Date of Award

6-2017

Degree Name

Master of Science in Engineering

Department

Chemical and Paper Engineering

First Advisor

Dr. Andro Mondala

Second Advisor

Dr. Brian Young

Third Advisor

Dr. James Springstead

Access Setting

Masters Thesis-Abstract Only

Restricted to Campus until

6-2027

Abstract

Phosphorus (P) is an important mineral for sustaining agricultural production, as well as a contributing factor in eutrophication of aquatic ecosystems. One of the main forms of P pollution is particulate bound P in runoff and erosion streams. The overall goal of this study is to investigate the extraction and recovery of P from these minerals through the use of low molecular weight organic acids (LMWOAs), namely citric and oxalic acids, which are typically generated by soil-derived fungi. Mixtures of citric and oxalic acid were investigated for their effectiveness in releasing bound P from sediments collected from the shore of a eutrophic lake in the Kalamazoo, MI. Pure citric acid, 2:1 and 1:1 (molarity ratio) oxalic:citric acid mixtures were most effective at P extraction from sediments. Extractions using pure citric and 2:1 oxalic:citric acids further underwent factor screening and optimization studies. Initial acid pH, sediment loading, and initial acid concentration all had significant effects on the removal of P from the sediment. Both mixtures were optimized via response surface analysis using a central composite design experiment. Extractions of both acid mixtures showed significant interactions between initial pH, solids loading, and acid concentration with regards to their effect on P solubilization and removal efficiency. Statistical models were developed to predict P removal efficiency, and predicted capability of 100% P removal . The findings of this study will be used a basis for further development of an economical and inherently benign P recovery technology from a previously unexplored renewable P source to reduce dependence on mined P sources and nutrient pollution in our nation’s aquatic resources.

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