Technical Data Sheets for Ecosan Components 03 Composting Toilets

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technical data sheets for ecosan components ecosan program - Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH

03 Composting Toilets SOLID GREY RAIN BIOWASTE FAECES URINE WATER WATER

A General Description COLLECTION • Waterless toilet systems

• Receive mainly faeces, but treatment of urine and solid biowaste is possible as well TREATMENT • Dry organic bulking material should be added

• Produce a valuable soil conditioner with low pathogen UTILIZATION content • Suitable for both industrial and developing countries

A General description

conditions since their water content and substances causing bad odours. A General Description the nitrogen content are too high. Therefore an additive or so-called One main effect of the decomposition B Detailed information on different process in a composting toilet is the types of “Composting Toilets” bulking agent is recommended to lower the water content, to improve aeration considerable volume reduction (10-30% B.1 Single-vault composting toilets and to increase the carbon content of of the original mass), thus allowing the B.2 Multiple-vault composting the material. Wood, chips, bark chips, prolonged storage of waste in the toilets container. The emptying frequency B.3 Movable bucket / bin sawdust, paper and other substances are commonly used. depends on the size of the container, composting toilets the feeding rate and the composting B.4 Composting toilets with mixing devices rate (volume reduction). C Manufacturers and commercially The decomposition process in a available composting toilets composting toilet is rarely a real thermophilic composting with temperature rising above 50°C, which A.1 Basic principles would guarantee complete pathogen destruction and hygienization of the The basic principle of a composting waste. The pathogen content is reduced toilet system is the biological considerably in a composting toilet. However, complete pathogen degradation of excreta and toilet paper in a specially designed container. Urine destruction can only be achieved if is usually collected separately, or in Figure 1: Schematic of continuous good process conditions can be some types of composting toilets composting toilet (Davison, 2001) guaranteed, e.g. by using an advanced toilet design with insulation for collected and treated together with Since good aeration is very important, maintaining a high temperature within faeces. Organic food waste can be the container is usually equipped with a the whole composting chamber. added too. ventilation system that improves aeration of the material and provides The end product of a composting toilet Box 1: Optimum conditions for odour control. Moreover, with bulking is an odourless stabilized material, thermophilic composting, allowing agents, the pore spaces of the temperature to rise up to 50- which is very valuable as soil 70°C: composting pile can be increased; conditioner. It can be used directly for hence it will be less compact, leading to non-food plants or for agriculture use. • Good aeration better aeration. However, too much air Further treatment for hygienization such flow can remove too much heat and as additional heap-composting or • Moisture content 50-60% moisture, therefore the condition within prolonged storage (see box 2) • C/N ratio 30-35 the composter should not be too cool or increases hygienic safety of agicultural dry. use. Note that optimum conditions are rarely achieved in compos ting toilets. Another benefit of adding bulking A.2 Available technologies materials is to increase C/N ratio in The decomposition process is called order to attain the optimum composting Although there are many different “composting”, which is the degradation condition. Sometimes these bulking composting toilet designs that continue of organic matter by thermophilic materials also have an additional effect to evolve, the basic concept of aerobic bacteria and other micro on odour control by binding the composting remains the same. organisms. These bacteria rely on a good aeration of the material, on optimal moisture content and a specific carbon to nitrogen ratio. Human excreta and food waste alone do not provide those optimum

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technical data sheets for ecosan components ecosan program - Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH

