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 50degreeC; 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
ABSTRACT
In spite of numerous studies on Fe[VI] capacity in treating wastewater, no equations are presented yet for the design of a Fe[VI] treatment facility. In most studies, Fe[VI] has been mentioned as the most effective substance for wastewater treatment; however, none is currently available about the operation costs in treatment facilities. This paper aims to introduce the necessary equations for the design and development of facilities that use Fe[VI] through the electrolysis methods and conduct the necessary calculations regarding its navigation costs. As the first step, a pilot plant test was conducted to find the basic information for municipal wastewater treatment by Fe[VI]. Then, all the costs pertaining to electricity, acid and sodium hydroxide used in the treatment process were calculated to evaluate the total navigation costs. Our results indicates that treatment of every cubic meter of municipal wastewater would bear the following costs: US $1.17 for Fe[VI] production, US$ 2.52 for reducing the pH below 2 and US$ 146 for the production of 14 M sodium hydroxide solution. The overall costs for such facility would be equal to US$ 149.7. As it is demonstrated, the generation of 14 M sodium hydroxide solution is the most expensive element in the treatment process. It appears that the aforementioned cost is very high for the municipal treatment facilities; however, it might be appropriate for wastewaters that are resistant to biological methods. Nevertheless, more research is still needed to address this issue
ABSTRACT
Background: human hair can be used as an inexpensive and accessible adsorbent to remove a variety of pollutants from air. Although several studies have been done on removal of formaldehyde from wastewater by human hair, to date no study has investigated using hair to remove formaldehyde from air. Therefore, the aim of this study was to remove formaldehyde from synthetic contaminated air by a reactor packed with human hair
Methods: air contaminated with formaldehyde was introduced into a cylindrical reactor packed with human hair at the initial concentration of 8500 mg/L. Formaldehyde concentration was measured in the influent and effluent of the reactor to indicate formaldehyde removal efficiency. Other measurements of parameters effective on formaldehyde removal were taken including amount of human hair and environmental temperature
Results: results of this study revealed that each gram of human hair was able to remove 0.13 to 0.49 g of formaldehyde from air. Human hair adsorbed 98% of formaldehyde from synthetic contaminated air under 20degreeC. These results demonstrate that increased temperature had a negative effect on formaldehyde removal
Conclusion: results of this study show that human hair can be applied as a simple and inexpensive adsorbent to remove formaldehyde from industrial air exhaust. In addition, results of these tests can be considered as a small step to promote better air quality
ABSTRACT
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
ABSTRACT
Unmanaged gasses emitted from the landfills can lead to various environmental and health problems for the resident of such regions. Despite various studies conducted on prediction of emission rates of gaseous pollutant in landfills, no study in currently being conducted on the emission rates of carbon dioxide, methane, and non-methane organic compounds from the Marvdasht landfills. In the first steps of this study the required information were gathered first and then the necessary prediction calculations were handled by the LandGEM software. The study results suggest that the within the years of 2003 and 2031, the generation rates of carbon dioxide, methane and non-methane organic compounds will respectively be equal to 14×10[11], 4667×10[7] and 3.89×10[5] tons. Among the aforementioned gasses, in case of converting the methane energy capacity into the electrical energy, a total income of 1489 billion rials is achievable from the Marvdasht landfill within a course of 27 years of operation. However, it should be noted that no investigation was conducted on the initial and operation costs in this study. In this study, by calculating all of the required information for the design and construction of a biogas collection and extraction system in the landfill of Marvdasht, the necessary means for the appliance of such plan has been provided
ABSTRACT
Background: The biogases are the mixture of gases produced through the microbial decomposition of organic waste which are amply observed in the landfills. The main purpose of this study was to estimate the emission rates of landfill gases such as carbon dioxide, methane and non-methane organic compounds [NMOCs] in the solid waste landfill of Rodan city in Hormozgan province
Methods: All the necessary information such as population, geographic and climate of Rodan city were collected. Solid waste analysis was then conducted. Afterward, the LandGEM software is used in this study for the purpose of estimation of total biogas, methane, carbon dioxide and NMOCs emission from Rodan's landfill
Results: The analysis of results showed that only 24.18% of the produced waste in this city is perishable. The calculations indicate that the peak of biogas production which is equal to 420 tons per year would be achieved in the year 2019. The production rates of carbon dioxide and methane in the same year would be equal to 308 and 112 tons per year respectively. The pollutants transmittance calculations in the vicinity of the landfill revealed that the maximum pollutant concentration is within the maximum distance of 200 m
Conclusion: The results obtained in this study could be used for the purpose of design and installation of extraction or incineration equipment in the landfill of Rodan