Comparative study of Fe²⁺/H₂O₂ and Fe²⁺/persulfate systems on the pre-treatment process of real pharmaceutical wastewater

Advanced oxidation technologies based on hydroxyl radical(center dot OH) and sulfate radical (SO4-center dot) are two common types of advanced oxidation technologies, but the application of advanced oxidation to wastewater pretreatment has not been reported much and is generally limited to simulated wastewater experiments with a single target pollutant. In this paper, by comparing the pretreatment of Fe2+/H2O2 and Fe2+/persulfate systems in real pharmaceutical wastewater, combined with the results of 3D fluorescence and GC-MS, the differences between the two systems in terms of the removal rate of TOC, COD, and NH3-N, the optimal catalyst dosage, the range of applicable pH, and the structure of pollutants in the reacted effluent were discussed in detail to help engineers to make the best choice according to different water quality conditions in practical applications. The results showed that the Fe2+/H2O2 system had higher pollutant removal rates (TOC:71.9%, COD:66.9%, NH3-N:34.1%), but it also required higher catalyst Fe2+ concentration (6.0 g/L), and the effluent water showed the characteristic peaks of the aromatic proteins. The Fe2+/persulfate system had a wider pH range (pH approximate to 3-7) and is more advantageous in treating wastewater containing more cyclic organic compounds, but the effluent contains some sulfur-containing compounds.