GIZ publication explains the design, use and operational requirements of composting toilets. Ample examples for composting toilets from around the world are included in the publication to show that these types of toilets have a wide range of applications under a variety of circumstances (for wealthy or poor people; for cold, hot, wet or dry climates; for urban or rural settings). The appendix contains a listing of suppliers.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2010): Basic overview of Composting Toilets (with and without urine diversion). Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 22.11.2010]. PDF

    The publication explains the purposes of urine diversion, its benefits and challenges, possibilities of urine treatment and reuse in agriculture. It provides an overview on design and operational aspects for equipment needed, such as waterless urinals and urine diversion toilets. An appendix with a worldwide listing of suppliers for waterless urinals and urine diversion toilet pedestals and squatting pans is also available.

  • Cover image of a reference book or miscellany.

    ECOSAN CLUB (Editor) (2011): Toilets. Vienna: Ecosan Club. URL. PDF

    The first part of a sanitation system is the „user interface“, i.e. the toilet, pedestal, pan or urinal. It is an important part of the sanitation system because this is the part the user comes in contact with. Acceptance of a sanitation system therefore often mainly depends on the acceptance of the user interface. This paper gives an overview on developments of different technologies for user interfaces (UDDTs and urinals). The contributions present developments in different geographical regions: South America, East Africa and the Eastern Europe, the Caucasus and Central Asia (EECCA) countries.

  • Cover image of a reference book or miscellany.

    WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume IV. Excreta and Greywater Use in Agriculture. Geneva: World Health Organisation. URL [Accessed: 26.02.2010]. PDF

    Volume IV of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater recognizes the reuse potential of wastewater and excreta (including urine) in agriculture and describes the present state of knowledge as regards potential health risks associated with the reuse as well as measures to manage these health risks following a multi-barrier approach.

  • Cover image of a reference book or miscellany.

    WINBLAD, U.; SIMPSON-HERBERT, M. (2004): Ecological Sanitation - revised and enlarged edition. (pdf presentation). Sweden: Stockholm Environment Institute. URL [Accessed: 04.08.2010]. PDF

    This book is one of the most fundamental and important books that defined the concept of ecological sanitation. The first version came out in 1998 - this version presents the findings of over ten years of research and development in ecological sanitation supported by SIDA (Swedish International Development Cooperation Agency).

  • Cover image of a reference book or miscellany.

    JENKINS, J. (2005): The Humanure Handbook. A Guide to Composting Human Manure. Grove City: Joseph Jenkins Inc. . URL [Accessed: 16.08.2010].

    A comprehensive book on recycling human excrement without chemicals, high technology or pollution. Well written, practical, and thoroughly researched, this self-published book is built on nearly twenty years of experience by the author, who tells us about every aspect of dealing with excrement on the home-scale level. Only available for free as web book.

  • Cover image of a reference book or miscellany.

    NIWAGABA, C. (2007): Human Excreta Treatment Technologies - prerequisites, constraints and performance. Uppsala: Swedish Agricultural University (SLU), Department of Biometry and Engineering. PDF

    The thesis consists of three papers, the first of which investigates incineration of faecal matter as a treatment and sanitation method using a locally fabricated incinerator made of steel sheets. The second and third papers investigate composting of faeces and food waste at two size scales, using 78-litre and 216- litre wooden reactors.

  • Cover image of a reference book or miscellany.

    NWP (Editor) (2006): Smart Sanitation Solutions. Examples of innovative, low-cost technologies for toilets, collection, transportation, treatment and use of sanitation products. Amsterdam: Netherlands Water Partnership (NWP). URL [Accessed: 13.04.2010]. PDF

    Smart Sanitation Solutions presents examples of low-cost household and community-based sanitation solutions that have proven effective and affordable. A wide range of innovative technologies for toilets, collection, transportation, treatment and use of sanitation products that have already helped thousands of poor families to improve their lives is illustrated.

  • Cover image of a reference book or miscellany.

    WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume IV. Excreta and Greywater Use in Agriculture. Geneva: World Health Organisation. URL [Accessed: 26.02.2010]. PDF

    Volume IV of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater recognizes the reuse potential of wastewater and excreta (including urine) in agriculture and describes the present state of knowledge as regards potential health risks associated with the reuse as well as measures to manage these health risks following a multi-barrier approach.

  • Cover image of a reference book or miscellany.

    U.S. EPA (Editor) (1999): Composting Toilets. Washington: United States Environmental Protection Agency, Office of Water. URL [Accessed: 16.08.2010]. PDF

    Factsheet including information related to microbial die-off rates and health risks.

  • Cover image of a reference book or miscellany.

    WATER AID (Editor) (2011): Construction of Ecological Sanitation Latrine. Kathmandu: Water Aid. URL [Accessed: 19.10.2011]. PDF

    This document sets out the principles for adopting an ecological sanitation approach, as well as providing guidance on the construction ecological sanitation latrines and their operation. It is intended to support sanitation field practitioners and WaterAid in Nepal ’s partners in the delivery of appropriate services and technologies to fit the needs of different users. .It is also equally hoped that this document will be of value to other organisations and sector stakeholders involved in sanitation promotion and ecological sanitation.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2010): Appendix: Range of manufacturers and commercially available composting toilets. Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 22.11.2010]. PDF

    List of supplier for commercially available composting toilets.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2010): Methods of Using "Toilet Compost" in Agriculture. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    This document gives a simple overview over toilet compost, its preparation and fields of application.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2004): The Toilet That Makes Humus. An Account of the Fossa Alterna System and its Usefulness in Rural and Peri-Urban Communities. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    This easily understandable presentation deals with making humus in shallow pits by means of the Fossa alterna. Foci are set on: - How the Fossa alterna works (in Zimbabwe, Mozambique, Malawi) - Stages of construction - Routine management - Changing pits - Potential problems - Hand washing devices - Humus from the Fossa alterna - Enhanced growth of vegetables with “Fossa humus”

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2004): Plant Trials Using Fossa Alterna Humus. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    The ultimate proof of the usefulness of eco-humus and urine in agriculture is to demonstrate its effect on plant growth and yield directly. This chapter describes a series of trials in which the growth and yield of vegetables planted in humus derived from the Fossa alterna were studied.

Case Studies

  • Cover image of a reference book or miscellany.

    BERGER, W. (2009): Results in the Use and Practise of Composting Toilets in Multi Storey Houses in Bielefeld and Rostock, Germany. Hamburg: Berger Biotechnik AG. URL [Accessed: 22.11.2010]. PDF

    This is a an article concerning composting toilets in four story buildings.

  • Cover image of a reference book or miscellany.

    BERGER, W. (2009): Results in the Use and Practise of Composting Toilets in Multi Storey Houses in Bielefeld and Rostock, Germany- Presentation. Hamburg: Berger Biotechnik AG. URL [Accessed: 22.11.2010]. PDF

    This is a a presentation concerning composting toilets in four story buildings.

  • Cover image of a reference book or miscellany.

    HOLMER, R.; SuSanA (Editor) (2009): UDD Toilets with Reuse in Allotment Gardens.. (pdf presentation). Cagayan de Oro Philippines: Sustainable Sanitation Alliance. URL [Accessed: 11.08.2010]. PDF

    Case study on an urban agriculture project with urine reuse in Northern Mindanao, Philippines.

  • Cover image of a reference book or miscellany.

