A demonstration-scale PFAS treatment system has successfully removed PFAS from heavily contaminated leachate at a Tennessee landfill site.
The Challenge
Per- and poly-fluoroalkyl substances (PFAS) represent a challenging pollution concern all over the world posing a significant risk to human health and the environment. As PFAS chains do not break down easily, the compounds are now being detected in industrial wastewaters, landfill leachate, and wastewater treatment plants.
Concerns about PFAS contamination from landfills are driving wastewater treatment plants to stop receiving leachate unless effective pretreatment is completed.
PFAS removal from landfill leachate is particularly difficult to treat due to the complex chemistry, inconsistent feed quality, suspended solids and varying flow rates. Current options are limited and typically require comprehensive and expensive pre-treatment.
The Solution
In 2022, one of the largest solid waste companies in the United States invited the Australia-based Water and Carbon Group (WCG) and its US partner, Leachate Management Specialists (LMS), to demonstrate WCG’s proprietary LEEF System® at one of their Tennessee landfills.
The LEEF System® (Low Energy Evaporative Fractionation) is an innovative solution for the removal of PFAS from complex waste streams using minimal energy and no chemicals or consumables. Utilizing foam fractionation, the system removes up to 100% of targeted compounds and is effective without costly pre-treatment.
The LEEF System® is modular, so it is easy to scale up to fit a facility’s treatment needs. This flexibility allows the system to be customized to meet site-specific challenges for different leachate characteristics and flow. The flexible and robust modular system can be assembled to treat any volume from 5,000 gpd to 500,000+ gpd. The technology has already been successfully deployed at a landfill leachate treatment plant in the northern Australian city of Darwin, treating 36,000 gallons of complex leachate each day, in a zero liquid discharge operation.
To show capability in the US, WCG constructed a mobile demonstration-scale system that consists of four fractionators housed in a 40-foot shipping container that can be easily deployed throughout the country.
In July 2022, the system was commissioned at the Tennessee landfill site to treat three diverse raw leachates and one reverse osmosis concentrate (ROC). The streams were highly co-contaminated including:
- Ammonia ranging from 380 mg/L to more than 3,800 mg/L
- Total Dissolved Solids (TDS) between 5,700 mg/L and 50,800 mg/L
- Chemical Oxygen Demand (COD) from 3,600 mg/L to over 24,000 mg/L
In addition, PFOA in the streams was between 1,400 ng/L and 5,100 ng/L and PFOS from 68 ng/L to nearly 400 ng/L.
Results
The Tennessee demonstration was a success with the LEEF System® consistently removing PFAS compounds to below limits of detection, which ranged from <4 to <369 ng/L, while concentrating them into the small volume of foamate.
PFOA in the ROC was reduced from 5,110 ng/L to <8.85 ng/L as its foamate reached 233,000 ng/L, clearly indicating a highly successful removal. Interestingly, PFOS in one of the raw feeds started out as non-detected at <333 ng/L and ended up enriching in the foam to 37,800 ng/L, proving the LEEF System® is indeed capturing the compounds, even if initial raw concentrations are below laboratory detection limits.
The resulting foamate was between 0.5% and 2.0% of the initial raw influent volume. Foamate generation is highly influenced by background surfactants in the leachate, and physical characteristics such as temperature. Foamate can be further concentrated in a full-scale system through additional site-specific design components including additional foam fractionation concentration, alternative vessel orientation, and the LEEF System’s® solar distillation feature.
In addition to priority compounds, the Tennessee demonstration revealed the LEEF System® was able to deplete other PFAS that were initially present in the leachate streams, such as PFBS, PFHxA, PFDoA, PFHpS, 6:2 FTS, 5:3 FTCA, 7:3 FTCA, and others.
To discuss how the LEEF System® can be used to treat PFAS in leachate or industrial wastewater, or to arrange a demonstration at your site in the United States, contact us.
