Desalination & Membrane Water Treatment Equipment worked example

Membrane Fouling Loss with permeate flow lost to fouling of 6 m³ / hr: a worked example

Suppose permeate flow lost to fouling falls to 6 m³ / hr. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate lost permeate production or added operating cost from membrane fouling over a runtime period so operators can compare cleaning timing and production impact.

The inputs for this scenario

  • Permeate flow lost to fouling: 6 m³ / hr (the input this scenario stresses; the baseline uses 12)
  • Hours run in fouled condition: 8 hr (held at the documented default)
  • Sale or replacement value of permeate: 3.5 $ / m³ (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Lost permeate volume = permeate loss from fouling × fouled operation runtime.
  • Lost permeate volume works out to 48 units at these inputs, and this is the headline figure for the scenario.
  • Fouling-related production loss cost works out to 168 $ at these inputs.
  • Fouled operation runtime works out to 8 hr at these inputs.
  • Value of lost permeate works out to 3.5 $ / unit at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where permeate flow lost to fouling sits at 12 m³ / hr and the headline result is 96 units, this scenario comes in 50% below the baseline at 48 units.
  • It computes the permeate volume lost over a fouled run period and converts that volume into a production-loss cost using the per-m³ value of permeate. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Lost permeate volume: 48 units (headline result)
  • Fouling-related production loss cost: 168 $
  • Fouled operation runtime: 8 hr
  • Value of lost permeate: 3.5 $ / unit

Run it with your numbers

  • To rerun this with your own numbers, open the live Membrane Fouling Loss calculator, set permeate flow lost to fouling to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.