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Midreshet Ben-Gurion, Israel

Theitler D.J.,Tel Aviv University | Nasser A.,Water Quality Research Laboratory | Gerchman Y.,Haifa University | Kribus A.,Tel Aviv University | Mamane H.,Tel Aviv University
Journal of Water and Health

The response of a representative virus and indicator bacteria to heating, solar irradiation, or their combination, was investigated in a controlled solar simulator and under real sun conditions. Heating showed higher inactivation of Escherichia coli compared to the bacteriophage MS2. Heating combined with natural or simulated solar irradiation demonstrated a synergistic effect on the inactivation of E. coli, with up to 3-log difference for 50 °C and natural sun insolation of 2,000 kJ m-2 (compared to the sum of the separate treatments). Similar synergistic effect was also evident when solar-UV induced DNA damage to E. coli was assessed using the endonuclease sensitive site assay (ESS). MS2 was found to be highly resistant to irradiation and heat, with a slightly synergistic effect observed only at 59 WC and natural sun insolation of 5,580 kJ m-2. Heat treatment also hindered lightdependent recovery of E. coli making the treatment much more effective. © IWA Publishing 2012. Source

Nasser A.M.,Water Quality Research Laboratory | Vaizel-Ohayon D.,Mekorot | Aharoni A.,Mekorot | Revhun M.,Technion - Israel Institute of Technology
Journal of Applied Microbiology

The present study was conducted to review factors affecting the prevalence and concentration of Giardia in raw wastewater. The removal and inactivation efficiency of Giardia by wastewater treatment technologies was also reviewed. Data published for the prevalence of Giardia in wastewater and the removal by wastewater treatment plants was reviewed. Giardia cysts are highly prevalent in wastewater in various parts of the world, which may reflect the infection rate in the population. In 23 of 30 (76·6%) studies, all of the tested raw wastewater samples were positive for Giardia cysts at concentrations ranging from 0·23 to 100000cystsl-1. The concentration of Giardia in raw wastewater was not affected by the geographical region or the socio-economic status of the community. Discharge of raw wastewater or the application of raw wastewater for irrigation may result in Giardia transmission. Activated sludge treatment resulted in a one to two orders of magnitude reduction in Giardia, whereas a stabilization pond with a high retention time removed up to 100% of the cysts from wastewater. High-rate sand filtration, ultrafiltration and UV disinfection were reported as the most efficient wastewater treatment methods for removal and disinfection of Giardia cysts. Wastewater treatment may not totally prevent the environmental transmission of Giardia cysts. The reviewed data show that a combination of wastewater treatment methods may results in efficient removal of Giardia cysts and prevent their environmental transmission. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology. Source

Nasser A.M.,Water Quality Research Laboratory
Journal of Water and Health

Cryptosporidium is a protozoan parasite that infects humans and various animal species. The environmental stability and the low infectious dose of Cryptosporidium facilitate its transmission by water and food. Discharge of untreated wastewater may result in waterborne or foodborne Cryptosporidium outbreaks, therefore a suitable treatment may prevent its dissemination. Most studies on the prevalence of Cryptosporidium oocysts in wastewater have reported a concentration range between 10 and 200 oocysts/L and a prevalence of 6 to 100%. Activated sludge has been found to be ineffective for the removal of Cryptosporidium oocysts. Stabilization ponds and constructed wetlands are efficient for the reduction of Cryptosporidium from wastewater, especially when the retention time is longer than 20 days at suitable sunlight and temperature. High rate filtration and chlorine disinfection are inefficient for the reduction of Cryptosporidium from effluents, whereas ultrafiltration and UV irradiation were found to be very efficient for the reduction of Cryptosporidium oocysts. Adequate tertiary treatment may result in high quality effluent with low risk of Cryptosporidium for unrestricted irrigation and other non-potable applications. © IWA Publishing 2016. Source

Shtarker-Sasi A.,Hebrew University of Jerusalem | Castro-Sowinski S.,Hebrew University of Jerusalem | Castro-Sowinski S.,University of the Republic of Uruguay | Matan O.,Hebrew University of Jerusalem | And 5 more authors.
Desalination and Water Treatment

This study aimed at testing the application of nano-composites of micelle-montmorillonite for removal of bacteria and parasites from water. The suitability of these complexes for efficient adsorption of microorganisms was expected on account of their large surface areas, large excess of positive charge, and existence of large hydrophobic domains. Tests included removal from water of bacteria: Gram negative (Escherichia coli K-12), Gram positive (Bacillus megaterium), and a protozoan parasite, Cryptosporidium parvum. Micelles of the organic cations Benzyldimethylhexadecylammonium (BDMHDA), or Octadecyltrimethylammonium complexed with the clay-mineral montmorillonite were shown to reduce by 3-6 orders of magnitude the numbers of microorganisms in water as tested in suspension and by filters (20 cm in length) packed with the complexes mixed with excess sand (100:1, w/w). Respiration tests demonstrated that E. coli K-12 cells adsorbed to micelle (BDMHDA)-montmorillonite complex lost their viability. Kinetics of filtration of E. coli by two filters in series was adequately simulated by a model which considers convection, adsorption. and desorption. Filtration of E. coli K-12 cells demonstrated that they stayed adsorbed and inactivated by the complex within the column filter without re-growth in water. These results suggest that filters including micelle-montmorillonite composites can secure the safety of drinking water in case of threatening increases in the number of pathogenic microorganisms in the water. © 2013 © 2013 Balaban Desalination Publications. Source

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