Analysis & Modeling in CFD of the Mixing in an Industrial Anaerobic Membrane Bioreactor

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Mixing in chemical process is a common unit operation and a potential study field in relation to energy consumption and efficiency. Especially in the case of membrane bioreactors, mixing component is vital, given the existence of microorganisms in the system. Parameters such as temperature and pH should be monitored for proper metabolism of microorganisms and this is carried out by mixing in the system among other parameters. Therefore, the need for proper mixing bioreactor system becomes a key issue, especially when contrasted energy savings against treatment efficiency.

According to above, this work is based on obtaining a good mixing system in a bioreactor, through the study of the hydrodynamics of the current system (an impeller of high energy consumption) and proposed modifications to both the reaction tank geometry and to process inputs and outputs. The study was conducted using computational tools, particularly CFD using STAR-CCM+®. The results show that the current reactor (the one with the impeller) leads to unnecessarily high costs and generating overt mixing into the reactor and this leads to the changes proposed. In order to obtain good mixing, it was decided to remove the impeller, add a set of baffles to the center of the tank and change the process inputs. In this way, good mixing levels (evident in the distribution of velocity streamlines) was obtained and the costs associated with the mixing system (motor and impeller) were reduced.

Author Company: 
Universidad de los Andes
Author Name: 
Jorge López