How to Design an RO / NF System

Step 4 - Select Average Membrane Flux (Design Flux)

Step 1: Consider Feed Source, Feed Quality, Feed / Product Flow, and Required Product Quality
Step 2: Select the Flow Configuration and Number of Passes
Step 3: Select Membrane and Element Type
Step 4: Select Average Membrane Flux (Design Flux)
Step 5: Calculate the Number of Elements Needed
Step 6: Calculate the Number of Pressure Vessels Needed
Step 7: Select the Number of Stages
Step 8: Select the Staging Ratio (Array Ratio)
Step 9: Balance the Permeate Flow Rate
Step 10: Example

Select Average Membrane Flux (Design Flux)

RO / NF systems are usually designed for a specific permeate flow rate (GPD or l/h) and a specific system recovery. These numbers, and the specific feed water source, are the information required to estimate the number of membrane elements, pressure vessels and stages as flows:

Select the design flux (GFD or l/m2h) based on pilot data, customer experience or the typical design fluxes according to the feed source from the Membrane System Design Guidelines (126KB PDF).

Membrane System Design Guidelines (126KB PDF)
Screening Test, Application Test and Pilot Test (38KB PDF)

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