h i g h l i g h t s O 3-EO enhances by 2.5 times the mineralization of phenol when compared to O 3 alone. O 3-EO reduces by half the time to achieve a phenol mineralization >90%. Ozonation alone fails on phenol mineralization and on diminishing toxicity. Toxicity onto Latuca sativa is only eliminated by the coupled treatment (O 3-EO).

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In this work, a comparison of the performances of different AOPs in the phenol and 4-chlorophenol (4-CP) degradation at lab and pilot scale is presented. It was found that, in the degradation of phenol, the performance of a coupled electro-oxidation/ozonation process is superior to that observed by a photo-Fenton process. Phenol removal rate was determined to be 0.83 mg L−1 min−1 for the coupled process while the removal rate for photo-Fenton process was only 0.52 mg L−1 min−1. Regarding 4-CP degradation, the complete disappearance of the molecule was achieved and the efficiency decreasing order was as follows: coupled electro-oxidation/ozonation > electro-Fenton-like process > photo-Fenton process > heterogeneous photocatalysis. Total organic carbon was completely removed by the coupled electro-oxidation/ozonation process. Also, it was found that oxalic acid is the most recalcitrant by-product and limits the mineralization degree attained by the technologies not applying ozone. In addition, an analysis on the energy consumption per removed gram of TOC was conducted and it was concluded that the less energy consumption is achieved by the coupled electro-oxidation/ozonation process.

The objective of this work is to study, for the first time, the photodegradation of 4-chlorophenol (4CP) catalyzed by a calcined Mg–Zn–Al layered double hydroxides (MgAlZn LDHs) in a co-current downflow bubble column (CDBC) photoreactor at pilot scale. The effect of initial organic compound concentration (C 4CP0 ), temperature (T), and mass catalyst over reaction rate (−r 4CP ) was elucidated. An intrinsic kinetic regime was established, and a single-site Langmuir–Hinshelwood mechanism was determined to occur during the organic compound oxidation. The catalyst was characterized by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES), and ultraviolet–visible light (UV/vis) spectrophotometry. The reaction progress was verified by UV/vis spectrophotometry and total organic carbon (TOC) content. Degradation and mineralization rate were found to be dependent on T and 4CP concentration. In the range of studied operating conditions, a maximum of 94% 4CP was degraded, while 70% total organic carbon removal was achieved.