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close this bookBetter Farming Series 32 - Biogas 2: Building a Better Biogas Unit (FAO, 1986, 47 p.)
View the document(introduction...)
View the documentPreface
View the documentIntroduction
Open this folder and view contentsHow to build a better small biogas unit
Open this folder and view contentsPutting in the waste
View the documentTime
Open this folder and view contentsTemperature
View the documentScum
View the documentWhen the gas is made
View the documentTaking care of your biogas unit
View the documentMaking more biogas
Open this folder and view contentsWhat more can you do?


110. Sometimes a hard layer of scum may form on top of the waste mixture in your biogas unit. If this happens, less gas will be made and gas will not collect in the inner tube.

Hard layer of scrum

111. If the waste is well mixed before it is put into unit, there will be less chance for scum to form and your biogas unit will make gas well.

112. Scum is more likely to form if you use plant materials than if you use only animal waste.

113. To keep scum from forming, shake your biogas unit from time to time. The drawing below shows you how.

Shake the oil drum