LiqTech Water’s Marine Applications are installed with cross-flow filtration for reduced fouling and increased recovery rate.
LiqTech marine WTUs are low-pressure ultrafiltration systems installed with housings containing ceramic membranes arranged in a cross-flow configuration. Cross-flow filtration is a process in which the feed stream flows tangentially to the membrane surface. This tangential cross flow works as a rinsing mechanism due to the turbulence on the membrane surfaces, which helps redistribute particulate matter back into the feed water and maintain high flux. Thanks to the high cross-flow rate, fouling is reduced, and recovery is increased. The WTU can be customized to match various filtration needs.
Cross Flow Filtration
The pressure difference across the membrane drives clean water, i.e., permeate through the membrane. This process separates the feed water into two streams, named permeate and retentate. First, the permeate passes through the membrane layer. This is filtered liquid. The retentate is retained by the membrane layer and consists of rejected particles. The permeate is led to a permeate tank, while the retentate is upconcentrated and bled from the cross-flow loop. Due to the high cross-flow rate, the recovery is increased significantly, delivering a high concentration of liquid sludge.
The cross-flow generates a shear force on the membrane surface, which sweeps away particles and solutes, ensuring minimal solids build-up. This is essential as solids build-up can block the filter. Cross-flow prolongs membrane efficiency by reducing fouling and the need for chemical cleaning, meaning operational downtime. It is crucial to preserve a high cross-flow velocity to continually sweep away particles and solutes to maintain clean membrane surfaces, ensuring a high recovery rate.
Thanks to the robust properties of our silicon carbide ceramic membranes, they can operate at extremely high cross-flow velocities. In addition, silicon carbide (SiC) is the second hardest material globally, ensuring a high degree of mechanical strength.
Advantages of Cross Flow Filtration:
- Reduces fouling
- Reduces need for backwash & CIP
- Reduces operational downtime
- Delivers a high concentration of liquid sludge
