Objective To investigate the biodegradation of tetrachloroethylene （PCE） by acclimated anaerobic sludge using different co-substrates, i.e., glucose, acetate, and lactate as electron donors. Methods HP-6890 gas chro...Objective To investigate the biodegradation of tetrachloroethylene （PCE） by acclimated anaerobic sludge using different co-substrates, i.e., glucose, acetate, and lactate as electron donors. Methods HP-6890 gas chromatograph （GC） in combination with auto-sampler was used to analyze the concentration of PCE and its intermediates, Results PCE could be degraded by reductive dechlorlnation and the degradation reaction conformed to the first-order kinetic equation. The rate constants are klaetate〉kglucose〉kacetate. The PCE degradation rate was the highest in the presence of lactate as an electron donor. Conclusion Lactate is the most suitable electron donor for PCE degradation and the electron donors supplied by co-metabolic substrates are not the limiting factors for PCE degradation,展开更多
A series of batch-type experiments with acetate acid as the primary substrate were performed using enrichment cultures developed from the anaerobic sludge to investigate the effect of acetate acid on tetrachloroethyle...A series of batch-type experiments with acetate acid as the primary substrate were performed using enrichment cultures developed from the anaerobic sludge to investigate the effect of acetate acid on tetrachloroethylene （PCE） biodegradation. Experimental results indicated that acetate acid was an efficient electron donor in affecting the biotransformability of PCE. Trichloroethylene （TCE） was the primary dehalogenation product, and small amounts of dichloroethylenes （DCEs） were also detected. No significant further DCEs degradation was detected. PCE degradation rate in the experiment was 36.6 times faster than background rate in natural groundwater.展开更多
Trichloroethylene (TCE) is a chlorinated liquid that is commonly used for metal degreasing, household and industrial dry cleaning, and in paints and glues. Tetrachloroethylene, also known as perchloroethylene (PCE), i...Trichloroethylene (TCE) is a chlorinated liquid that is commonly used for metal degreasing, household and industrial dry cleaning, and in paints and glues. Tetrachloroethylene, also known as perchloroethylene (PCE), is an excellent solvent for organic materials. PCE is volatile, highly stable, non-flammable and widely used in dry cleaning. A new method has been developed for measuring TCE and PCE in ambient air in real-time. Based upon the chemical fingerprinting and concentration levels, the method was able to isolate the source of the emissions to the responsible facility. Real-time monitoring was accomplished by utilizing a low pressure chemical ionization source (LPCI) interfaced to a tandem mass spectrometer (TAGA). Monitoring the response of specific parent/daughter ion pairs, the TAGA was used to measure concentrations of TCE and PCE. By optimizing various TAGA parameters, detection limits (DL) as low as 0.5 μg/m3 was achieved for TCE and PCE. Unlike methods using cartridge sampling and GC/MS analysis, this new method provides a real time measurement for a wide range of TCE and PCE concentrations. This unique method was applied in 2000 and 2002 to measure TCE emitted from a manufacturer of stainless steel tubing in Eastern Ontario. The maximum half-hour average concentration of TCE measured downwind of the facility was 1300 μg/m3 and the maximum instantaneous level was measured at 115,000 μg/m3. The information collected by the TAGA unit was used by the Standard Development Branch of Ontario Ministry of the Environment to adopt the half-hour Point of Impingement (POI) standard of TCE to be 36 μg/m3 in 2010. This method successfully identified and simultaneously measured TCE and PCE during a 2011 air monitoring survey of a hazardous waste disposal and treatment facility in Southern Ontario.展开更多
The effects of tetrachloroethylene (C2Cl4) on sphalerite leaching in FeCl3HCl were investigated in view of simultaneous mass transfer and reaction, and the leaching models with and without organic solvent C2Cl4 were d...The effects of tetrachloroethylene (C2Cl4) on sphalerite leaching in FeCl3HCl were investigated in view of simultaneous mass transfer and reaction, and the leaching models with and without organic solvent C2Cl4 were derived. The leaching experiments and the SEM results show that C2Cl4 is an effective organic solvent for sphalerite leaching in FeCl3HCl system to be accelerated and for the sulfur to be separated. Adding C2Cl4 in the FeCl3HCl medium will turn the kinetic model controlled by sulfur layer diffusion with process activation energy of 67.9 kJ/mol into mixed diffusion with the energy reduced to 55.1 kJ/mol when 20 ml of C2Cl4 was added.展开更多
基金This work was supported by the National Science Foundation of China (Grant No. 40102027 50325824 50578151 and BeijingNatural Science Foundation 8052017).
