The electrochemical elimination of coliforms from water using BBD/Ti or graphite anodes: a comparative study

Abstract

The elimination of total and fecal coliforms, from raw surface water, was carried out by electrochemical oxidation using either boron doped diamond (BDD/Ti) or graphite (GP) anodes, in a chloride-free medium. The optimal values of the operation parameters, maximizing the coliform elimination percentage, were determined using statistical experimental design. The current density (j: 2–20 mA/cm2), the conductivity (σ: 500–900 μS/cm) and the anode materials (An) were considered as variables to perform the Box-Behnken experimental design together with the response surface methodology analysis for optimization. The statistical analysis indicated that, in the evaluated range, the disinfection efficiency increased with an increase in j and decreased with an increase in σ. The following optimal conditions for the elimination of total and fecal coliforms were found: j: 10 mA/cm2, σ: 500 μS/cm and BDD/Ti used as anode material. The BDD/Ti electrode let to achieve complete coliform elimination after ca. 20 min of reaction while the GP one needed ca. 27 min. In water treated with both BDD/Ti and GP anode, after 7 days, any coliforms growth was observed. As a result of the oxidation process, the total organic carbon and nitrite concentration decreased while nitrate concentration increased.

The Optimization of Operational Variables of Electrochemical Water Disinfection Using Response Surface Methodology

“…This is expected as an increase in the spacing also increases the ohmic resistance and decreases the generation of electrochemically generated disinfecting agents, which subsequently lowers the disinfection efficiency. These results are in agreement with [36]. GilPavas et al [37] remarked that an increase in current density increases the disinfection of E. coli, and the effect is independent of the electrode type used.…”