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Chlorine Dose Calculator

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)

  1. Dose = 5 + 1 = 6.00 mg/L
  2. Feed = 8.0 x 6 x 8.34 = 400.3 lb/d
  3. 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.

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