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Cultivation of Nannochloropsis salina and Dunaliella tertiolecta Using Shale Gas Flowback Water and Anaerobic Digestion Effluent as Cultivation Medium

Racharaks, Ratanachat
http://rave.ohiolink.edu/etdc/view?acc_num=osu1406289883

Abstract Details

2014, Master of Science, Ohio State University, Food, Agricultural and Biological Engineering.
Microalgae have been extensively studied for their capabilities in producing more lipids per acre than agricultural crops. Because of high costs, this technology has yet been proven economical on a large scale. Currently unreported is the use of flowback water from shale gas exploration as a way to reduce costs by meeting the water demand of marine microalgae cultivation. Additionally, while anaerobic digestion (AD) effluent has been shown as a promising alternative nutrient source for microalgae cultivation, unreported is the use of AD effluent as a nutrient supplement for the cultivation with flowback water. This study hypothesized that the combination of the flowback water, as the source of water, and the AD effluent, as the source of nutrients, may act as a growth medium for marine microalgae cultivation. To validate this hypothesis, three marine microalgal strains were evaluated on the ability to adapt to different concentrations of the AD effluent in the flowback water. Among the microalgal candidates, it was determined that Nannochloropsis salina and Dunaliella tertiolecta, microalgal strains previously considered as candidates for biofuels and pigment production, were the most tolerant to the inhibitors found in the flowback water and the AD effluent. These microalgal strains were found to achieve the highest average biomass productivity in the medium composed of the flowback water supplemented with the AD effluent loading of 6%. Algal growth in this medium was then compared to growth in a medium composed of commercial nutrients and salts at similar initial inorganic nitrogen (~132 mg L-1 N), salinity (~42 g L-1), and pH (~7.97) levels. Comparable growth in both media was found with the specific growth rates of 0.293 and 0.348 day-1 and the average biomass productivities of 225 and 275 mg L-1 day-1for N. salina and D. tertiolecta, respectively. Analysis of the lipid content and profile of both strains cultivated in the medium composed of the flowback water supplemented with the 6% AD effluent further indicated that the medium had little effect on the lipid productivity of both microalgal strains. A parameter evaluated was the cetane number of the total microalgal fatty acids. The cetane number is an indicator of the potential fuel quality of the microalgal-derived biodiesel as a higher cetane number implies easier ignition and lower nitrous oxide emissions. While a minor decrease of 1.84% was observed for the cetane number of N. salina, no significant differences were observed for D. tertiolecta when compared to the values obtained in a medium composed of commercial nutrients and salts. These results suggested that comparable lipids with similar profiles could be produced by using the medium composed of the flowback water and the AD effluent. Another objective of this research was to evaluate the effects of chemicals and microbial communities in the AD effluent and the flowback water on algal growth and sedimentation. By autoclaving the algal growth media, that contained different combinations of the nutrient and salinity sources, it was determined that the ability to examine the influence of the microbial activity was not feasible due to the significant losses of ammonium concentrations from the autoclaving process. A greater difference in the specific growth rate of D. tertiolecta was found after cultivation in the autoclaved and non-autoclaved media containing commercial salts than the difference found after cultivation in the autoclaved and non-autoclaved media containing the flowback water. The specific growth rate of D. tertiolecta in the autoclaved media containing commercial salts and the autoclaved media containing the flowback water, however, were not significantly different. As D. tertiolecta is a known microalga sensitive to concentrations of free-ammonia, it was hypothesized that the higher ionic strength of the flowback water may minimize ammonia, derived from the loading of the AD effluent, from dissociating into free-ammonia in the growth media. Further research is still necessary to reveal the mechanisms involved as the autoclaving process may have also effected concentrations of unknown growth inhibitors. This research found that cultivation of marine microalgae in shale gas flowback water is feasible and, when coupled with AD effluent, may be able to result in comparable growth and lipid productivities to values achieved by using commercial nutrients and salts. The ability to use shale gas flowback water and AD effluent to cultivate marine microalgae may reduce production costs and improve the economic viability of the algae biofuels industry.
Yebo Li (Advisor)
Peter Ling (Committee Member)
Jiyoung Lee (Committee Member)
114 p.
Agricultural Engineering
microalgae; biofuels; shale gas; Nannochlorpsis salina; Dunaliella tertiolecta; lipids; anaerobic digestion effluent

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Citations

  • Racharaks, R. (2014). Cultivation of Nannochloropsis salina and Dunaliella tertiolecta Using Shale Gas Flowback Water and Anaerobic Digestion Effluent as Cultivation Medium [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406289883

    APA Style (7th edition)

  • Racharaks, Ratanachat. Cultivation of Nannochloropsis salina and Dunaliella tertiolecta Using Shale Gas Flowback Water and Anaerobic Digestion Effluent as Cultivation Medium. 2014. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1406289883.

    MLA Style (8th edition)

  • Racharaks, Ratanachat. "Cultivation of Nannochloropsis salina and Dunaliella tertiolecta Using Shale Gas Flowback Water and Anaerobic Digestion Effluent as Cultivation Medium." Master's thesis, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406289883

    Chicago Manual of Style (17th edition)

osu1406289883
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This open access ETD is published by The Ohio State University and OhioLINK.