Comparison between UVA- and zero-valent iron-activated persulfate processes for degrading propylparaben

The potential benefits of zero-valent iron-activated persulfate (Na2S2O8) oxidation in enhanced dewaterability of sludge, along with the associated mechanisms were investigated in this study. The sludge dewaterability was evaluated in terms of specific resistance to filtration (SRF) and water content. Based on these indexes, it was observed that ZVI-S2O82 oxidation effectively improved sludge dewaterability. The optimal conditions to give preferable dewaterability were found when the molar ratio of ZVI/S2O82− was 5:1 and pH value was 3.0. The most important mechanism was proposed to be the degradation of extracellular polymeric substances (EPS) incorporated in sludge flocs and rupture of microbial cells. Three-dimensional excitation–emission matrix fluorescence spectra revealed that the powerful SO4− and ·OH generated from ZVI-S2O82− system destroyed the particular functional groups of ﬂuorescing substances (aromatic protein-like and tryptophan protein-like substances), resulting in the release of bound water and the subsequent enhancement of dewaterability. Therefore, ZVI/S2O82− oxidation is an alternative approach showing great potential to be applied in sludge treatment plants.

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Iprodione Removal by UV-Light-, Zero-Valent Iron- and Zero-Valent Aluminium-Activated Persulfate Oxidation Processes in Pure Water and Simulated Tertiary Treated Urban Wastewater

Water ◽

10.3390/w13121679 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1679

Author(s):

Bahareh Montazeri ◽

Olga Koba-Ucun ◽

Idil Arslan-Alaton ◽

Tugba Olmez-Hanci

Keyword(s):

Metal Ion ◽

Pure Water ◽

Zero Valent Iron ◽

Superior Performance ◽

Urban Wastewater ◽

Oxidation Processes ◽

Heterogeneous Catalytic ◽

Metal Ion Release ◽

Uv C ◽

Activated Persulfate

The degradation of iprodione (IPR), a once frequently used but recently banned dicarboximide fungicide, by UV-C light-, zero-valent iron- (ZVI), and zero-valent aluminium (ZVA)-activated persulfate (PS) oxidation processes was comparatively studied in distilled (pure) water (DW) and simulated, tertiary treated urban wastewater (SWW). The performance of PS-activated oxidation processes was examined by following IPR (2–10 mg/L) removal, PS (0.01–1.00 mM) consumption, metal ion release (for the two heterogeneous catalytic oxidation processes), dissolved organic carbon (DOC) removal as well as hydroxylated aromatic and low molecular weight aliphatic degradation products. The effect of pH and PS concentrations on IPR removal was examined in DW. While the experiments in DW highlighted the superior performance of UV-C/PS treatment (with 78% DOC removal after 120 min at pH = 6.2), the performance of UV-C/PS treatment decreased sharply (to 24% DOC removal after 120 min at pH = 6.8) in the complex wastewater matrix (in SWW). Complete IPR (in 20 min) and 40% DOC (in 120 min) removals were obtained with ZVI/PS treatment (1 g/L ZVI, 1.5 mM PS, pH = 3.0), which was the most effective oxidation process in SWW. The treatment performance was strongly influenced by the SWW constituents, and UV-C/PS treatment appeared to be the most sensitive to it.

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