What is an Ultrafiltration (UF) ?

Ultrafiltration and reverse osmosis stand as membrane filtration technologies with a rich history. Dating back to 1907, ultrafiltration has undergone remarkable advancements, particularly in the early 1960s when thin film composite (TFC) ultrafiltration membranes emerged. This breakthrough propelled the widespread adoption of ultrafiltration across diverse industries, including municipal and industrial water treatment, food and beverage processing, outdoor emergency setups, hotels, and more.

This article delves into the workings of ultrafiltration, its various usage scenarios, and the notable advantages offered by this transformative technology.

1. What is Ultrafiltration (UF)?

Ultrafiltration, along with microfiltration (MF), nanofiltration (NF), and reverse osmosis (RO) processes, operates as a separation method using a porous membrane driven by pressure differentials. This technique facilitates the separation of suspended solids and high molecular weight solutes through smaller diameter perforated membranes.

Ultrafiltration membranes typically feature perforations, often measuring between 0.1-0.01 microns, preventing larger molecules from passing to the permeate side. Consequently, rejected constituents, such as suspended solids, remain on the retentate side, while treated water and low molecular weight elements like minerals pass through to the permeate side.

What is Ultrafiltration (UF) (1)

2. The Working Principle of Ultrafiltration Systems.

The treatment of water via ultrafiltration is technically a physical process based on size alienation. The filtration process is either crossflow or direct flow filtration. Below is a summary of crossflow and direct-flow ultrafiltration processes.

1)Crossflow filtration.

Crossflow filtration can also be addressed as tangential filtration. It is characterized by the inlet water flowing along the membrane’s surface resulting in the generation of two streams, the filtrate/permeate and the retentate which contains the rejected molecules. By constantly filtering water using tangential filtration, you can mitigate the accumulation of solids on the membrane’s surface thereby averting membrane clogging. Crossflow filtration is viable for the following types of ultrafiltration membranes:

  • Spiral wound UF membranes.
  • Hollow fiber UF filters.
  • Tubular UF membranes.

 Figure 2 Cross-flow UF filtration.

2)Direct flow UF filtration.

This is also commonly referred to as dead-end UF filtration whereby pressure is exerted to force the feed water through the UF membrane pores. Unlike crossflow filtration, dead-end filtration operates semi-continuously. This facilitates regular unclogging/cleaning of the ultrafiltration membranes. Direct flow filtration is ideal for treating lowly concentrated feed water (particulates).

Direct flow UF filtration (1)

3. What does Ultrafiltration Remove?

Ultrafiltration systems represent significant advancements over microfiltration systems, primarily due to their smaller-sized membrane perforations, ranging from 0.1 to 0.01 microns. This allows them to effectively remove more suspended solids and microorganisms compared to microfiltration (MF) systems. Only constituents measuring less than 20 nm are permitted to pass through these finely tuned membranes. Here is a list of contaminants effectively separated from freshwater by ultrafiltration skids:

 

  • Protein
  • Viruses and bacteria
  • Endotoxins
  • Microplastics
  • Silt and silica
  • Silica
  • Silt
  • Endotoxin
  • Chlorine-resistant organisms
  • Organic matter
  • High molecular weight solute
  • Other suspended solids

However, ultrafiltration systems are not effective in eradicating low molecular weight pollutants like minerals and dissolved salts. Feedwater with high concentrations of dissolved solids necessitates the use of reverse osmosis systems.

4. Types and Applications of Ultrafiltration (UF) Membranes.

 

PVDF hollow fiber ultrafiltration membrane RO pretreatment

Municipal sewage & industrial wastewater advanced treatment and reuse

Residential water and commercial water treatment

PES hollow fiber ultrafiltration membrane Endotoxin removal

Concentration and separation

Food, beverage, water purification, and other life sciences

PVDF-reinforced UF membrane Municipal sewage treatment and reuse

Industrial wastewater treatment and reuse

Landfill Wastewater Treatment

Water reuse

PTFE flat UF membrane MBR

 

5. Advantages of Ultrafiltration Systems.

Ultrafiltration systems have gained prominence in diverse sectors thanks to their high impurity rejection rates, cost-efficiency, and versatility. Below we discuss the chief advantages of utilizing ultrafiltration water treatment systems.

  • Consistently high-quality potable water.

The deployment of an ultrafiltration system is chiefly intended to remove suspended solids and microbes. Irrespective of the feed water concentration and composition, ultrafiltration systems guarantee a high-grade filtrate devoid of suspended molecules with a molecular weight surpassing 20nm.

