Microbubble-Assisted Cleaning-in-Place Process for Ultrafiltration System and Its Environmental Performance

Area of Science:

• Dairy processing technology
• Membrane science and engineering
• Environmental sustainability in food production

Background:

• Membrane filtration, particularly ultrafiltration (UF), is crucial in dairy processing for separation, concentration, and fractionation.
• Membrane fouling, especially cake formation, significantly hinders UF performance in dairy applications.
• Current cleaning in place (CIP) methods for UF systems are resource-intensive, leading to substantial environmental impacts due to high water, chemical, and energy consumption.

Purpose of the Study:

• To investigate the effectiveness of microbubble (MB)-assisted cleaning in place (CIP) for pilot-scale ultrafiltration (UF) systems in the dairy industry.
• To evaluate the impact of microbubbles on membrane flux recovery and fouling removal during UF of model milk.
• To assess the environmental benefits of incorporating microbubbles into the CIP process through life cycle assessment.

Main Methods:

• Implementation of micron-scale air-filled bubbles (microbubbles, MBs) into cleaning liquids for a pilot-scale UF system.
• Conducting MB-assisted CIP at varying bubble number densities and flow rates during the concentration of model milk.
• Utilizing comparative life cycle assessment to quantify the environmental impact of MB-assisted CIP versus conventional CIP.

Main Results:

• Microbubble addition significantly increased membrane flux recovery by 31-72% across tested conditions, with bubble density and flow rate having minimal impact.
• While alkaline wash was key for protein foulant removal, MBs did not show a significant effect due to system operational uncertainties.
• Life cycle assessment revealed that MB-assisted CIP achieved up to 37% lower environmental impact compared to control CIP.

Conclusions:

• Microbubble-assisted CIP is a novel and effective method for enhancing membrane cleaning in pilot-scale dairy UF systems.
• This technology demonstrates potential for reducing water and energy consumption in dairy processing.
• The incorporation of microbubbles offers a promising pathway to improve the overall environmental sustainability of the dairy industry's cleaning operations.