Mahmood Derakhshan; Mojtaba Fazeli
Volume 5, Issue 4 , October 2017, , Pages 144-152
Abstract
Background:Petrochemical wastewaters are a critical environmental challenge in industrial zones due to the amount of pollutants they release into the environment. Therefore, finding a solution for treatment of the wastewater has become the priority of the researchers. The main objective of this research ...
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Background:Petrochemical wastewaters are a critical environmental challenge in industrial zones due to the amount of pollutants they release into the environment. Therefore, finding a solution for treatment of the wastewater has become the priority of the researchers. The main objective of this research is improvement of petrochemical wastewaters’ biodegradability using Fenton oxidation process and defining the effective parameters on the efficiency of this technique.Methods: In this research, the capability of Fenton method for promoting the biodegradability of hardly-decomposable wastewaters of petrochemical complexes was studied. The actual wastewater of Karoon and Maroon petrochemical complexes were used in this research. Design of the experiments and also the analysis of the experimental results were carried-out using Response Surface Methodology (RSM) with four variables and four parameters. A rector with sizes of 60, 20 and 20 cm was designed and built. The ranges of CODin, H2O2 concentration, Fe2+ dosage, and TDS variation were 1000-2500 mg/L, 1000-4000 mg/L, 500-3000 mg/L, and 4500-11500 mg/L, respectively, and the average ratio of BOD/COD in the inlet stream was 0.09.Results:The range of BOD/COD in the outlet stream was 0.19-0.37 which decreased with the COD growth. The trend of biodegradability promotion with increase in H2O2 concentration and Fe2+ dosage was ascending, while the effect of TDS on biodegradability was not noticeable.Conclusion:The optimum conditions for achieving maximum efficiency of the reactor were COD=1375 mg/L, [H2O2] = 2509.27 mg/L, [Fe2+] = 1753.49 mg/L and TDS = 8622.9 mg/L and the BOD/COD ratio was 0.32.
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; Mohammad Reza Shirdarreh; Mohammad Faramarzian
Volume 2, Issue 1 , January 2014, , Pages 15-25
Abstract
Background: Amoxicillin is widely used as an antibiotic in the modern medicine. Due to its chemical structure, polarity, activity level, antibiotic specifications, and environmental sustainability, Amoxicillin leaks into the groundwater, surface waters, and drinking water wells. Many physical and chemical ...
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Background: Amoxicillin is widely used as an antibiotic in the modern medicine. Due to its chemical structure, polarity, activity level, antibiotic specifications, and environmental sustainability, Amoxicillin leaks into the groundwater, surface waters, and drinking water wells. Many physical and chemical methods have been suggested for removing Amoxicillin from aquatic environments. However, these methods are so costly and have many performance problems. Methods: In this study, biodegradation of Amoxicillin by submerged biological aerated filter (SBAF) was evaluated in the aquatic environment. In order to assess the removal of Amoxicillin from the aquatic environment, this bioreactor was fed with synthetic wastewater based on sucrose and Amoxicillin at 3 concentration levels and 4 hydraulic retention times (HRTs). Results: The maximum efficiency for Amoxicillin and Soluble Chemical Oxygen Demand (SCOD) removal was 50.8% and 45.3%, respectively. The study findings showed that Stover- Kincannon model had very good fitness in loading Amoxicillin in the biofilter (R2 > 9 9%). T here w as n o a ccumulation o f Amoxicillin in the biofilm and the loss of Amoxicillin in the control reactor was negligible. This shows that removal of Amoxicillin from the system was due to biodegradation. Conclusions: It can be concluded that there was no significant inhibition effect on mixed aerobic microbial consortia. It was also observed that Amoxicillin degradation was dependent on the amount of Amoxicillin in the influent and by increasing the initial Amoxicillin concentration, Amoxicillin biodegradation increased, as well.
