Marziyeh Ansari Shiri; mansooreh dehghani; Mohammad Reza Samaei
Volume 4, Issue 3 , July 2016, , Pages 121-128
Abstract
Background: Atrazine is a widely used herbicide. The increasing salinity of many water resources has had a negative effect on atrazine biodegradation. The aim of this study was to isolate atrazine degrading bacteria in semi-salinity media. Methods: Nine selected bacterial species were cultivated on ...
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Background: Atrazine is a widely used herbicide. The increasing salinity of many water resources has had a negative effect on atrazine biodegradation. The aim of this study was to isolate atrazine degrading bacteria in semi-salinity media. Methods: Nine selected bacterial species were cultivated on the mineral salt broth culture medium containing atrazine (50, 100, 500 mg/L), NaCl concentration (10 g/L), and 2% (wt/vol) agar. The bacteria with higher growths in the atrazine medium (500 mg/L) were selected. Then, those with higher growths were transferred to the medium with atrazine concentration of 1000 mg/L. The atrazine biodegradation rates by Ochrobactrum oryzae and consortium bacteria (all of the nine bacteria species) were compared by cultivating separately on the mineral salt broth containing atrazine concentration of 30 mg/l, and NaCl concentration of 10 g/L in the incubation time of 10 day and HPLC analysis. Results: The results indicated that Ochrobactrum oryzae had the highest growth compared to the other investigated bacteria (Acinetobacter radioresistens, Paenibacillus lautus, and Bacillus sp) in the mineral salt broth culture medium containing atrazine concentrations (1000 mg/L), NaCl (10 g/L), and 2% (wt/vol) agar. In the Ochrobactrum oryzae and bacterial consortium comparison, atrazine biodegradation rate in the culture medium containing NaCl, by Ochrobactrum oryzae, was higher than bacterial consortium and atrazine biodegradation rate in the culture medium with no NaCl addition, by Ochrobactrum oryzae, was lower than bacterial consortium. Conclusion: Based on the results, Ochrobactrum oryzae was significantly capable of atrazine biodegradation in the semisalinity aqueous environment.
Mohammad Ali Baghapour; Mansooreh Dehghani; zahra elhamiyan
Volume 4, Issue 1 , January 2016, , Pages 14-21
Abstract
AbstractBackground: Dyes are visible materials and are considered as one of the hazardous components that make up the industrial waste. Dye compounds in natural water, even in very low concentrations, will lead to environmental problems. Azo dyes are compounds with one or more –N=N– groups and are ...
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AbstractBackground: Dyes are visible materials and are considered as one of the hazardous components that make up the industrial waste. Dye compounds in natural water, even in very low concentrations, will lead to environmental problems. Azo dyes are compounds with one or more –N=N– groups and are used in textile industry. Because of its low price, solubility, and stability, azo dyes are widely used in the textile industry. Direct Red 81 (DR81) is one of the azo dyes, which is removed from bodies of water, using various methods. This study aimed to assess DR81 dye removal by Fenton oxidation and the effects of various parameters on this process.Methods: Decolorization tests by Fenton oxidation were performed at dye concentrations of 50, 500, 100 and 1000 mg/L; hydrogen peroxide concentrations of 0, 10, 30, 60 and 120 mg/L; iron (II) sulfate heptahydrate concentrations of 0, 3, 5, 20 and 50 mg/L; and pH levels of 3, 5, 7 and 10 for durations of 5, 10, 20, 30, 60 and 180 minutes.Results: The optimal condition occurred at a dye concentration of 20 mg/L, hydrogen peroxide concentration of 120 mg/L, bivalent iron concentration of 100 mg/L, pH of 3, and duration of 30 minutes. Under such conditions, the maximum dye removal rate was 88.98%.Conclusion: The results showed that DR81 could be decomposed and removed by Fenton oxidation. In addition, the removal of Direct Red 81 (DR81) depends on several factors such as dye concentration, reaction time, concentrations of hydrogen peroxide and iron, and pH.
Mansooreh Dehghani; Mahshid Ghadami; Talat Gholami; Marzieh Ansari Shiri; Zahra Elhameyan; Mohammad Reza Javaheri; narges shamsedini; Samaneh Shahsavani
Volume 3, Issue 4 , October 2015, , Pages 139-145
Abstract
Background: Recently, there has been a great concern about the consumption of dyes because of their toxicity, mutagenicity, carcinogenicity, and persistence in the aquatic environment. Reactive dyes are widely used in textile industry. Advanced oxidation processes are one of the cost-effective methods ...
