Forward osmosis treatment of algal-rich water: Characteristics and mechanism of membrane fouling

Membrane fouling is an inevitable problem in forward osmosis (FO) treatment of algal-rich water (ARW). Natural ARW has a complex composition. Therefore, the coexisting components (Ca2+, natural organic humic acid [HA], and inorganic particulate kaolinite) in the influence of ARW on FO membrane fouling were studied. The analysis of extended Derjaguin-Landau-Verwey-Overbeek theory and the confocal laser scanning microscopy revealed that the addition of coexisting components increased the attraction between pollutants and membranes, as well as among pollutants to varying degrees, and promoted the development of membrane fouling. Furthermore, Ca2+ and HA aggravated irreversible membrane fouling. All coexisting components changed the distribution and thickness of the fouling layer, and the addition of Ca2+ increased the content of extracellular organic matter (proteins and polysaccharides). The present results enhance the understanding of the mechanism through which natural ingredients affect microalgal membrane fouling and provide a basis for membrane fouling control to treat ARW.

Automated summary

The study found that the addition of coexisting components increased the attraction between pollutants and membranes, promoting the development of membrane fouling, especially with Ca2+ and HA exacerbating irreversible membrane fouling.