title: Investigation of quaternary ammonium silane-coated sand filter for the removal of bacteria and viruses from drinking water.
abstract: OBJECTIVE
  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.
  
  
  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 log(10) 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 log(10) 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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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.
authors: Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.
authors: A A
authors: AA
authors: Torkelson
authors: A K
authors: AK
authors: da Silva
authors: D C
authors: DC
authors: Love
authors: J Y
authors: JY
authors: Kim
authors: J P
authors: JP
authors: Alper
authors: B
authors: B
authors: Coox
authors: J
authors: J
authors: Dahm
authors: P
authors: P
authors: Kozodoy
authors: R
authors: R
authors: Maboudian
authors: K L
authors: KL
authors: Nelson
mesh_terms: D000256:Adenoviridae / Q000302:isolation & purification; D060766:Drinking Water / Q000382:microbiology*; D004926:Escherichia coli / Q000302:isolation & purification; D005374:Filtration / Q000379:methods*; D006812:Humic Substances; D017909:Levivirus / Q000302:isolation & purification; D017955:Poliovirus / Q000302:isolation & purification; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D060753:Water Quality
chemical_list: D060766:Drinking Water; D006812:Humic Substances; D000644:Quaternary Ammonium Compounds; D012821:Silanes; D012822:Silicon Dioxide