This investigation was carried out to establish a new domestic landfill gas(LFG)generation rate model that takes into account the impact of leachate recirculation.The first-order kinetics and two-stage reaction(FKTSR)...This investigation was carried out to establish a new domestic landfill gas(LFG)generation rate model that takes into account the impact of leachate recirculation.The first-order kinetics and two-stage reaction(FKTSR)model of the LFG generation rate includes mechanisms of the nutrient balance for biochemical reaction in two main stages.In this study,the FKTSR model was modified by the introduction of the outflow function and the organic acid conversion coefficient in order to represent the in-situ condition of nutrient loss through leachate.Laboratory experiments were carried out to simulate the impact of leachate recirculation and verify the modified FKTSR model.The model calibration was then calculated by using the experimental data.The results suggested that the new model was in line with the experimental data.The main parameters of the modified FKTSR model,including the LFG production potential(L0),the reaction rate constant in the first stage(K1),and the reaction rate constant in the second stage(K2)of 64.746 L,0.202 d^(–1),and 0.338 d^(–1),respectively,were comparable to the old ones of 42.069 L,0.231 d^(–1),and 0.231 d^(–1).The new model is better able to explain the mechanisms involved in LFG generation.展开更多
Electrochemical oxidation of polyethylene glycol(PEG) in an acidic(pH 0.18 to 0.42) and high ionic strength electroplating solution was investigated. The electroplating solution is a major source of wastewater in the ...Electrochemical oxidation of polyethylene glycol(PEG) in an acidic(pH 0.18 to 0.42) and high ionic strength electroplating solution was investigated. The electroplating solution is a major source of wastewater in the printing wiring board industry. A paraffin composite copper hexacyanoferrate modified(PCCHM) electrode was used as the anode and a bare graphite electrode was used as the cathode. The changes in PEG and total organic carbon(TOC) concentrations during the course of the reaction were monitored. The efficiency of the PCCHM anode was compared with bare graphite anode and it was found that the former showed significant electrocatalytic property for PEG and TOC removal. Chlorides present in the solution were found to contribute significantly in the overall organic removal process. Short chain organic compounds like acetic acid, oxalic acid, formic acid and ethylene glycol formed during electrolysis were identified by HPLC method. Anode surface area and applied current density were found to influence the electro-oxidation process, in which the former was found to be dominating. Investigations of the kinetics for the present electrochemical reaction suggested that the two stage first-order kinetic model provides a much better representation of the overall mechanism of the process if compared to the generalized kinetic model.展开更多
In order to design and predict the dechlorination processes for remediating the halogenated aromatic com- pounds in the biobarrier system applied in situ, an anaerobic continuous-flow column was set up with the introd...In order to design and predict the dechlorination processes for remediating the halogenated aromatic com- pounds in the biobarrier system applied in situ, an anaerobic continuous-flow column was set up with the introduction of an enriched 2, 4, 6-trichlorophenol （TCP） reductive dechlorinating consortium. The fates of TCP and its metabo- lites were simulated according to the first-order sequential dechlorination kinetic model. The enriched TCP anaerobic dechlorinating consortium dechlorinated 100 p.mol/L TCP to 4-chlorophenol （4-CP） via 2,4-dichlorophenol （DCP） in 10 d. The consortium was predominated with the phylum of Firmicutes and Bacteroidetes, based on the PCR- denaturing gradient gel electrophoresis （DGGE） analysis. After the consortium was applied to the colunm, the ex- perimental data in the steady state were fitted by the least square method, and the first-order dechlorination kinetic constants from TCP to 2,4-DCP, from 2,4-DCP to 4-CP and from 4-CP to phenol, were 1.58 d-1, 2.23 d 1 and 0.206 d-1, respectively. According to the fitting results, the required biobarrier width for the complete remediation of TCP, 2,4- DCP and 4-CP were 126 cm, 130 cm and 689 cm, respectively. The dechlorination/degradation of 4-CP must be in- creased when the technology is applied to the real site.展开更多
基金the Specialized Research Fund for the Doctoral Program of Higher Education(No.20050027002)。
文摘This investigation was carried out to establish a new domestic landfill gas(LFG)generation rate model that takes into account the impact of leachate recirculation.The first-order kinetics and two-stage reaction(FKTSR)model of the LFG generation rate includes mechanisms of the nutrient balance for biochemical reaction in two main stages.In this study,the FKTSR model was modified by the introduction of the outflow function and the organic acid conversion coefficient in order to represent the in-situ condition of nutrient loss through leachate.Laboratory experiments were carried out to simulate the impact of leachate recirculation and verify the modified FKTSR model.The model calibration was then calculated by using the experimental data.The results suggested that the new model was in line with the experimental data.The main parameters of the modified FKTSR model,including the LFG production potential(L0),the reaction rate constant in the first stage(K1),and the reaction rate constant in the second stage(K2)of 64.746 L,0.202 d^(–1),and 0.338 d^(–1),respectively,were comparable to the old ones of 42.069 L,0.231 d^(–1),and 0.231 d^(–1).The new model is better able to explain the mechanisms involved in LFG generation.
文摘Electrochemical oxidation of polyethylene glycol(PEG) in an acidic(pH 0.18 to 0.42) and high ionic strength electroplating solution was investigated. The electroplating solution is a major source of wastewater in the printing wiring board industry. A paraffin composite copper hexacyanoferrate modified(PCCHM) electrode was used as the anode and a bare graphite electrode was used as the cathode. The changes in PEG and total organic carbon(TOC) concentrations during the course of the reaction were monitored. The efficiency of the PCCHM anode was compared with bare graphite anode and it was found that the former showed significant electrocatalytic property for PEG and TOC removal. Chlorides present in the solution were found to contribute significantly in the overall organic removal process. Short chain organic compounds like acetic acid, oxalic acid, formic acid and ethylene glycol formed during electrolysis were identified by HPLC method. Anode surface area and applied current density were found to influence the electro-oxidation process, in which the former was found to be dominating. Investigations of the kinetics for the present electrochemical reaction suggested that the two stage first-order kinetic model provides a much better representation of the overall mechanism of the process if compared to the generalized kinetic model.
基金Supported by Grant-in-Aids for Scientific Research from the Ministry of Education,Culture,Sports,Science and Technology of Japan (No.23310055 and No.23658272)
文摘In order to design and predict the dechlorination processes for remediating the halogenated aromatic com- pounds in the biobarrier system applied in situ, an anaerobic continuous-flow column was set up with the introduction of an enriched 2, 4, 6-trichlorophenol （TCP） reductive dechlorinating consortium. The fates of TCP and its metabo- lites were simulated according to the first-order sequential dechlorination kinetic model. The enriched TCP anaerobic dechlorinating consortium dechlorinated 100 p.mol/L TCP to 4-chlorophenol （4-CP） via 2,4-dichlorophenol （DCP） in 10 d. The consortium was predominated with the phylum of Firmicutes and Bacteroidetes, based on the PCR- denaturing gradient gel electrophoresis （DGGE） analysis. After the consortium was applied to the colunm, the ex- perimental data in the steady state were fitted by the least square method, and the first-order dechlorination kinetic constants from TCP to 2,4-DCP, from 2,4-DCP to 4-CP and from 4-CP to phenol, were 1.58 d-1, 2.23 d 1 and 0.206 d-1, respectively. According to the fitting results, the required biobarrier width for the complete remediation of TCP, 2,4- DCP and 4-CP were 126 cm, 130 cm and 689 cm, respectively. The dechlorination/degradation of 4-CP must be in- creased when the technology is applied to the real site.
