Background: In this study, ferrate (VI) and ultraviolet (UV) radiation were employed to remove hydrogen sulfide from municipal wastewater resulting in a reduction in chemical oxygen demand (COD). Although ferrate (VI) and UV have been used individually for the removal of a few pollutants from urban and industrial wastewater, there exists no study to investigate the effectiveness of simultaneous utilization of both methods for the removal of hydrogen sulfide and reducing COD. Methods: This study aims to compare the application of UV, ferrate (VI) and UV/ferrate (VI) for the removal of hydrogen sulfide and COD from municipal wastewater in batch mode. Moreover, the effect of many parameters such as ferrate (VI) concentration, temperature, hydraulic retention time (HRT) and pH on ferrate (VI) oxidation power, were investigated. Results: The results of this study demonstrated that for pH less than 2, higher pollutant removal efficiency was obtained. COD removal efficiency could increase up to 68% by adding 1.68 mg/L of ferrate (VI), almost 100% of hydrogen sulfide was removed by the same concentration of ferrate (VI). Both hydrogen sulfide and COD removal efficiencies increased as temperature increased to 50°C; nevertheless, further increase in temperature had negative effect on the removal efficiency. The use of UV/ferrate (VI) increased the removal efficiency of both hydrogen sulfide and COD when compared with the use of UV and ferrate (VI) individually. UV method was not effective in the removal of hydrogen sulfide. Conclusion: The research findings shed new light on wastewater treatment systems employing UV/ ferrate (VI) to decrease both the hydrogen sulfide and COD of municipal wastewater. This new findings will assist in the inaccurate design and effective operation of such systems which can be employed to maintain or improve environmental quality.

Antibiotics are resistant to biodegradation, and their removal by biological processes is difficult. The purpose of this study was to investigate the removal of azithromycin from water using ultraviolet radiation (UV), Fe (VI) oxidation process and ZnO nanoparticles. The effect of different parameters such as pH, temperature, hydraulic retention time (HRT), the concentration of Fe (VI) and ZnO nanoparticles and UV intensity on the removal of azithromycin from water was investigated. The optimal conditions for the removal of azithromycin were a pH of 2, a temperature of 25 • C, a HRT of 15 min, and a ratio of ZnO nanoparticles to the initial concentration of azithromycin (A/P) of 0.00009 which was fitted by Langmuir isotherm. In addition, the optimal conditions for the removal of azithromycin using UV radiation were a pH of 7, a temperature of 65 • C, a HRT of 60 min, and UV radiation power of 163 mW/cm 2 . For the Fe (VI) oxidation process, the optimal conditions were a pH of 2, a temperature of 50 • C and a HRT of 20 min. Also, the optimal ratio of Fe (VI) to the initial concentration of antibiotic was between 0.011 and 0.012. The results of this study showed that the Fe (VI) oxidation process, UV radiation, and ZnO nanoparticles were efficient methods for the removal of azithromycin from water.

Journal homepage: www.zums.ac.ir/jhehp Background: The aim of this study is to compare UV, ferrate (VI) and UV/ferrate (VI) methods for removal of hydrogen sulfide and chemical oxygen demand (COD) from municipal wastewater under a continuous condition. Methods: The experiment was divided into three parts: 1) pollutants removal by using ferrate (VI) alone; 2) pollutants removal using UV alone; 3) pollutants removal using a combination of UV/ferrate (VI). The electrolysis process was utilized to generate ferrate (VI). Results: The results showed that UV had the highest pollutants removal, so that 89% and 85% of hydrogen sulfide and COD were removed from the wastewater, respectively. UV/ferrate (VI) ranked as the next most efficient method. This method removed 65% and 73% of hydrogen sulfide and COD, respectively from the wastewater. Conclusion: Using ferrate (VI) alone had the lowest pollutant removal efficiency, with 41% and 48% of hydrogen sulfide and COD removal from wastewater, respectively. UV has a higher ability to remove hydrogen sulfide and COD from wastewater, compared with UV/ferrate (VI) and ferrate (VI) alone.

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Background: Wastewater contaminated with dyes such as Reactive Blue 203 can produce a lot of health problems if it is released into the environment without a suitable treatment. Although there are several studies on dye removal from wastewater, removal of Reactive Blue 203 has not been investigated by hybrid methods. Therefore, the aim of this study was to investigate the removal of Reactive Blue 203 from aqueous solution, using combined processes of zinc oxide (ZnO) nanoparticles, Fe(VI) oxidation process, and UV radiation. Methods: The removal of dye from aqueous solution using ZnO nanoparticles, Fe(VI) oxidation process, and UV radiation was individually evaluated. Then, the results of combined methods were compared. Hydraulic retention time (HRT), pH, and temperature were the most important factors which were investigated in this study. Results: ZnO nanoparticles, Fe(VI) oxidation process, and UV radiation were able to remove 97%, 71%, and 47% of the dye in the optimal conditions, respectively. Also, the removal of dye using combination of Fe(VI) oxidation process/UV radiation, ZnO nanoparticles/Fe(VI) oxidation process, and ZnO nanoparticles/UV radiation under optimum conditions was 100%. It seems that the combined methods were significantly more effective than the methods alone for removal of dye from water. Conclusion: UV radiation alone is a simple and efficient method for removal of Reactive Blue 203 from water. Removal of Reactive Blue 203 using Fe(VI) oxidation process can be completed in a fraction of second, therefore, it can be categorized as a rapid reaction.