title: Demonstration of the Enhanced Disinfection of E. coli Water Contamination by Associated Solar Irradiation with Potassium Persulfate.
abstract: BACKGROUND
  Tremendous amount of researches have investigated the issue of water photodisnfection. The aim of this research is to illustrate the influences of bacterial density, turbidity, exposure time and potassium persulfate (KPS) dosage on the efficacy of associated solar disinfection (SODIS) with KPS for E. coli (ATCC: 25922) eradication as an efficient and inexpensive process.
  
  
  METHODS
  Desired bacterial density and turbidity was achieved by spiking of 0.5 Mc Farland (1.5×10(8) cell/ml) and sterile soil slurry in 1 liter of the commercially bottled water.
  
  
  RESULTS
  The highest value of UVA solar irradiation measured at 13.30 p.m was 5510 μW/Cm(2). Increase of bacterial density from 1000 to 1500 cell/ml led to an increase in disinfection lapse time, except in 2 mMol/l KPS. Spiking of 0.1 mMol/l of KPS was not effective; however, increase of KPS dosage from 0.1 mMol/l to 0.7, 1.5 and 2 mMol/l led to the enhancement of disinfection time from 4 h to 3 h and 1 h, respectively. For bacterial density of 1000 cell/ml, increasing KPS dosage up to 0.7 mMol/l had no improved effect; however, beyond this dosage the disinfection time decreased to 1 h. Without KPS and up to 150 NTU within 4 h exposure time, E. coli disinfection was completed. In 2 mMol/l KPS and 1000 and 1500 cell/ml, the 2 h contact time was sufficient up to 150 and 100 NTU, respectively; moreover, complete disinfection was not achieved at higher turbidity.
  
  
  CONCLUSIONS
  Association of KPS with SODIS can lead to decreasing of water disinfection time.
authors.affiliation: Health Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Ghader
authors.initials: G
authors.lastname: Ghanizadeh
authors.affiliation: Dept. of Environmental Health Engineering, Health School, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Naseri Ara
authors.affiliation: Dept. of Microbiology, Faculty of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Davoud
authors.initials: D
authors.lastname: Esmaili
authors.affiliation: Health Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Masoumbeigi
keywords: Disinfection; E. coli; Potassium persulfate; Solar irradiation; Water