Photobioreactor for Microalgae Cultivation

The goal of this project is to build a bench scale photo bioreactor for micro algae cultivation. Micro algae is an excellent resource with wide reaching applications, from waste water purification to biodiesel production. We aim to design a system capable of producing micro algae in a cost effective and efficient manner.

Background
Photo Bioreactors are devices often used to produce micro algae commercially. Some of the challenges of photo bioreactor design are supplying sufficient light to the micro algae and preventing the micro algae from sticking to the sides of the bioreactor. At least one design counters these problems by containing to algae in very long, narrow glass tubing. The issue with this is the fragility of the glass, and the fact that the entire system must be shut down should any part of the glass tubing break. This is costly and inefficient. A more robust and inexpensive design is desirable.

Design Task
Our task is to design a bench scale photo bioreactor for research purposes. It should be designed to maximize efficiency and minimize cost, and thus should be composed of relatively inexpensive materials.

Design Process
The problem as it was given to us allowed a lot of room for creativity. There are a variety of possible designs for an air lift reactor, including external loop airlift, flat internal loop, and concentric internal loop. We eventually settled on the concentric internal loop design, composed of two concentric cylinders, where fluid flows up the inner cylinder and down the outer, driven by a bubble lifter. The bubble lifter also serves to introduce carbon dioxide into the system. Lighting will be provided by LEDs. The cylinders will be made of a clear plastic. Further details will be worked out as we finish calculations and progress in the project.