Membranes in the Fast Lane

Ceramic membranes provide solution for auto parts manufacturing process

An automotive parts manufacturing plant in Abruzzo, Italy, was using polymeric membranes to remove oil from water it used to rinse parts. The rinse water contained between 6% and 7% oil, and the customer wanted to remove more than 95% of the oil from the water so the water could be reused in the plant. The membranes that were installed in the plant became irreversibly fouled and required replacement every two months. The plant started evaluating alternative membrane products to reduce the costly membrane replacements and unreliability.

Due to their rigid construction material and broad chemical resistance, ceramic ultrafiltration membranes were evaluated. Since the plant was already operating with a polymeric ultrafiltration membrane in a cross flow configuration, the customer decided to install the membranes directly into the manufacturing line to determine whether the ceramic membranes were a viable alternative to their current membrane system.

The Ceramic Membrane Solution

The customer selected QUA CeraQTM ceramic membranes due to the company’s experience in water and wastewater purification. The membranes are tubular and operate in an inside-out configuration. The tubular design reduces the permeate pressure drop and allows the system to operate at a lower pressure with a high permeate flux. Additionally, the tubular design eliminates the possibility of dead pockets within the membrane, thus reducing the chance of fouling. The membrane is an alumina-based ceramic membrane with a coating that ensures a long service life and a high degree of permeate recovery. 

QUA worked closely with one of its OEM partners to develop a process to remove the oil from water. A 0.05 µm pore size was selected based on historical test data performed by QUA on oil and water separation. 

The membranes are designed to operate in a cross flow configuration to allow for the highest recovery. The 0.05 µm membrane was found to remove more than 95.5% of emulsified engine oil from water in several pilot tests.  

After it was reconfigured to accept QUA CQ-50 ceramic membranes, the system was quickly commissioned. Reconfiguration and commissioning was relatively simple and took approximately one week. During the commissioning, the permeate flow rate was measured to be 2 gal per minute. 

The customer was pleased with the ease of commissioning, installation and performance of the membranes. Due to backpulsing capabilities, cleaning the membranes was simplified, and operating and maintaining these membranes was not an issue. The customer decided to make this their permanent solution to filter the oily wastewater from the automotive manufacturing process for reuse. 

The membranes have been operating for almost a year without any fouling issues and have exceeded the project expectations. The customer now is able to reuse water effectively and decrease their total water footprint, an important step for the plant’s long-term, sustainable success.

Ceramic Membranes Gain Traction

As membrane treatment becomes more widespread for many applications, new techniques to treat difficult water continue to be developed. 

Polymeric membranes have traditionally been used successfully to treat water, but as with any treatment technique, they have their limitations. The membranes can encounter issues in treating waters that require great robustness due to their high fouling tendencies or temperatures. As various industrial needs become more complex and water reuse, due to scarcity, is mandated, new membrane materials have been developed and used to treat challenging water.

The first ceramic membranes were produced in France in the 1980s for uranium enrichment in the nuclear industry. Once they proved successful, the ceramic membrane industry was born. Because of the strength and durability of the ceramic materials and their ability to operate at higher temperatures and pressures, the membranes were considered for harsh environments where polymeric membranes were unable to be used.

Ceramic membranes are made from inorganic materials, such as alumina, titania, zirconia oxides, silicon carbide and other materials. The higher installed cost of the membranes meant that adoption of the technology was previously limited to niche applications where filtration was absolutely necessary and other technologies were not viable.

Over time, ceramic membranes proved robust. Chemical resistance, operating temperature ranges, mechanical strength, and higher flux rates and flux stability are characteristics that set the ceramic membrane apart. In addition, materials and manufacturing processes have reduced the cost of the technology, making installation more economically feasible.

Applications where ceramic membranes have been successfully applied include industrial process water, food and beverage processing, laundry wastewater treatment, textile effluent treatment, pulp and paper processing, drinking water filtration and oily wastewater treatment.

Oil and water separation has been a difficult process to perform using a polymeric membrane and typically has required many unit processes for an effective solution. With their robustness and capability in reducing unit processes, ceramic membranes are becoming recognized as a cost-effective solution for this challenging application. 

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About the author

Kamakshi Sharma is technology development engineer for QUA Group LLC. Sharma can be reached at [email protected].