Mohammad Reza Samaei; Majid Nozari; Marziyeh Ansari Shiri; Mehdi Mokhtari; Asghar Ghasemi; Reza Rezaei Javanmardi
Volume 5, Issue 2 , April 2017, , Pages 44-50
Abstract
Background:Discharge of raw or treated wastewater containing linear alkyl benzene sulfonate (LAS) into the environment causes significant public health and environmental problems. The purpose of this study was the treatment of hospital wastewater using an intermittent cycle extended aeration system (ICEAS).Methods:Experiments ...
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Background:Discharge of raw or treated wastewater containing linear alkyl benzene sulfonate (LAS) into the environment causes significant public health and environmental problems. The purpose of this study was the treatment of hospital wastewater using an intermittent cycle extended aeration system (ICEAS).Methods:Experiments were carried out on Yazd Shohaday-e-Kargar hospital wastewater treatment system and samples were collected in a 2 month period from the influent and effluent of the system. The used pilot study carried out consisted of two zones: pre-react and main react zones. They were divided using a baffle wall. Firstly, wastewater enters a pre-react zone and then through the opening at the bottom of the baffle wall it enters the main react zone. The cycle time and flow rate for the system were considered 6 h and 2 L/h, respectively. Then, the necessary tests were performed on the system’s influent and effluent.Results:The removal of BOD5, COD, and LAS by ICEAS were 94.54%, 92.97%, and 84.99%, respectively. The averages of SVI, F/M, MLSS and MLVSS in the system were 113 mL/g, 0.086 Kg.BOD5/Kg.MLSS.d, 4327 mg/L and 3172 mg/L, respectively.Conclusions:This work showed the excellent efficiency of ICEAS to effectively remove BOD5, COD, and LAS from hospital wastewater. The results of this research can help to manage wastewater treatment in hospitals.
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.