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Application of Advanced Oxidation Process To Improve the Performance of Biological Treatment of Pharmaceutical Pollutants

Mohammad Hosseini, Mohammad | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58171 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Yaghmaei, Soheila; Ghobadinejad, Zahra
  7. Abstract:
  8. Management of pharmaceutical wastewater is a serious environmental challenge due to the presence of bioactive compounds and their high stability in the environment and can play an important role in controlling persistent and resistant pollutants. Metformin, as a widely used drug in the treatment of type 2 diabetes, is considered one of the persistent and resistant pollutants in aquatic environments and has significant negative effects on the health of ecosystems. In this study, sodium chloride was initially selected as the optimal electrolyte from among the electrolytes sodium chloride, sodium sulfate, and sodium acetate. Then, the effective parameters including: electrolyte concentration (1 to 5.5 g/L), current density (2 to 16 mA/cm2), initial metformin concentration (5 to 20 mg/L), electrode distance (2 to 6 cm), solution temperature (25 to 45 °C), pH (3 to 10), and reaction time (up to 180 min) in metformin removal were investigated. Under optimal conditions (sodium chloride concentration 4 g/L, current density 12 mA/cm2, initial concentration 10 mg/L, electrode distance 2 cm, temperature 25 °C, and pH 7), the metformin removal efficiency reached 100% in 180 min; however, due to high energy consumption (4 kWh/m3), the use of a combined electrochemical-biological method was investigated. In this method, the wastewater was treated for 1 hour under electrochemical process and using Enterobacter cloacae microorganism for 1 day, which achieved a removal efficiency of more than 99.5%. It was also found that in the pure biological process (without pretreatment), Enterobacter cloacae achieved a 74% removal rate of metformin after an eight-day period. The degradation pathway of metformin was identified using gas chromatography-mass spectrometry analysis and wastewater mineralization showed that COD and TOC were reduced by 65 and 62%, respectively. The scavenger test and fluorescence spectroscopic analysis also showed that hydroxyl radicals played the most role in the removal of metformin. In the biological process, the naphthalene dioxygenase enzyme had the highest activity and the laccase enzyme had the second highest activity in the removal of metformin. Finally, the detoxification test through germination and seedling growth test showed that the effluent from the combined process was less toxic and provided a safer environment for seed growth. This study demonstrated that the combined electrochemical-biological process is an efficient and sustainable method for removing metformin from pharmaceutical effluent and reducing its environmental risks
  9. Keywords:
  10. Metformin ; Electrochemical Treatment ; Advanced Oxidation Process ; Laccas Enzyme ; Naphthalene Dioxygenase Enzyme ; Biological Treatment ; Pharmaceutical Pollutants

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