Adhesion of Escherichia coli to Iron-Coated Sand in the Presence of Humic Acid: A Column Experiment

Column experiments were performed to examine the influence of humic acid on the attachment of Escherichia coli to iron-coated sand. Results show that, in the coated sand, the average mass recovery was 2.9% in deionized water and increased sharply to 94.6% at a humic acid concentration of 16 mg/L. In leaching solution containing both humic acid and phosphate, the mass recovery increased from 26.0 to 94.6%, by increasing the portion of humic acid from 0 to 100% (from 0 to 16 mg/L). In addition, the mass recovery (94.6%) at a humic acid concentration of 16 mg/L was much larger than that (26.0%) at the same concentration of phosphate. This study presents information regarding the role of humic acid in the adhesion of bacteria to iron-coated sand and helps to enhance the knowledge of bacterial removal in positively charged porous media. Water Environ. Res., 81, 125 (2009).