Characteristics of foulants of forward osmosis membranes used in municipal wastewater concentration processes

This study investigated the organic matter that causes fouling in the forward osmosis (FO) membrane filtration system used in wastewater concentration processes. The development of the fouling of FO membranes caused by actual municipal wastewater was compared with that of the fouling caused by solutions containing artificial foulants (i.e. Aldrich humic acid, bovine serum albumin, and sodium alginate). This comparison shows that the development of the fouling was underestimated when using the artificial foulants. The characteristics of the foulants were investigated using fluorescence excitation-emission matrix spectra and liquid chromatography-organic carbon detection analyses. The results obtained by these advanced analytical methods indicated that the so-called biopolymers (i.e. organic macromolecules mainly comprising polysaccharides and proteins) were the major components of the foulants. In contrast, hydrophobic organic matter, such as humic substances, was not a dominant component.