Application of mathematical modelling for investigating oxygen transfer energy requirement and process design of an aerobic continuous stirred tank fermenter

2017 ◽  
Vol 103 ◽  
pp. 39-48 ◽  
Author(s):  
John J. Fitzpatrick ◽  
Karina Gonçalves de Lima ◽  
Eoin Keller
Keyword(s):  
Mathematical Modelling ◽  
Process Design ◽  
Oxygen Transfer ◽  
Energy Requirement ◽  
Stirred Tank ◽  
Transfer Energy ◽  
Continuous Stirred Tank

scholarly journals Insights from Mathematical Modelling into Process Control of Oxygen Transfer in Batch Stirred Tank Bioreactors for Reducing Energy Requirement

2020 ◽  
Vol 4 (2) ◽  
pp. 34 ◽  
Author(s):  
John J. Fitzpatrick ◽  
Franck Gloanec ◽  
Elisa Michel
Keyword(s):  
Oxygen Transfer ◽  
Energy Savings ◽  
Energy Requirement ◽  
Minimum Energy ◽  
Stirred Tank ◽  
Time Segment ◽  
Control Approach ◽  
Working Volume ◽  
Batch Bioreactors ◽  
Sudden Decrease

Significant energy savings can be made in aerobic stirred tank batch bioreactors by the manipulation of agitator power (Pag) and air flowrate per unit working volume (vvm). Control is often implemented to maintain the oxygen concentration in the bioreaction liquid (COL) at a constant value. This work used model simulations to show that controlling the Pag and vvm continuously over time, such that it is operated at or near the impeller flooding constraint results in the minimum energy requirement for oxygen transfer (strategy Cmin); however, this might prove impractical to control and operate in practice. As an alternative, the work shows that dividing the bioreaction time into a small number of constant Pag time segments (5–10), where a PID controller is used to control vvm to maintain COL constant in each segment, can achieve much of the energy saving that is associated with Cmin. During each time segment, vvm is increased and a sudden decrease in COL is used to detect the onset of flooding, after which there is a step increase in Pag. This sequence of Pag step increases continues until the bioreaction is completed. This practical control approach was shown to save most of the energy that is associated with Cmin.

scholarly journals Insights from Mathematical Modelling into Energy Requirement and Process Design of Continuous and Batch Stirred Tank Aerobic Bioreactors

2019 ◽  
Vol 3 (3) ◽  
pp. 65
Author(s):  
John J. Fitzpatrick
Keyword(s):  
Oxygen Transfer ◽  
Energy Requirement ◽  
Electrical Energy ◽  
Stirred Tank ◽  
Input Design ◽  
Trade Offs ◽  
Design Variables ◽  
Minimum Total Energy ◽  
Working Volume ◽  
Aerobic Bioreactors

Bioreaction kinetics, oxygen transfer and energy modelling were applied to stirred tank aerobic bioreactors. This was done to investigate how key input design variables influence bioreactor size, feed and wasted substrate, and electrical energy requirements for aeration and cooling, and to compare batch and continuous modes of operation. Oxygen concentration in the liquid is a key input design variable, but its selection is challenging as it can result in design trade-offs. Reducing its value caused a decrease in electrical energy requirement, however this tended to increase the working volume of the bioreactor. The minimum or near-to-minimum total energy requirement for oxygen transfer occurred when operating at the onset of flooding throughout the bioreaction time. For typical KS values, continuous mode of operation required a much smaller bioreactor volume, due to higher operating cell concentration, and this is a major advantage of continuous over batch.

Sustainable Integrated Process Design and Control for a Continuous-Stirred Tank Reactor System

2014 ◽  
Vol 625 ◽  
pp. 466-469 ◽  
Author(s):  
Siti Aminah Zakaria ◽  
Mohd Jufri Zakaria ◽  
Mohd Kamaruddin Abd Hamid
Keyword(s):  
Process Design ◽  
Design Analysis ◽  
Stirred Tank ◽  
Mathematical Programming Problem ◽  
Integrated Process ◽  
Continuous Stirred Tank Reactor ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Continuous Stirred Tank ◽  
And Control

The objective of this paper is to highlight the use of a two-dimensional (2D) sustainability index in performing a sustainable integrated process design and control (Sustain-IPDC) for a continuous-stirred tank reactor (CSTR) system. Sustain-IPDC for a CSTR system is formulated as a mathematical programming problem and solved by decomposing it into six sequential hierarchical sub-problems: (i) pre-analysis, (ii) design analysis, (iii) controller design analysis, (iv) sustainability analysis, (v) detailed economic analysis, and (vi) final selection and verification. The proposed methodology is applied to the production of cyclohexanone using a CSTR. The results show that the proposed methodology is capable in finding an optimal solution for a CSTR design problem that satisfy design, control, sustainability and economic criteria in an easy and systematic manner.

Removal of lead by sulfate-reducing bacteria in anaerobic continuous stirred tank reactors

2016 ◽  
Vol 14 (3) ◽  
pp. 557-561
Author(s):  
Nguyễn Thị Yên ◽  
Kiều Thị Quỳnh Hoa
Keyword(s):  
Sulfate Reducing Bacteria ◽  
Stirred Tank ◽  
Synthetic Wastewater ◽  
Terminal Electron Acceptor ◽  
Stirred Tank Reactors ◽  
Sulfate Reducing ◽  
Sulfide Production ◽  
Continuous Stirred Tank ◽  
Continuous Stirred Tank Reactors ◽  
Reducing Bacteria

Lead contaminated wastewater negatively impacts to living organisms as well as humans. In recent years, a highly promising biological process using the anaerobic production of sulfide ions by sulfate-reducing bacteria has presented itself as an alternative option for the removal of lead. This process is based on microbial utilization of electron donors, such as organic compounds (carbon sources), and sulfate as the terminal electron acceptor for sulfide production. The biogenic hydrogen sulfide reacts with dissolved heavy metals to form insoluble metal sulfide precipitates Removal of lead by an enriched consortium of sulfate-reducing bacteria (DM10) was evaluated sulfate reduction, sulfide production and lead precipitation. Four parallel anaerobic continuous stirred tank reactors (CSTR, V = 2L) (referred as R1 - R4) were fed with synthetic wastewater containing Pb2+ in the concentrations of 0, 100, 150 and 200 mg L-1 of lead and operated with a hydraulic retention time of 5 days for 40 days. The loading rates of each metal in R1- R4 were 0, 20, 30 and 40 mg L-1 d-1, respectively. The results showed that there was no inhibition of SRB growth and that lead removal efficiencies of 99-100% for Pb2+ were achieved in R2 (100 mg L-1) and R3 (150 mg L-1) throughout the experiment. For the highest lead concentration of  200 mg L-1, a decrease in efficiency of removal (from 100 to 96%) was observed at the end of the experiment. The obtained result of this study might help for a better control operation and performance improvements of reactors.

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