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Fedje K.K.,Chalmers University of Technology | Fedje K.K.,Renova AB | Stromvall A.-M.,Chalmers University of Technology
Science of the Total Environment | Year: 2015

Excavation followed by landfilling is one of the most common methods for treating soils contaminated with metals. Removing the metals through soil washing not only allows valuable substances to be recovered, but also results in cleaner soil residues. In this project a method for leaching and recovering Cu from polluted soils using acidic wastewater is further developed and evaluated, with special attention to the leaching process. In addition, the qualities of the soil residues are assessed in order to investigate how the proposed remediation method affects the soil properties. Soil samples highly polluted with copper (Cu) were collected from two sites in Sweden. After acidic leaching and water washing, the Cu content of the soil samples was reduced five times or more. The original soils could not even be deposited in landfills for hazardous waste; however after treatment of the soils according to the proposed method, the Cu leaching decreased six-fold and the solid residue was safe enough to be deposited in landfills for non-hazardous waste. The soil function "soil as filter and buffer for heavy metals" was evaluated using the TUSEC (technique for soil evaluation and categorization for natural and anthropogenic soils) manual. Originally the soils were of "low" i.e. class 4 or "very low capacity of binding and buffering heavy metals" i.e. class 5, while after the remediation process, both soils were categorized as Class 5. To summarize, the proposed method clearly shows potential not only for remediation of Cu polluted soils but also indicate a potential for recovery and reuse of Cu from the leachates generated. Even though the previously highly polluted soils could not be directly put back at the original sites, the solid residues could be deposited in landfills for non-hazardous waste, which is an improvement, considering the original soils could not even be deposited in a landfill for hazardous waste. © 2015 Elsevier B.V. Source


Gao B.,Atkins Consultants Shenzhen Co. | Fedje K.K.,Chalmers University of Technology | Fedje K.K.,Renova AB | Stromvall A.-M.,Chalmers University of Technology
Journal of Solid Waste Technology and Management | Year: 2015

Phosphorus (P) is an essential non-renewable resource and phosphorus recovery from secondary sources has been frequently discussed. In this study, a modified acidic dissolutionprecipitation method was developed for P recovery from sorted municipal solid waste incineration (MSWI) samples of bottom ash (BA) and fly ash (FA). The initial experiments revealed that 2 h leaching in 2.5 M HCl optimized P leaching. However, large amount of toxic metals was released. Solid phase extraction (SPE) of the leachates indicated that chelating disks removed the toxic trace metals effectively, but also extracted large amounts of P. For this reason, the procedure was not included in the suggested P recovery process. The P leaching efficiencies, i.e. the ratio of P leached from the original ash, were 30-57 %. The overall P recovery efficiencies, i.e. the ratio of P recovered from the original ash, were 33-62 %. The P content in the final precipitation products varied between 1% (BA) and 2% (FA). Although in Europe the precipitation product can be applied as a fertilizer without further treatment, this is not recommended until the amount of toxic trace metals has been reduced. However, it can serve as an alternative to low grade phosphate rock. Source


Fedje K.K.,Chalmers University of Technology | Fedje K.K.,Renova AB | Modin O.,Chalmers University of Technology | Stromvall A.-M.,Chalmers University of Technology
Metals | Year: 2015

Excavation followed by landfilling is the most common method for treating soils contaminated by metals. However, as this solution is not sustainable, alternative techniques are required. Chemical soil washing is one such alternative. The aim of this experimental lab-scale study is to develop a remediation and metal recovery method for Cu contaminated sites. The method is based on the washing of soil or ash (combusted soil/bark) with acidic waste liquids followed by electrolytic Cu recovery by means of bioelectrochemical systems (BES). The results demonstrate that a one- or two-step acidic leaching process followed by water washing removes >80 wt. % of the Cu. Copper with 99.7–99.9 wt. % purity was recovered from the acidic leachates using BES. In all experiments, electrical power was generated during the reduction of Cu. This clearly indicates that Cu can also be recovered from dilute solutions. Additionally, the method has the potential to wash co-pollutants such as polycyclic aromatic hydrocarbons (PAHs) and oxy-PAHs. © 2015, by the authors. Source


Karlfeldt Fedje K.,Renova AB | Karlfeldt Fedje K.,Chalmers University of Technology | Ekberg C.,Chalmers University of Technology | Skarnemark G.,Chalmers University of Technology | And 2 more authors.
Waste Management and Research | Year: 2012

Large volumes of ash from combustion of municipal solid waste are produced and most of it is landfilled. As this type of ash contains significant amounts of metal compounds the landfilling strategy is not optimal when considered from a resource conservation perspective. A better situation would be created if metals were recovered from the ash. In the present study leaching and solvent extraction was applied for release and separation of copper from municipal solid waste combustion fly ashes. The results showed promising results with Cu yields of 50-95%. The yield was heavily dependent on the efficiency of the initial leaching of Cu from the ash. © The Author(s) 2012. Source


Modin O.,Chalmers University of Technology | Wang X.,Chalmers University of Technology | Wu X.,Chalmers University of Technology | Rauch S.,Chalmers University of Technology | And 2 more authors.
Journal of Hazardous Materials | Year: 2012

In a microbial bioelectrochemical system (BES) living microorganisms catalyze the anodic oxidation of organic matter at a low anode potential. We used a BES with a biological anode to power the cathodic recovery of Cu, Pb, Cd, and Zn from a simulated municipal solid waste incineration ash leachate. By varying the control of the BES, the four metals could sequentially be recovered from a mixed solution by reduction on a titanium cathode. First, the cell voltage was controlled at zero, which allowed recovery of Cu from the solution without an electrical energy input. Second, the cathode potential was controlled at -0.51. V to recover Pb, which required an applied voltage of about 0.34. V. Third, the cathode potential was controlled at -0.66. V to recover Cd, which required an applied voltage of 0.51. V. Finally, Zn was the only metal remaining in solution and was recovered by controlling the anode at +0.2. V to maximize the generated current. The study is the first to demonstrate that a BES can be used for cathodic recovery of metals from a mixed solution, which potentially could be used not only for ash leachates but also for e.g. metallurgical wastewaters and landfill leachates. © 2012 Elsevier B.V. Source

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