In-Situ and Ex-Situ Treatment of PFAS in Soils
      

Cornelsen, with partners Rembind, Savron and TRS Group, bring three technologies to our clients to treat PFAS in soils.

   

  • Powder adsorbents that bind PFAS in soils - When mixed with soil ex-situ Rembind adsorbent binds strongly to PFAS compounds, preventing them from leaching into groundwater.  In-situ mixing of Rembind can similarly intercept - Field Proven

  • Smouldering combustion - a new approach for PFAS impacted soils in which the waste is destroyed in an energy efficient manner after mixing it with a porous matrix of activated carbon as a surrogate fuel reaching temperatures in excess of 1000 deg C.

  • Thermal conduction heating - patented FlexHeater® elements are used to attain temperatures required to volatilise the PFAS and achieve greater than 99% reductions in PFAS concentrations in both in-situ and ex-situ soil applications.

Ex-Situ & In-Situ PFAS Treatment 

RemBind® is a rapid, low-cost remediation solution that binds up PFAS to prevent leaching which can cause harm to human health and the environment. The PFAS is permanently neutralised as simulated by US EPA test methods.    RemBind® has been independently validated by authorities worldwide and has been used to treat 1,000’s of tonnes of PFAS soil across Europe, USA and Australia.

RemBind® is a powdered adsorbent that binds strongly to per- and polyfluoroalkyl substances (PFAS) in soil, preventing them from leaching into groundwater where they can cause serious harm to the environment and human health.  RemBind® contains a patented blend of ingredients including aluminium hydroxide, carbon and clays.  This mixture mimics and enhances the PFAS binding capacity of natural soils.

1/2

Conclusions

  • GAC can be used to support smouldering combustion to achieve temperatures that destroy PFAS when added to soils at ~40 to 60 g/kg

  • PFAS absorbed to GAC or soils can be treated via smouldering combustion resulting in non-detectable levels in soils, sand and ash

  • Hydrofluoric Acid was generated suggesting that complete decomposition of PFAS via smoldering combustion is possible

  • Some decomposition products may form that can be scrubbed from gas emissions using GAC (which can then be added back to support the smouldering in next batch

STARx Smouldering Combustion

A study conducted under the US Department of Defense (DoD) Strategic Environmental Research Program (SERDP) explored the application of smouldering combustion (STAR) to treat per- and polyfluoroalkyl substance (PFAS)-impacted soils and media.

 

Due to the high thermal stability of PFAS, temperatures greater than 700°C are required to destroy these compounds and temperatures at or above 1000°C are necessary to minimize production of short chain volatile organic fluorines (VOFs) and fluorinated dioxins and furans (PFDD/F). Hydrofluoric acid (HF) will be produced in greater abundance, and VOF and PFDD/F in lesser abundance, with increasing completeness of PFAS combustion.

 

As the PFAS are not contaminants that can support smoldering combustion in and of themselves like hydrocarbons and coal tars, a surrogate fuel is required. 

This study examined treating: (1) PFAS-impacted soils amended with a surrogate fuel (GAC); (2) PFAS-impacted liquid by absorbing the PFAS in the liquid to a solid surrogate fuel (GAC); and, (3) co-treatment of PFAS contaminated soils with PFAS containing GAC.

Smouldering Combustion.webp

SERDP Proof of Concept Study

trs_group_no_tag_RGB_edited.png

Thermal Treatment of PFAS in Soils

TRS developed a thermal remediation technique for the treatment of semi-volatile organic compounds (SVOCs), including coal tar, mercury, PCBs and perfluoroalkyl and polyfluoroalkyl substances (PFAS) in soil.

 

Multiple bench tests and field demonstrations were used to determine optimal temperature ranges for PFAS soil desorption and volatilization, As temperatures approach 350 to 400°C, similar ranges of thermal conduction heating (TCH), significant thermal desorption was observed. When soils were maintained in this temperature range for 10 to 14 days, TRS achieved greater than 99.9% reductions in PFAS concentrations.

In 2020, the Department of Defense (DOD) awarded TRS and its co-performers three PFAS treatment projects funded by the Environmental Security Technology Certification Program (ESTCP), two of which focused on thermal desorption of PFAS from soil.

TRS received a patent for the FlexHeater® remediation services in February 2019. With substantial PFAS soil concentration reductions observed at temperatures achievable by TCH, thermal treatment has been shown to be an effective method to achieve low PFAS concentration limits. 

ESTCP Proof of Concept Study