Removal of sediment whether from navigation channels or for specific construction projects,requires dredging.In Denmark,current options are to bypass the dredged marine sediment,use it(e.g.filling or feeding coast),or...Removal of sediment whether from navigation channels or for specific construction projects,requires dredging.In Denmark,current options are to bypass the dredged marine sediment,use it(e.g.filling or feeding coast),or if the sediment cannot be used for any of these purposed or is contaminated(but below relevant action levels),it is typically dumped at sea.This option can have adverse impacts for the ecosystems receiving the sediment,yet in Denmark,most of the dredged marine sediment is dumped at sea.Instead of being regarded as a waste,dredged marine sediment needs to be considered a valuable resource.In this way,dredged marine sediment can benefit society and the environment,and have a'beneficial use'.The reasons why beneficial use of sediments is not yet a common practice is many folds and requires a change to long-established dredging and dumping practices.In this article we will update options for beneficial use of dredged marine sediment that are available worldwide,while as much as possible suggesting its applicability in Denmark as an example to hopefully stimulate beneficial use practices of dredged marine sediment.展开更多
Beneficiation study on samples of baryte ore from Azare in the Plateau State of Nigeria was carried out using chemical analysis, atomic absorption spectrophotometric analysis, jigging and magnetic separation. Results...Beneficiation study on samples of baryte ore from Azare in the Plateau State of Nigeria was carried out using chemical analysis, atomic absorption spectrophotometric analysis, jigging and magnetic separation. Results show that Azare baryte can profitably be concentrated for use in oil drilling and other industrial purposes. Barium sulphate content in the head ore analyzed, is 98%. Comparison between jigging and magnetic separation shows that jigging produces a more satisfactory result.展开更多
<span style="font-family:Verdana;">Rural communities in sub</span><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span>...<span style="font-family:Verdana;">Rural communities in sub</span><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span><span style="font-family:Verdana;">Saharan Africa (SSA) are always faced with the challenge of securing safe water for beneficial uses. Most communities lack a centralized water supply system and, thus, each residence utilizes the treatment method that they can afford. This study evaluated three treatment methods for drinking water in the Njala University and Mokonde communities in southern Sierra Leone. In the perceived natural treatment, residents in the Mokonde community believe that groundwater has been purified by the soil media and, hence, does not require further treatment. In the conventional treatment, the Njala University Water Works use sand filtration and chlorine disinfection to treat water from the Taia River. The third treatment method, first flush diversion, was introduced by Njala University researchers in 2014. We studied the populations of coliform bacteria and </span><i><span style="font-family:Verdana;">E. coli</span></i><span style="font-family:Verdana;"> in untreated and treated water samples to determine if each of the treatment methods supported the beneficial use of drinking. This study concludes that the natural filtration does not remove pathogens in the well water. Even though the first flush and conventional treatments were efficient in reducing microbial populations in the water, the World Health Organization’s 100% removal guideline was not achieved most of the time. Therefore, all three treatment methods did not support the beneficial use of drinking. Further treatment was needed to render the water potable.展开更多
As species we humans generate excessive amounts of waste and hence for sustainability we should explore innovative ways to recover them.The primary objective of this study is to demonstrate an efficient and optimum wa...As species we humans generate excessive amounts of waste and hence for sustainability we should explore innovative ways to recover them.The primary objective of this study is to demonstrate an efficient and optimum way to recover chromium and iron from chromite ore processing residues(COPR)for the production of chrome steel and stainless steel.In Hudson County,New Jersey,there are more than two million tons of leftover COPR.Part of COPR was used as fill materials for construction sites,which spread the problem to a larger area.With high solubility along with their toxicity leached chromate from COPR is threatening the environment as well as human health.In this research,COPR was thermally treated to recover iron with chromium by applying techniques used in steel manufacturing.An extensive experimental program was performed using a Thermo-Gravimetric Analyzer(TGA)and bench scale tests to thermally treat the processed chromium contaminated soils with carbon and sand at varying temperatures and under reducing environment.The optimum chemical composition of COPR and additives to be used in the melts were evaluated based upon the thermodynamic properties of the mixture to ensure good phase separation,least amounts of iron and chromium oxides in the slag and minimum variability of final product(steel or iron with chromium).The impact of other oxides on the steel making process was evaluated to minimize the adverse impact on the process.The research demonstrated the feasibility of recovering a valuable construction material(chrome steel)from a waste(COPR).展开更多
基金During the drafting of the manuscript C.L.received funding from the Independent Research Fund Denmark Grant No.1127-00033B.
