Development of Slow Release Compounds for the Aerobic Cometabolic Treatment of Complex Mixtures of COC Released from Low Permeability Zones
Abstract
A novel process was developed for the passive aerobic cometabolic treatment of contaminant mixtures in groundwater. Rhodococcus rhodochrous ATCC 21198 was utilized which can concurrently oxidize 1,4-dioxane (1,4-D) and diverse mixtures of chlorinated aliphatic hydrocarbons (CAHs) after growth on 1-butanol and 2-butanol. Methods were developed to co-encapsulate orthosilicates as slow-release compounds (SRCs) that hydrolyze to produce these alcohols and ATCC 21198 in gellan-gum hydrogel beads. ATCC21198 grows within the hydrogel beads and upon diffusion into the beads the contaminants are transformed. In batch reactors containing the gellan-gum beads successive additions of a mixture of 1,1,1-trichloroethane (1,1,1-TCA), cis-dichloroethene (cis-DCE), and 1,4-D were transformed with rates of transformation correlated with the rates of alcohol release, oxygen consumption, and CO2 production. In continuous flow columns packed with the gellan-gum beads over 99% removal of a mixture of 1,1,1-TCA, cisDCE, and 1,4-D was achieved with a hydraulic residence time of approximately 12 hours. The columns performance was negatively affected when cis-DCE was replaced by 1,1-dichloroethene (1,1-DCE), due to 1,1-DCE transformation product toxicity. A 3-D physical aquifer model using a funnel-and-gate treatment system containing co-encapsulated gellan-gum beads was used to demonstrate the concept of a passive cometabolic permeable reactive barrier (CPRB).
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2022
- Accession Number
- AD1187017
Entities
People
- Lewis Semprini
- Michael R Hyman
Organizations
- North Carolina State University
- Oregon State University