A school, an opportunity
By Dan-Eric Archer — Make possible an innovative sewage treatment system for a school in Kenya. The solution will produce biogas to be used in the school kitchen replacing liquid petroleum gas and firewood. This saves money badly needed for teachers and books and also have a direct positive environmental impact. As a good example it will help the technology spread and potentially have a huge impact in the entire region.
There is an neglected potential for recycling of nutrients and energy from individual sewage treatment systems globally. Carbon dioxide neutral energy, food production, water use and sustainable use of nutrients are some of the most demanding issues to solve in the world today. Anaerobic digestion adopted for sewage treatment is relevant for the solution of all the mentioned issues. A local system in small scale has several advantages; easier to control chemicals going into the system, less need for infrastructure and incentive for local food production.
Effects of the project:
-The gas produced would replace LPG and firewood otherwise used for cooking.
-The normally used pit latrine would be avoided with problems of hygiene, smell and cost for emptying.
-Biofertilizer produced can be sold or given to local farmers to replace chemical fertilizer. (some cultures have issues with this but the farmers of Ngong Hills seem to be ok with it. The biofertilizer need, of course to be properly hygienizised from pathogens.)
-The system would be a natural part in the students education on systainability. 'Waste is nothing but resources in the wrong place'.
-The installation would be a model for other school, hospitals and villages so that the technology can spread.
-There is of course also the direct environmental impact of reduced GHG emission in the air, reduced deforestation and reduced euthrophicating substances in the ground water.
Biogas
The suggested system is calculated to provide 0.05 m³ or 0.33 kWh biogas per person and day. It is estimated that every person consume 0.035 kg or 0.5 kWh LPG per day. (Equivalent of using a normal gas stove at maximum power for 20 minutes) Considerably less energy can be sufficient for cooking if measures like use of solar heaters for hot water and soaking or sprouting of beans (staple
food) are made. The price of LPG is about 11 KES per kWh (160 KES per kg) thus 290,000 KES per year is saved if biogas replace this.
Nutriets
The biofertilizer produced has a value of 400 KES per person and year. This is estimated with data from Swedish statistics agency SCB on nutrient need for crops in Sweden. Kenyan cultivation is about two times as intensive since crops grow all year round, thus need more nutrient input. This gives that the hygenisized substrate will be enough to fertilize 17.6 acres of cropland when there are 200 students in the school. This will then increase linearly when more students arrive. Standard procedure in Kenya is to apply two 50 kg bags of NPK fertilizer per acre and year. One bag cost about 2 500 KES (though prices are increasing) thus the value of produced biofertilizer is 88 000 KES per year. [one KES equals 0.007 EUR]
There are today a few public institutions in Kenya that have installed biogas digesters for sewage treatment. However, these are of so called Chinese fixed-dome type that are easy to use but do not provide proper hygienization and low biogas yields. They are also fairly expensive and complicated to build because of the gas tight concrete structure that has to be built on site. Cement is also a material with relatively large environmental impact that cannot really be recycled.
The school itself is a boarding school that will allow kids from the Kibera slum on the outskirts of Nairobi to get a high school education that they would otherwise not afford. It is built by the initiative of a class from the pedagogic institution of Göteborg University that traveled to Kenya as a study trip in 2009. Read more here: http://endavagen.blogg.se/ (Swedish)
Effects of the project:
-The gas produced would replace LPG and firewood otherwise used for cooking.
-The normally used pit latrine would be avoided with problems of hygiene, smell and cost for emptying.
-Biofertilizer produced can be sold or given to local farmers to replace chemical fertilizer. (some cultures have issues with this but the farmers of Ngong Hills seem to be ok with it. The biofertilizer need, of course to be properly hygienizised from pathogens.)
-The system would be a natural part in the students education on systainability. 'Waste is nothing but resources in the wrong place'.
-The installation would be a model for other school, hospitals and villages so that the technology can spread.
-There is of course also the direct environmental impact of reduced GHG emission in the air, reduced deforestation and reduced euthrophicating substances in the ground water.
Biogas
The suggested system is calculated to provide 0.05 m³ or 0.33 kWh biogas per person and day. It is estimated that every person consume 0.035 kg or 0.5 kWh LPG per day. (Equivalent of using a normal gas stove at maximum power for 20 minutes) Considerably less energy can be sufficient for cooking if measures like use of solar heaters for hot water and soaking or sprouting of beans (staple
food) are made. The price of LPG is about 11 KES per kWh (160 KES per kg) thus 290,000 KES per year is saved if biogas replace this.
Nutriets
The biofertilizer produced has a value of 400 KES per person and year. This is estimated with data from Swedish statistics agency SCB on nutrient need for crops in Sweden. Kenyan cultivation is about two times as intensive since crops grow all year round, thus need more nutrient input. This gives that the hygenisized substrate will be enough to fertilize 17.6 acres of cropland when there are 200 students in the school. This will then increase linearly when more students arrive. Standard procedure in Kenya is to apply two 50 kg bags of NPK fertilizer per acre and year. One bag cost about 2 500 KES (though prices are increasing) thus the value of produced biofertilizer is 88 000 KES per year. [one KES equals 0.007 EUR]
There are today a few public institutions in Kenya that have installed biogas digesters for sewage treatment. However, these are of so called Chinese fixed-dome type that are easy to use but do not provide proper hygienization and low biogas yields. They are also fairly expensive and complicated to build because of the gas tight concrete structure that has to be built on site. Cement is also a material with relatively large environmental impact that cannot really be recycled.
The school itself is a boarding school that will allow kids from the Kibera slum on the outskirts of Nairobi to get a high school education that they would otherwise not afford. It is built by the initiative of a class from the pedagogic institution of Göteborg University that traveled to Kenya as a study trip in 2009. Read more here: http://endavagen.blogg.se/ (Swedish)
Dan-Eric Archer
Läser masterprogrammet Sustainable Energy Systems på Chalmers. Håller på med friidrott. Gillar att ge mig ut på lite äventyr ibland, just nu på cykel till Kenya. Aktiv i JAK Medlemsbank som är en mycket bra sak.
Location: Göteborg, Sweden
Website: http://www.twowheelssouth.emulsionen.org/
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