In order to obtain the reasonable operating conditions and minimize the power consumption in the stirred bioreactor, the hydrodynamic experiments in the stirred bioreactor have been taken to obtain the basic data. Sub...In order to obtain the reasonable operating conditions and minimize the power consumption in the stirred bioreactor, the hydrodynamic experiments in the stirred bioreactor have been taken to obtain the basic data. Subsequently, an Eulerian model for the gas–liquid–solid three phase flow in the stirred bioreactor has been proposed and the CFD simulation has been conducted. By comparing the results of experiment and simulation, it can be concluded that the simulation results were consistent with the experimental data. The inner relationship between operating variables and indicators could be obtained by comparing the results of just suspension speed, gas holdup, power consumption and operational maps, further the reasonable operating conditions could be also determined under the minimum power consumption. The operational maps could provide the theoretical foundation for industrial application of the gas–liquid–solid stirred bioreactors under the low solid concentration(no more than 20 wt%).展开更多
Instantaneous flow field and temperature field of the two-phase fluid are measured by particle image velocimetry （PIV） and steady state method during the state of onflow. A turbulent two-phase fluid model of stirred...Instantaneous flow field and temperature field of the two-phase fluid are measured by particle image velocimetry （PIV） and steady state method during the state of onflow. A turbulent two-phase fluid model of stirred bioreactor with punched impeller is established by the computational fluid dynamics （CFD）, using a rotating coordinate system and sliding mesh to describe the relative motion between impeller and baffles. The simulation and experiment results of flow and temperature field prove their warps are less than 10% and the mathematic model can well simulate the fields, which will also provide the study on optimized-design and scale-up of bioreactors with reference value.展开更多
-In plant cell culture on large scale,we have studied two types of biore-actors-Airlift reactor and stirred tank reactor-under the same volume and work conditions. It shows that the value of volumetric oxygen transfer...-In plant cell culture on large scale,we have studied two types of biore-actors-Airlift reactor and stirred tank reactor-under the same volume and work conditions. It shows that the value of volumetric oxygen transfer coefficient K1a in airlift is a little higher than that in stirred tank reactor at the aeration rate of 0.1~0.3vvm:the mixing time tm in both of them is small respect to the culture period.The shear stress in stirred tank reactor is higher than that in airlift reactor,but its influence is not negative at all. When the value or the shear stress in medium is low-er than a critical value,it will be favorable to the dispersion of cells and promotes the growth of cells.This result is verified in the experiment we have conducted in the airlift reactor and stirred tank reactor.展开更多
Numerical simulations of turbulent flows in a stirred dead-end membrane bioreactor are performed by using the RNG k-? model based on the finite volume method with the software Fluent. Comparisons of numerical and expe...Numerical simulations of turbulent flows in a stirred dead-end membrane bioreactor are performed by using the RNG k-? model based on the finite volume method with the software Fluent. Comparisons of numerical and experimental results confirm the reliability and the feasibility of the constructed model. The flow structures such as the wake flows and the circulation loops in the stirred flows are well simulated. An increase of stirring speed is proposed to minimize the low velocity region. The single vane stirrer is found to be beneficial for biological separations. Results suggest that the increase of the vane number can enhance the mixing effect in the flow domains. However, a circular disk stirrer goes against the formation of vertical circulations. The six-vane stirrer is found to be able to provide a uniform distribution of the high shear stress.展开更多
Two anaerobic membrane bioreactors(AnMBRs)equipped with different membrane pore size(0.4 or 0.05μm)were operated at 25℃and fed with domestic wastewater.The hydraulic retention time(HRT)of the reactors was shortened....Two anaerobic membrane bioreactors(AnMBRs)equipped with different membrane pore size(0.4 or 0.05μm)were operated at 25℃and fed with domestic wastewater.The hydraulic retention time(HRT)of the reactors was shortened.The microbial communities of the two AnMBRs were investigated by 16S rRNA gene amplicon sequencing to see the effects of HRT.The predominant Archaea was an aceticlastic methanogen Methanosaeta.The composition of hydrogenotrophic methanogens changed with the HRTs:the population of Methanobacterium was higher for longer HRTs,whereas the population of unclassified Methanoregulaceae was higher for shorter HRTs.The Anaerolineae,Bacteroidia and Clostridia bacteria were dominant in both of the reactors,with a combined relative abundance of over 55%.The relative abundance of Anaerolineae was proportional to the biogas production performance.The change in the population of hydrogenotrophic methanogens or Anaerolineae can be used as an indicator for process monitoring.The sum of the relative abundance of Anaerolineae and Clostridia fluctuated slightly with changes in the HRT in both AnMBRs when the reactor was stably operated.The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage.A principal coordination analysis revealed that the changes in the microbial community in each reactor were consistent with the change of HRT.In addition,both the HRT and the stability of the process are important factors for maintaining microbial community structures.展开更多
基金Supported by the National Natural Science Foundation of China(21476049,21506033)Department of Science and Technology of Fujian Province,China(2014R1004-3,2015J01052,2016H4023 and FG-2016005)
文摘In order to obtain the reasonable operating conditions and minimize the power consumption in the stirred bioreactor, the hydrodynamic experiments in the stirred bioreactor have been taken to obtain the basic data. Subsequently, an Eulerian model for the gas–liquid–solid three phase flow in the stirred bioreactor has been proposed and the CFD simulation has been conducted. By comparing the results of experiment and simulation, it can be concluded that the simulation results were consistent with the experimental data. The inner relationship between operating variables and indicators could be obtained by comparing the results of just suspension speed, gas holdup, power consumption and operational maps, further the reasonable operating conditions could be also determined under the minimum power consumption. The operational maps could provide the theoretical foundation for industrial application of the gas–liquid–solid stirred bioreactors under the low solid concentration(no more than 20 wt%).
