There are three different configurations in terms of the shape of membrane as shown below.
Flat sheet Hollow fiber Tubular
- Plate and frame (PF) – It was developed for relatively small scale applications that deal with high membrane fouling potential. But the module structure is complex to seal the spaces among the membrane plates and pressure loss across the module is high due to the zigzag flow. Today, PF is primarily used for electrodialysis, leachate filtration, etc.
Plate and frame (PF) with mechanical agitation – FMXTM (Filmax) was developed by BKT for difficult water to filter especially with high solids contents . Module structure is similar to conventional PF modules shown above, but there are rotating vortex generators in between two membrane plates. This module has a high potential for filtering the water that cannot be filtered by conventional membrane modules, e.g. digestate & livestock wastewater, fruit juice, leachate, frac/flowback water, etc. MF, UF, NF, RO membranes can be equipped on both sides of discs depending on the filtration purpose. More information is available here.
- Spiral Wound (SW) – Developed in 1970’s to make plate & frame modules more compact for the feed with low fouling potential. It provides large specific surface area at relatively low costs. Feed water flows through feed channel parallel to the axis. The permeate travels permeate channel to be collected in the center pipe as shown in the figure below. This module configuration is most commonly used with the membranes with tight pore sizes such as UF, NF, and RO.
SW module structure (from MTR Inc.)
- Hollow fiber in pressure vessel – Uses pressure as a driving force to filter water. It is commonly used for surface water treatment, tertiary filtration of secondary effluent, product recovery, etc.
- Immersed (or submerged) module – Modules without pressure vessel are directly immersed in feed water. Permeate is obtained by vacuum pressure. It is most commonly used in MBR (iMBR) for wastewater treatment, surface water treatment, and tertiary filtration. Both hollow fiber and flat sheet membranes can be used.
|GE’s immersed hollow fiber module||Kubota’s immersed flat sheet module|
- Tubular – Traditionally used for pressure filtration with feed water recirculation through lumen. Air bubbles are introduced to the bottom of the vertically mounted modules with multi-tubes in recently developed Norit’s AirliftTMmodules to aid the scouring effect of feed water circulating through the lumen by pump.
Table 1. Summary of membrane and module configurations.
|Membrane configuration||Module configuration or operating method||Driving force||Pore size||Common Applications||Example (Links)|
|Flat Sheet (FS)||Plate and frame (PF)||Pressure||MF/UF||WWT, EDI||Pall DT™, Electrocell (EC)|
|Immersed membranes||Vacuum||MF/UF||iMBR||Kubota, Toray Membray,Mycrodyne Bio-Cel®, Pure Envitech SBM|
|Spiral wound (SW)||Pressure||UF/RO||DS, PR||Dow Filmtec, Hydranautics, Toray Romembra, Woongjin CSM®|
|Hollow Fiber (HF)||Contained in pressure vessels||Pressure||MF/UF/RO||WT, PR, etc.||Asahi Microza®, Toyobo Hollowsep®, GE ZW1500|
|Immersed module without pressure vessels||Vacuum||MF/UF||WT, iMBR||GE ZW500, Asahi Microza®,Mitsubishi Sterapore™, Econity|
|Tubular (TB)||Pressure filtration||Pressure||MF/UF||WWT, PR, sMBR||Koch Abcor®, ITT PCI,|
|Vacuum filtration with bubbling||Vacuum||MF/UF||sMBR||Norit AirliftTM|
DS: Desalination, ED: Electrodialysis, PR: Process Recovery, WT: Water Treatment, WWT: Wastewater Treatment
© Seong Hoon Yoon