Date of Award
Doctor of Philosophy
Dr. John B. Miller
Dr. Steven B. Bertman
Dr. Andre R. Venter
Dr. Carla M. Koretsky
Eutrophication resulting from excess nutrient loads is a major environmental issue that affects surface water quality and causes surplus primary production, thereby reducing dissolved oxygen concentrations. A method for managing nutrients in surface waters involves absorption of excess nutrients by deliberately cultivating benthic algal turf biomass, then harvesting it for a variety of uses, including biofuels, soil amendments, or feed supplements, thus coupling nutrient removal to additional economic drivers.
The goals of this work are to (1) evaluate the composition of algal biomass grown to remove surface water nutrients, (2) compare biomass grown at different geographic locations and in dissimilar water conditions, and (3) investigate uses for the biomass products.
The algal biomasses harvested from a range of locations, were characterized by measuring organic and inorganic carbon, nitrogen, phosphorus, and ash profiles. Algal biomass grown on wastewater effluent has the highest nutrient content and lowest ash (40 wt% C, 7.0 wt% N, >1.0 wt% P, 32 wt% ash) while that grown in brackish water had the lowest nutrient content and highest ash (10 wt% C, 1.0 wt% N, 0.13 wt% P, 79 wt% ash). The algal turfs were also analyzed for silica and toxic metals. Silica in the algal turf was partitioned into biogenic and terragenic origin. Algae harvested from freshwater locations had ≤ 3.5 wt% biogenic silica while mixed fresh-salt water locations had biogenic silica content ranging from 10-27 wt%. Metals composed 0.045 wt% to 0.075 % of the total dry algal biomass, with relative concentrations of As > Cu ≈Cr > Co ≈ Mo > Cd.
The potential for using algal biomass as bio-ethanol feedstock was investigated by quantifying the monosaccharides in freshwater algal turf, which include glucose, galactose, xylose, mannose, ribose, and arabinose, varying from 2-30 % based on ash free dry mass. The application of biochar made from algal biomass for sorption of pharmaceuticals from water was assessed using model compounds. The order of sorption was 2-[4-(2-methylpropyl)phenyl]propanoic acid ≈ 2,4-dinitroaniline > 2-phenylethanol ≈ 2-phenylethylamine.
Two commonly used analytical methods, the Boehm Titration and molybdenum blue colorimetric method, were investigated for applicability to biomass analysis. Systematic errors inherent in the methods indicate that they are inappropriate for analyzing non-standard materials.
Hampel, Kristin, "The Characterization of Algae Grown on Nutrient Removal Systems and Evaluation of Potential Uses for the Resulting Biomass" (2013). Dissertations. 183.