REMEDIATION TECHNIQUES
BIOREMEDIATION
We use bioremediation to clean up contaminated soil and water by breaking down hazardous substances with the help of living organisms and nutrients. It can be done in situ or ex situ using various techniques such as land farming, composting, biopiles, and bioventing. Bioremediation is effective for reducing concentrations of nearly all constituents of petroleum products typically found at underground storage tank sites.
ENHANCED IN-SITU BIODEGREDATION
The iSOC system delivers high levels of dissolved oxygen to groundwater for enhanced in-situ bioremediation. Oxygen Release Compounds (ORC) and Hydrogen Release Compounds (HRC) can also be used to accelerate natural biodegradation of contaminants. ORC delivers controlled oxygen release for up to 12 months, while HRC enhances natural attenuation rates for chlorinated hydrocarbons.
METALS REMEDIATION COMPOUND
MRC™ is a controlled release product that removes dissolved metals from groundwater and provides a substrate for biodegradation of chlorinated compounds. It slowly releases an organic sulphur compound that immobilizes metals into the aquifer matrix as mineral solids and generates dissolved hydrogen for up to 24 months. MRC™ is non-toxic and does not displace contamination or interfere with natural groundwater flow. When all active material is released, no residue remains.
AIR SPARGING
Air sparging is a remedial technology that reduces concentrations of volatile organic compounds in soil and groundwater. It involves injecting contaminant-free air into the subsurface saturated zone, causing hydrocarbons to transfer from a dissolved state to a vapour phase, which is then vented through the unsaturated zone. Air sparging is commonly used with Soil Vapour Extraction (SVE) and is more effective for constituents with greater volatility and lower solubility, and for soils with higher permeability. It has been found to be effective in reducing concentrations of volatile organic compounds (VOCs) found in petroleum products at underground storage tank (UST) sites. Proper use of air sparging may require it to be combined with other remedial methods.
MONITORED NATURAL ATTENUATION
The process of Monitored Natural Attenuation (MNA) involves monitoring groundwater to confirm whether natural processes are decreasing contaminant concentrations in soil and groundwater without human intervention. It relies on natural physical, chemical, and biological processes to reduce risks posed by contamination. MNA works most successfully where source removal of the pollutant has taken place, and is suitable for almost any hydrocarbon spill in soils or groundwater. However, regular monitoring is required to ensure pollution does not migrate off-site or pose a significant risk to other receptors. While MNA can be cheaper than other methods, monitoring for many years can be costly, and regulators may place restrictions on development while it is ongoing.
SOIL VAPOR EXTRACTION
Soil vapor extraction (SVE) is a remedial technology that removes harmful chemicals from the soil. It involves applying a vacuum through wells near the contamination source to draw out vapors that are then treated before release. SVE can enhance biodegradation of some contaminants and may require water table depression pumps in high groundwater areas.
IN-SITU THERMAL DESORPTION
In-situ Thermal Desorption (ISTD) is a soil remediation technology that uses conductive heating and vacuum to treat soils impacted with volatile and semi-volatile contaminants. The process heats the target zone, vaporizes contaminants and pore water, and extracts them through a Soil Vapour Extraction (SVE) system. ISTD is effective for a wide range of contaminants, including DNAPLs, PCBs, and PAHs. The technology is advantageous as it treats contaminated soils in place, reducing exposure to workers and neighbors. ISTD is faster and more effective than traditional SVE treatments, reducing timescales by up to 70%.
PUMP & TREAT
Pump and treat (P&T) is a groundwater remediation technology where contaminated groundwater is pumped to the surface and treated to remove contaminants before being discharged or reinjected. It works best when the source of contamination is removed. P&T is often used in combination with other technologies, and comprehensive monitoring is needed to verify effectiveness.
SOIL STABILISATION
Stabilisation/solidification (S/S) is a soil remediation technology that reduces the mobility of contaminants by adding binders to produce stable and solid constituents. Inorganic cementitious binders, such as Portland cement or lime, are usually used to transform contaminated materials into new, solid, non-leachable products. This technology offers an immediate solution to prevent further spreading of contaminants and allows for rapid implementation of treatment, enabling the redevelopment of contaminated sites or reuse of waste materials. It is cost-effective and competitive with other remediation methods including landfilling.
PERMEABLE REACTIVE BARRIERS
Permeable reactive barriers (PRBs) are in situ remedial technology for treating contaminated groundwater impacted by VOCs. A PRB allows groundwater to flow through while preventing or reducing contaminant flux using treatment agents like zero-valent metals, chelators, sorbents, compost, and microbes. The contaminants are either degraded to non-toxic end products or retained in a concentrated form.