How to Calculate Solvent Reuse and Solvent Loss Costs
Introduction To Solvent Reuse And Solvent Loss
Understanding and accurately calculating solvent reuse and solvent loss costs is essential for managing expenses in botanical extraction. These costs impact production economics, regulatory compliance, and product quality. Here’s a guide to breaking down and calculating solvent reuse and solvent loss costs.
Solvent Loss Costs
Solvent loss refers to the fraction of solvent that cannot be recovered during each extraction cycle. Even with advanced recovery systems, some solvent is inevitably lost. For example, if a process uses 40 liters of solvent per cycle and achieves a 95% recovery rate, 2 liters (5%) are lost per cycle.
Step-by-step calculation:
Solvent loss costs represent an ongoing expense that accumulates with each production day.
- Determine loss per cycle:
Loss per Cycle (L) = Solvent Used per Cycle (L) × (1 – Recovery Rate)
Example: 40 L × 0.05 = 2 L - Calculate daily loss:
Total Daily Loss (L) = Loss per Cycle (L) × Cycles per Day
Example: 2 L × 8 cycles = 16 L - Estimate cost of lost solvent:
Loss Cost per Day (USD) = Total Daily Loss (L) × Cost per Liter
Example: 16 L × $2 = $32
Solvent Reuse Costs
Under Good Manufacturing Practices (GMP), solvents can only be reused a limited number of times before being discarded to avoid contamination buildup. For instance, if a solvent can only be reused for four cycles, fresh solvent must be introduced after these cycles, incurring a reuse cost.
Step-by-step calculation:
- Determine solvent usage per batch:
Each batch involves multiple cycles. For a solvent reused four times, the batch cost is:
Batch Cost (USD) = Solvent Used per Cycle (L) × Reuse Limit × Cost per Liter
Example: 40 L × 4 × $2 = $320 - Calculate the number of full batches per day:
Full Batches = Total Cycles per Day ÷ Reuse Limit
Example: 8 cycles ÷ 4 = 2 batches - Account for remaining cycles:
Remaining Cycles = Total Cycles per Day mod Reuse Limit
Example: 8 mod 4 = 0 - Total daily reuse cost:
Total Reuse Cost (USD) = Batch Cost × Full Batches + Remaining Cycle Costs
Example: $320 × 2 = $640
Final Considerations
Combining solvent loss and solvent reuse costs gives the total solvent management cost. Optimizing solvent recovery and reducing usage frequency—such as through CO₂ extraction—can dramatically lower these expenses, improve product quality, and align with sustainable production goals.
