Photo-Fenton like process as polishing step of biologically co-treated olive mill wastewater for phenols removal

In this study, UVC or sunlight assisted photo-Fenton like process (PFI) using iron(III) iminodisuccinate (Fe-IDS) as catalyst was investigated for the first time as post-treatment method of a Moving Bed Biofilm Reactor (MBBR) for the treatment of olive mill wastewater (OMW). Hydraulic retention time for the MBBR process was 24 h, while the treatment time for the PFI process was 3 h under UVC or solar light irradiation. Before the MBBR treatment, OMW was centrifuged and mixed with synthetic urban wastewater to simulate conditions in a real wastewater treatment plant (WWTP). The MBBR was highly effective in reducing Biological Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) (97 and 91%, respectively), but less effective (57%) in the removal of total phenols (TPHs). PFI was optimized for TPHs removal through response surface methodology. UVC driven PFI allowed to reach higher TPHs removal than sunlight driven PFI. Fe (III) dosage was set at 2 mg/L while optimum H2O2 dosage resulted to be 144 mg/L. In these conditions, the UVC driven process allowed to obtain a TPHs removal of 99%, reaching a final TPHs concentration of 0.07 & PLUSMN; 0.01 mg/L.

Automated summary

This study investigated the use of UVC or sunlight assisted photo-Fenton like process (PFI) using iron(III) iminodisuccinate (Fe-IDS) as catalyst as a post-treatment method for olive mill wastewater (OMW) in a Moving Bed Biofilm Reactor (MBBR). The MBBR effectively reduced BOD5 and COD by 97% and 91% respectively, but was less effective (57%) in total phenols (TPHs) removal. PFI was optimized for TPHs removal, with UVC driven PFI achieving higher removal compared to sunlight driven PFI. Under optimized conditions, the UVC driven process achieved a TPHs removal of 99% with a final concentration of 0.07±0.01 mg/L.