Research by Hekai Zhang, et. al, in a Chemosphere article dated July, 2023 entitled Relationships between Per-and Polyfluoroalkyl Substances (PFAS) and Physical-Chemical Parameters in Aqueous Landfill Samples concluded that PFAS concentrations in landfill leachates have significant correlations with TOC, alkalinity, ammonia, and COD.  Remtech set out to see if similar laboratory PFAS and field COD correlations could be established this wastewater matrix.

Laboratory COD correlation curves with a field COD meter resulted in a R value of 0.9987.  PFAS versus field COD meter correlations resulted in a R values ranging from 0.9992 to 1.0. Field COD meters have the potential to reduce PFAS lab costs by identifying trends that suggest PFAS treatment efficiencies have been achieved.

When COD values are less than 10 mg/l after GAC filtration, PFAS concentrations are typically less than 100 ppt. Correlation curves need to prepared for each specific waste stream.

Bench-Scale Treatment Train

PFAS Aeration, Sand Filtration and Three GAC Filters in Series

PFNA              

PFDA                 

PFBS               

PFPeS               

PFHxS              

PFHpS            

PFOS                 

PFNS             

4:2 FTS             

6:2 FTS              

8:2 FTS            

PFOSA              

NetFOSE       

GenX               

PFMBA            

3:3 FTCA          

5:3 FTCA         

PFDS               

23 PVP            

Remtech's bench-scale treatability tests can provide engineering information including carbon mass, flowrates/sf, the number and size of GAC and/or multi media columns, and media contact times, for the design of full-scale systems.

Remtech's mobile multi-media treatment system was designed based on bench-scale activated carbon tests were run on heavily contaminated runoff water from a chemical plant fire extinguished with AFFF foam. Treatment performance samples were run by an independant testing lab.  Untreated total PFAS concentrations of 2.55 mg/l (2,550,000 ppt) (Table 1) resulted in PFAS removal efficiencies listed in Table 2 for the six (6) of the twenty-three (23) EPA proposed PFAS regulated analytes (listed in RED).  Six of the PFAS analytes were Below Detection Limits (BDL) with ng/l sensitivities. Analyte removal efficiencies for TSS, COD, TOC, and VOCs exceeded 94.45%.

Wastewater PFAS influent and effluent concentrations are typically in the range of 50 to 200 ppt, landfill leachates 4,000 ppt, and drinking water 20 ppt.  Higher concentrations of PFAS occur near industrial discharges.  Other organic loadings including VOCs, Oil & Grease, TOC (Total Organic Carbon), COD (Chemical Oxygen Demand) and other analytes need to be removed prior to removing PFAS analytes. PFAS removal efficiencies increased when carbon contact times were increased from 10 to 20 minutes.  

The bench-scale treatment train consisted of concentration equalization of wastewater from over 20 frac tanks, clarification, aeration, sand filtration, and three (3) granular activated carbon filters in series. Coal based virgin GAC specifically designed for PFAS removal was selected.  A significant finding was that 28.65% of PFAS was removed by aeration.

Remtech's mobile treatment systems are designed to treat waste streams containing complex organics and PFAS for water, wastewater, landfill leachates, drinking water and other liquid and vapor matrices below proposed EPA proposed limits.  Remtech's design criteria for treatment of PFAS concentrations are over 1,000 times higher than what is typically present in environmental waste streams that ensures PFAS removal efficiencies below EPA proposed regulatory limits.

Mobile treatment train configurations for PFAS reduction may include solids clarification, flow/concentration equalization (Remtech's FRACAIR magnetic aeration system), air stripping, and multi-media filtration.

     ▸  PFAS Landfill Leachate Treatment

     ▸  PFAS Groundwater Treatment

     ▸  PFAS Wastewater Treatment

     ▸  PFAS Drinking Water Treatment

     ▸  Activated Carbon Treatment of Complex Organics

     ▸  PFAS Treatment of Vapor Emissions

Remtech can assist you with your treatability, design/build, or PFAS mobile treatment project by filling out our eform below.

Field COD Meter vs Lab COD Correlation Curve

BDL in sample

BDL in sample

100

100

100

100

99.98

100

99.97

100

100

100

BDL in sample

100

BDL in sample

BDL in sample

BDL in sample

BDL in sample

BDL in sample

PFBA                    

PFPeA               

PFHxA                     

PFHpA  

100

100

100     

100

Column 3

Column 2

Column 1

Field COD Meter, mg/l

Lab PFAS, ppb

Field COD Meter, mg/l

Lab PFAS, ng/l

Field COD Meter mg/l vs Lab PFAS, ng/l

Table 1: Raw PFAS Analyte Concentrations

Table 2: PFAS GAC Removal Percent