What two samples are necessary to calculate the VSR through an anaerobic digester?

To calculate the Volatile Solids Retention (VSR) through an anaerobic digester, it is essential to obtain samples of both the feed sludge and the digested sludge. The feed sludge represents the material entering the anaerobic digester, while the digested sludge is the output after the anaerobic digestion process has taken place.

The calculation of VSR involves determining the difference in volatile solids content between these two types of sludge. By analyzing the volatile solids concentration in both samples, operators can assess how effectively the anaerobic digestion process is breaking down organic matter. This information is critical for evaluating the performance and efficiency of the digester, allowing for adjustments to be made if necessary.

Other options, such as influent and effluent samples or primary and secondary sludge, do not provide the direct comparison needed for calculating VSR in the context of anaerobic digestion. The focus on feed and digested sludge specifically aligns with assessing the treatment's impact on volatile solids, which is the key metric in this scenario.