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Background: Nowadays, international concern about the impact of antibiotic residues on the environment increased and their removal has received a lot of consideration. The aim of this study was to investigate the efficiency of Fenton’s advanced oxidation process (H2O2/Fe+2) in sulfadiazine antibiotic removal from aqueous solutions. Materials and Methods: An experimental-laboratory scale study was done on a synthetic wastewater containing sulfadiazine antibiotic with 0.079, 0.19, and 0.47 mM concentrations under Fenton’s process. Then optimal values of affecting parameters, such as initial antibiotic concentration, molar ratio of reagents, [Fe+2] and [H2O2] concentration, detention time, and pH, were determined. The discharged effluent analyzed by HPLC-UV to identify the antibiotic residues. Results: The results showed that the optimal parameters in the Fenton’s oxidation process to remove the sulfadiazine included antibiotics at pH 3.5, molar ratio of [H2O2] / [Fe +2] equal to 1.5, and contact time of 15 minutes, respectively. In these optimal conditions, the efficiency of removal of antibiotic in concentrations of 0.079, 0.19, and 0.47 mM were 99.82%, 97.97% and 78.23% and the wastewater COD removal degrees were 83.33%, 78.57%, and 78.57%, respectively. Conclusion: The experiments showed the efficient removal of sulfadiazine antibiotic in wastewater by Fenton’s oxidation process. The efficiency of this method can also be considered in eliminating other antibiotics resistant to biological treatment

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Background: The presence of nitrate in drinking water causes various health and environmental problems. The aim of this study was to evaluate the efficacy of nitrate reduction by Fe/H2O2 process and adsorption on activated carbon. Materials and Methods: This experimental study investigated nitrate oxidation by advanced oxidation process of Fe°/FeІІ/FeШ/H2O2 at pH 2-10, nitrate concentrations of 50-300 mg/L. After adjusting the pH, 0.5, 1, 2, 5, and 10 g/L values of GAC, PAC, H2O2/GAC, and Fe/H2O2/GAC together with H2O2 at retention times of 15, 30, 45, 60, and 90 minutes, respectively, were added and mixed. Results: At retention time of 10 minutes and 0.5 mL H2O2 and 1 g/L from Fe°, FeІІ, and FeІІІ, the removal efficacy was 88.5, 84 and 78%, respectively. At 50 mg/L nitrate and 0.5, 1, and 10 mg/L GAC concentrations, the removal efficacy was 56.5, 93.6, and 82.6%, respectively. The nitrate removal efficiency at pH=4 was approximately 50%, whereas at pH=3 with 30% efficacy, it increased to 80%. Conclusion: Modified Fe/H2O2 process with iron nano-particles and activated carbon adsorption can effectively reduce nitrate under optimal conditions. The use of activated carbon at a concentration of 1 g/L increased the removal efficiency of nitrate to 90%.

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Background: Naphthalene is a polyaromatic hydrocarbon (PAH_s) present in many water sediments. This study evaluated the performance of UV/H₂O₂ reaction to decompose naphthalene in the aqueous solution.

Materials and Methods: It was an experimental-laboratory study. A one liter cylindrical glass reactor was used for performing all degradation experiments. The radiation source was a low pressure mercury UV lamp emitting at 254 nm (30 W, UV-C) which was placed above a batch photoreactor for UV/H₂O₂ experiments and different concentrations of H₂O₂ (5, 10, 15, 20, 25 and 30 mg/L) were tested.

Results: In 15 mg/L naphthalene in UV/H₂O₂ system and reaction times 5, 10, 20, 30, 40, 50, 60, 100 and 120 minutes, 15, 28, 31 , 36, 42, 52, 56, 73 and 59.5% naphthalene removal efficiencies were observed and COD removal efficiencies in reaction times 5, 10, 20, 30, 40, 50, 60, 100 and 120 minutes, 22, 38, 45, 61.5, 67.5, 70, 80, 88.5 and 76 % were observed. When the initial pH values were 3, 4, 5, 6, 7,9, 10 and 12 the naphthalene removal efficiency was approximately 75.8, 63.4, 62, 58.5, 44.8, 35.8 and 30%, respectively, with UV/H₂O₂ system.

Conclusion: The experimental results of this study suggested that the dosages with 20 mg/L H₂O₂ at pH= 3 with 2.8 W/cm² UV intensity (254 nm) provided the optimal operation conditions for the mineralization of naphthalene yielding a 73% mineralization efficiency after 100 minutes of reaction time.