[Digestion] Ideal pH and temperature

[Warren Weisman]

My two cents---based on experience instead of books---

Ideal pH balance for anaerobic digestion is a little
on the alkaline side, between pH 7.0-8.5. 

Couple rules of thumb... if no flammable biogas is
present after a few days 3-5, but you're getting good
CO2 activity, use lime or ash to adjust the pH
balance. 

Also, a red or yellow flame generally means
over-acidity. Remove some old material and inlet some
fresh stuff. A nice blue flame means happy
micro-organisms. 

Ideal temperature for AD is same as for us 99 F or 37
C. It will make biogas at temperatures lower than
this, but production will fall off drastically. Higher
temperature, thermophillic digestion, is unstable and
will not produce more biogas to offset the energy
needed to heat the digesters. General rule of thumb,
don't let your digester get too hot to be
uncomfortable to touch. Shade it from the sun if
necessary. 

Warren Weisman
USA



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