by Prof. Dr. Werner Müller
The more than 10,000 municipal wastewater treatment plants in Germany will need almost 4,400 gigawatt hours of electricity per year, and emit around 3 million tonnes annually from digester gas (Federal Environment Agency, http://www.umweltbundesamt.de/presse/presseinformationen/klaeranlagen-leisten-einen-beitrag-klimaschutz , 23:08:15), representing about 53.7 kWh and 36.6 kg per inhabitant. At least comparable figuess of gas are likely to apply also in outhouses. The digester gas methane contributes with about 16% to the total anthropogenic greenhouse gas emission with. The carbon dioxide equivalent for methane is at a time horizon of 100 years 25: Thus, if there is 1 kg of methane and 1 kg of carbon dioxide released, so the greenhouse effect of this methane will have been 25 times as powerful in 100 years in retrospect as the greenhouse effect of carbon dioxide ( https://www.aid.de/landwirtschaft/klimawandel_faq_klimawandel.php, Issuer: aid infodienst Ernährung, Landwirtschaft, Verbraucherschutz e. V., supported by the Federal Ministry of Agriculture). Many treatment plants are now trying to absorb this gas and to mix the public gas. But it would be for economic reasons does not make sense to build a network of centralized sewage treatment plants only in developing countries. In addition water must be handled more economically in tropical countries as in Central Europe. The technique of water toilets in developing countries should not be used more than in the cities.
The biogas is produced in toilets when the uric acid in the urine to soften the feces and prevents the decomposition by bacteria. This mixing of urine and faeces also takes place in an outhouse. When dry, composted faeces. Already 40 years ago the sculptor Friedensreich Hundertwasser has tested and described a composting toilet in the self-experiment. ( http://www.mueller-wolff-web.de/hundertwasserklo.htm , 23:08:15) According to Hundertwasser a smell can be prevented on the principle of cat litter by covering with humus, which rapidly induces the formation of compost. Hundertwasser has the feces urine mixture dehumidified while modern dry toilets, a urine separation at the source make. (see
http://www.oekohaus-online.de/index.php/de/Trockentoilette-Produktinformation/c-KAT100 , 23:08:15) The construction of a dry toilet is eg described on https://www.youtube.com/watch?v=eOrr3PlD9vw. The production of the individual parts can be arranged by simple means.
One problem is that urine separation without collecting container is offered in Internet for at least 90 €. plus Shipping. (see.
or http://www.separett.de/toiletten-de , 23:08:15) The relative high price is probably due to the six-digit production costs for an injection mold, with the plastic parts are made, and the small numbers. On the basis of large amounts of a price of € 25 would be realistic; at least if they were produced in China.
An initiative from a developing country could develop a project to set up 1,000 dry toilets in the villages. With them were at an average of 4 users annually to 146.4 methane avoided. The supply could be taken over by a local carpenter, the kits could offer in different versions according to the model of YouTube. They might be sold directly from a van in the villages. For the needed 1,000 urine screens with funds from the German or European development assistance should be provided at reduced prices for 25 €. The households could then be offered a grant of € 25 if they would be for a scientific application study is available that could perform a local university. At intervals of 3 months the users' experience could be collected. This data would be delivered to optionally transfer the method to other developing countries.