Energy Saving Electrochemical Process for the Removal of Bacterial Spores from Water Using Sodium Fluoride and Ethanol

Effective electrodisinfection of Bacillus subtilis spores with low energy consumption was achieved at room temperature through the synergistic interaction effects of sodium fluoride (NaF) (mg.L-1) and ethanol (mg.L-1), voltage applied (V), pH, and reaction time. B. subtilis (103 spores mL-1) were eliminated with an energy saving of nearly 85% at 0.68 Wh at 4 mg.L-1 NaF and 0.4 mg.L-1 ethanol, using 20 cm(2) stainless steel electrodes in a batch reactor containing 200 mL of tap water. Lower energy consumption was achieved on the removal of B. subtilis spores (10(3).mL(-1)) at pH 7-7.2 after 60 min. No B. subtilis spores appeared in colony growth assays following water treatment with 0.05 A and 7 V at neutral pH for this duration. The optimization of treatment parameters allowed for the prediction of B. subtilis spore removal in concert with process selectivity according to energy constraints. This study reveals a promising solution to low-cost B. subtilis spore removal without generating sludge or changing water quality.