    DAWA, S.; KREUTZER, G.; PANESAR, A. (2009): Improved traditional composting toilets with urine diversion, Leh, Jammu and Kashmir State, India - draft. Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 02.08.2010]. PDF

    In Leh, a small town in Jammu and Kashmir, people try to replace traditional sanitation systems by waterborne toilet systems. This project tries to revitalise the traditional ecological sanitation practice that is threatened to fall into oblivion. Different improvements of the traditional Ladhaki toilets are suggested. Due to an extremely dry climate, it is possible to process human excreta indoors without prior diversion of urine, by using a combination of soil composting and dehydration.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2010): Introducing Low Cost Productive Sanitation in a Peri-Urban Settlement. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    The following presentation deals with low cost ecological toilets (Fossa alterna) which were introduced at Hopley Farm, a settlement close to Harare, Zimbabwe. The presentation addresses the following topics: - How the alternating shallow pit system works - Local agricultural practice - Linking sanitation to agriculture - Testing for effect of urine - Linking sanitation to forestry

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2010): Ecological Sanitation in Malawi. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    This illustrative presentation on ecological sanitation in Malawi, focuses on the concept of ecological sanitation, types of eco-toilets and basic methods of recycling nutrient from human excreta.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2003): Experiments with Ecological Sanitation and Pit Emptying in Maputaland, South Africa. A Description of Visits Made in 2000 and 2003. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    This document describes the experimental design of ecological sanitation and pit-emptying trials in Maputaland, South Africa. It describes the situation found at field visits in 2000 and 2003.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2007): The Arborloo Book for Ethiopia. How to Make a Simple Pit Toilet and Grow Trees and Vegetables. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    This booklet describes how to make a toilet which is both low cost and easy to make. Builders and artisans are not required, once the householder has learned the basic methods of construction.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2007): Lessons from a Low Cost Ecological Approach to Sanitation in Malawi. Washington: Water and Sanitation Program (WSP). URL [Accessed: 20.06.2013]. PDF

    Low cost Ecological Sanitation programs in Malawi have led to the building of over 11,000 compost-producing toilets since 2003. While the toilets are affordable and simple to construct, the fact that they convert human waste into valuable odour-free compost, enables cost recovery for households and is a prime driver in popularizing EcoSan designs. This field note summarizes the lessons learned thus far in Malawi’s efforts to popularize ecological sanitation.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2005): Ecological Sanitation in Southern Africa. Many Approaches to a Varied Need. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 21.06.2013]. PDF

    This document describes the ecological sanitation situation in South Africa, focussing on the range of technological options, promotional methods and recycling methods and the problem areas.

  • Cover image of a reference book or miscellany.

    MUELLEGGER, E. (Editor); LANGEGRABER, G. (Editor); LECHNER, M. (Editor) (2011): Solutions for Mountain Regions. Vienna: Ecosan Club. URL [Accessed: 01.07.2013]. PDF

    This Sustainable Sanitation Practice (SSP) issue contains the following contributions: 1. Source Separating Solutions for Mountain Regions, 2. "Gloggnitzer Huette" Sanitation System, 3. Solid Waste Management in Mountain Refuges.

  • Cover image of a reference book or miscellany.

    MUELLEGGER, E. (Editor); LANGEGRABER, G. (Editor); LECHNER, M. (Editor) (2010): The ROSA Project. Vienna: Ecosan Club. URL [Accessed: 01.07.2013]. PDF

    The ROSA project stands for Resource-Oriented Sanitation concepts for peri-urban areas in Africa. This Sustainable Sanitation Practice (SSP) issue contains the following contributions: 1. Introduction to the ROSA Project, 2. From Pilot Units to Large-Scale Implementation - Ethiopia, 3. Implementation of UDDTs at Schools - Kenya, 4. Urban Agriculture for Sanitation Promotion, 5. Operation an Maintenance in Practice, 6. Experiences from Strategic Sanitation Planning, 7. Main Findings and Main Achievements.

  • Cover image of a reference book or miscellany.

    KRAMER, S.; PRENETA, N.; KILBRIDE, A. (2013): Delivering Water, Sanitation and Hygiene Services in an Uncertain Environment: Thermophilic Composting of Human Wastes in Uncertain Urban Environments. A Case Study from Haiti. Oakland: Sustainable Organic Integrated Livelihoods (SOIL). URL [Accessed: 01.11.2013]. PDF

    This paper describes the project of constructing a thermophilic composting site in Haiti after the earthquake in 2010. The composting facilities have treated over 500,000 gallons of human waste in the past three years, converting it to pathogen free compost, over 10,000 gallons of which has been sold for use in agriculture and reforestation projects. The experience of thermophilic composting in Haiti is unique in scale and duration and can have global implications for waste treatment in both emergency and development contexts.

