Semester of Graduation

Summer 2021

Degree

Master of Science in Civil Engineering (MSCE)

Department

Department of Civil and Environmental Engineering

Document Type

Thesis

Abstract

The research reported in this thesis was conducted to investigate whether protein hydrolysis associated with endogenous decay of biomass produced following the addition of a readily fermentable substrate is a potential source of precursors that can ultimately be transformed to toluene and p-cresol in environments undergoing enhanced bioremediation.

A packed column intended to represent a laboratory-scale section of an aquifer was seeded with groundwater and then supplied with molasses-amended groundwater for a two-day interval. The injected molasses concentration and surface loading rate were selected to be representative of conditions in the vicinity of injection wells at a Superfund Site in south Louisiana (USA) where toluene and p-cresol were observed following the subsurface injection of molasses as an electron donor intended to stimulate anaerobic dechlorination of vinyl chloride and other halogenated organics. Total amino acid analysis of biomass grown on sand in the packed column revealed that total phenylalanine and total tyrosine were present in the biomass/sand at concentrations that could account for the toluene and p-cresol concentrations measured in the subsequent biomass/sand serum bottle time series experiment, as well as account for past toluene and p-cresol concentrations measured in the groundwater wells at the field site following subsurface molasses injection.

To further investigate anaerobic protein transformation as a source of precursors ultimately converted to toluene and p-cresol, and to investigate whether molasses-grown biomass was anomalous in its ability to provide precursors that can be ultimately converted to toluene and p-cresol, experiments were conducted to experimentally test the toluene and p-cresol production potential of two proteinaceous products derived from milk. Serum bottles with protein products containing high quantities of phenylalanine and tyrosine were shown to accumulate appreciable concentrations of toluene and p-cresol, while serum bottles supplied with protein products containing very low quantities of phenylalanine and tyrosine accumulated very low amounts of p-cresol and did not accumulate toluene.

Committee Chair

Moe, William M.

Available for download on Monday, May 20, 2024

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