Process flow scheme of RO membrane for sugar concentration
08 Jul 2025
Here is the professional English translation of the RO Membrane Concentration Process for Sugar Solutions:
I. Process Objectives
| Parameter | Target |
|---|---|
| Initial Sugar Concentration | 10-20 °Brix (sucrose/fructose solution) |
| Target Concentration | 25-40 °Brix (membrane limit to avoid crystallization) |
| Sugar Rejection Rate | ≥99.5% |
| Energy Savings vs. Evaporation | 60-70% reduction |
| Flavor Compound Retention | >95% |
II. Process Design (Three-Stage RO System)
graph TB
A[Raw Sugar Solution] --> B[Pretreatment]
B --> C1[Stage 1 RO (Low Pressure)]
C1 -->|Concentrate| C2[Stage 2 RO (Medium Pressure)]
C2 -->|Concentrate| C3[Stage 3 RO (High Pressure)]
C1 & C2 & C3 --> D[Permeate Reuse/Discharge]
C3 --> E[Concentrated Sugar Syrup] III. Core Process Details
1. Pretreatment System (Critical Fouling Control)
| Unit | Function |
|---|---|
| Vibrating Screen | Remove solids (≥100μm) |
| Enzymolysis Tank | Dose α-amylase for starch syrup (55°C hydrolysis to prevent fouling) |
| UF System | Remove proteins/colloids (10kDa MWCO) |
| Antiscalant Dosing | Specialized sugar antiscalant (e.g., Pentair GL series to inhibit CaSO₄) |
Pretreated Water Quality:
- SDI₁₅ <2 | Turbidity <0.5 NTU | Colloids <10 ppm
2. Multi-Stage RO Concentration
| Stage | Operating Parameters | Recommended Membranes | Features |
|---|---|---|---|
| Stage 1 | Pressure: 15-25 bar Recovery: 40% |
Hydranautics ESPA2-LD | Low-energy pre-concentration to 20-25°Bx |
| Stage 2 | Pressure: 35-50 bar Recovery: 30% |
Toray TMG20D-400 | Anti-fouling coating for high viscosity |
| Stage 3 | Pressure: 60-80 bar Recovery: 20% |
DuPont™ Filmtec Fortilife™ | Ultra-high pressure for 40°Bx concentrate |
Sugar Rejection Performance:
Sugar Type Molecular Weight (Da) RO Rejection Rate Glucose 180 99.2-99.6% Sucrose 342 99.8-99.9% Maltodextrin 1,000+ >99.99%
3. Concentrate Post-Treatment
- Crystallization Control: Maintain concentrate at 45°C during transfer
- Pasteurization: 80°C/15s treatment (microbial inactivation)
-
Downstream Integration:
Switch to evaporation when >40°Bx to avoid membrane clogging
IV. Key Equipment List
| System | Equipment |
|---|---|
| Pretreatment | Plate heat exchanger (enzyme temp control), auto-backwash UF, online turbidimeter |
| RO System | Plunger-type HP pump (80bar), 316L stainless pressure vessels, energy recovery device |
| Control System | PLC+HMI (auto pressure/flow adjustment, real-time osmotic pressure monitoring) |
| Cleaning System | CIP unit (alkaline protease + citric acid) |
V. Technical Advantages
-
Energy Comparison
Concentration Method Energy to 30°Brix (kWh/m³ water) Triple-effect evaporation 90-120 MVC 40-60 3-Stage RO 15-25 -
Quality Enhancement
- Prevents Maillard reaction (<45°C vs evaporation >70°C)
- 32% higher aroma retention (GC-MS verified)
VI. Critical Considerations
-
Fouling Control
- Pulse flush every 8 hrs (3 min, 2.5× flow rate)
- Weekly CIP (0.1% NaOH + 0.03% SDS)
-
Concentration Limit
- Online refractometer cuts system at >40°Bx
-
Viscosity Management
- Heat Stage 2+ concentrate to 40-45°C (reduces viscosity by 30-50%)
Industry Case: Fructose syrup manufacturer results
Parameter Evaporation RO Process Energy cost $12.3/ton $4.0/ton Fructose degradation 8-12% <1% Processing time 4.5 hours 1.2 hours
RO Sugar Concentration Mechanism
[Sugar solution] → HP pump → RO membrane surface
↑ Water permeation → Permeate (low sugar)
↓ Sugar retention → Concentrate (high sugar)
* Cross-flow velocity >1.5 m/s prevents polarization Request membrane flux calculation tools or P&ID diagrams for detailed engineering support.
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