Calcium cation interactions with polysaccharides and proteins in wastewater UF membrane fouling

Abstract

The role of divalent calcium cations in bio-flocculation and their interactions with wastewater components such as biopolymers (proteins, polysaccharides, nucleic acids and lipids) are crucial in membrane fouling. In this work, the interactions between calcium cations and sodium alginate (a model polysaccharide) and meat extract (a complex protein mixture) were investigated. Dead-end stirred cell and crossflow ultrafiltration experimental matrices were carried out. The alginate–calcium interaction was found to be a more severe foulant of the membrane than the meat-extract–calcium. The alginate–calcium membrane fouling was almost completely irreversible, while 40% of the membrane fouling was reversible with the meat-extract–calcium filtration experiments. Membrane fouling by alginate and meat extract was greater when the two coexisted in the feed stream than when they existed as individual components.