How can an operator cure a sour anaerobic digester?

To cure a sour anaerobic digester, it's important to address the conditions that lead to the souring, primarily caused by imbalances in the microbial population and the accumulation of volatile fatty acids. Reducing the sludge feed helps decrease the organic load on the digester, allowing the microorganisms that thrive in anaerobic conditions to better process the remaining organic material. Ensuring adequate mixing is also crucial, as it facilitates proper distribution of nutrients and maintains an even environment for microbial activity, preventing localized acid accumulation and enhancing the overall digestion process.

This approach not only stabilizes digestion but also promotes the growth of the methanogens, the microorganisms responsible for converting volatile fatty acids into biogas. In contrast, increasing heat and aeration would create conditions unsuitable for anaerobic digestion, while adding more sludge without adequate mixing could exacerbate the souring by increasing the organic load further. Increasing chemical treatments might provide temporary relief but does not address the underlying biological issues of a sour digester effectively.