Date of Award

5-2020

Degree Type

Thesis

Degree Name

Departmental Honors

Department

Biological and Irrigation Engineering

Abstract

Bioreactors are a space-efficient method of growing cells en masse for industrial operations by suspending the cells in an agitated vessel full of cell culture media. Adherent cell lines can be grown on microcarriers in bioreactors to reduce the space needed for petri dishes or flasks in the lab. One of the important factors in cell culture is changing the cell media to remove cell waste, secreted products, and/or replenish the nutrients available. Bioreactors face unique challenges with media changes, as cells should not be removed from a culture when media is changed. Currently, some labs let the cells settle to the bottom of the bioreactor for 30-45 min before decanting the spent media and refilling the tank with new media. This limits the cells’ access to oxygen and nutrients, and can cause the cells to die or stop producing a product of interest. This project provides bioreactor users with three single-use products that separate microcarriers from media in a continuous flow, to shorten the time adherent cells are outside of their ideal environment. The Honors extension of this project evaluates the adherent cell lines commonly used in industry, and calculates the stress induced on the microcarriers based on the fluid mechanics of the proposed designs. The designs selected for this project utilize gravitational and centrifugal settling with an inclined settler, lamella separator, and hydrocylone and were designed to operate with two peristaltic pumps to control flow rates, and separate a solution of dilute microcarriers. The Honors extension of this project also includes a robust explanation of the mechanism of settling for each design, and more clearly detail show the results can be used to customize a separator to address the needs of a lab. Flow rates were tested to determine the most effective inlet and permeate streams to maximize settling for high flow rates. Two prototype designs–the inclined settler and the lamella separator –had a separation efficiency greater than 99% for a moderate flow rate above 2.083 L/hr (50 L over 24 hours), and calculations of the maximum fluid shear forces were negligible compared to forces generated by bioreactor agitators. These designs can be scaled up to larger bioreactor cultures to allow for higher throughput and more efficient product separation, leading to longer bioreactor experiments with reduced risk of undue cell stress or death.

Available for download on Saturday, May 01, 2021

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Faculty Mentor

Ron Sims