文摘Removal of sediment whether from navigation channels or for specific construction projects,requires dredging.In Denmark,current options are to bypass the dredged marine sediment,use it(e.g.filling or feeding coast),or if the sediment cannot be used for any of these purposed or is contaminated(but below relevant action levels),it is typically dumped at sea.This option can have adverse impacts for the ecosystems receiving the sediment,yet in Denmark,most of the dredged marine sediment is dumped at sea.Instead of being regarded as a waste,dredged marine sediment needs to be considered a valuable resource.In this way,dredged marine sediment can benefit society and the environment,and have a'beneficial use'.The reasons why beneficial use of sediments is not yet a common practice is many folds and requires a change to long-established dredging and dumping practices.In this article we will update options for beneficial use of dredged marine sediment that are available worldwide,while as much as possible suggesting its applicability in Denmark as an example to hopefully stimulate beneficial use practices of dredged marine sediment.
文摘Beneficiation study on samples of baryte ore from Azare in the Plateau State of Nigeria was carried out using chemical analysis, atomic absorption spectrophotometric analysis, jigging and magnetic separation. Results show that Azare baryte can profitably be concentrated for use in oil drilling and other industrial purposes. Barium sulphate content in the head ore analyzed, is 98%. Comparison between jigging and magnetic separation shows that jigging produces a more satisfactory result.
文摘<span style="font-family:Verdana;">Rural communities in sub</span><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span><span style="font-family:Verdana;">Saharan Africa (SSA) are always faced with the challenge of securing safe water for beneficial uses. Most communities lack a centralized water supply system and, thus, each residence utilizes the treatment method that they can afford. This study evaluated three treatment methods for drinking water in the Njala University and Mokonde communities in southern Sierra Leone. In the perceived natural treatment, residents in the Mokonde community believe that groundwater has been purified by the soil media and, hence, does not require further treatment. In the conventional treatment, the Njala University Water Works use sand filtration and chlorine disinfection to treat water from the Taia River. The third treatment method, first flush diversion, was introduced by Njala University researchers in 2014. We studied the populations of coliform bacteria and </span><i><span style="font-family:Verdana;">E. coli</span></i><span style="font-family:Verdana;"> in untreated and treated water samples to determine if each of the treatment methods supported the beneficial use of drinking. This study concludes that the natural filtration does not remove pathogens in the well water. Even though the first flush and conventional treatments were efficient in reducing microbial populations in the water, the World Health Organization’s 100% removal guideline was not achieved most of the time. Therefore, all three treatment methods did not support the beneficial use of drinking. Further treatment was needed to render the water potable.
基金The work described in this study was supported by a research contract from the New Jersey Department of Environmental Protection.
文摘As species we humans generate excessive amounts of waste and hence for sustainability we should explore innovative ways to recover them.The primary objective of this study is to demonstrate an efficient and optimum way to recover chromium and iron from chromite ore processing residues(COPR)for the production of chrome steel and stainless steel.In Hudson County,New Jersey,there are more than two million tons of leftover COPR.Part of COPR was used as fill materials for construction sites,which spread the problem to a larger area.With high solubility along with their toxicity leached chromate from COPR is threatening the environment as well as human health.In this research,COPR was thermally treated to recover iron with chromium by applying techniques used in steel manufacturing.An extensive experimental program was performed using a Thermo-Gravimetric Analyzer(TGA)and bench scale tests to thermally treat the processed chromium contaminated soils with carbon and sand at varying temperatures and under reducing environment.The optimum chemical composition of COPR and additives to be used in the melts were evaluated based upon the thermodynamic properties of the mixture to ensure good phase separation,least amounts of iron and chromium oxides in the slag and minimum variability of final product(steel or iron with chromium).The impact of other oxides on the steel making process was evaluated to minimize the adverse impact on the process.The research demonstrated the feasibility of recovering a valuable construction material(chrome steel)from a waste(COPR).
