Bacteria transport through goethite-coated sand: effects of solution pH and coated sand content

Colloids Surf B Biointerfaces. 2008 Jun 1;63(2):236-42. doi: 10.1016/j.colsurfb.2007.12.003. Epub 2007 Dec 14.

Abstract

This study investigated the transport of bacteria through goethite-coated sand, focusing on the effects of solution pH and coated sand content on the transport of Escherichia coli ATCC 11105. The first set of column experiments was performed in columns (length 30 cm, diameter 5 cm) packed with quartz sand coated with goethite in solution having a pH in the range of 6-9. The second was carried out in columns (length 30 cm, diameter 2.5 cm) with varying coated sand contents ranging from 0 to 100%. Results indicate that the bacteria transport in the coated sand was influenced by solution pH. Around pH 6 and 7, bacterial mass recoveries were low at 2.4-6.7% while they were high at 76.3-81.6% around pH 8 and 9. Around pH 8, the positively charged coated sand may convert to being negatively charged, causing an electrostatically repulsive interaction between the coated sand and bacteria, thus effecting a sharp change in the mass recovery. Results also reveal that the mass recovery decreased from 76.7 to 2.7% as the coated sand content increased from 0 to 100%, showing the nonlinear dependency of mass recovery on the content of coated sand. This study demonstrates the importance of the solution pH and coated sand content in the adhesion of bacteria to goethite-coated sand and furthermore contributes to the knowledge of bacterial removal in positively charged porous media.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Physiological Phenomena*
  • Hydrogen-Ion Concentration*
  • Iron Compounds / chemistry*
  • Microscopy, Electron, Scanning
  • Minerals
  • Silicon Dioxide*
  • Spectrum Analysis / methods

Substances

  • Iron Compounds
  • Minerals
  • goethite
  • Silicon Dioxide