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: 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
Hippocampal damages, which are accompanied by inflammation, are among the main causes of epilepsy acquisition. We previously reported that chronic intracerebroventricular [i.c.v.] injection of lipopolysaccharide [LPS] modulates epileptogenesis in rats. There is a network of gap junction channels in the hippocampus that contribute to epileptogenesis. Gap junction channels are formed by oligomeric protein subunits called connexins [Cx]. Astrocytic Cx43 and neuronal Cx36 are expressed in the hippocampus. In order to find out the possible role of gap junctions in seizure-modulating effect of LPS and neuroinflammation, we studied the effect of central administration of LPS on expression of Cx36 and Cx43 in rat hippocampus. LPS, 2.5 micro g/rat/day, was injected i.c.v. to male Wistar rats for 14 days. mRNA and protein abundance of Cx36, Cx43 and IL1-beta were measured in rat hippocampus by real time-PCR, Western blot and ELISA techniques, at the beginning, in the middle, and at the end of the treatment period. IL1-beta protein level was significantly increased 6 h after first injection of LPS. Cx36 and Cx43 mRNA expression did not alter during chronic administration of LPS. A selective decrease in Cx43 protein expression was observed after 7 injections of LPS. It is suggested that Cx43 containing gap junctions in the hippocampus is down-regulated in response to chronic injection of LPS. This event can inhibit propagation of toxic and noxious molecules to neighboring cells and modulate hippocampal excitability and epileptogenesis