In this thesis, we develop three models for the harvesting of bioalgae based upon existing models for the treatment of wastewaters. For the first model, we consider the single reactor continuous flow bioreactor with recycle. In the second and third models, we consider the standard reactor cascade (SRC) without and with recycle respectively. The (extended) models examined in this thesis is based upon original research that have not been previously examined in the literature. In each chapter, we investigate the fixed harvesting strategy and determine the value for the harvesting parameter that will maximise the yield.
The steady-state operation of all three models are examined and their stability determined as a function of the residence time. In particular, we study the change in behaviour of microalgae growth and substrate concentration in the presence of self-shading. The reaction is assumed to be a biological process governed by Monod growth kinetics with a decay coefficient for the microorganisms.
One consideration is that if we are using pollutants to cultivate microalage, we must also maintain a maximum allowable concentration of the pollutants in the wastewater that is flowing out of the reactor(s). This means that we might not be able to extract the maximum amount of bioalgae because that may allow more pollutants to escape than legally permitted.