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Showing 3 results for E. Coli
Investigation of E. coli Removal from PollutedWater Using  Electrolysis Method
A Rezaee, G Kashi, A Jonidi Jafari, A.r Khataee,
Volume 4, Issue 2 (9-2011)
Abstract

Background and objective: The conventional chemical and physical methods for water disinfection include the application of ultraviolet (UV), chlorination, and ozonation. Water disinfection by electrochemical methods has been increasingly carried out recently. The goal of this applied - analytical research is to investigate the removal of E. coli bacteria, as the index of water microbial contamination, from drinking water by electrochemistry method.
Materials and Methods: In this study, the contaminated water sample was prepared through adding 102 and 103 E. coli bacteria per ml of drinking water. The contaminated water entered into the electrochemical reactor and different conditions were studied, included pH (6, 7, and 8), number of bacterium (102 and 103 per milliliter), time (5, 10, 20, and 40 min), distance between electrodes (2,2.5, 3, and 3.5 cm), and voltage (10, 20, 30, and 40 volts).
Results: The findings indicated the indirect correlation between bacteria removal efficiency and the variable distances between two electrode. The results indicated the direct correlation between bacteria removal efficiency and the variables voltage and electrolysis times. The results showed that the best conditions for removal of 102 and 103 bacteria per milliliter obtained at pH 7, electrolysis time of 10 min, distance between electrodes 2 cm, in the voltage 20 and 30 volts, respectively.
Conclusion: The results of this study indicate that voltage and electrolysis time have the most significant effect on electrolysis efficiency. Research findings showed that electrolysis is a promising method for removal of E. coli bacterium from drinking water.


Comparison of CuO and TiO2 Nanoparticles toxicity and Antibacterial Properties in the Solid Media
Bijan Bina, Mohamadmahdi Amin, Mohamadreza Zare, Ali Fatehizadeh, Mohsen Mohseni, Mahdi Zare, Ali Toulabi,
Volume 6, Issue 2 (9-2013)
Abstract

Background and Objectives: Toxicity assessment of material related to nanotechnology is necessary before excess development of this industry. On the other hand, specific characteristic of nanomaterials can be used in disinfection of other material. In this study toxicity and antibacterial properties of nano-TiO2 and nano-CuO were investigated with four bacterial species in solid media.

Material and Methods: Stock suspension of nanoparticles (10g-TSS/L) was diluted using Muller Hinton Agar to achieve 5-6000mg-TSS/L concentration. We prepared three Petri dishes for each concentration and refined bacteria were cultured on these Petri dishes. After culturing of these bacteria on the media containing nanoparticles, growth inhibition was determined. According to this data, 50% growth inhibition (EC50), no observed effect concentration (NOEC) and 100% growth inhibition were determined.

Results: Our results showed that toxicity of TiO2 is more than CuO in solid media. In this regard, nano-TiO2 EC50 for Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa was calculated 181, 571, 93 and 933mg-TSS/L respectively. These figures for nano-TiO2 were 2550, 1609, 946, and 1231mg-TSS/L respectively.

Conclusion: This study showed that compared with other bacteria studied, E. aureus due to high sensitivity and E. coli due to high resistance to both TiO2 and CuO nanoparticles are more proper as bioindicator in toxicity test and antibacterial test respectively.


Simultaneous removal of nitrate and microbial pollution from water by the electro-catalytic activity of iron and magnetic nanoparticles supported on nickel foam
Zohreh Akbari Jonoush, Abbas Rezaee, Ali Ghaffarinejad,
Volume 15, Issue 2 (8-2022)
Abstract
Background and Objective: This study aimed to provide an effective electro-catalytic system for the simultaneous reduction of nitrate and disinfection of contaminated water by the electro-catalytic performance of Ni-Fe/Fe3O4 cathode.
Materials and Methods: At first, the Ni-Fe electrode was synthesized by the electro-deposition process. Then its physical properties were analyzed by scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and photoelectron X-ray spectroscopy (XPS). Simultaneous disinfection and reduction of nitrate were performed under the following conditions: 15 mg Fe3O4 nanoparticles, pH 6.5, NaCl 10 mM, 50 mg/L nitrate, 105 CFU/mL and current density 4 mA/cm2.
Results: According to the results obtained in the absence of nitrate, 100 % of Escherichia coli bacteria were disinfected after 12 minutes. In the presence of nitrate, the time of complete disinfection increased to 120 minutes. In the absence of bacteria, 83% of nitrate was removed in 240 minutes, and in the presence of bacteria, the nitrate reduction efficiency increased slightly to 88%. In the nitrate reduction process, nitrite (0.22 mg/L) and ammonium (3.6 mg/L) were produced. In the presence of bacteria, the amounts of nitrite and ammonium produced increased to 0.42 mg/L and 7.3 mg/L.
Conclusion: The results show the outstanding ability of Ni-Fe/Fe3O4 electrode in electro-catalytic reduction of nitrate and disinfection of contaminated water separately and simultaneously with high efficiency and high selectivity to nitrogen.

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