Desalination & Membrane Water Treatment Equipment worked example

Membrane Flux Rate at 68% target flux attainment: a worked example

This worked example runs the membrane flux rate numbers for a tougher week than the baseline: 68% target flux attainment instead of the typical 95%. Compare actual membrane permeate flux against the design or normalized target flux for RO, NF, UF, or MF systems so operators can spot fouling, compaction, or underloading.

The inputs for this scenario

  • Actual normalized membrane flux: 8 LMH or GFD (held at the documented default)
  • Design or rated membrane flux: 250 LMH or GFD (held at the documented default)
  • Target flux attainment: 68 % (the input this scenario stresses; the baseline uses 95)

Working through the calculation

  • The calculation starts from the formula this tool documents: Membrane flux attainment = actual normalized membrane flux ÷ design or target membrane flux × 100.
  • Membrane flux attainment works out to 3.2 % at these inputs, and this is the headline figure for the scenario.
  • Flux attainment gap to target works out to 64.8 points at these inputs.
  • Actual normalized membrane flux works out to 8 count at these inputs.
  • Design or target membrane flux works out to 250 count at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where target flux attainment sits at 95% and the headline result is 3.2 %, this scenario lands almost exactly on the baseline at 3.2 %.
  • Use it during daily performance normalization, after a CIP to confirm flux recovery, or when benchmarking a fouled skid against its commissioning baseline. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Membrane flux attainment: 3.2 % (headline result)
  • Flux attainment gap to target: 64.8 points
  • Actual normalized membrane flux: 8 count
  • Design or target membrane flux: 250 count

Run it with your numbers

  • To rerun this with your own numbers, open the live Membrane Flux Rate calculator, set target flux attainment to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.