Structural characteristics of hazardous organic dyes and relationship between membrane fouling and organic removal efficiency in fluidized ceramic membrane reactor

In this study, combined effect of types of anionic dye compounds and solution pHs on organic removal efficiency and membrane fouling on the alumina-based microfiltration (MF) flat-tubular membrane was investigated using a laboratory-scaled, fluidized bed membrane reactor at constant permeate flux operation. For the Congo-Red dye solution at the solution pH of 6, there was no increase in suction pressure with only 10% of organic removal efficiency measured by ultraviolet-visible (UV-Vis) spectrometer during operational period. However, lowering the solution pH to 4.5 accelerated suction pressure increase while higher than 90% organic removal efficiency was achieved. At the solution pH of 4.5, a zwitterion nature characterized by Congo-Red dye compound resulted in more deposit of cake layer on membrane than that formed at higher pH. In the case of Tartrazine and Acid Orange 7 which are categorized as anionic dye compound, the increase in suction pressure with time was much slower than that observed with Congo Red at same solution pH (4.5) and permeate flux (40 L m(-2)h(-1)). Our results suggested that higher fouling rate should be associated closely with higher organic removal efficiency in ceramic MF membrane filtration. Regardless of types of dye compounds tested, granular activated carbon (GAC) fluidized in submerged ceramic membrane reactor was found to be propitious tool to reduce membrane fouling with excellent organic removal due to adsorption functionality and scouring action provided by GAC fluidization on membrane. (C) 2019 Elsevier Ltd. All rights reserved.