Waste cellulose acetate-based dynamic membrane for NOM-containing river water filtration

Abstract

Excessive leaching of natural organic matter (NOM) from swamp forests into water resources poses significant challenges for water treatment plants, primarily due to its high variability. In this study, a waste-based cellulose acetate (W-CA) membrane was explored as a dynamic membrane for the filtration of real river water containing NOM and compared to a commercial-based CA (C-CA) membrane. The membranes were fabricated and thoroughly characterized. The results revealed that the W-CA membrane exhibited greater hydrophilicity, as indicated by a static contact angle of 84°, compared to the hydrophobic nature of the C-CA membrane (104°). The mean pore diameters of the C-CA and W-CA membranes were 4.4 µm and 5.3 µm, respectively, suitable as the base for a dynamic filter. The formation of a dynamic cake filtration layer (identified mainly as humic and fulvic acids) was confirmed from visual observation, SEM image and the decrease in the pore sizes. It was further validated from the cake layer as the dominant fouling mechanism obtained from a curve fitting analysis. Despite the W-CA and C-CA membranes respectively showed a high steady-state river water permeabilities of 348 and 226 L/(m2 h bar) respectively, they were still unable to fully remove NOM (27% removal for W-CA and 39% removal for C-CA membrane), suggesting the necessity for further developments. This study underscores the potential of W-CA membranes for water treatment while promoting a circular economy by converting waste into valuable resources and sustainable products.