Investigation of quaternary ammonium silane-coated sand filter for the removal of bacteria and viruses from drinking water
Article first published online: 30 AUG 2012
© 2012 The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 113, Issue 5, pages 1196–1207, November 2012
How to Cite
Torkelson, A.A., da Silva, A.K., Love, D.C., Kim, J.Y., Alper, J.P., Coox, B., Dahm, J., Kozodoy, P., Maboudian, R. and Nelson, K.L. (2012), Investigation of quaternary ammonium silane-coated sand filter for the removal of bacteria and viruses from drinking water. Journal of Applied Microbiology, 113: 1196–1207. doi: 10.1111/j.1365-2672.2012.05411.x
- Issue published online: 17 OCT 2012
- Article first published online: 30 AUG 2012
- Accepted manuscript online: 26 JUL 2012 12:15AM EST
- Manuscript Accepted: 17 JUL 2012
- Manuscript Revised: 7 JUL 2012
- Manuscript Received: 10 MAY 2012
- drinking water;
- Escherichia coli ;
- household water treatment and safe storage;
- MS2 coliphage;
- quaternary ammonium silane
To develop an anti-microbial filter media using an attached quaternary ammonium compound (QAC) and evaluate its performance under conditions relevant to household drinking water treatment in developing countries.
Methods and Results
Silica sand was coated with dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride via covalent silane chemistry. Filter columns packed with coated media were challenged with micro-organisms under different water quality conditions. The anti-bacterial properties were investigated by visualizing Escherichia coli (E. coli) attachment to coated media under fluorescence microscopy combined with a live/dead stain. A 9-cm columns with a filtration velocity of 18 m h−1 achieved log10 removals of 1·7 for E. coli, 1·8 for MS2 coliphage, 1·9 for Poliovirus type 3 and 0·36 for Adenovirus type 2, compared to 0·1–0·3 log10 removals of E. coli and MS2 by uncoated sand. Removal scaled linearly with column length and decreased with increasing ionic strength, flow velocity, filtration time and humic acid presence. Escherichia coli attached to QAC-coated sand were observed to be membrane-permeable, providing evidence of inactivation.
Filtration with QAC-coated sand provided higher removal of bacteria and viruses than filtration with uncoated sand. However, major limitations included rapid fouling by micro-organisms and natural organic matter and low removal of viruses PRD1 and Adenovirus 2.
Significance and Impact of the Study
QAC-coated media may be promising for household water treatment. However, more research is needed on long-term performance, options to reduce fouling and inactivation mechanisms.