Term of Award

Fall 2019

Degree Name

Master of Science, Civil Engineering

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Civil Engineering and Construction

Committee Chair

Francisco Cubas

Committee Member 1

George Fu

Committee Member 2

John T. Van Stan

Abstract

Organic matter release from anaerobic sediment during thermal stratification period in summer months causes water quality deterioration in the Occoquan Reservoir. The reservoir is used as an indirect potable water reuse system, supplying water to almost two million people. Excess organic matter accumulation in summer months can act as disinfection by-products (DBPs) precursors causing human health risks. This laboratory-based study focuses on characterization of organic matter released from both aerobic and anaerobic sediments using fluorescence properties. Fluorescence excitation emission matrices (EEMs) and Parallel Factor Analysis (PARAFAC) model were used for characterization of organic matter. From anaerobic sediment, three different kinds of organic matter released to water column: high molecular weighted humic-like material, fulvic-like material, and protein substances. When protein-like substances were found in characterization, the phosphate and total nitrogen concentration were also high, suggesting increased phytoplankton productivity. The relative percentage of humic-like material was higher at the beginning of the experiment, while in the end, protein percentage was higher due to increased biosynthesis activities by phytoplankton. Furthermore, the percentage of humic-like materials increased when the system started getting anaerobic and reduced. Humic substances while reacting with chlorine (disinfectant) in water treatment plants, aid in the formation of carcinogenic DBPs. It was observed that nitrate-rich water supply reduced the formation of phosphate, ammonia, and protein, although it could not prevent organic matter accumulation from anaerobic sediment. Ammonia, under certain conditions, supports the formation of toxic nitrosamines. Therefore, by supplying nitrate-rich water to decrease ammonia release, the formation of nitrosamines can be reduced. This study provides essential information regarding characterization of organic matter released from anaerobic sediments. Water treatment plants can use it to take appropriate treatment procedures so that DBPs formation, which has adverse impacts on human health, can be reduced.

Research Data and Supplementary Material

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