A well-operated digester typically receives sludge with what percentage of volatile solids?

A well-operated digester receiving sludge typically has a volatile solids content in the range of 70-75%. Volatile solids are organic materials that can be broken down by bacteria during the digestion process. At this percentage, the sludge contains a high enough concentration of organic matter, which is conducive to effective microbial activity and digestion.

The digestion process relies on the microorganisms breaking down volatile solids to produce biogas and reduce the overall mass of the sludge. A range of 70-75% indicates a balance where the organic material is sufficient to promote efficient digestion without being excessively high, which could lead to operational challenges, such as inhibition of microbial activity or the risk of foaming and scum formation. This range optimizes the digester's performance, leading to better biogas production and substantial reduction in sludge mass, key goals in wastewater treatment processes.