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Chemical Feed Calculator

Convert a target dose into pounds per day and gallons per day of product.

Chemical Feed Rate

Formula

Active, lb/d = Q, MGD x Dose, mg/L x 8.34
Product, lb/d = Active / (Strength / 100)
Product, gpd = Product lb/d / (8.34 x SG)
mL/min = gpd x 3,785.41 / 1,440
Inputs used
  • Flow (MGD)
  • Dose (as the active chemical) (mg/L)
  • Product strength (active) (%)
  • Product specific gravity

Worked example (White River WRRF, fictional)

  1. Active = 8.0 x 20 x 8.34 = 1,334.4 lb/d
  2. Product = 1,334.4 / 0.485 = 2,751.3 lb/d
  3. Volume = 2,751.3 / (8.34 x 1.33) = 248.0 gpd
  4. Pump = 248.0 x 3,785.41 / 1,440 = 652 mL/min

Tips

  • Product strength and density come from the supplier SDS or certificate of analysis.

Results are estimates for operator use. Check units and inputs, and confirm decisions with plant data and procedures.

This calculator also appears on ActivatedSludge.com, our consulting site. Results are for training and operator use; always follow your plant’s procedures.