文摘Objective To investigate the biodegradation of tetrachloroethylene （PCE） by acclimated anaerobic sludge using different co-substrates, i.e., glucose, acetate, and lactate as electron donors. Methods HP-6890 gas chromatograph （GC） in combination with auto-sampler was used to analyze the concentration of PCE and its intermediates, Results PCE could be degraded by reductive dechlorlnation and the degradation reaction conformed to the first-order kinetic equation. The rate constants are klaetate〉kglucose〉kacetate. The PCE degradation rate was the highest in the presence of lactate as an electron donor. Conclusion Lactate is the most suitable electron donor for PCE degradation and the electron donors supplied by co-metabolic substrates are not the limiting factors for PCE degradation,
文摘A series of batch-type experiments with acetate acid as the primary substrate were performed using enrichment cultures developed from the anaerobic sludge to investigate the effect of acetate acid on tetrachloroethylene （PCE） biodegradation. Experimental results indicated that acetate acid was an efficient electron donor in affecting the biotransformability of PCE. Trichloroethylene （TCE） was the primary dehalogenation product, and small amounts of dichloroethylenes （DCEs） were also detected. No significant further DCEs degradation was detected. PCE degradation rate in the experiment was 36.6 times faster than background rate in natural groundwater.
文摘Trichloroethylene (TCE) is a chlorinated liquid that is commonly used for metal degreasing, household and industrial dry cleaning, and in paints and glues. Tetrachloroethylene, also known as perchloroethylene (PCE), is an excellent solvent for organic materials. PCE is volatile, highly stable, non-flammable and widely used in dry cleaning. A new method has been developed for measuring TCE and PCE in ambient air in real-time. Based upon the chemical fingerprinting and concentration levels, the method was able to isolate the source of the emissions to the responsible facility. Real-time monitoring was accomplished by utilizing a low pressure chemical ionization source (LPCI) interfaced to a tandem mass spectrometer (TAGA). Monitoring the response of specific parent/daughter ion pairs, the TAGA was used to measure concentrations of TCE and PCE. By optimizing various TAGA parameters, detection limits (DL) as low as 0.5 μg/m3 was achieved for TCE and PCE. Unlike methods using cartridge sampling and GC/MS analysis, this new method provides a real time measurement for a wide range of TCE and PCE concentrations. This unique method was applied in 2000 and 2002 to measure TCE emitted from a manufacturer of stainless steel tubing in Eastern Ontario. The maximum half-hour average concentration of TCE measured downwind of the facility was 1300 μg/m3 and the maximum instantaneous level was measured at 115,000 μg/m3. The information collected by the TAGA unit was used by the Standard Development Branch of Ontario Ministry of the Environment to adopt the half-hour Point of Impingement (POI) standard of TCE to be 36 μg/m3 in 2010. This method successfully identified and simultaneously measured TCE and PCE during a 2011 air monitoring survey of a hazardous waste disposal and treatment facility in Southern Ontario.
基金Supported by the National Science Foundation of China (No. 20276074)
文摘The effects of tetrachloroethylene (C2Cl4) on sphalerite leaching in FeCl3HCl were investigated in view of simultaneous mass transfer and reaction, and the leaching models with and without organic solvent C2Cl4 were derived. The leaching experiments and the SEM results show that C2Cl4 is an effective organic solvent for sphalerite leaching in FeCl3HCl system to be accelerated and for the sulfur to be separated. Adding C2Cl4 in the FeCl3HCl medium will turn the kinetic model controlled by sulfur layer diffusion with process activation energy of 67.9 kJ/mol into mixed diffusion with the energy reduced to 55.1 kJ/mol when 20 ml of C2Cl4 was added.
