Date of Award

May 2021

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Engineering

First Advisor

Hamid Seifoddini

Committee Members

Chad Penn, Benjamin Church, Matthew Petering, Wilkistar Otieno

Keywords

Agricultural tile drainage, Flow-through model, Industrial by-products, Phosphorus removal, Phosphorus sorbing materials, Statistical analysis

Abstract

Due to nutrient pollution, agriculture is one of the major sources of pollution in water bodies. Every time it rains, fertilizers, pesticides, and animal waste wash nutrients and pathogens—such as bacteria and viruses—into waterways. As rainfall increases due to climate change, the water problem will worsen. One of the nutrients that extensively contributes to the degradation of water quality is phosphorous (P). In this research, the performance of electric arc furnace (EAF) steel slag was investigated as a P sorbing materials (PSM) according to the conditions present in a P removal structure designed for treating water discharge from an agricultural tile drainage system. Unlike the successful trials of removing P from water runoff, this promising PSM has not been successfully applied for removing phosphorous from water discharge from an agricultural tile drainage system. Consequently, this research aims to study the applicability of this material for this specific application. A simulated flow-through experiment was used to evaluate the P removal efficiency of the slag in different conditions. The effects of slag particle size distribution, presence of bucarbonate in inflow solution, incubation in an anaerobic condition, and chemical treatment on the adsorption capacity of the steel slag were studied. A statistical approach was used to determine the significant predictor variables, the empirical models of the design curves according to each condition, and the type of correlation among the predictor variables and the response variable, namely, maximum removal capacity (mgP/Kg). The results show that reducing the slag particle size distribution and the presence of bicarbonate decrease the P removal capacity of the slag, while the aluminum treatment increases the P removal capacity and reduces the negative effect of bicarbonate on the P removal. Additionally, incubation in water with or without alkalinity does not seem to affect the P removal of the regular steel slag. The result of this study shed light on the reasons and potential solutions for the challenges regarding the application of the P removal structure filled with by-product PSM for treating water discharge from agricultural tile drainage systems.

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