A composting toilet has two basic elements: a place to sit (or to squat) and Box 2: Suggested alternative recommendations for primary treatment of dry faeces before use at household level. No addition of new material. (Schönning and a composting chamber. Apart from Stenström, 2004) those basic elements, a ventilation system is highly recommended in order Treatment Criteria Comment to stimulate aeration and prevent odour. Storage (only 1,5-2 years Will eliminate most bacterial pathogens, Available systems can be distinguished treatment) at ambient substantially reduce viruses, protozoa is as follows: temperature 2-20°C and parasites, some soil-b ova may persist Toilet seat and composting container Storage (only >1 year As above in the same unit, or separate treatment) at 20-35°C Some composting toilet systems have Storage and alkaline pH >9 during Temperature <35°, moisture content the seat and the composting container treatment > 6 months >25° or lower pH will prolong the time spatially separate, e.g. the toilet seat is for absolute elimination in the ground floor and the container is situated below in the basement, Low-tech or high-tech With proper management the toilet is connected by a vertical tube. Other easy to use and to maintain, and the The systems range from low-tech final product is a high-quality compost systems have the toilet seat in the same (simple, non-electric, but more care is unit with the container. In that case, soil conditioner for garden or required) to high-tech (complex, electric, agriculture. containers are usually smaller and have very low labour work, but higher cost) to be emtied more often. systems. Low-tech composters are Compared to dehydration toilets, Urine diversion or not simple reactors in which all is collected composting toilets require higher costs and allowed to decompose in at in term of excreta management. The The toilet can be designed either with ambient temperature. They require the most important difference between this or without urine diversion. user to take a more active role in the technology and that of dehydration is day-to-day maintenance of the unit. the moisture content of faeces within Detailed information on urine diversion High-tech units can be equipped with the vault (around 50% comparing to can be found in the GTZ technical data electric fans, automatic mixers and 25% in dehydration toilet). Composting sheet for urine diversion (01) on thermostatically controlled heaters and toilets need organic bulking materials to http://www.gtz.de/en/themen/umwelt- require very low level of user increase carbon content whereas infrastruktur/wasser/9397.htm intervention. dehydration toilet can use also other dry It should be noted that without urine absorbents as ash or dry soil to lower Single-vault (continuous) or multiple- diversion, more bulking agent needs to the moisture content. The nutrients in vault (batch) be added in order to significantly lower products from composting toilet are moisture level and increase C:N ratio to Either multiple chambers batch com- more readily available to plants than attain the optimum treatment conditions. posting, e.g. EcoTech Carousel, or sin- those from dehydration toilet. Urine adds more water than is gle chamber continuous composting Compared to VIP/pit latrines, necessary and it has a very high process shown in figure 1, e.g. Clivus composting toilets can be built above nitrogen content. The moisture content multrum, Clivus minimus, BioLet, etc. ground level as permanent structure. of faeces without urine (66-80%), plus are feasible to use. There is no need for digging deep pit the addition of toilet paper and bulking and periodical replacement of the facility material are sufficient for good On-site or off-site composting when pits are full. processing. Most composting toilets process the Composting toilets are sealed systems Many composting toilets also have a material on-site in a composting cham- that exclude any infiltration of drainage system to allow evacuation of ber that is located directly under in the contaminated liquids into the liquids. These liquids are called toilet seat or in the basement of the groundwater or other harmful emissions leachate and have very high building. Other systems however use into the environment. concentrations of nutrients, organics movable collection bins or containers and also contain pathogens. Leachate that are emptied frequently and where Composting toilets can close the needs to be collected, treated and the material is then transported to an nutrient cycle, turning a dangerous reused if possible. Urine diversion external site for treatment. waste product into safe compost, usually allows to avoid or to A.3 Applicability without smell, hassle, or fly problems. considerably reduce leachate production. Composting toilets eliminate the need They are usually less expensive than for flushing water. No water supply (no conventional septic systems or sewered Self-constructed or commercially expensive installation for infrastructure systems (if costs for sewerage and procured like water supply line and sewerage) is wastewater treatment are considered) treatment and they will reduce There are many designs and models necessary. Furthermore, it allows for the household total water consumption by offered by manufacturers all over the recycling of valuable plant nutrients via at least 25%. world with a large range of prices. compost products. However composting toilets can also be This technology is suitable for both In several projects composting toilets self-constructed. Manufactured toilets industrialized and developing countries, have also been successfully are often more expensive than self- especially in arid regions and regions implemented in houses with several constructed systems. without piped water or sewers. It works floors. without water and wastewater In term of operation and maintenance, connection. composting toilets are most suitable

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technical data sheets for ecosan components ecosan program - Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH

when users are committed to operate sources and the Environment, Sida, the system carefully. Composting toilets Stockholm, Sweden. need more care than dehydration toilets in the case of low-tech systems. Montgomery, T., 1990, On-Site wastewater treatment systems, Technical Bul- A.4 Further reading letin No. 6, The New Alchemy Institute. Esrey, St. A., et. al., 1998, Ecological Peasey, A., 2000, Health aspects of dry sanitation. Department for Natural sanitation with waste reuse. Task No. Resources and the Environment, Sida, 324, WELL. Stockholm, Sweden.: Well-illustrated Reed, B. and Shaw, R. Using human book concerning different types of waste, technical brief no. 63, WELL. composting toilet as well as performance and health issues. Del Porto, D. and Steinfeld, C., 2000, The composting toilet system book. The Center for Ecological Pollution Preven- tion (CEPP), 1 st ed. with additions.: information on several types of composting toilet system, including practical ap- plication and maintenance.

Jenkins, Joseph, 2005, The Humanure handbook – a guide to composting human manure, Joseph Jenkins Inc, Grove City, USA.

Élain, Christophe, 2005, Un petit coin pour soulage la planète – Toilettes sè- ches et histoires d’eau, Éditions Goutte de Sable, Athée, France.

A.5 References

Crennan, L., waterless toilets, Home, Technical Manual: design for lifestyle and the future, www.greenhouse.gov.au

Davison, L. and Schwizer, B., 2001,

Waterless composting toilets, septic safe, Environment & Health Protection Guidelines: On-site Sewage Manage- ment for Single Households.

Esrey, St. A., et. al., 1998, Ecological sanitation. Department for Natural Re-

 2006, GTZ technical data sheets for ecosan components authors: GTZ ecosan team (Christine Werner, Nathasith Chiarawatchai, Florian Klingel, Patrick Bracken) Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH ecosan program Dag-Hammarskjöld-Weg 1-5 65760 Eschborn, Germany T +49 6196 79-4220 F +49 6196 79-7458 E [email protected] I www.gtz.de/ecosan

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