Membrane Fouling at the Service of UF/MF: Hollow Fiber Membrane Adsorber

Membrane fouling in UF/MF is a problem that has been attracting considerable intellectual and engineering resources over almost 40 years. A lot of efforts, such as high tangential flows, vibration, air sparging and the like, have been taken to minimize its negative impact on the performance of UF/MF filters [1]. All these efforts are associated with increased operating and maintenance costs, and, as a result, UF/MF is still not competitive with conventional technologies for most applications in water and wastewater treatment. At the same time, particle deposition, or collection, on adsorbents and bed grains has been successfully used in water treatment for many decades [2, 3]. Membrane surface plays the role of a particle collector in a UF/MF water treatment filter, but, in contrast to adsorbents and bed grains, the formation of cake in the existing UF/MF filters has a negative effect on their production rate. Therefore, the idea of harnessing membrane fouling, instead of struggling against it, in order to produce an additional (to permeate) amount of clarified water in UF/MF filters looks very attractive. Consider a hollow fiber (HF) filter in which the feed suspension is supplied to the HF shells (Fig. 1). The distinctive feature of such a hollow fiber membrane (HFM) adsorber will be an additional product stream, filtrate 3, produced due to the particle collection on the HF surfaces. Let us assess this design from physical considerations.