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Background: Recently, there has been a great concern about the consumption of dyes because of their toxicity, mutagenicity, carcinogenicity, and persistence in the aquatic environment. Reactive dyes are widely used in textile industry. Advanced oxidation processes are one of the cost-effective methods for the removal of these dyes. The main aims of this study were determining the feasibility of using Fenton process in removing Reactive Red 198 (RR-198) dye from aqueous solution and determining the optimal conditions. Methods: This is a cross-sectional study conducted at a laboratory scale. A total of 69 samples were considered and the effect of pH, Fe (II) concentration, H2O2 concentration, initial dye concentration and reaction time were investigated. Results: According to the results, a maximum removal efficiency of 92% was obtained at pH of 3 and the reaction time of 90 min; also, the concentration of Fe (II), H2O2, initial dye concentration were 100 mg/L, 50 mg/L, and 100 mg/L, respectively. The results revealed that by increasing the concentration of Fe (II), H2O2 and initial dye, the removal efficiency was increased. Conclusions: The results showed that Fenton process could be used as a cost-effective method for removing RR-198 dye from textile wastewater efficiently.
narges shamsedini; Mohammad Ali Baghapour; Mansooreh Dehghani; Simin Nasseri
Volume 3, Issue 3 , July 2015, , Pages 94-100
Abstract
Background: Atrazine is one of the most widely used triazine herbicides which has been used for controlling broadleaf and grassy weeds for many years. Its widespread use in water has caused environmental concern because of frequent detection of atrazine in aquatic systems where this herbicide has been ...
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Background: Atrazine is one of the most widely used triazine herbicides which has been used for controlling broadleaf and grassy weeds for many years. Its widespread use in water has caused environmental concern because of frequent detection of atrazine in aquatic systems where this herbicide has been spilled. Therefore, the purpose of this study was to determine the herbicide removal efficiency at the optimal conditions. Methods: The effect of different parameters including pH at three different levels (3-11), the initial concentration of atrazine at three different levels (0.1-10 mg/L), and reaction time at five different levels (0-120 min) on the removal of atrazine in the aqueous phase using ultraviolet radiation (1020 μw/cm2) was investigated. Finally, the data were analyzed using SPSS software (version 16). Results: The results demonstrated that atrazine removal rate increased by increasing pH, initial atrazine concentration, and reaction time. The maximum rate of atrazine removal (99.2%) at optimal condition occurred in pH=11, atrazine concentration=10 mg/L at 30 min. Conclusion: According to the findings, it can be concluded that the UV-A process is an effective and commodious method for reducing atrazine in polluted water resources.
majid nozari; Mohammad Reza Samaei; Mansooreh Dehghani
Volume 2, Issue 3 , July 2014, , Pages 113-124
Abstract
Background: Among Alkanes, N-Alkanes with medium chain have been identified as the most important contaminants of the soil. N-hexadecane (C16H34) with low solubility in water also belongs to this group and has been used by many researchers as a model contaminant. The present study aimed to investigate ...
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Background: Among Alkanes, N-Alkanes with medium chain have been identified as the most important contaminants of the soil. N-hexadecane (C16H34) with low solubility in water also belongs to this group and has been used by many researchers as a model contaminant. The present study aimed to investigate the effect of the external source of carbon (glucose) as co-substrate on removal of hexadecane from the soil.Methods: In this study, a Slurry Sequencing Batch Reactor (SSBR) was used as a pilot by a bacterial consortium, including bacterium Acinetobacter radioresistens, Bacillus subtilis, and Pseudomonas aeruginosa, in order to remove different concentrations of hexadecane (1,4,7, and 10 percent).Sampling was performed four times during the sedimentation step. Then, the samples were analyzed by GC-FID and the results were analyzed statistically.Results: The results showed that hexadecane removal (%) by the microbial consortium was higher in lower initial concentrations in such a way that the biological removal of hexadecane was respectively 45.95%, 38.55%, 34.39%, and 32.40% in the concentrations of 1%, 4%, 7%, and 10% on the third day. Moreover, adding the external carbon source (glucose) on the first day caused a 16% increase in hexadecane removal, which is 1.4 times more than the amount of hexadecane removal in the conditions without co-metabolism.Conclusion: The results showed that SSBR could be used as an exit-situation effective method for hexadecane removal in low concentrations through considering the effective factors in its function, such as dissolved oxygen, pH, and temperature. Also, adding the secondary carbon source could be effective in hexadecane removal from the soil. Yet, this effect might vary on different days.