Ceramic membrane reactor integrated with UV/O3/Catalyst Beads for treating real textile wastewater: Enhanced effluent quality, fouling control and molecular transformations of DOM

Abstract

A ceramic membrane reactor (CMR) was employed to treat real textile wastewater with the simultaneous use of UV, O3, and photocatalytic beads for dissolved organic matter (DOM) transformation and membrane fouling control. The O3 treatment exhibited high performance in color removal. Simultaneous use of UV and ozonation (UV/O3) resulted in 91% and 64% color and chemical oxygen demand (COD) removal, respectively, and delayed (3-fold) fouling time compared to UV alone. A combination of TiO2-loaded polymeric beads with UV/O3 (UV/O3/Beads) further enhanced the color (96%) and COD (86%) removal as well as improved fouling control by 9-folds compared to the control (Air alone) experiment. Three-dimensional excitation-emission matrix (3-D EEM) fluorescence spectra revealed minimum DOM and synergistic effects of UV, O3, and photocatalytic beads (UV/O3/Beads) in the degradation of fluorescent DOM. The •OH radicals were leading in degrading organic pollutants during the treatment. Transformations of heteroatomic DOMs were confirmed by the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). S-containing compounds in the treated samples appeared in a reduced state (lower H/C and O/C ratios), indicating the transformation of R–SO3 to R–S–R. Whereas N-containing DOM was mostly oxidized. UV/O3 rapidly transformed dye molecules to colorless, creating suitable conditions for photocatalytic beads for accelerated degradation of pollutants. Also, the PTR-TOF-MS analysis revealed the successful removal of toxic VOCs (Methanethiol, Allylamine, Cyclohexenes, Butanes, Propanes, and Hydrazines) from wastewater by the UV/O3/Beads treatment. Based on these findings, DOM transformations could be better understood, and the simultaneous application of heterogeneous photocatalysis and UV/O3 could be safely recommended as a promising technology for treating industrial wastewater.