How to Design an RO / NF System

Step 1 - Consider Feed Source, Feed Concentration, Feed / Product Flow and Product Quality

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

Consider Feed Source, Feed Concentration, Feed / Product Flow and Product Quality

The membrane system design depends on the available feed water and the application. The system design information and the feed water analysis should, therefore, be collected first.

A) Choose feed water source (e.g. well water with SDI <3, surface water with SDI <5, etc.)

B) Choose overall feed water concentration in TDS (ppm) or individual (specific) ions.

C) Individual ion concentration from water analysis is always preferred.

System Design Introduction (56KB PDF)
Feed Water Type and Analysis (136KB PDF)
Membrane System Design Guidelines (126KB PDF)

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