Consequently, ultrafiltration is utilized in wastewater treatment, salt-water desalination, and groundwater filtration. UF systems are ideal upgrades to microfiltration systems owing to their small-sized pores. With a competent ultrafiltration skid, you are guaranteed impurity removal rates ranging from (90-99%).

  • Does not necessitate the use of chemicals.

Ultrafiltration systems only necessitate the use of chemicals when cleaning the UF membranes and other components. The operation of ultrafiltration processes without the addition of chemicals ensures that there is no alteration to the water’s taste or odor. Additionally, it lessens the operational costs of ultrafiltration systems. The process of ultrafiltration is strictly a physical process reliant on pressure and semi-permeable membranes.

  • Diverse capacity ranges.

Different entities demand specialized ultrafiltration systems with unique capacities. Thankfully, NEWater manufactures numerous UF systems characterized by varying capacity ranges. This ensures that large-scale and small-scale enterprises have unlimited access to unique UF systems perfect for their respective applications.

Typical capacity ranges on standard UF systems vary from 10,000 GPD to over 1M GPD. For smaller or enormous capacities, our engineers provide customized solutions. NEWater’s comprehensive ultrafiltration systems cater to household, commercial, and industrial applications.

  • Low energy consumption.

Compared to other water filtration systems like Nanofiltration and reverse osmosis, the energy consumption of ultrafiltration systems is relatively low.  This is primarily because of their low operating pressure requirements. For household UF systems, the normal inlet pressure can be sufficient to initiate the ultrafiltration process.

Bigger UF systems such as industrial and commercial plants necessitate high-pressure pumps to generate adequate pressure. In addition to energy efficiency, NEWater’s ultrafiltration skids support varying power voltage and frequency options, 220V-480V, 50-60Hz.

Additional benefits of using ultrafiltration systems include:

  • Compact designs.
  • Low operating pressure.
  • Proficiency in removing bacteria and viruses.
  • Low operational costs.

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6. Microfiltration vs Ultrafiltration

Microfiltration, with a filtration precision of 0.1-50 microns, is suitable for coarse filtration tasks such as removing sediment, rust, odor, and color in water. It employs elements like PP, activated carbon, and ceramic filters, commonly applied in whey and skimmed milk production. However, due to its lower accuracy, it falls short in eliminating bacteria and other harmful substances, providing only average results against sediment and rust.

Microfiltration vs Ultrafiltration (1)

In contrast, ultrafiltration boasts a precision range of 0.001-0.1 microns, enabling the removal of rust, sediment, suspended solids, colloids, bacteria, and large organic matter. This process retains essential mineral elements, making it ideal for producing mineral and mountain spring water. With a water recovery rate exceeding 95%, ultrafiltration is efficient, easily maintained through flushing and backwashing, and enjoys a longer service life.

Choosing between the two depends on budget constraints and specific water treatment needs. Ultrafiltration, with its higher flow rate, excellent removal efficiency, versatility, and compatibility with other filtration methods, emerges as a more cost-effective solution compared to microfiltration.

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7. The Difference Between Reverse Osmosis System, Nanofiltration System and Ultrafiltration System.

The key distinctions between reverse osmosis (RO), nanofiltration (NF), and ultrafiltration (UF) lie in filtration accuracy, applications, and operating costs. 

Reverse osmosis provides very high accuracy, making it suitable for desalination and purification. Nanofiltration, with moderate accuracy, is applied in water softening and selective ion separation. Ultrafiltration, with lower accuracy, excels in removing suspended solids, bacteria, and viruses. Operating costs vary, with RO generally higher, NF moderate, and UF ranging from low to moderate.

The table below introduces you to the differences between the three.

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8. Application Fields of Ultrafiltration Systems.

Ultrafiltration (UF) systems showcase versatility in treating various water sources, making them ideal for applications such as brackish water, wastewater, groundwater, and seawater treatment. These systems are effective as stand-alone solutions and can also complement other plants, particularly in conjunction with reverse osmosis (RO). UF systems are frequently employed for pretreating feed water with high silt density before it enters RO systems.

Many users find ultrafiltration to be a cost-efficient water treatment solution when compared to alternative distillation and filtration methods like reverse osmosis and nanofiltration. The broad spectrum of applications for UF includes:

  • Pretreatment for reverse osmosis
  • Municipal water purification
  • Chemical industry
  • Food industry
  • Medicine
  • Starch recovery
  • Concentrated plant protein production
  • Clarification of beverages
  • Sludge concentration and dehydration

This versatility, coupled with its cost-effectiveness, positions ultrafiltration as a preferred choice for a wide range of water treatment needs in diverse industries.

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9. Ultrafiltration Plants Configuration.

