Question

What happens if the organic matter is not stirred while in process of digestion?

(a) It will evaporate

(b) It solidifies

(c) It will form hard scum on layer

(d) It gets struck to digester walls

I have been asked this question in quiz.

The query is from Anaerobic Fermentation topic in chapter Biomass Energy of Energy Engineering

Answer 1

Right choice is (c) It will form hard scum on layer

Easy explanation: Some method of stirring the slurry in a digester is always advantageous, if not essential. If not stirred, the slurry will tend to settle out and form a hard scum on the surface, which will prevent release of biogas.