Ultrafiltration: How It Works & Its Difference with RO

In water resource management, several methods might be used, including ultrafiltration. Ultrafiltration is a water management technique that uses membrane separation technology, either for potable water or wastewater.

This article discusses water resources management using ultrafiltration, including the definition of how it works. To learn more about ultrafiltration, read this article until the end.

What Is Ultrafiltration?

Ultrafiltration is a water treatment method that utilizes a semipermeable membrane to filter bacteria, viruses, organic matter, and other pollutants from water. According to the Handbook of Industrial Membranes, materials and particles that can be retained by ultrafiltration membranes have a molecular weight of 1,000-1,000,000.

This filtration process will impact the odor, taste, and color of the water to disinfect it. Generally, the sizes of this membrane are 0.01 and 0.1 microns, trapping the organisms and particles.

However, the membranes are wide enough to pass solutes, such as salts and minerals, which are beneficial to water. Typically, ultrafiltration membranes are made of polymers and have microscopic pores that set the accuracy of the filtration results.

Thanks to the filtration technology, ultrafiltration is often compared with reverse osmosis, nanofiltration, and microfiltration. Yet, what makes it different is the molecular size trapped in the membrane.

Then, what is ultrafiltration used for? Here are some benefits of ultrafiltration generally:

Water softening.
Wastewater management.
Removing macromolecules and particles for potable water production.
Food industry.
Replacement of water treatment facilities' secondary and tertiary filtration stages.
Filtration of effluent from pulp mills.

How Ultrafiltration Works

Ultrafiltration is a method of filtering water using a semipermeable membrane. A semipermeable membrane is a thin layer that can separate substances or materials when a driving force is applied across the membrane.

The mechanism of ultrafiltration is quite simple, in which water will pass the membrane under pressure, making the larger substances trapped in the membrane surface. Some substances filtered in this system include bacteria, viruses, protozoa, high molecular weight organic matter, colloids, and solids.

On the other hand, solutes and water can pass through the membrane pores. Ultrafiltration is a chemical-reaction-free process because it focuses on separating physical pollutants. As a result, the water’s chemical composition remains still, and the water becomes clean from other microorganisms and pollutants. In general, ultrafiltration has several stages as follows:

Pre-filtration: Before water gets into the ultrafiltration system, the water will enter the initial stage to filter out larger particles that potentially damage the ultrafiltration membrane.
Pressure application: Pressure is in to suck the water through the membrane.
Membrane separation: Once the water passes through the membrane, the contaminants will stop on the membrane surface.
Water collection: Permeate (filtered water) passes through the membrane, and it is collected for further processing.
Concentrate removal: The retained contaminants will collect on the feed side and form concentrate. It will then be periodically purged from the system.
Backwashing: The ultrafiltration system must be cleaned by reversing the water flow to make the system clean and the membrane work effectively.

Advantages of Ultrafiltration

The most important benefit of ultrafiltration is that it effectively removes pollutants, making the potable or industrial water safe. Ultrafiltration is also suitable for areas with poor-quality water, making the water produced safer to use.

Equally important, this method does not remove the salt and minerals from the water. You also do not need to worry about chemically polluted water since this process does not use chemicals.

In addition, because it does not use chemicals, the water filtration process becomes more environmentally friendly and does not cause waste that could potentially pollute the surroundings.

The maintenance and operation costs of this method are also lower than other water treatment technologies, making it suitable for MSMEs, communities, and households.

Differences Between Ultrafiltration and Filtration

Ultrafiltration and filtration have a similar goal: purifying the water from physical pollutants. Then, what makes both methods different? Here is the explanation:

1. Technology

Traditional filtration uses physical filters, such as activated carbon and sand, to retain large particles and dissolve beneficial substances. Ultrafiltration, on the other hand, uses cutting-edge membrane technology that is so porous that it can retain microscopic contaminants.

2. Pore Sizes

The filtration pore sizes are bigger than ultrafiltration, which is about 1–1,000 microns. In contrast, ultrafiltration has smaller pores of 0.01 and 0.1 microns, making it able to filter tiny particles.

3. Water Quality

Ultrafiltration technology produces better quality water than traditional filtration because it filters out molecular-sized substances and particles. As a result, water is safer and cleaner.

4. Contaminant Removals

Traditional filtration is ideal to remove larger particles and some types of microorganisms. Contrastingly, ultrafiltration is a method that not only filters bigger particles but also the smaller ones, like bacteria and viruses.

5. Application

Both methods are used to manage water, either potable water, industrial water, or wastewater. Yet, ultrafiltration is commonly used in fulfilling highly purified water demand.

Differences Between Ultrafiltration and Reverse Osmosis

Besides filtration, ultrafiltration is also often compared to reverse osmosis (RO). Both can be categorized as effective water filtration systems widely used in various sectors. In fact, both also use membranes. The following are the differences between ultrafiltration and RO:

1. Membrane

RO uses a semipermeable membrane separating 95–98% of inorganic solutes from the water. Inversely, ultrafiltration uses a hollow fiber membrane, retaining microscopic contaminants. Moreover, ultrafiltration is a filtering system, while reverse osmosis is a process of separating molecules.

2. Removed Substances

Ultrafiltration only removes very small solids but can pass mineral substances, such as magnesium and calcium, in the water. RO removes all the minerals in the water, so the water produced is very pure.

3. Storage Need

Ultrafiltration does not need storage tanks because it is connected directly to the special faucet, while RO needs storage tanks due to the cross-flow filtration process.

That concludes the information about ultrafiltration. Ultrafiltration is considered an effective water purification method because it can remove microscopic contaminants and improve water quality.

Ultrafiltration is also utilized in many water management applications, including what Krakatau Tirta Industri (KTI) always does. The Chandra Asri Group-affiliated company offers water management solutions, such as demineralized water, clean water, and wastewater management.

With ultrafiltration, biological treatment, and ion exchange, we are not only ensuring that the industry gets quality clean water and demineralized water but also ensuring that wastewater is managed efficiently and sustainably.

Thus, make sure to fulfill your industrial water needs with Krakatau Tirta Industri!