Fluidized-bed Fenton coupled with ceramic membrane separation for advanced treatment of flax wastewater

Fluidized-bed Fenton coupled with ceramic membrane separation to treat the flax secondary effluent was investigated. The operating variables, including initial pH, dosage of H₂O₂ and Fe⁰, air flow rate, TMP and pore size, were optimized. The distributions of DOMs in the treatment process were analyzed. Under the optimum condition (600mgL^-1H₂O₂, 1.4gL^-1 Fe⁰, pH=3, 300Lh^-1 air flow rate and 15psi TMP), the highest TOC and color removal efficiencies were 84% and 94% in the coupled reactor with 100nm ceramic membrane, reducing 39% of total iron with similar removal efficiency compared with Fluidized-bed Fenton. Experimental results showed that the ceramic membrane could intercept catalyst particles (average particle size >100nm), 10.4% macromolecules organic matter (AMW>20000Da) and 12.53% hydrophobic humic-like component. EEM-PARAFAC identified four humic-like (M1-M4) and one protein-like components (M5), and the fluorescence intensities of M1-M5 in the secondary effluent were 63.27, 63.05, 33.41, 16.71 and 0.72 QSE, respectively. After the coupled treatment, the removal efficiencies of M1(81%), M2(86%) were higher than M3, M4(63%, 61%). Pearson correlation analysis suggested that M1, M2 and M3 were the major contributors to the cake layer, and M4, M5 might more easily lead to pore blockages.