Ultra-Filtration

Summary

Product Identification

DOW™ Ultrafiltration modules are made from high-strength, hollow fiber membranes with an outside-in flow configuration. They are designed for the pressure-driven separation of materials from a feed solution, removing particulate and microbial contaminants but not ions or small molecules.

Key features:

• Nominal Pore Diameter: 0.03 µm for removal of bacteria, viruses, and particulates including colloids.
• Membrane Material: PVDF polymeric hollow fibers, hydrophilic for easy cleaning and wettability.
• Housing Material: U-PVC, eliminating the need for separate pressure vessels and resistant to UV light.
• Fiber Dimensions: 1.3 mm outside diameter, 0.7 mm inside diameter.
• Flow Configuration: Outside-In, tolerant of high feed solids and allowing air scour cleaning.
• Connections:
  • SFP 2660:
    • Feed and Product: DN 50 Victaulic
    • Concentrate: DN 32 Threaded
    • Air: 3/8 inch Threaded
  • SFP 2860/2880:
    • Feed and Product: DN 50 Victaulic
    • Concentrate: DN 50 Victaulic
    • Air: 3/8 inch Threaded

Mechanical / Hydraulic

The DOW™ Ultrafiltration modules are available in SFX-2660, SFX-2860, and SFX-2880 models.

Module Specifications:

• SFX-2660:
  • Length: 1860 mm (73.2")
  • Diameter: 165 mm (6.5")
  • Surface Area: 33 m² (355 ft²)
  • Volume per Module: 16 L (4.2 gal)
  • Weight (water filled): 41 kg (90 lbs)
  • Shipping Weight (w/o packaging): 25 kg (55 lbs)
  • Fibers/Module: 5,760
  • Housing: UPVC
• SFX-2860:
  • Length: 1860 mm (73.2")
  • Diameter: 225 mm (8.9")
  • Surface Area: 51 m² (549 ft²)
  • Volume per Module: 35 L (9.3 gal)
  • Weight (water filled): 83 kg (183 lbs)
  • Shipping Weight (w/o packaging): 48 kg (106 lbs)
  • Fibers/Module: 9,000
  • Housing: UPVC
• SFX-2880:
  • Length: 2360 mm (92.9")
  • Diameter: 225 mm (8.9")
  • Surface Area: 77 m² (829 ft²)
  • Volume per Module: 39 L (10.3 gal)
  • Weight (water filled): 100 kg (220 lbs)
  • Shipping Weight (w/o packaging): 61 kg (135 lbs)
  • Fibers/Module: 10,000
  • Housing: UPVC

See the official PDF for exact tabulated values for detailed dimensions (L1, L2, L3, W1, W2).

Air Scour Parameters:

• Maximum Inlet Pressure: 2.5 bar (36 psi)
• Air Flow per Module: 5 to 12 Nm³/h (3 - 7 scfm)
• Air-Water Mix Entrance Pressure: ≤ 1.0 bar (14 psi)
• Air Quality: Non-oil compressed air

Clean In Place (CIP) Flux:

• Cleaning Flux per Module: 1.0 – 1.5 m³/h (6.6 - 8.8 gpm)

Operating Limits

DOW Ultrafiltration Operating Conditions:

• Feed Pressure, Maximum at Inlet at 20 ºC: 6.25 Bar (93.75 psi)
• Operating Transmembrane Pressure (TMP) (Maximum): 2.1 Bar (30 psi)
• Filtrate Flux @25C: 40 - 120 L/m²/hr (24 - 70 gfd)
• Temperature (UPVC limited): 1 – 40 ºC (34 - 104 ºF)
• Operating pH Range: 2 - 11
• NaOCl, Cleaning Maximum: 2,000 ppm

Feed Water

DOW Ultrafiltration module designs are based on qualified feed water conditions. The modules can tolerate periodic excursions up to the maximum allowable values. A safety screen of 150 – 300 microns is recommended on the feed to the UF system.

