Microbial physiology and culture (Practical Oxygen Transfer in a Essay

Microbial physiology and culture (Practical Oxygen Transfer in a Stirred Tank Reactor) - Essay Example In this experiment, this method is used in the determination of KLa. This process is important since it is applied in many fermentation processes which undergo aerobic reactions. This allows meeting the necessary metabolic demands of aerobic microorganisms. In this process, air is passed through a reactor at a constant flow rate at given speed in revolutions per minute. From the data, CL and time, it’s able to calculate KLa using the formula. Drawing a graph of  against time produces a straight line whose gradient is KLa (Karimi, 2013). Question 1 RPM = 200 From the graph, Thus M=0.0594 KLa=3.564 RPM at 400 From the graph, Thus Therefore the slope, m=0.0146 Thus, KLa = 0.0146*60 = 0.876 h-1 RPM at 600 From the graph, Thus Therefore the slope, m=0.0343 Thus, KLa = 0.0343*60 = 2.058 h-1 RPM at 800 From the graph, Thus Therefore the slope, m=0.0344 Thus, KLa = 0.0344*60 = 2.064h-1 Second practical Flow rate 0.5 Rpm 500 From the graph, Thus Therefore the slope, m=0.0114 Thus, KLa = 0.0114*60 = 0.684h-1 Flow rate 1.50 Rpm 500 Start air concentration 5.7 From the graph, Thus Therefore the slope, m= Thus, KLa = *60 = 2.07h-1 Flow rate 2.0 Rpm 500 Start air concentration 5.7 From the graph, Thus Therefore the slope, m= 0.0594 Thus, KLa = 0.0594*60 = 3.564h-1 Question 2 KLa F N Log KLa Log N 3.564 1 200 0.551938 2.30103 2.058 1 600 0.313445 2.778151 2.064 1 800 0.31471 2.90309 Since Log KLa= y log N + constant From the graph, The equation y=-0.4234X + 1.5199 Therefore the constant y=0.4234 KLa F N Log KLa Log F 0.684 0.5 500 -0.16494 -0.30103 2.07 1 500 0.31597 0 3.564 1.5 500 0.551938 0.176091 Since Log KLa= X log F + constant From the graph, The equation y=-1.5127X + 0.2973 Therefore the constant x=1.5127 Question 3 Factors affecting KLa in STR: 1. Culture Conditions 2. Operation of the fermenter 3. Impeller Design Question 4 Increase in the values of the above stated factors reduces the time for the dissolved oxygen concentration. Question 5 Why KLa ra ther than KL It is extremely impossible to measure KL alone. Therefore, to make KL measurable it has to be combined with a to form KLa (Volumetric mass – transfer coefficient) which is easier to determine Question 6 Polarographic oxygen electrode measure Polarographic system is used to measure dissolved oxygen. In this system, the measurement device known as a transducer is the Clark oxygen electrode. An oxygen monitor is the processing (coupling Device) and the recording device is a computer aided data system. Question 7 Importance of KLa KLa is important since it facilitates establishment of efficiency and also it helps in quantifying effects of operating variables that has to be applied on the provision of oxygen. Question 8 Techniques of determining KLa Sulfite oxidation technique In this process, the Oxygen transfer rate is determined by the oxidation of sulfite solution. Gassing-out techniques In this process, the estimation of KLa is done by monitoring the increase of dissolved oxygen in during the process of aeration and agitation. Question 9 From the graphing and the trend of the graph, it can be determined that as the agitation speed increases, the time taken for the dissolved oxygen to reach dissolved oxygen concentration is shortened. Bibliography Karimi, A., 2013. Oxygen mass transfer in a stirred tank bioreactor using different