Continuous-flow titration of low iron doses to promote photo-Fenton and photo-Fenton-like processes at neutral pH

• Type: Article in International Scientific Journal
• Date: 2023

Authors

Santos, C (Author) Other; Herraiz Carboné, M (Author) Other; Lacasa, E (Author) Other; Sáez, C (Author) Other; Montes, R (Author) Other; Quintana, JB (Author) Other; Rodil, R (Author) Other; Gomes, AI (Author) Other; Vitor Vilar (Author) FEUP

Journal

Title: Chemical Engineering Journal

Vol. 476

ISSN: 1385-8947

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Associated Projects

Healthy Waters - Healthy Waters - Identification, Elimination, Social Awareness and Education of Water Chemical and Biological Micropollutants with Health and Environmental Implications

Other information

Authenticus ID: P-00Z-8FM

DOI: 10.1016/j.cej.2023.146655

Abstract (EN): Photo-Fenton (PF) is a promising process for degrading a wide range of contaminants of emerging concern (CECs) present in urban wastewater (UWW) after secondary treatment, mitigating their spread in aquatic systems. However, the near-neutral pH of UWW poses a challenge to PF performance. In this research, a tubular membrane photoreactor, designed for continuous titration of Fe2+, is explored to promote the PF process for the tertiary treatment of UWW. The application of persulfate (PF-like) as an alternative oxidant and the impact of phosphate (PO43-) content in UWW were also assessed. Process efficiency was evaluated in continuous mode, applying low residence times (RT: 6.1, 36.6, and 73.2 s) and low Fe2+ doses (1, 2, and 5 mg L-1), for the oxidation of 19 CECs (each spiked at 10 mu g/L), in demineralized water (DW) and secondary-treated UWW. Despite the persistence of certain short-chain perfluoroalkyl substances (PFAS) and saccharine across all conditions tested, the PF-like process exhibited superior performance when compared with PF, attaining higher removals for most target CECs, especially for melamine. In UWW, for an RT = 73.2 s, [Fe2+] = 5 mg L-1, and [oxidant] = 1.2 mM, PF process removed 7 CECs > 60 % and PF-like 10 CECs > 60 %. Moreover, higher residual concentrations of Fe2+ and lower precipitation of PO43- were observed for PF-like treatments, evidencing its advantages for tertiary treatment. These results emphasize the importance of photoreactor design to achieve efficient PF/PF-like at neutral pH, avoiding the use of chelating agents while managing iron concentrations compatible with UWW discharge or reuse limits.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12