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In-Situ Surfactant Flushing

Cornelsen Ltd. is the authorised distributor of Tersus Advanced Surface Kinetics (TASK) surfactant and related products, including the patented methods for in-situ surfactant and chemical oxidation flushing (US Patent Nos. 6,913,419 and 7,021,863).  TASK anionic surfactant formulations have the unique ability to selectively desorb and liberate sorbed petroleum hydrocarbons from soil and fractured bedrock surfaces allowing for their improved mass recovery and or improved treatment by other remediation techniques.

Supported by nearly two decades of research and formulation testing at the University of Oklahoma, TASK™ addresses a wide range of applications related to hydrocarbon contamination, including:

In situ soil and groundwater remediation

  • Pump & treat enhancement
  • Groundwater recirculation
  • Direct injection

Ex-situ soil washing

The Basics

Non-aqueous phase liquids (NAPLs) are organic liquids, such as gasoline and diesel that are sparingly soluble in water. NAPL contamination commonly exists as blobs that become trapped within the formation. As they do not readily dissolve or mix with water, these compounds can remain as separate phase liquids for decades.

Because of the interfacial forces between NAPLs and groundwater, they are difficult to remove from the subsurface. NAPLs can be lighter than water (LNAPL), such as the aforementioned compounds, or denser than water (DNAPL), such as chlorinated ethenes. Surfactant Enhanced Aquifer Remediation involves the injection of specialty compounds with a molecular structure that has an affinity for the NAPL and groundwater. These compounds, called surfactants, can enhance the mobility and recovery of the trapped separate phase liquids. Surfactants can also facilitate the desorption of contaminant mass on matrix solids.

Surfactants are most appropriate for the removal of LNAPLs.  For example, if you get grease on your clothing, you do not attempt to clean them by just adding water. You also use a detergent. Soaps and detergents are examples of surfactants.

Please note that the removal of NAPL will enhance the effectiveness of bioremediation and chemical oxidation processes.

Choosing the Right Surfactant

The subsurface environment is notoriously difficult to remediate. Contact of the surfactant with the LNAPL and maintaining hydraulic control are exceedingly important. Also, choosing the right surfactant is critical. Factors to consider are the LNAPL itself, the groundwater chemistry and matrix mineralogy.

Currently, the conventional wisdom is to inject non-ionic surfactants, as their chemistries will work in a wide variety of applications. Unfortunately, they easily adsorb to soil particles. Thus, when applying non-ionic surfactants, you end up wasting a significant amount of money just dealing with the matrix demand. Furthermore, soils remove non-ionic surfactants from water just like activated carbon removes organic contaminants from water. The manufacturers of non-ionic surfactants typically recommend using 4 to 8% surfactant in the injectate.

Tersus’ approach is quite different; deploying anionic (negatively charged) surfactants.  Their core expertise lies in the understanding of surfactant chemistry, which yields significant benefits to our customers; namely, you can reduce the amount of surfactants by almost an order of magnitude.


TASK anionic biodegradable surfactants provide considerable advantages

Dramatic reduction in cost

  • Minimal surfactant mass – usually 0.5 to  0.9 weight percent
  • 1 to 1.4 pore volumes for up to 95% mass removal
  • No creation of a stable-emulsion, which dramatically reduces treatment costs – the oil separates from the water in a holding tank in less than 30 minutes
  • Easy to handle waste stream
  • Any surfactants remaining in the subsurface are easily biodegradable


Surfactant Interfacial Force

(oil and water)

Injection Vol. Interfacial Force with Surfactant
Non-ionic 30 to 50 mNewtons/meter 4 to 8% 5 mNewtons/meter
TASK™ (Anionic) 30 to 50 mNewtons/meter 0.5 to 0.9% 10-2 to 10-3 mNewtons/meter

Applying the correct anionic surfactant (e.g., TASK-GRO™ or TASK-DRO™) reduces the amount of surfactant required and improves the effectiveness of the remedy


Tersus has formed a strategic alliance with Surbec Environmental.  Founded in 1997 at the University of Oklahoma, Surbec has nearly two decades of experience advancing the science of surfactant molecular design and NAPL recovery.  Surbec’s attention to the science of surfactant chemistry has made it the industry leader.

We offer off-the-shelf surfactants for specific NAPLs, such as jet fuel, diesel and gasoline.

For larger, more complex problems, Surbec, in conjunction with the University of Oklahoma, optimizes the anionic surfactant formulation for the site specific geochemistry and NAPL.

By removing NAPLs, surfactants can enhance the effectiveness of bioremediation and chemical oxidation technologies.

Together with Tersus, we can help design a surfactant flushing application that best fits your sites unique characteristics. Most applications can utilize existing site infrastructure, leading to a cost-effective treatment.  If required, Engineering design services will be performed by the Tersus Environmental of NC, PLLC.