Removal of contaminants of emerging concern by solar photo electro-Fenton process in a solar electrochemical raceway pond reactor*

This work proposes the degradation of different contaminants of emerging concern (CECs) present in a secondary effluent from a municipal wastewater treatment plant in a solar electrochemical raceway pond reactor (SECRPR), applying the solar photo electro-Fenton (SPFE) process. Tap water and a secondary effluent were enriched with 100 mu g L-1 of 7 CECs to study the degradation of these compounds by the SPEF process in a SEC-RPR. Among the results obtained, an elimination over 96% and 90% of 5 CECs (progesterone, estradiol, ibuprofen, diclofenac and estrone) was achieved, while sulfamethazine and carbamazepine were eliminated by 73, 37% and 80, 66% after 1 h of treatment, respectively. In turn, a secondary effluent that already achieved the minimum organic load standards established by Chilean regulations was treated in a SEC-RPR by applying different electrochemical advanced oxidation processes (EAOPs). However, regardless of the applied treatment (SPEF, electro-Fenton and electro-oxidation/H2O2), it was possible to further reduce the organic content and even mineralize it. These experiments were performed at pH 3, with Na2SO4 0.05 mM, Fe2+ 0.05 mM and applying a current density of 20 mA cm-2. The SPEF process implemented in a SEC-RPR is presented as an excellent alternative for the treatment of municipal wastewater, due to the large contact area between the effluent and UV radiation, in addition to the continuous and homogeneous generation of H2O2, which allows for the production of hydroxyl radicals in solution, favoring the degradation and mineralization of pollutants.

Automated summary

This study proposes the use of solar electrochemical raceway pond reactor (SECRPR) with solar photo electro-Fenton (SPFE) process to degrade emerging contaminants of concern (CECs) in municipal wastewater treatment plant effluent. The results show that 96% and 90% elimination of 5 CECs (progesterone, estradiol, ibuprofen, diclofenac and estrone) was achieved, while sulfamethazine and carbamazepine were eliminated by 73%, 37% and 80%, 66% respectively. The SPFE process implemented in a SEC-RPR proves to be an excellent alternative for the treatment of municipal wastewater due to its large contact area between the effluent and UV radiation, continuous and homogeneous generation of H2O2, and production of hydroxyl radicals in solution, enhancing the degradation and mineralization of pollutants.