While it is troubling to have an environmental issue at your worksite or workplace, a broad spectrum of contamination situations are treatable. There are two broad types of environmental remediation, based on where treatment mechanisms are applied:
- Ex-situ – having the ground excavated and treated; and
- In-situ – treatment while the soil remains within the subsurface.
Types of environmental remediation techniques
While you can think of ex-situ and in-situ technologies as two types of environmental remediation techniques, those are categories. There are dozens of specific types of environmental remediation techniques, as you can see in this abridged list:
#1. Activated carbon-based technology
In situ soil and groundwater remediation requires a method that introduces activated carbon (AC)-based amendments. Amendments commonly used include bioremediation, in situ chemical oxidation (ISCO), and in situ chemical reduction (ISCR).
Biological processes are used to remediate groundwater via this in-situ form of remediation.
Another of the natural types of environmental remediation, this permeable reactive barrier (PRB), is an in-situ method that treats groundwater using biological processes. (See below for more information.)
#4. Bioremediation – cometabolic
In a quest for carbon and energy, microbes reduce and oxidize metabolites. In the process, a cofactor or enzyme is created, which is leveraged for decontamination through cometabolic bioremediation.
#5. Electrokinetic-enhanced remediation
This form of environmental remediation introduces an electrical current to remove contaminants by stimulating ions to move within the subsurface.
#6. Environmental dredging
If there is sediment beneath the contaminated water, you can remove it, treat it, and/or move it elsewhere through environmental dredging.
#7. Environmental fracturing
This form of environmental remediation is often used to increase the efficiency of soil vapor extraction (SVE), in situ bioremediation, is situ chemical oxidation/reduction (ISCO/ISCR), pump & treat (P&T), and other primary technologies. Environmental fracturing creates or expands openings in soil or bedrock to enhance groundwater and soil cleanup effectiveness.
#8. Excavation and off-site disposal
Off-site, permitted disposal facilities can take care of contaminated material if you transport it to them.
#9. Groundwater circulating wells
A circulation pattern is introduced to groundwater for this subsurface remediation method. Groundwater passes through a screened section into a well. After that, it is pumped into another screened section and then reenters the aquifer.
#10. Groundwater pump & treat
This technique starts by pumping contaminated non-aqueous phase liquid (NAPL) or groundwater out of the subsurface. Above ground, it is treated and then discharged.
#11. Horizontal remediation wells (HRWs)
Using horizontal directional drilling (HDD), horizontal remediation wells (HRWs) are set up underground, either at a shallow angle or parallel to the ground surface. Obstructions at the surface may make it difficult for vertical wells to access relevant areas, so HRWs can be useful.
#12. In situ chemical reduction (ISCR)
You may want to degrade metallic oxyanions, use precipitation or adsorption to immobilize metals or degrade toxic organic compounds to compounds that are not as toxic. This in situ method achieves those ends through the introduction of reductants or reductant-generating materials.
#13. In situ flushing
One of the more straightforward types of environmental remediation, in situ flushing, is conducted with the injection of a liquid solution or water into a contaminated area. It uses flooding to decontaminate.
#14. In situ chemical oxidation (ISCO)
This process generally uses redox (reduction/oxidation) reactions to chemically convert hazardous compounds to ones that are less toxic or nontoxic. Hydrogen peroxide and ozone are examples of oxidizing agents.
#15. In situ pH control
If you have groundwater or soil that has a low or high pH, you can use this in situ method to neutralize it.
#16. Landfill and soil capping
Sometimes separation is powerful. These containment methods separate the ground surface from a contamination source area or waste body by creating a barrier.
#17. Monitored natural recovery (MNR) and enhanced monitored natural recovery (EMNR)
These two approaches are used to remedy sediment contamination. They are often used in conjunction with amendments, sediment capping, dredging, or other technologies.
#18. Monitored natural attenuation (MNA)
This method meets remediation objectives by reducing the concentration of a contaminant. It uses biological, chemical, and physical processes that naturally occur in situ.
#19. Multi-phase extraction (MPE)
You can target problematic groundwater, vapor, and light non-aqueous phase liquid (LNAPL) through MPE. This technology can remove any of those three at the same time.
#20. Permeable reactive barrier (PRB)
By blending subsurface management of fluid flow with a passive biological or chemical treatment zone, you can rid groundwater of its dissolved-phase contaminants using a PRB. A dissolved contaminant plume is treated as it flows through this in situ technology.
You can remediate contaminants in groundwater, surface water, sediment, or soil with vegetation. Capable of clearing away, destroying, stabilizing, containing, or moving contamination, these six plant mechanisms empower phytotechnologies:
#22. Soil vapor extraction (SVE)
Typically performed in situ (but sometimes ex-situ), rids unsaturated (vadose) zone soil of organic contaminants that are volatile and semivolatile. The technology works by inducing controlled airflow with a vacuum.
#23. Soil washing
Based on particle size, a water-based system separates bulk soil from contaminants attached to fine soil particles. To aid in the removal of heavy metals and organics, you can adjust the pH of the wash water. Additionally, you can augment it with a chelating agent, surfactant, or basic leaching agent.
#24. Solidification/stabilization (S/S)
Solidification reduces the surface area that is vulnerable to leaching by reducing contaminant migration. The process either forms a coating over waste or creates a solid material that encapsulates it. Stabilization makes it more difficult for waste to leach by reducing solubility or immobilizing hazardous substances.
#25. Solvent extraction
Soil can be separated from metal or organic contaminants by performing extraction with an organic solvent. The technology uses an extraction unit to blend contaminated soil and the solvent. The resulting solution is then sent through a separator.
The Role Of Environmental Remediation Services
As you can see, dozens of environmental remediation techniques can be used to clean up a site. At AOTC, we’re problem-solvers. We implement proactive and cost-effective remedies to help fast-track your project. Discover how our environmental remediation services can help you.