Hydrogen sulfide and organic compounds removal in municipal wastewater using ferrate (VI) and ultraviolet radiation

Abstract

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.

Comparing the ZnO/Fe(VI), UV/ZnO and UV/Fe(VI) processes for removal of Reactive Blue 203 from aqueous solution

“…UV is a powerful radiation that is applied for wastewater treatment alone or with photocatalytic oxidants (31). Talaiekhozani et al reported that UV radiation can be efficiently used to remove hydrogen sulfide from municipal wastewater (32). Using UV radiation with photocatalytic oxidants such as ZnO or TiO 2 can improve pollutants removal (33).…”

Comparison of Azithromycin Removal from Water Using UV Radiation, Fe (VI) Oxidation Process and ZnO Nanoparticles

“…By increasing the pH from 11 to 13, the efficiency of antibiotic removal was reduced from 41% to 15% using UV radiation. As reported by [48], an increase of pH causes an increase in the removal efficiency of organic compounds and hydrogen sulfide by UV radiation. Moreover, [32] found that the optimal pH for the removal of 1, 9-Dimethyl-Methylene Blue Zinc Chloride Double Salt by UV irradiation was in the range of 9.8 to 13.5.…”

“…The relationship between pH and antibiotic removal efficiency by Fe (VI) can be described using the equation y = −0.0509x + 0.716 with an R 2 of 0.95. Several studies have reported similar results for the removal of hydrogen sulfide and organic compounds from domestic wastewater and formaldehyde from synthetic wastewater using Fe (VI) [48,52].…”

“…Advanced oxidation processes are a set of chemical treatment procedures designed to remove organic materials from water by oxidation through reactions with hydroxyl radicals. pH is one of the most important parameters affecting chemical reactions in this method [48]. The results showed that increasing the pH was an important parameter in the removal of antibiotic by the Fe (VI) oxidation process.…”

“…Meanwhile, by increasing the UV-radiation power to 163 mW/cm 2 , the removal efficiency reached 41%. Some other studies have shown that increasing UV power could strongly increase the pollutant removal efficacy [48]. For instance, the photo-electro-Fenton process can be used for the removal of metronidazole from wastewater.…”