Fouling mitigation in tubular membranes by 3D-printed turbulence promoters

TL;DR

This study explores how 3D-printed turbulence promoters, especially Kenics static mixers and twisted tape geometries, enhance flux and reduce fouling in tubular membrane filtration, offering a simple, energy-efficient solution.

Contribution

It introduces novel 3D-printed mixer geometries and demonstrates their effectiveness in improving membrane filtration performance compared to traditional designs.

Findings

Kenics mixer achieves up to 140% flux increase.

All static mixers increase permeate flux at the same energy cost.

Certain geometries outperform others in fouling mitigation.

Abstract

Despite intensive research, fouling remains a severe problem in membrane filtration. It is often controlled by applying turbulent flow which requires a higher energy consumption. So-called turbulence promoters or static mixers can be inserted into the flow channel of tubular membranes. They deflect the fluid, induce vortices, enhance particle back-transport and increase the shear rate at the membrane surface, thus mitigating fouling. However, little is known how the geometry of such turbulence promotors affects the reduction of fouling. We investigate how different 3D-printed mixer geometries affect fouling and improve the flux during filtration with humic acid. Most mixer geometries used in the present study are based on a twisted tape; a Kenics static mixer is investigated as well. Static mixers with changing diameter prove to be less effective than twisted tape mixers with constant diameter which lead to an increase in permeate flux of around 130%. The highest flux improvement of 140% can be reached by applying a Kenics mixer. Regardless of their geometry, all investigated static mixer cause higher permeate fluxes at same specific energy consumption. Again, the Kenics mixer proves to be the most efficient static mixer. The presented mixer geometries can be fabricated with undercut injection molding techniques and represent a simple and viable option to make tubular membrane based filtration processes more efficient.