Scum
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
