Membranes

What is membrane filtration?

Membrane filtration is a physical separation process that uses a semi-permeable membrane to separate suspended or dissolved substances in a fluid mixture based on their size, shape, or chemical properties. It is commonly used in industries such as water treatment, oil and water produced water, food and beverage production, pharmaceuticals, chemicals and biogas industry. With the help of membrane filtration, the overall production costs can be reduced while at the same time increasing product quality.

The membrane filters consist of either organic (polymeric) or inorganic (ceramic) materials. The two defined factors of separation size and separation process influence the process efficiency of the various membranes.

BOLLFILTER types of membranes

BOLLFILTER offers two different types of membranes:

Discover the full potential of our membranes. Click here to contact us and receive detailed information tailored to your needs.

Types of membrane filtration

When it comes to membrane filtration possibilities, membrane filtration is typically categorized into four widely recognized types, based on the size of particles they are designed to separate from the feed liquid. These types, arranged by increasing pore size, are reverse osmosis, nanofiltration, ultrafiltration, and microfiltration.

Reverse Osmosis (RO):
Reverse osmosis is a filtration process that uses a semi-permeable membrane to remove ions, molecules, and larger particles from water or other liquids. It is highly effective in separating dissolved salts, contaminants, and impurities, producing highly purified water.

Nanofiltration (NF):
Nanofiltration is a filtration technique that removes dissolved substances, such as divalent and larger monovalent ions or organic molecules, while allowing smaller solutes like sodium and chloride to pass through. It is often used for water softening, partial desalination, and the removal of organic matter.

Ultrafiltration (UF):
Ultrafiltration employs membranes with slightly larger pores to separate macromolecules, proteins, oils, and suspended solids from liquids. It is commonly used in applications such as wastewater treatment, protein recovery, and the food and beverage industry.

Microfiltration (MF):
Microfiltration is a process that removes larger particles, such as bacteria, suspended solids, and some viruses, using membranes with relatively large pores. It is frequently used in sterilization, beverage production, and the separation of fine particulates.

Crossflow Filtration VS Dead-End Filtration principle

The filtration methods used depend on the type of membrane. There are two different types. One is the Dead-End Principle (plate membrane) and the other is the Crossflow Filtration Principle (tubular membrane).

Material properties of membranes

Our ceramic membranes consist of three layers:

Substrate (provides mechanical strength)
Interlayer (as supportive layer)
Membrane (gives selectivity efficiency)

Tubular Membranes — See how tubular membrane filtration works! Tubular filtration technology used in our Bollbrane.

SiC properties compared to other materials

Silicon carbide (SiC) is among the hardest materials in the world. Our SiC ceramic membrane technology provides extreme durability combined with mechanical robustness. The material also stands for the highest flux, high permeability as well as a high level of hydrophilicity (water-loving material). Add to this it is resistant to corrosion too.

In addition to our SiC ceramic membranes, BOLL also offers aluminum oxide membranes (Al2O3) as a versatile solution for various filtration needs. While aluminum oxide membranes provide reliable performance, BOLL SiC membranes dominate in some categories, making them the superior choice for demanding applications.

Features	SiC	AI2O3	Polymer
Life time	+++	+++	+
Flux	+++	++	+
Chemical resistance	+++	++	+
Cost savings	+++	+++	+
Operating TMP	+++	++	+
Temperature resistance	+++	+++	+
Fouling behavior	+++	++	+

Advantages of SiC-membranes

High Flux

High flux due to ultrathin membrane layer and high porosity substrate.

This results in:

High flow on small foot-print for more compact plants
Low pressure operations
Lower energy consumption

Anti Fouling

Due to low zeta potential, SiC membranes have a remarkable anti fouling property.

This leads to:

Longer filtration cycles (without backwash)
Less maintenance for cleaning
Lower energy expenditure

Chemical resistant

Silicon Carbide is almost universally chemical-resistant (pH 0-14).

This enables:

Treatment of highly corrosive feed water
More adaptability in cleaning

Thermal resistant

SiC membranes are particularly resistant to rapid, shock-like temperature changes. Heat can be transferred fast and there are hardly any tensions in the membrane that could lead to damage.

Hydrophilic and Lipophobic

SiC membranes are very hydrophilic due to low contact angle between water and membrane surfaces. Combined with the lipophobical attribute, this alows an optimized oil-water emulsion separation.

Possible applications BOLLFILTER membranes

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Michael Hormes Director Business Unit Fine Filtration Technology

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