Facilitated Transport of Triclosan in the Receiving Environment of an Onsite Wastewater Treatment System: Agent of Aquatic Concern

Author

Adrienne L. Roach, University of Tennessee - Knoxville

Date of Award

5-2006

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering Technology

Major Professor

John R. Buchanan

Committee Members

Jaehoon Lee, Mark Radosevich

Abstract

Triclosan (TCS) is an antibacterial found in a host of consumer products ranging from toothpaste to textiles. While initially confined to health care settings, the increased popularity of antimicrobial products has resulted in a surge of products containing this compound and can currently be found in over 700 consumer products. The fate of TCS in wastewater treatment plants (WWTPs) and loss mechanisms once exposed to the environment is a topic that has gained much attention over recent years. However, similar research in onsite systems, where its presence and subsequent persistence can have similar adverse environmental effects, is lacking. It is the objective of this study to examine the interaction of TCS to a sorbing medium in the presence of treated effluent from an onsite wastewater treatment system (OWTS). Experiments conducted to examine factors that govern this behavior were centered around three main points of interest: 1) the interaction of TCS to the sorbing medium in the presence and absence of DOM, 2) the mobility of TCS in the presence and absence of DOM, and 3) the effect DOM with a high and low organic carbon concentrations on sorption and mobility. Laboratory scale batch sorption equilibrium and column transport studies were used to observe the solution interaction of TCS in the presence of a sorptive material, 100% quartz sand. Treatments consisted of three solutions: 1) low organic content (LOC) wastewater filtrate (<0.45µm), 2) high organic content (HOC) wastewater filtrate (<0.45µm), and 3) 5 mM CaCl₂ serving as the organic free control (NOC). Human derived wastewater from OWTSs was collected for wastewater treatment solutions. Sorption data fit to the Freundlich isotherm model indicates the greatest amount of TCS sorption to sand in the presence of CaCl₂ as compared to LOC and HOC treatments. The Freundlich sorption coefficient (K_F) revealed the least amount of sorption in the LOC treatment. Statistical analysis showed significant differences (P<0.001) between all three treatment means. Based on isotherm results, TCS has the potential to be preferentially transported by DOM. Column transport experiments also indicate the potential for facilitated transport by DOM in both LOC and HOC treatments. Breakthrough curves demonstrate earlier breakthrough in DOM treatments as compared to NOC. Although DOM treatments (LOC and HOC) were not found to be significantly different from each other, both were significantly different from the NOC treatment (P<0.001). Batch and transport results indicate potential for the facilitated transport of TCS by DOM. However, predicted (batch sorption) and calculated (CXTFIT v2.0) retardation factors did not correlate well with each other. Equilibrium effects were expected to be the dominant factor behind this discrepancy.

Recommended Citation

Roach, Adrienne L., "Facilitated Transport of Triclosan in the Receiving Environment of an Onsite Wastewater Treatment System: Agent of Aquatic Concern. " Master's Thesis, University of Tennessee, 2006.
https://trace.tennessee.edu/utk_gradthes/1776