Permeable reactive barrier

1
AGRG Arsenic Geochemistry Research Group
Remediation technique for As contaminated soil
using indigenous bacteria
Permeable reactive barrier using nanoscale iron
particles in As contaminated subsurface

• Permeable reactive barrier
• immobilization of As and
• heavy metals in the mining areas
• Keeping the groundwater flow

• Emplacement of nano-particle
• Emplacement into reactive
• barrier
• Finding the optimal condition

• Nanoscale iron particle
• innovative barrier material
• High surface area and reactivity

• Biological treatment
• microbe activity depending on C-source
• Removal of As by leaching mechanism

• Source of arsenic
• Natural source volcanic action, rock erosion
• Industrial product semiconductors, herbicides

Low reactivity, bad permeability, high cost of
terrestrial excavation in classic PRB
Contamination of downstream waters, soil, and
terrestrial plants by the release of arsenic and
heavy metals
The optimal emplacement condition of nano
particles technique of deposition and injection
of nano particle
Investigation of mobilization of As by increase
of microbial activity depending on supplying
C-source
Techniques development to reduce the extensive
excavation, to enhance the reactivity, and to
keep the good permeability
Development of remediation technique for As
contamination soil
Expected effect Remediation of As/heavy
metal-contaminated subsurface around the metal
mining areas
Development of Electrokinetic Soil Process to
remediate the Heavy metal in soil
Phyto-remediation/extraction of toxic elements
from soils
Phytoextraction Process
DC power supply

• A cost-effective remediation technique for large
  areas with low-level contamination
• Hyperaccumulators can accumulate elements in the
  above-ground biomass.
• Using traditional harvest process to remove
  toxic elements in the soils

O2
H2

• Advantages
• Effective in non-permeable soils
• such as clayey soils
• Application to various types of
• contaminants including organic
• and inorganic contaminants
• radionuclides
• Minimization of secondary impacts
• Low operational cost

H2O
H
OH-
metal
Cathode
Anode
Compacted soil cell
Electrode cell
Electrode cell
Phytoremediation cost effective, large areas,
public acceptance, hydraulic pumping
pressure, after closure maintenance, no
excavation, mineralizing organics
Soils are contaminated with heavy metals which
migrate and threaten human health
Soils having low permeability are resistant to
in-situ remediation techniques
Investigation into the mechanisms of
hyperaccumulation of As, Au and U
A candidate technology for this type of remedial
measure is electokinetic soil flushing
Using plants to extract toxic elements from
mining sites
Removal toxic elements from contaminated
sites and recovery of economic elements
Various enhancement techniques have been
proposed and used
2
MPRG Metal and PAH Research Group
Biosorption process using bacteria in metal
contaminated groundwater
In-situ immobilization of metals by bacteria
Biosorption mechanism on the surface of
bacteria - entrapment by cellular components
- active transport across the cell memebrane
- cation exchange or complexation - cell
surface adsorption

• Dissimilatory metal-reducing bacteria (Anaerobe)
• Metabolism with heavy metals in soil
  groundwater
• Transformation of heavy metals to more stable
  forms
• ? to more immobile forms of heavy metals
• for in-situ immobilization

Mechanisms of dissimilatory metal reduction -
Direct (biologic) mechanism - Indirect
(combined biologic-chemical) mechnism using
electron shuttle
Biosorption process in batch system
No excavation of contaminated soil groundwater
Commercial application for the in low
concentrated wastewater Advantages highly
selective, efficient, easy to operate,
cost-effective
Activation or injection of indigenous
metal-reducing bacteria with in-situ
Biosorption characteristics of heavy metals by
bacteria
Immobilization technique using bacteria as
effective adsorbent
Advantages of cost-effective and
environment-friendly remediation technology
Application to the removal and recovery of
heavy metals from contaminated groundwater in
permeable reactive barrier
Remediation process monitoring for
PAH-contaminated soil using Laser-induced
fluorescence(LIF)
Bioremediation of Organic-contaminated Soils
Using Biosurfactants

• Polycyclic Aromatic Hydrocarbons (PAHs)
• hydrophobic and most are practically insoluble
• persistence in the environment
• most exist in strongly adsorbed forms in soils

• Biosurfactants
• 1) unique chemical structures
• (beneficial for remediation)
• 2) naturally occurring, biodegradable product
• 3) possible to stimulate in-situ production
• at the site

• most aromatic exhibit high fluorescence
• quantum yields in uv-light,
• High selectivity and sensitivity for PAHs

• overcome the limitation of traditional
  analytical method
• quantification using time-resolved analysis

The highly desirable need for real time, in-situ
monitoring techniques for PAH-contaminated soils
remediation process
Synthetic surfactant ? low bioavailability in
biodegradation process due to
toxicity
Development of monitoring techniques for field
application based on the LIF spectroscopy showing
the high selectivity and sensitivity for PAHs
Biosurfactants ? high biodegradation rate due to
enhanced solubility and low toxicity
Investigation of the effecting variables on the
fluorescence intensity and collection of data
concerning calibration method and quantification
programm
Development of the Biosurfactant-Enhanced
Bioremediation Technique
Feasibility of biosurfactant-enhanced
biodegradation process to remediate the
PAHs-contaminated soil
Development of in-situ monitoring
technologies as a quantification/qualification
method for the continuous evaluation for
PAHs-contaminated soils