Poster 240 – Click on poster below to view presentation from author.
Nicholas Burgess
Auburn University
Co-Authors: Suan Shi, Jing Li, David Blerch
Aquaponics systems help to recover the nutrients in the wastewater from fish farming, but excess waste streams after recirculation to vegetable greenhouses may still contain high levels of nitrogen and phosphorus. These nutrients can result in eutrophication in receiving water bodies. The algal turf scrubber (ATS) is an effective way to further treat the wastewater while cultivating an algal biomass that can be used for specialized bioproducts such as production of lactic acid via fermentation. The objective of this research was to investigate the use of filamentous algae from an ATS treating aquaponics wastewater as a feedstock for lactic acid production. Algae cultured in an indoor ATS system using the aquaponics wastewater were harvested, dried, and collected from September 2019 to January 2020. The growth conditions of the filamentous algae in the ATS such as the dilution of the wastewater and the light levels were studied and optimized, resulting in mean productivity of 7 g m-2 d-1 based on weekly harvest. Composite algae samples were analyzed to determine carbohydrate levels and the ash content. These algae samples were fermented for lactic acid, and yields compared to prior blue-green algae harvested from the ATS system and to cucumber residues from the aquaponics system. Due to the less recalcitrant structure, algae do not require a complicated pretreatment step as lignocellulosic materials do. In addition, the fermentation process could be completed faster than the lignocellulosic material. The final lactic acid yields for the green algae were higher than for the blue-green algae and for the cucumber residues with pretreatment. Interestingly, the results of the green algae showed greater lactic acid yields with no pretreatment than with, suggesting a better biochemical makeup for lactic acid production from as-harvested biomass.
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Virtual Poster Symposium 
Congratulations on your recent graduation. Can you share what the next steps of this work might be?
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From the research, I would say that the next steps would involve identifying the algae species that could both be grown within the system using the source wastewater and whether its carbohydrate content could provide the most energy to the lactic acid fermentation. Otherwise, future research would involve double checking these results to ensure that experiment is running smoothly and the results are accurate or spinning off to test other areas and research that the algal community could be inserted into..
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