Microfiltration

Within water treatment, there are several filtration techniques. These are separated into four ranges, which are microfiltration, ultrafiltration, nanofiltration, and reverse osmosis. It is the rejection rate that sets the filtration ranges apart. MF separates the largest particles, whereas reverse osmosis separates the smallest particles. Therefore, MF is an excellent range to consider if you do not know your exact liquid filtration needs.

Many industries heavily use MF to concentrate, purify, and separate macromolecules. It can separate large suspended solids, such as bacteria, fat globules, and colloids. Smaller particles and dissolved solids are not retained unless they are coagulated. MF can both be used for pretreatment before other filtration applications within nanofiltration or reverse osmosis to protect the sensitive membranes and posttreatment after conventional filtration methods. 

Microfiltration is performed by a microfilter membrane. It is a pressure-driven technology, meaning that no chemicals are needed to separate the particles. Thus, it is a future-proof technology ensuring a cleaner future. A feed stream enters the membranes, and a feed pump triggers pressure, which will start the microfiltration process. This will separate the feed stream into two new streams, being the permeate and the retentate. The permeate is filtered liquid, which can pass through the porous microfilter membrane barrier. The retentate is concentrated feed water, consisting of particles retained by the microfilter membrane barrier.

Microfilter membranes can be produced of organic materials such as polysulfone, cellulose acetate, polyimide, or polycarbonate or inorganic materials such as zirconia, titania, or silicon carbide. Previously, polymeric microfilter membranes were preferred due to their low capital expenditure. Yet, the balance is flipping as ceramic membranes possess a much higher degree of chemical, mechanical, and thermal strength. This enables ceramic membranes to withstand microfiltration processes with aggressive fluids.

It is the membrane’s pore size that defines the size of particles that are retained. 

The microfiltration pore size is within the range of 0.1-10 µm. Within this filtration range, bacteria, fat globules, and colloids are retained. Smaller particles can pass through the membrane surface. Because the microfilter membrane has a relatively large pore size structure, it requires low pressure to force purification. Thus, the solution requires low energy, making it a low-cost solution.

The membranes and the membrane filtration system can be customized, ensuring the most effective solution to match your filtration needs. 

Based on more than 20 years of experience in water filtration, we have developed a state-of-the-art ceramic membrane. The ceramic membrane has some unique properties, including:

• Highest flux for any membrane material
• Chemically inert pH 0-14
• Thermally resistant up to 800 ˚C
• Hydrophilic material (water-loving)
• Abrasive feeds
• Low power usage and low pressure
• Long membrane life
• Low OPEX and low total cost of ownership

Microfiltration is ideal for water and wastewater treatment. The LiqTech membrane is employed in many large-scale industrial applications within various industries such as pool and spa, oil and gas, power plants, marine, food and beverage, and dairy.

Within water treatment, the technology is used to deliver clean water. Within wastewater treatment, the technology is used to run cleaner and compliant operations by removing harmful elements from wastewater streams.

Microfiltration (MF) and ultrafiltration (UF) are similar low-pressure membrane technologies used for separation processes in water treatment. Both methods can be used for pretreatment before other filtration applications and for posttreatment after conventional filtration methods. The main difference is the rejection rate, meaning the size of the particles the membrane can retain.

It is simply the membrane pore size that differs. Within microfiltration, the pore size is 0.1-10 μm. Within ultrafiltration, the pore size is 0.01-0.1 μm. Which method is the most suitable depends on the feed water and desired permeate quality.

Microfiltration and reverse osmosis (RO) are both membrane technologies used for separation processes in water treatment. Yet, they are on each end of the scale. Whereas MF will separate larger suspended solids, RO separates dissolved solids such as salts and sugar. Reverse osmosis can desalinate water to deliver clean drinking water. Reverse osmosis rejects everything but water molecules. While microfilter membranes have a pore size of 0.1-10 μm, RO membranes have a pore size of 0.0001-0.001 μm. As reverse osmosis membranes have a denser pore size structure, they require higher pressure to force purification than ultrafiltration membranes.