For a quick understanding of how to build a biogas plant please have a look at this video How to build a biogas plant - YouTube. How to build the new compact biogas plant The apparatus itself consists of: -Two plastic water tanks sold in sanitary and plumbing ware shops. One should be bigger than the other so that once the top of each tank is cut open, the smaller one can fit in the bigger one and move like a telescope“. The bigger tank (or drum) serves as a digester, and the smaller, placed upside down in the bigger one serves as the gas holder. -The inlet pipe: a 3cm diameter flexible pipe, a bit longer than the height of the tank, is fitted at the bottom side of the bigger tank. At the free extremity of the pipe , a funnel is fixed to facilitate the pouring of the quite fluid feedstock material. The pipe with the funnel are to be fixed loosely to the top of the tank, in upright position. This pipe will also serve as a purge in case of necessity. -The effluent outlet is fitted to the upper part of the bigger tank and determines the maximum level of matter in the tank. -The gas outlet is fitted to the smaller inner tank and directed toward a gas stove. -a frame structure is build above the tanks to stop the gas tank to fall open when too filled. It is possible to put a weight on the upper tank to increase gas pressure in the tank. Methane burns with a blue flame, without producing any smoke or soot. It is therefore an environmentally friendly cooking system. Thus, introduction of the new efficient, compact biogas system would not only help urban households in utilizing their domestic wet waste, but also help prevent millions of premature deaths of women and children in rural households due to indoor air pollution caused by smoke and soot from burning fuelwood in traditional chulhas. This markedly impacts the health of the people in the kitchen (mainly women) positively. Further reductions in pollution and energy use arise from not having to transport LPG cylinders to be re-filled. The small amount of solid residue produced by the biogas plant makes a good fertiliser. Methan, on the contrary of propane, is lighter than air, there is therefore little risk of an accumulation and explosion in case of a leak. In hot regions, the system could be placed in a garden or on an accessible roof terrasse, for it needs a relatively warm temperature. How to start the process? The system is first loaded with a slurry of about 20 kg of cattle dung, waste flour or starch and water.: The bacteria present in the intestine and consequently in the dung of the cattle are the bacteria that will break down the organic material into methane and carbon dioxide. After a waiting time of about 2 weeks, the gas should start to be emitted and the upper tank will raise. Test the gas by burning it: if it is combustible, you can start adding high calorie material. Feedstock: daily 1 kg to 1,5 kg mashed feedstock mixed with 10 to 15 litres water in the morning and the same in the evening. The feed can be waste flour, vegetable residues, waste food, waste oil, fruit peelings and rotten fruit. Oil cake, left over from oil-pressing, is another useful feedstock. Even rhizomes of banana, canna, nutgrass, non-edible seeds (e.g. Leucaena, Sesbania, tamarind, mango kernels) and spoilt grain serve as excellent feedstock material. Feedstock with large lumps (more than 20 mm) should be broken up with a food blender. Hand and pedal powered food blenders are being developed, for when electricity is not available. The digester should provides a steady supply of gas, typically 250 g of gas per day from 1 kg (dry matter) of feed. For further information contact Appropriate Rural Technology Institute (ARTI)
Posted on: Sat, 22 Mar 2014 09:22:19 +0000
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