Improvement on electrochemical inactivation of Escherichia coli and Clostridium perfringens by assisted alum nanocrystallites approach: parametric and cost evaluation
Bagher Hayati, Shahram Nazari, Soudabeh Alizadeh Matboo, Hasan Pasalari, Mohsen Arzanlou, Esrafil Asgari, Seyed Mohsen Mohseni
Abstract
ABSTRACT Electrocoagulation (EC) is an electrochemical method in water treatment. Nowadays, electrochemical disinfections have created great interest in water treatment as an alternative for conventional disinfection. In this study, the effects of electrochemical inactivation with monopolar electrodes on Escherichia coli and Clostridium perfringens bacteria removal from potable water by the EC process were investigated. In addition, the effects of initial pH, reaction time, current density, as well as inter-electrode distance and conductivity on abatement of selected bacteria along with operating costs have been studied. The structure and surface morphology of the alum nanocrystallites were investigated by X-ray fluorescence, N 2 adsorption–desorption, transmission electron microscopy, powder X-ray diffraction, and field emission-scanning electron microscopy. The experiments were performed in a batch reactor. According to the results, the optimum condition for removal efficiency of 100% E. coli and C. perfringens with an 0.6 USD/m 3 operation cost for the treated aqueous solution were as follows: reaction time = 25 min, initial pH = 7, inter-electrode distance = 2 cm, current density = 33.3 A/m 2 , electrical conductivity = 0.75 mS/cm, and initial bacteria count = 10 4 CFU/mL. Findings indicated that increasing pH from 7 to 9 can significantly decrease the removal efficiency for E. coli and C. perfringens from 100% to 74% and 71%, respectively. Increasing reaction time and current density decreased both strains significantly. Inter electrode distance had an intangible effect on strains abatement. Field Emission-Scanning Electron Microscopy analysis revealed morphological variations and the mechanism through which the killing and trapping of the bacteria by alum nanocrystallites occur. The present method is able to reduce the E. coli and C. perfringens count in potable water, which meets the drinking water standards according to WHO guidelines.