Since the early 1980’s there have been several different strategies designed and applied to the remediation of subsurface environment including physical, chemical and biological approaches.They have had varying degre...Since the early 1980’s there have been several different strategies designed and applied to the remediation of subsurface environment including physical, chemical and biological approaches.They have had varying degrees of success in remediating contaminants from subsurface soils and groundwater.The objective of this review is to examine the range of technologies for the remediation of contaminants, particularly petroleum hydrocarbons, in subsurfaces with a specific focus on bioremediation and electrokinetic remediation.Further, this review examines the efficiency of remediation carried out by combining bioremediation and electrokinetic remediation.Surfactants, which are slowly becoming the selected chemicals for mobilizing contaminants, are also considered in this review.The current knowledge gaps of these technologies and techniques identified which could lead to development of more efficient ways of utilizing these technologies or development of a completely new technology.展开更多
As a new technology used for the cleaning of chromium-contaminated soil, worldwide interest in ele- trokinetic （EK） remediation has grown considerably in recent times. However, owing to the fact that chromium exists...As a new technology used for the cleaning of chromium-contaminated soil, worldwide interest in ele- trokinetic （EK） remediation has grown considerably in recent times. However, owing to the fact that chromium exists as both cationic and anionic species in the soil, it is not an efficient method. This paper reports upon a study in which a process using approaching anodes （AAs） was used to enhance the removal efficiency of chromium by eletrokinetics. Two bench-scale experiments to remove chromium from contaminated soil were performed, one using a fixed anode （FA） and the other using AAs. In the AAs experiment, the anode moved toward the cathode by 7 cm every three days. After remediation, soil pH, total chromium, and fractionation of chromium in the soil were determined. The average removal efficiency of total chromium was 11.32% and 18.96% in the FA and AAs experiments, respectively. After remediation, acidic soil conditions throughout the soil were generated through the use of AAs, while 80% of the soil remained neutral or alkalic when using the FA approach. The acidic soil environment and high field intensity in the AAs experi- ment might have favored chromium desorption, dissolu- tion and dissociation from the soil, plus the mobility of chromium in the soil was also enhanced. The results demonstrate that AAs used in the process of EK remediation can enhance the efficiency of chromium removal from soil.展开更多
The mature fine oil sand tailings(MFT) remain as slurry in the tailings pond for long time. The dewatering and consolidation of MFT for sustainable management is an important task for the mining industry. The objectiv...The mature fine oil sand tailings(MFT) remain as slurry in the tailings pond for long time. The dewatering and consolidation of MFT for sustainable management is an important task for the mining industry. The objective of this study is to accelerate electrokinetic settling of MFT solids in suspensions in presence of optimal coagulant. In the first phase, optimal coagulant and coagulant dosage for settling of suspension are identified, i.e., ferric chloride at 350 mg/L. It is found that the chemical treatment is not much effective; the final solid content of the sediment is only 6.48% from an initial of 5%. In the second phase,combined coagulation and electrokinetic treatment is carried out to enhance the settling effect. The direct electric current is applied in continuous and intermittent modes on MFT suspensions placed in electrokinetic cell. The results show the final solid content reaches 23.74% under the combined application of350 mg/L ferric chloride and 218.75 V/m applied voltage gradient in the continuous mode. The intermittent current mode with 40% save in power consumption produces a settled sediment having 20.84% final solid content.展开更多
Convenient non-invasive flow monitoring would facilitate the operation and control in microfluidic chips,but is challenging due to the small space of microchannels and complex operation required in traditional optical...Convenient non-invasive flow monitoring would facilitate the operation and control in microfluidic chips,but is challenging due to the small space of microchannels and complex operation required in traditional optical methods.In this work,we propose a novel non-invasive strategy to probe microfluidic flows via streaming potential phenomenon.By sealing one side of the microchannel with a piece of hydrogel film,streaming potential inside the channel can be clearly detected by electrodes at outer surface of the hydrogel due to ion diffusion in the hydrogel.Flow is detected without sensors contacting with the internal liquid.Moreover,the electrodes shape like a tiny probe,which can move around mapping the flow distribution in a chip with the spatial resolution of 1 mm and flow rate detection limit of 3μL·min–1.Bubbles inside the channels can also be detected,due to the fluctuation of streaming voltage when gas-liquid interface flows through the electrode,showing an easy and potential way for multi-functional flow monitoring in microfluidic chips.展开更多
基金funded through Cooperative Research Center for Contamination Assessment and Remediation of the Environment (CRC CARE)the University of Newcastle.
