During anaerobic digestion, what are the operation conditions or chemicals added to inhibit the activity of methanogens and allow the digestor to operate in the acidogenesis phase for VFAs production?
The digestion process begins with bacterial hydrolysis of the input materials. Insoluble organic polymers, such as carbohydrates, are broken down to soluble derivatives that become available for other bacteria. Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. In Acetogenesis, bacteria convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Finally, methanogens convert these products to methane and carbon dioxide. The methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments.
One possibility would be to maintain a high organic loading. If the rate of acid formation exceeds the rate of acid conversion to methane, then the pH will drop and the methanogens will be inhibited. This is referred to as "going sour", and is undesirable (and is difficult to recover from) for anaerobic digestion of sludge. However, it might be useful if you want to limit methanogenesis and utilize the VFAs for another purpose. I hope this suggestion might be helpful!
As Prem Baboo said the methane formation is the last step in this process.
Low pH can help to inhibit methanogens and limit the reaction to acidogination
You can also use 2‐bromoethanesulfonate, which is an analog of coenzyme M that inhibits methanogenesis
To answer your question ,we have to know why you hope to inhibits methanogens bacterias?
High organic load and/or low HRT will be the efficiency to produce VFA.
Yann
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