Yesterday we visited a Bio-Gas plant that processed mostly straw into Bio-Gas. Just as straw is more difficult to process for animals than grains, it is also harder to produce Bio-Gas from than manure or sugar filled waste water from breweries. The molecules that make straw stiff also make the energy contained in the straw difficult for the bacteria in a Bio-Digester to access and convert to methane gas and carbon dioxide. This plant takes the straw and grinds it into a fine powder and then mixes this powder with warm water before feeding the mixture into a 500 cubic meter Bio-Digester. Grinding the straw makes it easier for the bacteria in the digester to break it down. The other unique thing about this plant is that they recycle the water used in the digester. The digested straw powder is separated from the water mechanically and the water is recycled through the system. This also maintains a steady population of bacteria in the system and eliminates the need for mixing of the digester contents.
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This project’s startup was subsidized by the government and encourages farmers in this semi- rural community to transport their waste straw to the plant instead of burning it by offering them bio- gas at production cost. Continue reading