A novel outside cycle anaerobic reactor was developed based on the characteristics of expanded granular sludge bed(EGSB) and other anaerobic reactors.It was demonstrated that the sludge wash-off at high liquid upflow ...A novel outside cycle anaerobic reactor was developed based on the characteristics of expanded granular sludge bed(EGSB) and other anaerobic reactors.It was demonstrated that the sludge wash-off at high liquid upflow velocities could be controlled efficiently and good performance was achieved during municipal wastewater treatment.In order to achieve accurate prediction and effective control of sludge settling property in the reactor developed,a dispersion model was established on the basis of mass balance and free settling theory of granular sludge,taking consideration of the relevance between sludge settling velocity and sludge concentration.The simulation results of sludge distribution was in good agreement with the measured results at different liquid upflow velocities.In addition,the concentration of suspended solids(SS) in the effluent was simulated by introducing the separation efficiency of three-phase separator.The standard deviation of the simulated data was less than 6%.Based on the relative concentration of the liquid-sludge mixture,the sludge blanket height could be calculated by quadratic interpolation.The sludge blanket heights were basically identical at various upflow velocities,while the sludge concentrations at the same height differed.展开更多
Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen （COD/TN） ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work...Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen （COD/TN） ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work, a novel sequencing batch biofilm reactor （NSBBR） was developed to enhance the nitrogen removal from wastewater with low COD/ TN ratio. The NSBBR was divided into two units separated by a vertical clapboard. Alternate feeding and aeration was performed in the two units, which created an anoxie unit with rich substrate content and an aeration unit deficient in substrate simultaneously. Therefore, the utilization of the influent carbon source for denitrification was increased, leading to higher TN removal compared to conventional SBBR （CSBBR） operation. The results show that the CSBBR removed up to 76.8%, 44.5% and 10.4% of TN, respectively, at three tested COD/TN ratios （9.0, 4.8 and 2.5）. In contrast, the TN removal of the NSBBR could reach 81.9%, 60.5% and 26.6%, respectively, at the corresponding COD/TN ratios. Therefore, better TN removal performance could be achieved in the NSBBR, especially at low CODfrN ratios （4.8 and 2.5）. Furthermore, it is easy to upgrade a CSBBR into an NSBBR in practice.展开更多
Efficient mixing and thermal control are important in the flow reactor for obtaining a high product yield and selectivity.Here,we report a heterogeneous chemical kinetic study of propene oxidation within a newly desig...Efficient mixing and thermal control are important in the flow reactor for obtaining a high product yield and selectivity.Here,we report a heterogeneous chemical kinetic study of propene oxidation within a newly designed catalytic jet-stirred reactor(CJSR).To better understand the interplay between the catalytic performances and properties,the CuO thin films have been characterized and the adsorbed energies of propene on the adsorbed and lattice oxygen were calculated using density functional theory(DFT)method.Structure and morphology analyses revealed a monoclinic structure with nano-crystallite size and porous microstructure,which is responsible for holding an important quantity of adsorbed oxygen.The residence time inside the flow CJSR(1.12–7.84 s)makes it suitable for kinetic study and gives guidance for scale-up.The kinetic study revealed that using CJSR the reaction rate increases with O_2concentration that is commonly not achievable for catalytic flow tube reactor,whereas the reaction rate tends to increase slightly above 30%of O_2due to the catalyst surface saturation.Moreover,DFT calculations demonstrated that adsorbed oxygen is the most involved oxygen,and it has found that the pathway of producing propene oxide makes the reaction of C_3H_6over CuO surface more likely to proceed.Accordingly,these findings revealed that CJSR combined with theoretical calculation is suitable for kinetic study,which can pave the way to investigate the kinetic study of other exhaust gases.展开更多
文摘A novel outside cycle anaerobic reactor was developed based on the characteristics of expanded granular sludge bed(EGSB) and other anaerobic reactors.It was demonstrated that the sludge wash-off at high liquid upflow velocities could be controlled efficiently and good performance was achieved during municipal wastewater treatment.In order to achieve accurate prediction and effective control of sludge settling property in the reactor developed,a dispersion model was established on the basis of mass balance and free settling theory of granular sludge,taking consideration of the relevance between sludge settling velocity and sludge concentration.The simulation results of sludge distribution was in good agreement with the measured results at different liquid upflow velocities.In addition,the concentration of suspended solids(SS) in the effluent was simulated by introducing the separation efficiency of three-phase separator.The standard deviation of the simulated data was less than 6%.Based on the relative concentration of the liquid-sludge mixture,the sludge blanket height could be calculated by quadratic interpolation.The sludge blanket heights were basically identical at various upflow velocities,while the sludge concentrations at the same height differed.
基金supported by the Project of Science and Technology of Zhejiangthe National Natural Science Foundation of China (No. 50878195)
文摘Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen （COD/TN） ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work, a novel sequencing batch biofilm reactor （NSBBR） was developed to enhance the nitrogen removal from wastewater with low COD/ TN ratio. The NSBBR was divided into two units separated by a vertical clapboard. Alternate feeding and aeration was performed in the two units, which created an anoxie unit with rich substrate content and an aeration unit deficient in substrate simultaneously. Therefore, the utilization of the influent carbon source for denitrification was increased, leading to higher TN removal compared to conventional SBBR （CSBBR） operation. The results show that the CSBBR removed up to 76.8%, 44.5% and 10.4% of TN, respectively, at three tested COD/TN ratios （9.0, 4.8 and 2.5）. In contrast, the TN removal of the NSBBR could reach 81.9%, 60.5% and 26.6%, respectively, at the corresponding COD/TN ratios. Therefore, better TN removal performance could be achieved in the NSBBR, especially at low CODfrN ratios （4.8 and 2.5）. Furthermore, it is easy to upgrade a CSBBR into an NSBBR in practice.
基金financial support from the Ministry of Science and Technology of China (2017YFA0402800)the National Natural Science Foundation of China (51476168 and 91541102)+1 种基金Recruitment Program of Global Youth Expertsthe support of Chinese Academy of Sciences for senior international scientists within the framework of PIFI program (2017PE0009)
文摘Efficient mixing and thermal control are important in the flow reactor for obtaining a high product yield and selectivity.Here,we report a heterogeneous chemical kinetic study of propene oxidation within a newly designed catalytic jet-stirred reactor(CJSR).To better understand the interplay between the catalytic performances and properties,the CuO thin films have been characterized and the adsorbed energies of propene on the adsorbed and lattice oxygen were calculated using density functional theory(DFT)method.Structure and morphology analyses revealed a monoclinic structure with nano-crystallite size and porous microstructure,which is responsible for holding an important quantity of adsorbed oxygen.The residence time inside the flow CJSR(1.12–7.84 s)makes it suitable for kinetic study and gives guidance for scale-up.The kinetic study revealed that using CJSR the reaction rate increases with O_2concentration that is commonly not achievable for catalytic flow tube reactor,whereas the reaction rate tends to increase slightly above 30%of O_2due to the catalyst surface saturation.Moreover,DFT calculations demonstrated that adsorbed oxygen is the most involved oxygen,and it has found that the pathway of producing propene oxide makes the reaction of C_3H_6over CuO surface more likely to proceed.Accordingly,these findings revealed that CJSR combined with theoretical calculation is suitable for kinetic study,which can pave the way to investigate the kinetic study of other exhaust gases.
