Date of Award

8-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Committee Member

Dr. Sarah A. White, Committee Chair

Committee Member

Dr. William H.J. Strosnider

Committee Member

Dr. Mark A. Schlautman

Abstract

Irrigation runoff from agriculture and specialty crops production remains a source of excess phosphorus (P) loading into aquatic systems. Iron hydroxide from coal mine drainage (CMD) was investigated in this study as an adsorbent for low-cost P removal from greenhouse and plant nursery runoff. The overall objectives of this study were to quantify the P sorption capacity, desorbability of P, and plant availability of P adsorbed to Blue Valley iron hydroxide (BVIO), a granular adsorbent obtained from oxidation of CMD. Batch sorption experiments were conducted to measure the effect of mixing BVIO with silica sand (1:1; BVIO:Sand, by weight) on P sorption capacity. Two solutions, deionized (DI) water and pond water, were evaluated for their effect on P sorption. The sorption capacities of BVIO and BVIO-amended sand (17.76 ±0.77 and 21.45 ±0.75 mg P/g BVIO, respectively) were well above those previously reported for BVIO (8-11 mg P/g BVIO). Water source (DI or pond) did not influence substrate P sorption capacity. Desorption of P from BVIO-amended sand was measured using batch experiments and a series of extracting solutions. Phosphorus desorption was measured over 96 hours for pond water (adjusted to either pH 6 or pH 10) and a 0.01 M CaCl2 solution. Exposure of P-saturated BVIO-amended sand to CaCl2 aided more P desorption than either pond water solution. The potential for reuse of P-saturated BVIO-amended sand as a fertilizer amendment was investigated through extraction with Mehlich III, a solution developed to measure plant-available nutrients in soils. Phosphorus adsorbed to BVIO is not readily available as assessed via Mehlich III extraction; rather CaCl2-labile P may better represent the plant-available fraction of total P. Concentrations of P desorbed after exposure to CaCl2 solutions (0.1 - 0.12 mg/L) were within nutrient recommendations for most plants. Low amounts of P may become available over time, similar to a controlled-release fertilizer. Results from this study demonstrated that BVIO-amended sand is a viable, low-cost adsorbent with potential for use to both remove P and permit its reuse in the greenhouse and plant nursery industry.

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