4×4040 RO Membranes 1 T/H – Simulation Calculation Guide?

4 × 4040 RO Membranes 1 T/H System: Simulation Calculation Method

Author: Sophia  

Water Treatment Engineer, VLLRO | 20 years in RO system design & simulation

The 1m³/h smallscale RO system – typically using 4 × ULP31‑4040 LP membranes – is widely used in Southeast Asian government water supply and commercial projects. But can it consistently deliver rated output under high‑salinity feed conditions? You cannot rely solely on membrane datasheets. You must run professional water treatment simulation software to verify production capacity.

In this guide, I will walk through the complete simulation calculation process for a 4‑membrane 1 T/H system – based on real Malaysia government project documentation – covering baseline parameters, step‑by‑step simulation logic, and extreme‑condition validation.

Core Baseline Parameters (Design Basis)

All calculations use industry‑standard benchmark conditions from original factory technical documents:

Core Simulation Logic

RO permeate flow is affected by feed TDS, temperature, operating pressure, and recovery rate. Relying on single‑membrane nominal flux creates significant errors. Professional simulation software uses iterative segmental calculation :

1. Input boundary conditions (TDS, temperature, membrane model, quantity, recovery)

2. Load single‑membrane flux and ≥99.5% rejection data

3. Iteratively calculate concentrate‑side salt concentration – correct osmotic pressure loss

4. Output two sets of results: standard and extreme high‑salinity conditions

Key correction principle: Higher feed TDS increases osmotic pressure – reducing permeate flux at the same pressure. The simulation applies a ±20% fluctuation margin (up to 1200 ppm) to verify system redundancy and prevent real‑world capacity shortfall.

Step‑by‑Step Simulation Process

Step 1: Input Membrane Parameters

In the simulation software, enter:

 Single‑membrane nominal flux and ≥99.5% rejection (Vontron ULP31‑4040)

 Pressure limit: 1.6 MPa (matched to 4040 housing)

 Arrangement: 4 membranes in parallel – no interstage boost – uniform feed pressure 0.6‑0.8 MPa

Step 2: Set Feed Water Quality & Temperature

Compare two simulation scenarios:

 Standard: TDS 1000 ppm, 25°C

 Extreme: TDS 1200 ppm (‑20% margin), 25°C

 Optional: Temperature compensation for 5‑40°C range (simulate winter production drop)

Step 3: Set Recovery & Piping Parameters

 Recovery fixed at 50% – automatic concentrate valve maintains 1:1 ratio

 DN20 piping – no diameter reduction losses – disable extra pressure loss correction in software

 Dual 5μm PP cartridges fully intercept particles – no additional fouling resistance added

Step 4: Match Pump Curve & Run Iterative Calculation

Input PLD2‑11 pump output range (0.6‑0.8 MPa). Software automatically calculates:

 Effective driving pressure at membrane surface

 Concentrate‑side salt concentration factor

 Real‑time flux per membrane

 Total permeate flow, system desalination rate, and product TDS

Step 5: Export Simulation Results & Validate Capacity

Conclusion: The system maintains stable 1.0 m³/h output under both standard and extreme high‑salinity conditions. Operating pressure stays within 0.6‑0.8 MPa – no pump overload, no capacity shortfall.

Summary

Simulation calculation is not just a formality – it is the only reliable method to verify that your 4‑membrane 1 T/H RO system will perform as promised under real‑world water quality fluctuations. Using the process above, you can confidently validate designs, approve equipment, and prepare technical documentation.

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