Photo-electro Fenton treatment process as new approach for efficient removal of microbial contamination from aqueous medium: Optimization and inactivation kinetics

Introduction and Objectives: Microbial contamination of water and the concern for public health are a global problem. Conventional methods for water disinfection such as chlorination and ozonation inevitably form harmful disinfection by-products (DBPs), which probably provide an unintended health hazard. As an alternative method, the photo-electro Fenton (PEF) process which generate hydroxyl radical (•OH) employed for efficient removal of Escherichia coli (E.coli) as representative of microbial contamination from the aqueous medium in the current work. Materials and Methods: This study carried out experimentally in a laboratory scale. The effect of main variables including initial E.coli concentration, solution pH, H2O2 dosage, current density, UV intensity, and reaction time on the efficiency of PEF process investigated. The design and process optimization performed using Design Expert 11 software. Results: Development of treatment model using analysis of variance (ANOVA) revealed that maximum E.coli removal efficiency of 99.7% occurred at the initial E.coli concentration 5×107 CFU mL-1, UV intensity of 12 W cm-2, H2O2 dosage of 620 μL L-1, current density of 7.5 mA cm-2, solution pH of 3.5, and the reaction time of 8.4 min. ANOVA displayed the non-significant lack of fit value (0.094), whereas, the predicted correlation coefficient values (Pred. R2=0.912) were reasonably in agreement with the adjusted correlation coefficient value (Adj. R2=0.907) demonstrating a satisfactory significant model for E.coli removal. The PEF process produces highly oxidizing species, the hydroxyl radical (•OH), which is mainly responsible for the inactivation of E.coli. Kinetics of inactivation process followed first-order kinetics model with the rate constants (Kapp) of 0.674 min-1. Conclusion: The obtained results revealed that the photo-electro Fenton process as a green technology was able to inactivate the E.coli in aqueous medium effectively.

Keywords:

Removal , Escherichia coli , Photo-electro Fenton process , Kinetic.