Combined Electro-Fenton and Biological Process for Treatment of Antidepressant Sertraline: Performance Enhancement and By-Products Monitoring

In this work, we evaluated the potential of combining Fenton's reagent and biological treatment to remove persistent pharmaceutical pollutants, specifically sertraline hydrochloride (SER-HCl) with a view to mineralizing it in an economical and ecological way. A single-compartment batch reactor containing a carbon felt cathode and a platinum anode was used to perform the electro-Fenton pretreatment of SER-HCl. GC-MS and LC-MS were used to identify the intermediate by-products and thus to suggest a probable path of degradation. In addition, tracking of inorganic ions as well as the nitrogen and chloride molecules liberated during SER-HCl electrolysis was determined by ion chromatography. Then, the continuous aerobic degradation of SER-HCl, was studied for a period of 21 days at around 25 °C. A complete degradation of SER-HCl (0.1 mM) was noted at 400 mA after 5 min of electrolysis. In addition, an improvement in the BOD5/COD ratio was observed from an initial value of 0.042 to 0.33 and 0.47 over 1.5 and 2 hours of electrolysis respectively. The solution should be biodegradable after 1.5 hours of electro-Fenton pretreatment, from which the pharmaceutical product oxidized to readily biodegradable compounds, mostly short-chain carboxylic acids, which are available for uptake by microorganisms. In this point, a biological process of the electrolysis co-products after 1 h and 30 min, and 2 h was then performed aiming at biodegrading the remaining products. As a result, the COD yield increased slightly throughout the 21 days to 90.7% and 94.2% for 1 h30min and 2 h, respectively, showing the suitability of the proposed coupled process.