Biogas DIY Training 1

Biogas is produced by anaerobic bacteria that degrade organic matter in four general stages:

1. hydrolysis,

2. acidification,

3. acetic acid production, and

4. methane production

 

The gas phase product of anaerobic digestion is named biogas and its yield depends significantly 

on the substrate or whatever raw material you used.

 

Unlike in cow where it has stomach divided physically into few compartments, we build a one 

stage anaerobic digester (4 in 1) which has invisible compartments as you can image at the 

lowest stage is where hydrolysis takes place then the next upper level is where acidification is 

going on and so forth until to the top level on the surface where the biogas is produced and 

released.

 

You can imagine in reverse as below:

4. Methanogenesis - acetic acid and methanoic acid turn into

methane and carbon dioxide

3. Acetogenesis - volatile fatty acids turn into acetic acid and

methanoic acid

2. Acidogenesis - organic molecules turn into volatile fatty acids

1. Hydrolisis - complex organic matter (eg. food waste) turn into

simpler organic molecules

 

So, at initial stage when you add food waste as raw material at pH of 3, 4 and 4.5 or so there 

has been no biogas produced yet. The best range to observing methane production is in the 

range of pH 6-8. 

 

The lack of gas production at low pH was attributed by total inhibition of methanogenic 

activity. While excessively alkaline conditions might trigger the disintegration 

of microbial granules and the consequent collapse of the digesting process.

 

Usually the pH of a stable digester is self-adjusting in which you do not have to intervene. 

Digester will become unstable if you feed over its capacity to handle the digestion process.

There is a parameter ratio to consider while feeding between the temperature you are 

operating, size of digester and volume of raw material you feed into it. 

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===> GO TO TRAINING BIOGAS 2

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 https://diybiogasgenerator.blogspot.com/2022/02/biogas-for-beginners-off-grid-eco-power.html