Calculate chlorine feed from demand and residual, as gas or hypochlorite solution.
Chlorine Dose and Feed
Formula
Dose = Demand + Residual lb/d Cl₂ = Q, MGD x Dose x 8.34 Hypochlorite, gpd = lb/d / (8.34 x SG x % available / 100)
Inputs used
- Flow (MGD)
- Chlorine demand (mg/L)
- Target residual (mg/L)
- Hypochlorite strength, % available Cl₂ by weight (optional) (%)
- Hypochlorite specific gravity (optional)
Worked example (White River WRRF, fictional)
- Dose = 5 + 1 = 6.00 mg/L
- Feed = 8.0 x 6 x 8.34 = 400.3 lb/d
- Solution = 400.3 / (8.34 x 1.2 x 0.125) = 320.0 gpd
Tips
- Ammonia in the effluent forms chloramines; plan for longer contact.
Results are estimates for operator use. Check units and inputs, and confirm decisions with plant data and procedures.