There are various UF system configurations, which dictate how users can deploy their ultrafiltration plant for optimum results. Primarily, membrane aeration and the vessel type determine the UF system configuration. Beneath are the varying system configurations feasible with varying ultrafiltration systems.

1)Aeration configuration.

Aeration configuration is founded on the application of bubbles to the UF membrane surface. The bubbles scrub off the constituents that have accumulated on the surface of the ultrafiltration membranes thereby mitigating membrane fouling. The following are the chief options for aeration ultrafiltration system configuration.

Separate aeration.

In separate aeration, the feed water is first aerated in a different container before being pumped into the chamber housing the UF membranes.

Integrated aeration.

Integrated configuration is characterized by the use of a single chamber to house the aerator and the UF membranes. An example of an integrated UF system configuration is a unit with a submerged tank whereby the membranes are above the aerator.

2)Submerged configuration.

The submerged configuration has numerous ultrafiltration membranes inserted into a pool of feed water held in a large container. The container is fitted with the appropriate inlet and outlet openings for smooth operation. Most Ultrafiltration units employ submerged configuration.

Figure 1 Ultrafiltration system.

3)Pressurized configuration.

As the name suggests, pressurized configuration involves housing ultrafiltration membranes in a pressurized chamber. In the pressurized configuration, there are numerous vessels each harboring an inlet and outlet which are ultimately linked by a header. This header is primarily responsible for merging the treated water from the numerous vessels into a single stream.

At NEWater, you are guaranteed unlimited access to comprehensive UF systems and other water treatment units at competitive prices.

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10. The Cost of Ultrafiltration Systems.

Major developments in ultrafiltration membrane technology have gradually shrunk the investment and operational costs of UF systems. Presently, the cost of treating water using ultrafiltration systems is at par with traditional media filters. The cost of purchasing UF equipment varies depending on;

  • Size.
  • Flow rate.
  • Customization.
  • Design.

These specifications differ in distinct ultrafiltration systems accounting for the variations in price tags. This makes price estimation quite difficult hence NEWater provides free price quotations on our website. In addition to the equipment cost, ultrafiltration systems command varying operational costs. Below, we discuss the primary operational costs resulting from the use of UF membrane treatment.

-Installation.

Firstly, the ultrafiltration system needs to be installed at the point of use. For turnkey UF systems, installation is less costly since the systems are majorly plug-and-play. Larger systems may demand professional installation services, which come at a price. NEWater provides on-site installation services for industrial UF systems at discounted prices. The installation cost will be determined once our engineers assess the quantity and quality of service needed.

-Power Consumption.

Power is necessitated to run pressure pumps and membrane cleaning systems in ultrafiltration systems. One of the main reasons behind the widespread adoption of ultrafiltration water treatment is the efficiency in energy consumption. The energy consumption of UF systems depends on the concentration of feed water. Highly concentrated raw water tends to consume more power to treat.

However, the average power consumption of ultrafiltration systems is roughly 0.2 kWh/m 3. Compared to other water treatment solutions such as reverse osmosis, UF is undoubtedly the more energy-efficient technology. The cost is determined by multiplying your region’s billing rate by the system’s energy consumption.

-Labor.

Larger ultrafiltration systems utilized by municipalities and various industries necessitated skilled human labor. The total labor costs vary significantly depending on the quantity and quality of service demanded. The wages are also prone to regulations from the respective labor laws in respective countries. For instance, the total labor costs of UF systems in China are approximately 0.2 yuan/ton of water.

-Maintenance costs.

Ultrafiltration systems require regular maintenance services for continued optimum services. Maintenance services demanded by an ultrafiltration system include membrane cleaning and replacement of damaged membrane elements. Thanks to the long-lasting nature of UF membranes, the maintenance costs are considerably low. With NEWater’s high-quality ultrafiltration membranes, you are assured of at least 12 months of high-quality services.

Ultimately, the comprehensive cost of acquiring and operating an ultrafiltration system is relatively cost-efficient. NEWater offers the best-priced UF systems thanks to our top-notch innovation in production processes and the use of cost-efficient yet highly effective equipment.

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11. Conclusion

Ultrafiltration stands as a widely employed water treatment technology across numerous industries. NEWater offers a range of ultrafiltration systems tailored to diverse needs, including residential uf systems, wastewater ultrafiltration systems, well water ultrafiltration systems, skid-mounted ultrafiltration systems, and containerized ultrafiltration systems. These solutions cater to a spectrum of industrial, commercial, and personal applications.

For personalized quotes and further information, feel free to reach out to our experienced engineers. They are ready to assist you in finding the right ultrafiltration system for your specific requirements. Contact us to explore how NEWater can meet your water treatment needs efficiently and effectively!

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