What is the consequence of lowering pH in an anaerobic digester?

Lowering the pH in an anaerobic digester can lead to decreased methane production, which is a critical aspect of the digester's function. In an anaerobic digestion process, optimal pH levels are usually maintained between 6.8 and 7.4 to support the activities of methanogenic bacteria, which are responsible for converting organic substrates into methane and carbon dioxide.

When the pH falls below this optimal range, it can inhibit the growth and metabolic activity of these methanogenic organisms. This inhibition prevents them from effectively breaking down organic materials, thereby reducing the overall production of methane. Additionally, a lower pH can alter the balance of microbial communities within the digester, leading to the dominance of acidogenic bacteria that produce acids instead of methane.

While it might be intuitive to think that lower pH could improve certain aspects of microbial metabolism, in the specific case of methane production in anaerobic digesters, maintaining a balanced and neutral pH is crucial for maximizing biogas yield. Hence, when pH levels drop significantly, methane production is adversely affected.