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PFAS in Biosolids
Mohammad M. Abu-Orf, Ph.D.
Vice President
Residuals and Biosolids Practice Leader
February 4th, 2020
Biosolids beneficial use has had its challenges!
Odors
Persistent public opposition
Land application errors
…and now PFAS
Biosolids beneficial use
recycles valuable nutrients
to the environment &
improve soil health
Agenda
• What are PFAS chemicals
• PFAS in the engineered water cycle
• Regulatory outlook for PFAS
• Solutions to address PFAS
challenges in biosolids
• Source control
• Volume reduction
• Advanced thermal processes
• What to do?
What are PFAS chemicals and
how did we get here?
Per-Polyfluoroalkyl substances (PFAS)
• Family of manmade
fluorinated chains (>4,000
chemicals)
• Perfluoroalkyl substances
• All H atoms attached to carbon
atoms are replaced by F atoms
• Short chain and long chain PFAS
• Polyfluoroalkyl substances
• H replaced by F on at least one C
atoms
• Some can degrade to PFAA
Terminal degradation
products (biotic and abiotic)
of precursor chemicalsSource: ITRC Factsheet, Naming Conventions and Physical and Chemical Properties of Per- and Polyfluoroalkyl Substances (PFAS)
PFAS discovery and manufacturing history
https://pfas-1.itrcweb.org/wp-content/uploads/2017/11/pfas_fact_sheet_history_and_use__11_13_17.pdfSource: ITRC Factsheet, History and Use of Per- and Polyfluoroalkyl Substances (PFAS)
PFAS is a national issue
https://www.ewg.org/interactive-maps/2019_pfas_contamination/map/
https://www.ewg.org/interactive-maps/2019_pfas_contamination/map/
Reasons for concern
• PFAS are ubiquitous and persistent
in the environment
• Humans are often exposed to PFAS
through food, dust, consumer products,
clothing, and water
• Half life in humans is several years
(slow elimination)
• Exposure is cumulative
• Longer-chain molecules bioaccumulate
more than shorter chain molecules
• Phase-out of PFOS and PFOA
• Manufacturers simply switch to shorter
chain PFAS
• Short-chain PFAS are MORE
CHALLENGING to treat
Health Effects
Animal laboratory studies:
• Reproductive and developmental, liver
and kidney, and immunological effects
• Tumors
Humans: in our blood for half a century!
• Consistent findings: increased cholesterol
levels among exposed populations
• limited findings related to:
• Infant birth weights
• Effects on the immune system
• Cancer (for PFOA)
• Thyroid hormone disruption (for PFOS)
PFAS in the engineered
water cycle
Fate and transport of PFAS within
the engineered water cycle
• Detected in drinking water
sources across the nation
• Detected in biosolids
• Detected in WRRFs effluents
Sources of PFAS to WWRFs
Domestic: mainly from consumer products
• 2006 survey in the USA documented that municipal wastewater,
with minimal industry input, can range from 60 to 220 ng/L PFAS
• Septic systems are expected to have slightly higher concentrations
Industrial: typical below
Emissions of perfluorinated alkylated substances (PFAS) from point sources-identification of relevant branches;
M. Clara, C. Scheffknecht, S. Scharf, S. Weiss, and O. Gans; Water Science & Technology; 2008, 51.8
Reasons for concern: water resources
recovery facilities (WRRFs)
• WRRFs don’t produce PFAS
• Precursors discharged to
WRRFs and degradation cause
• PFAS increase across biological
processes and
• PFAS increase effluent
concentrations
• PFAS found in effluents and
residuals in plants not receiving
industrial discharges
• Removal of PFAS is mainly due
to sorption to solids/residuals
• >6 carbon chains adsorb to solids
and removed in residuals Coggan et. al., Heliyon, 2019
Reasons for concern: land application (50% of residuals produced in the USA are land applied)
• PFAS are concentrated in residuals
• Common stabilization technologies, digestion, thermal
hydrolysis pretreatment, composting, drying do NOT remove
PFAS
• Highest concentrations found in residuals with direct industrial
input
• Land application “spreads” PFAS across the environment
• Detected in groundwater near land application of biosolids
• Found in residuals and soils (not impacted by industrial input)
after land application
Regularity outlook for PFAS
National Perspective
• In 2016, the EPA established a lifetime health advisory level of
70 parts per trillion (ppt) for individual or combined
concentrations of PFOA and PFOS in drinking water
• In February of 2019, the EPA released a PFAS Action Plan:
• Statement committing the agency toward developing a maximum
contaminant limit (MCL) for PFAS compounds for drinking water
• As of Feb 2020, EPA currently has not established national primary
drinking water regulations for PFOA and PFOS
• Biosolids is far behind:
• 503 Regulations don’t address emerging contaminants
• No approved EPA standard methods for measurement
No consistent regulatory approach
22 States have or are considering specific guidance or regulations related to PFAS in Drinking Water and/or Groundwater (Beyond EPA HAs)
State of Maine imposed a moratorium on
biosolids land application – March 22, 2019
• Testing of PFAS (PFOA, PFOS and PFBS) required for all
biosolids to be land applied
• Initial sampling and testing completed by May 7, 2019
Screening Concentrations for PFAS in Biosolids (Maine)
PFOA 0.0025 mg/kg
PFOS 0.0052 mg/kg
PFBS 1.9 mg/kg
Other New England and northeast states may consider restriction on biosolids land application
Solutions to address PFAS
challenges in biosolids
• Source control
• Volume/mass reduction
(does not destroy PFAS)
• Anaerobic digestion
• Thermal drying
• Incineration
• Advanced thermal
treatment (destroys PFAS)
• Drying/pyrolysis
• Drying/gasification
• Super critical water oxidation
• Hydrothermal liquefaction
Treating PFAS Chemical – Difficult to Treat!
