Highly gas permeable polymer membranes applied to algae aquaculture

This study investigates the theoretical feasibility of culturing microscopic algae in a completely enclosed, aqueous environment for extended periods of time. The principle question addressed here is whether a membrane exists that will allow sufficient gas exchange to support the photosynthetic CO2 requirements of the enclosed algae, while preventing water loss from the culture solution to the atmosphere. An aquaculture unit design and four membrane material candidates are proposed that should allow for successful enclosed algae aquaculture. Membrane oxygenators and bioreactors are discussed as related applications of gas permeable membranes. An introduction to algae aquaculture is given that includes explanations of the CO2 requirements of algae, the complex CO2-seawater equilibrium, oxygen toxicity and sterilization. The thermodynamics and kinetics of CO2 transport across gas/liquid interfaces and membranes are presented, and useful equations are developed which allow easy prediction of the success or failure of a proposed membrane enclosed aquaculture system.