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Calcimator

Membrane Flux Calculator

Calculate permeate flux, transmembrane pressure, and fouling indicators for membrane filtration systems (MF/UF/NF/RO).

Inputs

MGD
sq ft
bar
°F

Results

Permeate Flux

56.8 LMH

Specific Flux

113.6 LMH/bar

Fouling StatusLight Fouling
Temperature-Corrected Flux64 LMH (20°C)
Concentrate Flow0.2 MGD
Concentration Factor10×
Membrane Modules143
Pressure Vessels24
CIP Cleaning FrequencyEvery 14-30 days
Annual Energy Cost$4,796,962.00
Annual Membrane Cost$59,583.00
Concentrate Flow LPH31,541.67%
Specific Energy17.36
How to Use This Calculator
  1. Enter Feed Flow Rate (MGD) and Total Membrane Area (m²) installed in the system.
  2. Input Transmembrane Pressure (bar) — the operating pressure differential across the membrane.
  3. Set Water Temperature (°C) — flux increases with temperature; enter the design minimum for conservative sizing.
  4. Enter Recovery Rate (%) — the fraction of feed water converted to permeate.
  5. Review Permeate Flux (LMH) and Specific Flux (LMH/bar) to assess whether the system is operating within design parameters.
  6. Check Fouling Status and Temperature-Corrected Flux to identify if cleaning or backwash is needed.

How the result changes with Total Membrane Area

Total Membrane AreaPermeate FluxSpecific Flux
10,00928.4 LMH56.7 LMH/bar
35,0078.1 LMH16.2 LMH/bar
65,0044.4 LMH8.7 LMH/bar
90,0013.2 LMH6.3 LMH/bar

What each input means

Feed Flow Rate
Total feed flow rate to the membrane system.
Total Membrane Area
Total installed membrane area in square meters.
Transmembrane Pressure
Pressure difference across the membrane. MF/UF: 0.1-2 bar, NF: 3-10 bar, RO: 10-70 bar.
Water Temperature
Water temperature — affects viscosity and flux. Reference: 20°C.
Recovery Rate
Percentage of feed water converted to permeate. MF/UF: 90-95%, RO: 75-85%.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Feed Flow Rate = 2, Total Membrane Area = 5000, Transmembrane Pressure = 0.5, Water Temperature = 15 = 5 input(s) provided
  2. Calculate Permeate Flux
    Permeate Flux
    56.8 = 56.8
  3. Calculate Specific Flux
    Specific Flux
    113.6 = 113.6
  4. Calculate Fouling Status
    Light Fouling = Light Fouling
  5. Calculate Temperature-Corrected Flux
    Temperature-Corrected Flux
    64 = 64

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