Discipline: Technology and Engineering
Subcategory: Pollution/Toxic Substances/Waste
Session: 2
Darian Parker - University of Kentucky
Co-Author(s): Stephanie Kesner; Daniel Mohler; Eduardo Santillan-Jimenez; Michael Wilson; Mark Crocker
The purpose of this project is to research and develop microalgae-based technology that can beneficially reuse CO2 emissions. Like plants, algae can consume and use CO2 to grow photosynthetically, albeit due to the fact that microalgae grows at a much faster rate than plants they also consume much more CO2. Algae, being one of the fastest growing organisms on the planet, can double their mass every day. After screening over 150 strains of algae, Scenedesmus acutus was identified as the preferred strain. This strain shows continued growth over a wide range of temperature and pH, is easily harvested and displays high (~50 wt%) protein and a relatively large (~15 wt%) lipid content. In this project, photobioreactors (PBRs) are used to control the growth environment of microalgae and to provide them with CO2. Compared to ponds – the approach most commonly used to grow algae ? PBRs can better cope with limited land availability and constitute a closed loop system for algae cultivation. When growing algae using CO2 gas, PBRs can afford higher algae growth rates compared to open pond systems. With the proper growing conditions, algae can consume and use up to 75% of the CO2 gas that it is exposed to. Once the algae cells uptake CO2, they metabolize it into valuable proteins, carbohydrates and lipids that can be harvested and valorized. To do so, this project uses a polymeric flocculent, which allows to harvest the algae cheaply and simply. After flocculation, the harvested algae are placed on a nylon belt allowing gravity to filter extracellular water through a mesh that retains the dewatered algal biomass. At the end of this process, both water and nutrients can be recycled to the algae growth system efficiently. Lipids can then be extracted from the dewatered algae via in situ transesterification in a single step extraction process that uses a hexane/methanol/water mixture. In addition to lipids, carotenoids can also be extracted from the algae by coupling this extraction process with acetone-water HLPC. After combining the defatted algae with polymers and additives, the resulting biopolymer ? namely, polyhydroxyalkanoate (PHA) ? constitutes a low-cost, renewable alternative to some traditional plastics.
Funder Acknowledgement(s): NSF ; LSAMP
Faculty Advisor: Eduardo Santillan Jiminez, esant3@uky.edu
Role: I assisted in the gathering and organizing of data which includes performing lab tests on algae samples and the building and putting together of our photobioreactor system.