Aerobic digesters typically reduce volatile solids (VS) by:

Aerobic digesters typically reduce volatile solids (VS) by:

• A. 10-20%
• B. 40-50%
• C. 60-70%
• D. 80-90%

Answer: (D)

Aerobic digestion uses oxygen to oxidize organic matter, so the volatile solids present in the waste are consumed by microorganisms and converted to CO2 and water (plus some microbial biomass). When the system is operated properly—with adequate aeration, mixing, and enough retention time—the readily biodegradable portion of the volatile solids is largely oxidized, leading to a high percentage reduction. That’s why the typical outcome in a well-run aerobic digester is a substantial drop in volatile solids, often in the upper range of reductions, around 80-90%. The reduction is calculated by comparing the volatile solids content before digestion to after digestion, so effective oxidation directly translates to a large difference. If aeration or time are insufficient, the reduction would be much lower, but under good operation 80-90% is achievable.

Aerobic digestion uses oxygen to oxidize organic matter, so the volatile solids present in the waste are consumed by microorganisms and converted to CO2 and water (plus some microbial biomass). When the system is operated properly—with adequate aeration, mixing, and enough retention time—the readily biodegradable portion of the volatile solids is largely oxidized, leading to a high percentage reduction. That’s why the typical outcome in a well-run aerobic digester is a substantial drop in volatile solids, often in the upper range of reductions, around 80-90%. The reduction is calculated by comparing the volatile solids content before digestion to after digestion, so effective oxidation directly translates to a large difference. If aeration or time are insufficient, the reduction would be much lower, but under good operation 80-90% is achievable.