文摘Since the early 1980’s there have been several different strategies designed and applied to the remediation of subsurface environment including physical, chemical and biological approaches.They have had varying degrees of success in remediating contaminants from subsurface soils and groundwater.The objective of this review is to examine the range of technologies for the remediation of contaminants, particularly petroleum hydrocarbons, in subsurfaces with a specific focus on bioremediation and electrokinetic remediation.Further, this review examines the efficiency of remediation carried out by combining bioremediation and electrokinetic remediation.Surfactants, which are slowly becoming the selected chemicals for mobilizing contaminants, are also considered in this review.The current knowledge gaps of these technologies and techniques identified which could lead to development of more efficient ways of utilizing these technologies or development of a completely new technology.
文摘As a new technology used for the cleaning of chromium-contaminated soil, worldwide interest in ele- trokinetic （EK） remediation has grown considerably in recent times. However, owing to the fact that chromium exists as both cationic and anionic species in the soil, it is not an efficient method. This paper reports upon a study in which a process using approaching anodes （AAs） was used to enhance the removal efficiency of chromium by eletrokinetics. Two bench-scale experiments to remove chromium from contaminated soil were performed, one using a fixed anode （FA） and the other using AAs. In the AAs experiment, the anode moved toward the cathode by 7 cm every three days. After remediation, soil pH, total chromium, and fractionation of chromium in the soil were determined. The average removal efficiency of total chromium was 11.32% and 18.96% in the FA and AAs experiments, respectively. After remediation, acidic soil conditions throughout the soil were generated through the use of AAs, while 80% of the soil remained neutral or alkalic when using the FA approach. The acidic soil environment and high field intensity in the AAs experi- ment might have favored chromium desorption, dissolu- tion and dissociation from the soil, plus the mobility of chromium in the soil was also enhanced. The results demonstrate that AAs used in the process of EK remediation can enhance the efficiency of chromium removal from soil.
基金the support of The University of Western Ontario and the Natural Science and Engineering Research Council of Canada (NSERC)
文摘The mature fine oil sand tailings(MFT) remain as slurry in the tailings pond for long time. The dewatering and consolidation of MFT for sustainable management is an important task for the mining industry. The objective of this study is to accelerate electrokinetic settling of MFT solids in suspensions in presence of optimal coagulant. In the first phase, optimal coagulant and coagulant dosage for settling of suspension are identified, i.e., ferric chloride at 350 mg/L. It is found that the chemical treatment is not much effective; the final solid content of the sediment is only 6.48% from an initial of 5%. In the second phase,combined coagulation and electrokinetic treatment is carried out to enhance the settling effect. The direct electric current is applied in continuous and intermittent modes on MFT suspensions placed in electrokinetic cell. The results show the final solid content reaches 23.74% under the combined application of350 mg/L ferric chloride and 218.75 V/m applied voltage gradient in the continuous mode. The intermittent current mode with 40% save in power consumption produces a settled sediment having 20.84% final solid content.
基金supported by the National Natural Science Foundation of China(Grant Nos.51976141,52006123,62161160311).
文摘Convenient non-invasive flow monitoring would facilitate the operation and control in microfluidic chips,but is challenging due to the small space of microchannels and complex operation required in traditional optical methods.In this work,we propose a novel non-invasive strategy to probe microfluidic flows via streaming potential phenomenon.By sealing one side of the microchannel with a piece of hydrogel film,streaming potential inside the channel can be clearly detected by electrodes at outer surface of the hydrogel due to ion diffusion in the hydrogel.Flow is detected without sensors contacting with the internal liquid.Moreover,the electrodes shape like a tiny probe,which can move around mapping the flow distribution in a chip with the spatial resolution of 1 mm and flow rate detection limit of 3μL·min–1.Bubbles inside the channels can also be detected,due to the fluctuation of streaming voltage when gas-liquid interface flows through the electrode,showing an easy and potential way for multi-functional flow monitoring in microfluidic chips.