基金This project is supported by Provincial Science Technology Committee of Jiangsu China(No.BJ99025).
文摘Instantaneous flow field and temperature field of the two-phase fluid are measured by particle image velocimetry （PIV） and steady state method during the state of onflow. A turbulent two-phase fluid model of stirred bioreactor with punched impeller is established by the computational fluid dynamics （CFD）, using a rotating coordinate system and sliding mesh to describe the relative motion between impeller and baffles. The simulation and experiment results of flow and temperature field prove their warps are less than 10% and the mathematic model can well simulate the fields, which will also provide the study on optimized-design and scale-up of bioreactors with reference value.
文摘-In plant cell culture on large scale,we have studied two types of biore-actors-Airlift reactor and stirred tank reactor-under the same volume and work conditions. It shows that the value of volumetric oxygen transfer coefficient K1a in airlift is a little higher than that in stirred tank reactor at the aeration rate of 0.1~0.3vvm:the mixing time tm in both of them is small respect to the culture period.The shear stress in stirred tank reactor is higher than that in airlift reactor,but its influence is not negative at all. When the value or the shear stress in medium is low-er than a critical value,it will be favorable to the dispersion of cells and promotes the growth of cells.This result is verified in the experiment we have conducted in the airlift reactor and stirred tank reactor.
基金Project supported by the National Natural Science Foundation of China(Grant Nso.11402084,11572203 and 51505136)the Natural Science Foundation of Hunan Province(Grant No.2015JJ3051)
文摘Numerical simulations of turbulent flows in a stirred dead-end membrane bioreactor are performed by using the RNG k-? model based on the finite volume method with the software Fluent. Comparisons of numerical and experimental results confirm the reliability and the feasibility of the constructed model. The flow structures such as the wake flows and the circulation loops in the stirred flows are well simulated. An increase of stirring speed is proposed to minimize the low velocity region. The single vane stirrer is found to be beneficial for biological separations. Results suggest that the increase of the vane number can enhance the mixing effect in the flow domains. However, a circular disk stirrer goes against the formation of vertical circulations. The six-vane stirrer is found to be able to provide a uniform distribution of the high shear stress.
基金supported by Grant-in-Aids for JSPS Fellows(KAKENHI Grant nos.JP19J11931 and JP19J12023)Scientific Research(B)(KAKENHI Grant no.JP18H01564)+1 种基金Scientific Research(A)(KAKENHI Grant no.JP19H01160)from Japan Society for the Promotion of Scienceby Ministry of the Environment,Japan(Low Carbon Technology Research,Development and Demonstration Program:Innovative sewage treatment system for energy saving and energy production,20172019)。
文摘Two anaerobic membrane bioreactors(AnMBRs)equipped with different membrane pore size(0.4 or 0.05μm)were operated at 25℃and fed with domestic wastewater.The hydraulic retention time(HRT)of the reactors was shortened.The microbial communities of the two AnMBRs were investigated by 16S rRNA gene amplicon sequencing to see the effects of HRT.The predominant Archaea was an aceticlastic methanogen Methanosaeta.The composition of hydrogenotrophic methanogens changed with the HRTs:the population of Methanobacterium was higher for longer HRTs,whereas the population of unclassified Methanoregulaceae was higher for shorter HRTs.The Anaerolineae,Bacteroidia and Clostridia bacteria were dominant in both of the reactors,with a combined relative abundance of over 55%.The relative abundance of Anaerolineae was proportional to the biogas production performance.The change in the population of hydrogenotrophic methanogens or Anaerolineae can be used as an indicator for process monitoring.The sum of the relative abundance of Anaerolineae and Clostridia fluctuated slightly with changes in the HRT in both AnMBRs when the reactor was stably operated.The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage.A principal coordination analysis revealed that the changes in the microbial community in each reactor were consistent with the change of HRT.In addition,both the HRT and the stability of the process are important factors for maintaining microbial community structures.