  • Cover image of a reference book or miscellany.

    KILBRIDE, A.; KRAMER, S.; PRENETA, N. (2013): Delivering Water, Sanitation and Hygiene Services in an Uncertain Environment: Piloting Ecological Sanitation (EcoSan) in the Emergency Context of Port-au-Prince, Haiti, after the 2010 Earthquake. Oakland: Sustainable Organic Integrated Livelihoods (SOIL). URL [Accessed: 01.11.2013]. PDF

    The earthquake that struck Haiti in January 2010 and the cholera epidemic that followed from October 2010, resulted in one of the largest humanitarian relief efforts in history. Many of the internally displaced persons camps were located in urban neighbourhoods with high groundwater, making onsite sanitation extremely difficult. In response to these unique conditions a small local organization, SOIL, partnered with Oxfam Great Britain to pilot urine diversion EcoSan toilets in camps throughout Port-au-Prince. This briefing paper covers this pilot project from March 2010 through March 2012. During that 2-year period, SOIL’s toilets served over 20,000 people and treated more than 400,000 gallons of human waste, converting it to rich compost.

Awareness Material

  • Cover image of a reference journal article.

    DUNCAN, D. (2008): Is it Time to kill off the Flush Toilet?. In: TIME.com.URL [Accessed: 10.08.2008]. PDF

    Critical article on the conventional flush-and-forget toilet systems on the occasion of the World Toilet Summit and Expo in Macau.

Training Material

  • Cover image of a reference book or miscellany.

    CALVERT, P. (1999): Compost Toilets. Bourton on Dunsmore: Practical Action UK. URL [Accessed: 11.08.2010]. PDF

    This technical brief describes a compost toilet that has proven to be most effective in water-logged areas where pit-latrines and septic tanks are inappropriate.

  • Cover image of a reference book or miscellany.

    USAID (Editor) (n.y.): Constructing Compost Toilets. Washington: United States Agency for International Development (USAID). URL [Accessed: 11.08.2010]. PDF

    Technical brief on the construction of composting toilets.

  • Cover image of a reference book or miscellany.

    USAID (Editor) (n.y.): Designing Compost Toilets. Washington: United States Agency for International Development (USAID). URL [Accessed: 11.08.2010]. PDF

    Technical brief on the design of composting toilets.

  • Cover image of a reference book or miscellany.

    USAID (Editor) (n.y.): Operating and Maintaining Compost Toilets. Washington: United States Agency for International Development (USAID). URL [Accessed: 11.08.2010]. PDF

  • Cover image of a reference book or miscellany.

    VALLEY VIEW UNIVERSITY (Editor) (2008): Small scale composting of human faeces - in a Nutshell. Hohenheim: University of Hohenheim (Germany), Berger Biotechnik, Valley View University Ghana. URL [Accessed: 11.08.2010]. PDF

    This leaflet provides a summary on why and how to compost faeces.

  • Cover image of a reference book or miscellany.

    HOFFMANN, H. (2012): Construction of Bench Style Double Vault Urine Diversion Toilet and Alternatives. Lima: Rotaria del Peru SAC. URL [Accessed: 26.03.2012]. PDF

    The use of Urine Diversion (UD) in dry toilets allows faeces dehydration. Urine can be reused as urea, while faeces are dried in a double vault system of alternate use. The moisture comes out using ventilation pipes. After 2 years the end product can be emptied and reused without having any health risk. Water from washing can be treated in a constructed wetland and reused for instance for irrigation.

Important Weblinks

  • http://forest.mtu.edu/ [Accessed: 18.08.2010]

    A web portal giving an excellent introduction to composting toilets and latrine technology in developing countries. A brief introduction followed by the best links and sources available to put you on the road to ecological sanitation.

  • http://www.berger-biotechnik.com/ [Accessed: 18.08.2010]

    German provider of pre-fabricated composting toilets.