Qualified Feed Water Quality Parameters:

• Parameter | Unit | Design Basis | Maximum Allowable
• --- | --- | --- | ---
• Turbidity | NTU | <50 | 300
• TOC | mg/l | <10 | 40
• Particle Size | micron | <150 | 300
• CODMn | mg/l | <20 | 60
• Oil /Grease | mg/l | 0 | < 2
• pH continuous | - | 6-9 | 2-11
• Temperature | ºC | 25 | 40
• Cl₂ continuous | mg/l | 0.5 | 200
• TSS | mg/l | 50 | 100

Product Water

UF membranes reject solutes ranging in size from 0.03 microns and larger. The molecular weight cut-off (MWCO) is the molecular mass or weight of a solute that rejects greater than 90 percent, measured in Daltons (D).

Storage and Handling

Modules are shipped wetted and stored in a pH buffered 1% sodium metabisulphite solution. Glycerin can be added to the preservative to prevent freezing.

Uninstalled Modules:

• Store horizontally with connections/ports facing up.
• Stacking limit: 4 layers for 2660 and 2860 modules, 3 layers for 2880 modules.
• Storage temperature: 20 to 35ºC.
• Shelf life: 1 year from manufacture date in original packing.
• Preservative volume: 2 L for 2660, 4 L for 2860, 6 L for 2880.
• If exposed to freezing conditions, glycerin should be added to the preservative to achieve a 20% concentration. See the official PDF for exact tabulated values of glycerin concentration vs. freezing point depression.

Installed Modules (Skid Shutdown Summary):

• 0 to 48 hours: Air scour and backwash, close all valves.
• >2 days to 7 days: Air scour and backwash, close all valves, perform 30 to 60 minutes of operations daily OR air scour, backwash, add preservative then close all valves.
• >7 days to 90 days: Add preservative and renew preservative every three months.
• >90 days: Consult the manufacturer.
• Dry membrane fibers will irreversibly lose flux if allowed to dry out.

Cleaning

Backwash:

• Frequency: Once every 20 to 60 minutes
• Duration: 40 to 120 seconds
• Flux: 100 to 150 L/m²·h (60 - 90 gfd)

Chemically Enhanced Backwash (CEB):

• Frequency: As needed
• Duration: Backwash time plus soak of 5 to 20 minutes.
• Cleaning Solutions: 0.1% HCl, 2% Citric acid, 2% Oxalic acid, 0.1% NaOCl, 0.05% NaOH.

Clean In Place (CIP):

• Frequency: When TMP exceeds 1.0 bar above starting TMP (at same temperature).
• Duration: 120 minutes (recycle and soak) or longer.
• Cleaning Solutions: 0.2% HCl, 2% Citric acid, 2% Oxalic acid, 0.1% NaOH + 0.2% NaOCl.
• Temperature Range: 10 to 40 °C (34 - 104 ºF).

Integrity Testing

Two methods are commonly used:

Bubble Test:

1. Take module out of filtration mode and drain from the feed side.
2. Close feed and concentrate valves; align filtrate valve to drain through a transparent tube. Isolate the bank of modules being tested.
3. Pressurize the drained side with oil-free compressed air, slowly raising pressure to a maximum of 2 bars (29 psi).
4. Large continuous air bubbles in the transparent tube indicate broken fibers. Smaller, infrequent bubbles are due to air diffusion.

Pressure Hold/Decay:

1. Take UF unit or module out of filtration mode. Drain water from the feed side. Close feed and concentrate valves, keep filtrate valve open.
2. Pressurize the membrane module with oil-free compressed air, slowly raising pressure to a maximum of 2 bars (29 psi).
3. Close the air inlet valve.
4. Hold pressure for 10 minutes. The membrane is integral if the pressure drop is lower than 0.2 bar (2.9 psi). A pressure drop greater than 0.2 bar in 10 minutes (2.9 psi in 10 minutes) indicates compromised membrane fibers requiring repair.

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Disclaimer: This summary is based on extracted text and may not include all figures, footnotes, or the latest revisions from the official OEM PDF datasheet. For contractual data and complete product information, the specific OEM PDF revision used on the project must be consulted.

Official datasheet (PDF)

Lenntech datasheet mirror