Document Type

Dissertation - Open Access

Award Date

2021

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

First Advisor

Guanghui Hua

Keywords

Agricultural, Bioreactors, Nitrate, Phosphate, Water resources, Woodchips

Abstract

Nitrate and phosphate present in agricultural subsurface drainage water can impact surface water quality thus impacting the environment and human health by causing eutrophication and Methemoglobinemia in young infant. Biological denitrification and phosphate adsorption filters are treatments options that can help reduce nitrate and phosphate concentration from agricultural subsurface drainage before it can be discharged in surface water. The first objective of this dissertation was to determine the Michaelis-Menten kinetics model parameters for nitrate removal in bioreactors using the fresh, aged, and composted woodchips. The composted woodchips achieved a denitrification rate 2.4 times higher than the fresh woodchips which was in term achieved 2.9 times higher denitrification rate than the aged woodchips. Denitrification rates decreased at 5ºC compared to 22ºC for composted woodchips and fresh woodchips. The composted still performed better at low temperatures compared to fresh woodchips. The second objective was to determine the impact of different pairing configurations of woodchips and steel chips on nitrate and phosphate removal capacity and how the pairing configurations affect the DOC and iron leaching from the reactors. Three different reactors pairing configurations were evaluated in this project including woodchips followed by steel chips, steel chips followed by woodchips, and mixed woodchips/steel chips. The effect of low temperature (5℃) on phosphate removal capacity was studied. There was no statistical difference in nitrate and phosphate removed between all three reactors configurations. Three different reactors pairing configurations were evaluated in this project including woodchips followed by steel chips, steel chips followed by woodchips, and mixed woodchips/steel chips. The effect of low temperature (5℃) on phosphate removal capacity was studied. There was no statistical difference in nitrate and phosphate removed between all three reactors configurations.

Number of Pages

171

Publisher

South Dakota State University

Rights

Copyright © 2021 the Author

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