ABSTRACT
Background: 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
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 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
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 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 microw/cm[2]] 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
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 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, H[2]O[2] 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], H[2]O[2], 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
ABSTRACT
Expanding cities with rapid economic development has resulted in increased energy consumption leading to numerous environmental problems for their residents. The aim of this study was to investigate the correlation between air pollution and mortality rate due to cardiovascular and respiratory diseases in Shiraz. This is an analytical cross-sectional study in which the correlation between major air pollutants [including carbon monoxide [CO], sulfur dioxide [SO2], nitrogen dioxide [NO2] and particle matter with a diameter of less than 10 micro [PM10]] and climatic parameters [temperature and relative humidity] with the number of those whom expired from cardiopulmonary disease in Shiraz from March 2011 to January 2012 was investigated. Data regarding the concentration of air pollutants were determined by Shiraz Environmental Organization. Information about climatic parameters was collected from the database of Iran's Meteorological Organization. The number of those expired from cardiopulmonary disease in Shiraz were provided by the Department of Health, Shiraz University of Medical Sciences. We used non-parametric correlation test to analyze the relationship between these parameters. The results demonstrated that in all the recorded data, the average monthly pollutants standard index [PSI] values of PM10 were higher than standard limits, while the average monthly PSI value of NO2 were lower than standard. There was no significant relationship between the number of those expired from cardiopulmonary disease and the air pollutant [P > 0.05]. Air pollution can aggravate chronic cardiopulmonary disease. In the current study, one of the most important air pollutants in Shiraz was the PM10 component. Mechanical processes, such as wind blowing from neighboring countries, is the most important parameter increasing PM10 in Shiraz to alarming conditions. The average monthly variation in PSI values of air pollutants such as NO2, CO, and SO2 were lower than standard limits. Moreover, there was no significant correlation between the average monthly variation in PSI of NO2, CO, PM10, and SO2 and the number of those expired from cardiopulmonary disease in Shiraz
ABSTRACT
Background: Among Alkanes, N-Alkanes with medium chain have been identified as the most important contaminants of the soil. N-hexadecane [C[16]H[34]] 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
ABSTRACT
According to the literature, a large number of people working in industries and service providing personnel, such as firefighters, physicians, and nurses are shift workers. The spread of shift working in industrial societies and the incidence of the problems resulting from shift working have caused the researchers to conduct studies on this issue. The present study also aimed to investigate melatonin and cortisol circadian rhythms in the security guards of Shiraz University of Medical Sciences, Shiraz, Iran. The present study was conducted on 20 security guards of Shiraz University of Medical Sciences. In order to collect the study data, blood samples were taken from the study subjects in different times of the day [1, 4, 7, 10, 13, 16, 19, and 22] and cortisol and melatonin levels were determined using the radioimmunoassay and enzyme immunoassay techniques, respectively. The results showed that as the intensity of light increased at night, the plasma cortisol level increased, as well. Besides, no statistically significant difference was found between the plasma cortisol levels in natural light and 4500-lux light. On the other hand, a significant difference was observed between the plasma cortisol levels in natural light and 9000-lux light as well as 4500- and 9000-lux lights. The study findings also showed that as the intensity of light increased at night, the plasma melatonin level decreased. In addition, a statistically significant difference was found between the plasma melatonin levels in natural light and 4500-lux light. Nevertheless, no significant difference was observed between the plasma melatonin levels in the natural light and 9000-lux light as well as 4500- and 9000-lux lights. The present study aimed to investigate the subsequences of shift working in the security guards of Shiraz University of Medical Sciences and showed that occupational exposure to bright light could affect some biological markers, such as melatonin and cortisol secretion