Surface water nanofiltration incorporating (electro)coagulation - microfiltration pretreatment: fouling control and foulant/membrane characterization

摘要

Detailed post filtration membrane surface characterization (i.e. membrane autopsy) is a useful method to obtain insights into the nature of fouling so that steps can be taken to mitigate it. The objectives of this research are to evaluate different pretreatment alternatives to control fouling during surface water nanofiltration and to perform spectroscopic, microscopic and physicochemical characterization of nanofilter surfaces to identify major foulants and fouling mechanisms. Lake Houston water was nanofiltered following four different pretreatments: (1) microfiltration (MF) alone, (2) chemical (alum) coagulation-MF, (3) electrocoagulation-MF, and (4) electroflotation-MF [1]. Therefore, virgin and fouled NF membranes were extensively characterized in terms of hydrophobicity (contact angle), surface morphology (scanning electron microscopy (SEM) and atomic force microscopy (AFM)), organic functionalities and elemental composition (Fourier Transform Infrared (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) respectively) and acidic polysaccharides (Alcian Blue stain) to reveal the differences in foulant characteristics corresponding to each pretreatment and its relationship to flux.