Effect of Static Magnetic Field Pretreatment on Culturable Escherichia coli Reduction During Carbon Char Filtration

This study compared filtration through a granular carbonized material bed with static magnetic pretreatment followed by filtration. Model water was prepared by mixing treated municipal wastewater and tap water at a 1:1 volumetric ratio. Two filtration vessels of the same type, each containing 750 g of material from the same production batch, were used across three experimental series. Magnetic pretreatment lasted 10 min, with a locally measured magnetic flux density of 57 mT. Bacterial abundance was assessed using a most probable number (MPN) procedure with phenotypic and biochemical characterization of isolates. Percentage reductions in MPN estimates ranged from 52.31 to 90.00% after filtration alone and from 82.31 to 96.29% after pretreatment followed by filtration. Mean log reductions were 0.774 ± 0.392 and 1.144 ± 0.351, respectively. Both configurations decreased color, turbidity, electrical conductivity, and oxidation–reduction potential while increasing pH. The pretreated configuration yielded lower effluent MPN estimates in all three series. However, separate filtration units, repeated bed use, and the absence of matched sham-exposure and magnetic-field-only controls prevent attribution of these differences exclusively to magnetic exposure. The findings are preliminary and require controlled validation.