Calculate digester volatile solids reduction two ways.
Volatile Solids Reduction (Van Kleeck)
Formula
VSR = (VS in - VS out) / (VS in - VS in x VS out) x 100 (VS as fractions)
Inputs used
- Feed volatile solids (%)
- Digested volatile solids (%)
Worked example (White River WRRF, fictional)
- VSR = (0.791 - 0.630) / (0.791 - 0.791 x 0.630) x 100 = 55.0%
Volatile Solids Reduction (mass balance)
Formula
VSR = (VS in, lb/d - VS out, lb/d) / VS in, lb/d x 100
Inputs used
- Volatile solids fed (lb/d)
- Volatile solids leaving (lb/d)
Worked example (White River WRRF, fictional)
- Destroyed = 12,257 - 5,513 = 6,744 lb/d
- VSR = 6,744 / 12,257 x 100 = 55.0%
Tips
- Van Kleeck assumes fixed solids are conserved; grit and struvite can distort it.
Results are estimates for operator use. Check units and inputs, and confirm decisions with plant data and procedures.