Treatment of Wastewater Effluent Using Photo-Fenton Combined with Granular Activated Carbon Enhancing Microcontaminants Removal

One of the main weaknesses of advanced technologies for microcontaminants (MCs) removal is the challenge in scaling up. In this study the combination of photo-Fenton with Granular Activated Carbon (GAC) is proposed to maximize the potential benefits of both treatments while minimizing their drawbacks. Considering the previous optimization of photo-Fenton operational conditions, two dosages of iron (3 and 5 mg L-1) were tested with 40 mg L-1 of H2O2. The process was performed at neutral pH using Ethylenediamine-N,N '-disuccinic acid (molar rate 1:1) as chelating agent. To remove the selected MCs (benzotriazole, carbamazepine, clarithromycin and diclofenac) the lower concentration of iron was selected, in contrast to the 5 mg L-1 used for the model compound (indigo carmine). The GAC tests were performed in Rapid Small -Scale Columns characterizing two carbon sources, a fresh GAC and a regenerated one. When applied as stand-alone technology for the removal of indigo carmine, the fresh GAC showed a better adsorbance capacity but very close to the regenerated one. The same trend was observed for MCs but the breakthrough was not achieved. Via combining photo-Fenton and GAC, the treatment time of the first step was reduced from 20 minutes to 5 minutes which resulted in a decreased energy consumption from 167 Wh to 42 Wh. The breakthrough of both GAC types was achieved in similar number of bed volumes, while the GAC life time was extended between two and three times with the combination.