Water Ultrafiltration

Ultrafiltration: Better Water Processing Across a Range of Applications

Author: Brian Wise

What is ultrafiltration?

In layman’s terms, the ultrafiltration mechanism forces water under pressure through a semi-permeable membrane. Water passes effectively through the membrane, but most solids and pathogens are filtered out. Ultrafiltration makes it easy for individual municipalities to control their own reliable drinking water supplies, and various iterations of ultrafiltration are applied to specific water uses, from industrial to domestic.

What is ultrafiltration typically used for?

The ultrafiltration process facilitates water recycling and reuse, filtering out pathogens and pollutants for an end-product with almost zero physical solids. As such, this dynamic process can be applied to a wide range of water, wastewater, and fluid separation applications. The process may be employed to clean water in rural villages, provide safe drinking water for millions of people in cities around the world, recycle wastewater discharged from treatment plants, and even pretreat seawater used within reverse osmosis systems. A number of industries rely on ultrafiltration, which offers a cost-effective option to treat incoming water for processing, utility, and reuse needs. The chemical, oil and gas, power, paper, pharmaceutical, food and beverage, and plastics industries all depend on ultrafiltration to filter solids and pathogens from their water sources.


Around the world, innovators are harnessing the power of ultrafiltration, from cheese manufacturers to fruit juice producers. Dialysis and other blood treatment processes utilize ultrafiltration, as do laboratory-grade manufacturers, enzyme recovery specialists, and, of course, water and wastewater treatment facilities.

Nanostone Water has empowered organizations around the world with effective, cost-efficient ultrafiltration solutions. Coal refinement, for example, means major wastewater issues in China, where the industry booms. Because biological treatment isn’t enough to meet discharge requirements, Chinese coal refineries are taking advantage of Nanostone’s ultrafiltration technology to better enable effective reuse of their wastewater.

What does the ultrafiltration membrane remove?

Ultrafiltration is designed to remove microscopic particles in water; water and low-molecular weight solids easily pass through the membrane, while solids and solutes of higher molecular weight are kept from passing through. These high-weight substances include proteins, bacteria, pyrogens, colloids, and any other macromolecules larger than the membrane’s basic pore size. Ultimately, harmful particles, microbes, and other pathogens are retained, effectively filtering the water without the aid of costly, potentially harmful chemicals.

What is the difference between ultrafiltration & microfiltration?


Though ultrafiltration and microfiltration both pass liquids through semipermeable membranes, the difference lies in the membrane pore size. Microfiltration boasts a lager pore-size membrane—generally between 0.1 micron and 1 micron (100-1000 nanometers)—allowing water alongside monovalent and multivalent ions and viruses to pass through. Larger bacteria and suspended solids are typically retained with microfiltration, and the process is typically applied to oil refinement, wastewater treatment, and dairy production – all settings where some larger components benefit the final water product.

Ultrafiltration, on the other hand, features a much smaller pore size—generally between 0.01 micron and 0.10 micron (10-100 nanometers)—effectively blocking proteins, microplastics, colloidal silica, and viruses. For reliable solutions to drinking and wastewater issues, as well as a broad spectrum of industrial applications, ultrafiltration represents a sophisticated, cost-effective approach to broad-level water reuse.

What industries use ultrafiltration?


Municipalities around the world rely on ultrafiltration for clean drinking water, since the process successfully removes a range of potentially harmful pathogens and suspended solids from raw water. Without relying on harmful chemicals or complex production, ultrafiltration produces a constant end-product quality—regardless of changes in the feed water quality. A compact plant is appealing, and ultrafiltration has been proven capable of exceeding regulatory water quality standards. As municipalities worldwide face the realities of limited drinking water sources, more and more are reusing their wastewater, creating a new resource. Whether the goal is to recycle water for irrigation or create directly or indirectly potable water, ultrafiltration provides a physical barrier to harmful pathogens, enabling safe wastewater reuse. Learn more here.

Wastewater reuse by industrial facilities also depends on ultrafiltration. From chemical plants to food and beverage producers to power generators, industries based around the world are employing ultrafiltration to eliminate harmful elements in the wastewater left behind from conventional treatment methods and unlock a water source previously discharged as waste. Ultrafiltration is also frequently harnessed to produce process water – essentially the water used for manufacturing processes, from boiler make-up water and cooling tower make-up water to general coating, plating, rinsing, spraying, and washing water solutions. Residue from poor filtration can result in all manner of problems, from fouling the RO membranes in a boiler feed system to reducing the yield in the manufacturing process. Learn more here.

Types of membranes used for ultrafiltration

Ceramic filtration enables a three to ten times higher flux than polymeric membranes. With a high suspended-solids tolerance, ceramic filtration delivers a consistent end-product. Easy to maintain, able to recover permeability, and featuring a high chemical resistance, ceramic filtration is the logical choice for reliable, consistent water filtration.


Polymeric water filtration solutions, on the other hand, offer less membrane porosity and therefore a decreased flux rate, even when faced with similar feed water conditions alongside a ceramic counterpart. Polymeric membranes are more susceptible to fouling, and handle oil poorly. They’re much easier to damage than ceramic membranes and require costlier, more complicated maintenance. Learn more here.

Challenges with ultrafiltration


Occasional problems do arise with ultrafiltration, despite its many benefits. Fouling occurs when materials collect along the membrane’s surface, compromising its efficiency and boosting energy use. Many factors contribute to fouling, including pressure and flux within the filter. In the end, fouling almost always has to do with an overabundance of some material in the source water that is not entirely removed during normal hydraulic backwashing steps. Chemical cleaning, mechanical actions, and proper pretreatment typically solve the problem. With polymeric ultrafiltration membranes frequent chemical cleanings can cause membrane fiber damage, reduced permeability, and ultimately lead to a shortened life of the membrane filter. Ceramic membranes, with a higher tolerance for chemical exposure, do not suffer from the same performance degradation and shortened life from chemical cleanings.


Nanostone Water Case Studies

See how Nanostone Water has utilized our ceramic membranes in a wide variety of applications.

Read More