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Calcimator

Coagulant Dosing Calculator

Calculate alum, ferric chloride, or PACl feed rates from jar test results. Estimate alkalinity consumption and sludge production.

Inputs

MGD
NTU
mg/L
mg/L

Results

Coagulant Feed Rate

1,251 lbs/day

Liquid Feed Rate

235 gpd

CoagulantAluminum Sulfate (Alum)
Polymer Feed Rate8.34 lbs/day
Alkalinity Consumed13.2 mg/L as CaCO₃
Sludge Production551 lbs/day
Annual Chemical Cost$62,404.00
Cost per Million Gallons$34.19
30-Day Storage (liquid)7,049 gallons
Rapid Mix Volume1,736 gallons
Flocculation Volume86,806 gallons
P H Drop0.26
Thirty Day Supply (lbs)37,530
How to Use This Calculator
  1. Enter Plant Flow Rate (MGD) and Raw Water Turbidity (NTU) from your source water monitoring.
  2. Select Coagulant Type (alum, ferric chloride, PACl) based on your chemical supply agreement.
  3. Enter Optimal Dose (mg/L) from jar test results — adjust seasonally as source water quality changes.
  4. Add Polymer Dose (mg/L) if your plant uses a coagulant aid or filter aid polymer.
  5. Review Coagulant Feed Rate (lbs/day) and Liquid Feed Rate (gpd) to set pump outputs and verify chemical tank sizing.
  6. Check Alkali Consumption to determine if pH adjustment is needed to maintain coagulation efficiency.

How the result changes with Plant Flow Rate

Plant Flow RateCoagulant Feed RateLiquid Feed Rate
205,004 lbs/day939.8 gpd
7017,514 lbs/day3,289.5 gpd
13032,526 lbs/day6,109 gpd
18045,036 lbs/day8,458.6 gpd

What each input means

Plant Flow Rate
Treatment plant design flow rate.
Raw Water Turbidity
Source water turbidity in Nephelometric Turbidity Units.
Coagulant Type
1 = Alum, 2 = Ferric Chloride, 3 = Ferric Sulfate, 4 = PACl.
Optimal Dose (from Jar Test)
Optimal coagulant dose determined from jar testing. Typical alum: 10-60 mg/L.
Polymer Dose
Flocculant polymer dose. Typical: 0.1-1.0 mg/L. 0 if not used.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Plant Flow Rate = 5, Raw Water Turbidity = 15, Coagulant Type = 1, Optimal Dose (from Jar Test) = 30 = 5 input(s) provided
  2. Calculate Coagulant Feed Rate
    Coagulant Feed Rate
    1251 = 1251
  3. Calculate Liquid Feed Rate
    Liquid Feed Rate
    235 = 235
  4. Calculate Coagulant
    Coagulant = coag.name
    Aluminum Sulfate (Alum) = Aluminum Sulfate (Alum)
  5. Calculate Polymer Feed Rate
    Polymer Feed Rate
    8.34 = 8.34

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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