Pretreatment and Membrane Hydrophilic Modification to Reduce Membrane Fouling

Abstract

The application of low pressure membranes (microfiltration/ultrafiltration) has undergone accelerated development for drinking water production. However, the major obstacle encountered in its popularization is membrane fouling caused by natural organic matter (NOM). This paper firstly summarizes the two factors causing the organic membrane fouling, including molecular weight (MW) and hydrophilicity/hydrophobicity of NOM, and then presents a brief introduction of the methods which can prevent membrane fouling such as pretreatment of the feed water (e.g., coagulation, adsorption, and pre-oxidation) and membrane hydrophilic modification (e.g., plasma modification, irradiation grafting modification, surface coating modification, blend modification, etc.). Perspectives of further research are also discussed.

Self-cleaning and antifouling nanofiltration membranes—superhydrophilic multilayered polyelectrolyte/CSH composite films towards rejection of dyes

“…[30][31][32][33][34] Some inorganic nanomaterials (amorphous SiO 2 and mesoporous SiO 2 , TiO 2 , ZnO, and calcium silicate hydrates (CSH) etc.) 41,42 The hydrophilic membranes oen exhibit a strong suspending ability for the fouling due to weak surface interaction between the separate solute and membrane surfaces, 43,44 for example, TiO 2 selfassembled polymeric nanocomposite membranes can effectively mitigate membrane fouling during the ltration of membrane bioreactor (MBR) due to that addition of TiO 2 composite induces the improvement of hydrophilicity of the membrane. 33,[35][36][37][38][39][40] However, most of these works were concentrated on self-cleaning effect of transparent lms for antifogging and antireection.…”

Ferric Oxyhydroxide as Fouling Prevention Reagent for Low-Pressure Membranes

“…However, this treatment method has some disadvantages, especially fouling. There are different kinds of this process, especially colloidal fouling, organic fouling, inorganic scaling, biofouling (She et al, 2016), but colloidal fouling is the most unacceptable type (Sun et al, 2013).…”

“…However, in the case of colloidal fouling, backwash does not give sufficient result. Therefore, this gel layer can be removed only by chemical enhanced backwash (Sun et al, 2013). It reduces the work time of membranes and increases the consumption of chemicals for cleaning.…”

Synthesis of well‐defined amphiphilic block copolymers via AGET ATRP used for hydrophilic modification of PVDF membrane

“…Poly(vinylidene fluoride) (PVDF) is one of the most popular materials in chemical industry with excellent physical and chemical resistance, thermal stability, low toxicity, and low cost . However, because of the low surface energy and strong hydrophobicity of PVDF matrix, it suffers from significant nonspecific protein adsorption on the membrane surface where PVDF membranes are applied, which often causes severe membrane fouling resulting in a rapid decline of permeation flux . To improve the surface hydrophilicity of PVDF membranes, a large amount of work has been devoted to the surface modification of PVDF such as surface coating, surface grafting, UV photoirradiation, blending modification, and the incorporation of inorganic nanoparticles .…”

“…1,2 However, because of the low surface energy and strong hydrophobicity of PVDF matrix, it suffers from significant nonspecific protein adsorption on the membrane surface where PVDF membranes are applied, which often causes severe membrane fouling resulting in a rapid decline of permeation flux. [3][4][5] To improve the surface hydrophilicity of PVDF membranes, a large amount of work has been devoted to the surface modification of PVDF such as surface coating, 6 surface grafting, 7,8 UV photoirradiation, 9 blending modification, 10,11 and the incorporation of inorganic nanoparticles. 12,13 Blending modification is one of the most versatile approaches that can be applied to industrial-scale production.…”