Abstract

Background and Objectives: Due to the unique absorption and antibacterial properties of nanoparticles, their use in water and wastewater treatment to remove bacteria is spreading. This research aimed to study the effect of silver nanoparticles in the removal of Enterococcus faecalis isolated from industrial sewage.                                               

Material and Methods:  after preliminary studies, field studies including sampling of industrial wastewater was conducted.  First, Fecal Coliform, total coliform and Enterococcus faecalis of industrial Sewage were measured by standard methods of microbiology, then the effect of concentrations of 500, 250, 125, 62.5, 31.25, 15.62, 7.81, and 3. 9 PPM of isolated nanoparticles serial dilution method on Enterococcus faecalis and standard (PTCC 1339) was determined. Next,  and the turbidity of tube (OD), which represents growth of bacteria, was read at 600 nm with a spectrophotometer. After that,  all tubes were cultured on solid medium and the results were analyzed using SPSS 22.                                                                                                            

Results: fecal and total coliform contamination of industrial Sewage from slaughter and textile plant were approved and Enterococcus faecalis was isolated. The growth of isolates and standard bacteria was not controlled by any of these concentrations. None of the concentrations was able to remove the bacteria but the increase of concentration led to higher effect of nanoparticles, and in accordance with the type of bacteria, it was different, but the difference was not statistically significant.                                                                                                         

Conclusion: Although silver nanoparticles ,according to the concentration,  affect the Streptococcus faecalis, they cannot  completely remove bacteria. Therefore,  the economic factors and other involved factors need to be considered in the application of nanoparticles.                                                                                                           

Keyword: Silver nanoparticles, Enterococcus faecalis, industrial Sewage

 
 

ABSTRACT

           Background and Objectives: Hepatitis A virus (HAV) enters sewage through the stool of infected patients and contaminates freshwater and seawater. The aim of present study was quantitative molecular detection of HAV in raw and treated urban sewage samples from Isfahan, center of Iran.
           Material and methods: Sewage samples were collected from six urban treatment plants in cold and warm weather, between December 2016 and Jun 2017. Physicochemical indicators were measured immediately after sampling. Viral particles were isolated and concentrated by modified adsorption-elution method using Al³⁺-coated filters. Quantitative PCR was done for amplification of a fragment in the highly conserved 5′ noncoding region of the HAV genome.
           Results: Although the values of the indicators were lower in 67-83% of sewage samples in warm weather, no significant difference was detected between the physicochemical indicators of sewage samples. HAV was detected in three raw sewage samples collected in cold weather (copy number of 32590, 28400 and 14200 per µl) and in one treated sewage sample (copy number of 6500 per µl) collected in cold weather. Positive HAV sewage samples had been treated by activated sludge and aerated lagoon.
           Conclusion: We detected high frequency of HAV in raw urban sewage samples from Isfahan, Iran. This highlights the importance of paying extra attention to irrigation of farms with raw sewage. Based on the results of this study and previous studies, it can be concluded that the activated sludge system may be more effective for elimination of enteric viruses, such as HAV.
           Keywords: Hepatitis A virus, Sewage, Weather.