• Terminal PFAAs are extremely
stable compounds
• Strong C-F bond, and carbon
shielding
• Thermal destruction require
temperatures > 1,000◦C
(~1,850◦F)
• Sewage sludge incinerators
(SSI) range between 1,450◦F
to 1,600◦F
• Chemical hydrolysis,
oxidation and reduction is
challenging due to the
fluorine effect!
Perfluorooctanoic Acid (PFOA)
Source reduction: Michigan DEQ success
Source reduction efforts have resulted in substantial drop in
PFOS concentrations being discharged at the WWTPs
https://www.michigan.gov/pfasresponse/0,9038,7-365-88059_91299---,00.html
Volume reduction (wet tons)
• Does not remove PFAS, but concentrate it
• Reduce amount to be disposed of if PFAS is an
issue (hauling and tipping fees)
• Anaerobic digestion: ~ 35%
• Thermal drying w/o digestion: ~78%
• Thermal drying w/digestion: ~86%
• Incineration: reduces mass to ~96%
Advanced thermal treatment
Pyrolysis/gasification systems reaching
commercial scale
Parameter Combustion Gasification Pyrolysis
Temperature (°F) 1,650-2,000 1,100-1,800 390-1,100
O2 Supplied> Stoichiometric
(Excess Air)
< Stoichiometric
(Limited Air)None
By-ProductsFlue Gas (CO2,
H2O) and Ash
Syngas (CO, H2)
and Ash
Pyrolysis Gas, Oils,
Tars and Char
Biodry/pyrolysis (Bioforcetech Corp)
Silicon Valley Clean Water, CA: 20 wtpd (since 2017)Courtesy: Bioforcetech Corporation
Dry biosolids
PFOA = 89.1 ng/g
PFOS = 26.3 ng/g
Biochar
Non Detect
ND
Thermal drying/gasification (Ecoremedy, LLC)
Morrisville, PA. 70 wtpd,
30 from Morrisville. In
commissioning, 4Q 2019
Courtesy: Ecoremedy,
LLC
No testing on
PFAS, but similar
results expected
as Bioforcetech
TBD
Thermal drying/gasification
(Aries Clean Energy)
• Linden Roselle Sewerage
Authority, NJ
• 430 wtpd : largest gasification
facility globally
• Groundbreaking Oct 17, 2019
• Expected to start ~ end 2021-
2022
Courtesy: Aries Clean Energy
Thermal drying/energy recovery system
(Kruger, Veolia)
No testing on
PFAS, but similar
results expected
as Bioforcetech
TBD
• Buffalo, MN: 20 wtpd, since 2009!
• Largest facility is 50 MGD Pomorzany WWTP in Poland, Europe
High temperature and
pressure treatment
Super Critical Waste Oxidation (374Water)
Duke University
Testing on 3 different
sludges shows non-detect
for PFOS and >99.8% PFAS
removal!
What to do?
• Stay updated and informed, things are changing fast
• Keep an eye on regulations, federal and local
• May want to test PFAS in residuals and effluent, but
be prepared to communicate
• If an issue:
• Start the planning process: diversify outlets
• May want to identify sources, best option if feasible
• Look to update management plans
• There are options out there that can mitigate
Thank you for the privilege of your time!
Mohammad Abu-Orf, PhD
Cell: (856) 332-4030
Email if you like reference sources for any of
the facts mentioned in this presentation