What is the typical range for volatile fatty acids concentration in a sour digester that requires neutralization?

In wastewater treatment, particularly in anaerobic digestion processes, the concentration of volatile fatty acids (VFAs) can serve as an indicator of digester performance and potential issues such as acidification. When a digester is operating properly, VFA concentrations typically remain within an optimal range that encourages the growth of methanogenic bacteria.

A sour digester, which indicates that there is an accumulation of fatty acids leading to increased acidity, generally shows elevated VFA concentrations. The typical range for VFAs in such situations, prompting the need for neutralization, is generally recognized between 500 and 1000 mg/L. This range reflects the conditions under which neutralization is often necessary to restore balance and improve biological digestion efficiency.

The other ranges provided fall outside this typical threshold for acidic conditions observed in sour digesters. Concentrations below 500 mg/L often suggest a healthier digestion process, while levels exceeding 1000 mg/L can indicate severe acidification that may require immediate corrective actions. Thus, the choice of 500-1000 mg/L accurately captures the critical range when neutralization becomes essential in managing a sour digester.