Topic Area: 2a. In Situ Bioremediation Applications

Formatted Title:

Development, Characterization of Fermentation Steps, and Application of Humic Acid-Based Emulsified Oil for In Situ Bioremediation

Background/Objectives:

The in situ biological remediation of contaminants in groundwater, including chlorinated aliphatic hydrocarbons (CAHs) and nitrate, requires the injection of electron donors. Previous studies have employed vegetable oil, a cost-effective and safe option, as an electron donor. Typically, vegetable oils are emulsified using surfactants before injection into groundwater. However, certain surfactants have been found to pose ecological risks to aquatic organisms during long-term exposure. To address this issue, we developed an emulsified oil using humic acid, a naturally occurring, non-toxic, and low-cost material. This study evaluated the fermentation steps of the emulsified oil by analyzing its byproducts during stepwise degradation and assessing its potential for sustained electron supply. Additionally, the emulsified oil's efficacy in degrading both organic and inorganic contaminants was assessed through laboratory- and pilot-scale experiments.

Approach/Activities:

A lab-scale fermentation test (LFT) and a lab-scale degradation test (LDT) were conducted to evaluate the fermentation and contaminant degradation characteristics of the emulsified oil using batch reactors. For the LFT, emulsified oil was injected into reactors filled with groundwater at concentrations ranging from 0.1% to 1.0% (v/v), and the reactors were monitored. To assess the degradation of organic and inorganic contaminants during the LDT, trichloroethylene (TCE) and nitrate were selected as target contaminants. For the LDT, emulsified oil was injected into reactors filled with groundwater at concentrations of 0.1% and 0.5% (v/v), and the reactors were monitored. Control reactors without emulsified oil or with inhibited biological activity were also monitored for comparison. In the pilot-scale degradation test (PDT), the reduction of organic contaminants by the emulsified oil was assessed using push-pull and drift tests conducted in a TCE- and PCE-contaminated aquifer located in Iksan, Jeollabuk-do, South Korea.

Kyungjin Han

Affiliation

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(Group 1, Poster Board #76) Development, Characterization of Fermentation Steps, and Application of Humic Acid-Based Emulsified Oil for In Situ Bioremediation