Date of Award
Spring 5-8-2025
Degree Type
Thesis
Degree Name
Master of Science in Natural Science
Department
Chemistry and Biochemistry
First Advisor
Bidisha Sengupta, Ph.D
Second Advisor
Kefa Onchoke, Ph.D
Third Advisor
Darrell Fry, Ph.D
Fourth Advisor
Robert Friedfeld, Ph.D
Abstract
The effectiveness of wastewater treatment plants (WWTPs) relies on a sequence of primary, secondary, tertiary, and advanced treatment stages to remove contaminants. However, despite these processes, microbes can still thrive in treated water from WWTP, posing a significant threat to water quality and public health. This study investigates the suitability of treated water released from the tertiary stage in Nacogdoches, San Augustine and San Jacinto WWTPs into the environment by using bacterial biofilm formation. Bacillus thuringiensis viable cells at an optical density of 0.03 were used as a model organism, and Nacogdoches city tap water served as a reference for comparison. Microscopy studies confirmed the aggregation of bacterial cells and vertical biofilm architecture. Elemental analysis via SEM/EDS identified key elements such as C, N, O, P, Br, Na, S, and Cl supporting biofilm growth. Ion chromatography analysis revealed Cl⁻ excretion role in biofilm formation, F⁻, Br⁻, and PO₄³⁻ showed no influence, while SO₄²⁻ and NO₃⁻ significantly contributed to ECM development. Nacogdoches Cl₂ contact chamber samples exhibited the highest biofilm growth (9.2 µm height and 0.95 µm thickness), while San Jacinto samples showed the lowest (1.1 µm height and 0.59 µm thickness); Nacogdoches final treatment (SO2 contact chamber) and tap water showed similar biofilm characteristics. Antimicrobial potential of 0.3% methanolic extracts of mint and basil were explored to reduce biofilm formation. This study advocates for biofilm assay as an effective tool for evaluating the environmental safety of discharged water from WWTPs.
Repository Citation
Ogunlewe, Olabisi O., "BACTERIAL BIOFILM FORMATION AS A TOOL TO ASSESS CHEMICALLY TREATED WASTEWATER QUALITY IN DEEP EAST TEXAS" (2025). Electronic Theses and Dissertations. 594.
https://scholarworks.sfasu.edu/etds/594
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