Which condition would likely indicate a need to neutralize a digester?

The presence of a sour smell in a digester often indicates the production of volatile acids, which is a sign of an imbalance in the digestion process. This situation typically suggests that the pH is skewing towards acidic levels, leading to a need for neutralization to restore the proper environment for microbial activity essential for effective digestion. Effective anaerobic digestion relies on a stable pH range; thus, when volatile acids accumulate without adequate buffering, the resulting conditions can harm the microbial populations, impeding the digestion process.

In contrast, high pH levels could suggest an alkalinity problem that may require different management strategies rather than outright neutralization. Low temperature could lead to slow digestion rates but doesn't necessarily indicate a need for neutralization. Clear water, on the other hand, is often a sign of a well-functioning digester but does not directly suggest a need for any specific intervention like neutralization.