13 research outputs found

    REMOVAL OF ARSENIC FROM AQUEOUS SOLUTION BY PHOTOCATALYTIC UV IRRADIATION

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    The purpose of this research was to investigate the photocatalytic removal of arsenic from aqueous solution using UV/TiO2 process in a batch system. A 120 W UV lamp with irradiation 247 nm wave lenght inside a quartz jacket was submerged in the reactor to provide better irradiation of water samples in the presence of TiO2 nanoparticles. The optimum dosage of TiO2 was obtained equal to 1 g/L, with variation TiO2 dosage at constant pH and initial concentrations of arsenic. The effect of pH, contact time and initial concentration of arsenic was studied at the constant amount of TiO2(1g/L). The results showed that photocatalytic removal efficiency increased with increasing reaction time and TiO2 dosage. In addition, it was found that removal efficiency of arsenic decreased by increasing initial arsenic concentration and pH. In conclusion the results showed that UV/TiO2was an effective method in removal of arsenic from aqueous solutions

    REMOVAL OF ARSENIC FROM AQUEOUS SOLUTION BY PHOTOCATALYTIC UV IRRADIATION

    Get PDF
    The purpose of this research was to investigate the photocatalytic removal of arsenic from aqueous solution using UV/TiO2 process in a batch system. A 120 W UV lamp with irradiation 247 nm wave lenght inside a quartz jacket was submerged in the reactor to provide better irradiation of water samples in the presence of TiO2 nanoparticles. The optimum dosage of TiO2 was obtained equal to 1 g/L, with variation TiO2 dosage at constant pH and initial concentrations of arsenic. The effect of pH, contact time and initial concentration of arsenic was studied at the constant amount of TiO2(1g/L). The results showed that photocatalytic removal efficiency increased with increasing reaction time and TiO2 dosage. In addition, it was found that removal efficiency of arsenic decreased by increasing initial arsenic concentration and pH. In conclusion the results showed that UV/TiO2was an effective method in removal of arsenic from aqueous solutions

    MODELING AND ANALYSIS OF ALGAL BLOOMS IN ARAS DAM BY ARTIFICIAL NEURAL NETWORK

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    Man made practices have contributed to large-scale algal blooms that have caused serious ecological, aesthetic, water purification and water distribution problems. Aras Dam, which provides Arasful city with drinking water, has chronic algal blooms since 1990. This study addresses the use of artificial neural network (ANN) model to anticipate the chlorophyll-a concentration in water of dam reservoir. Operation tests carried out by collecting water samples from 5 stations and examined for physical quality parameters namely: water temperature, total suspended solids (TSS), biochemical oxygen demands (BOD), ortophosphate, total phosphorous and nitrate concentrations using standard methods. Chlorophyll-a was also checked separately in order to investigate the accuracy of the predicted results by ANN. The results showed that a network was highly accurate in predicting the Chl-a concentration. A good agreement between actual data and the ANN outputs for training was observed, indicating the validation of testing data sets. The initial results of the research indicate that the dam is enriched with nutrients (phosphorus and nitrogen). The Chl-a concentration that were predicted by the model were beyond the standard levels; indicating the possibility of eutrophication especially during fall season

    INVESTIGATION OF LEGIONELLA SPECIES IN TEHRAN’S HOSPITAL WATER SUPPLIES

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    The present work was performed to investigate the presence of Legionella spp. and its common species in hospital water supplies. Considering the drawback of culture method, polymerase chain reaction (PCR) assays were developed to detect the gene 16S rRNA regardless of the bacterial serotype. Four well-established DNA extraction protocols (freeze & thaw and phenol-chloroform as two manual protocols and two commercial kits) were examined and critiqued to release DNA from bacterial cells. A total of 45 samples were collected from seven distinct hospitals’ sites during a period of 10 months. The PCR assay was exploited to amplify a 654-bp fragment of the 16S rRNA gene. Legionella were detected in 13 samples (28.9%) by all of the methods applied for DNA extraction. Considerable differences were noted in the yield of extracted nucleic acids. Legionella were not detected in any of the samples when DNA extraction by freeze & thaw was used. Omitting this method and comparing manual protocol with commercial kits, Kappa coefficient was calculated as 0.619 with p < 0.05. Although no meaningful differences were found between the kits, DNA extraction with Bioneer kit displayed a higher sensitivity than classical Qiagen. Showerheads and cold-water taps were the most and least contaminated sources with 55.5 and 9 percent positive samples, respectively. Moreover two positive samples were identified for species by DNA sequencing and submitted to the Gene Bank database with accession Nos. FJ480932 and FJ480933

    Bioaccumulation and translocation factors of petroleum hydrocarbons in Aeluropus littoralis

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    Background: Polycyclic aromatic hydrocarbons (PAHs), which consist of fused conjugated aromatic rings, not only are toxic to humans and other living organisms, but will also pollute groundwater. These compounds can be point source or non-point source and are one of the most widespread organic pollutants. Some of them are suspected carcinogens and are linked to other health problems. This study was carried out to assess the petroleum hydrocarbon phytoremediation potential of the Aeluropus littoralis species. Accumulation of PAHs in roots and upper parts of A. littoralis has been determined. Translocation factor (TF) was also calculated. Methods: In this study, soil samples were taken from the vicinity of Isfahan oil refinery, and the PAHs compounds were analyzed with gas chromatography. One-meter soil columns were prepared from the control and contaminated soil. Unplanted A. littoralis treatments were also prepared to eliminate the effects of environmental factors on the reduction of oil-based contaminants. Seventeen weeks after planting, soil columns were sampled at 25, 50, 75, and 100 cm depths, and the concentration of petroleum hydrocarbons and number of oil-degrading bacteria were counted. Moreover, the roots and shoots of A. littoralis were separated and weighed. Results: Results indicated that A. littoralis reduced the concentration of petroleum hydrocarbons to a significantly higher extent than the control treatment. Increasing depth was associated with improved petroleum hydrocarbon concentrations and decreased number of oil-degrading bacteria. Mostly, the bioaccumulation factor (BAF) of PAHs was <1, which shows A. littoralis could be an excluder of PAHs. The results also showed that the TF of PAHs was less than one, and hence, A. littoralis could be considered as an accumulator of PAHs. Conclusion: It can be concluded that this species is suitable for use in the phytoremediation of PAHS contamination. For further confirmation, an evaluation under field conditions should be undertaken
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