Serving Georgia, Tennessee, Alabama, North Carolina, South Carolina, and Florida
PFAS BENCH-SCALE TREATABILITY TESTS
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 seven (7) 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.
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
Analyte PFAS Removal
Efficiency, %
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
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 leachates have significant correlations with TOC, alkalinity, ammonia, and COD. Remtech set out to see if similar PFAS and laboratory 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.
Rapid PFAS Testing
Table 1: Raw PFAS Analyte Concentrations
Table 2: PFAS GAC Removal Percent
Field COD Meter vs Lab COD Correlation Curve
Lab COD, mg/l
Field COD Meter, mg/l
↓
↓
↓
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
2
2