Emerging Contaminants:
Fate During Wastewater Treatment
and Strategies to Enhance Removal
David Quanrud
The University of Arizona
New Directions in Wastewater Treatment
AZ Water Association
21 October 2014
Outline
1. Let’s talk terminology: ECs and EDCs
2. Fate of estrogenic activity during WW treatment
– Comparison of AZ WWTPs
– WERF project: WWTP mass balances
3. How can we improve removal of ECs during WWT?
Terminology Salad
• Emerging contaminants (ECs)
• Compounds of emerging concern (CECs)
• Trace organic contaminants (TOrCs)
• Pharmaceutically active compounds (PhACs)
• Pharmaceuticals and personal care products (PPCPs)
• Endocrine disrupting compounds (EDCs)
• Hormonally active agents (HAAs)
Many terms are in use but they do not
all mean the same thing…
What is an emerging contaminant?
It is possible to distinguish 3 categories of emerging contaminants:
1. New compounds not previously present in the environment for which toxicity
is known/suspected (e.g. nanoparticles, PBDEs)
2. Compounds that have existed for a while but environmental contamination
issues were not appreciated until recently (e.g. estrogens)
3. “Legacy” contaminants for which new information exists on their toxicity
(e.g. arsenic)
A more accurate term:
“Compounds of emerging concern”
Number of articles by year
containing term “emerging contaminant”
(ScienceDirect literature search, 10-15-14)
800
700
600
500
400
300
200
100
2015
2014
2013
2012
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
0
Why are we more aware of ECs now?
•
•
•
•
Our Stolen Future (1996)
USGS national reconnaissance survey (2002)
Associated Press investigation (2008)
Increased usage over time (e.g. additives in hand soaps)
• Improved analytical methods! (ppb, ppt, ppq)
Caffeinated soap!
Examples of ECs
• Pharmaceuticals
–
–
–
–
–
over-the-counter
prescription
caffeine
nicotine
veterinary drugs
• Personal care products
–
–
–
–
soaps
sunscreens
cosmetics
bug sprays
• Industrial compounds
– flame retardants
– plasticizers
– bisphenol A
Some of the these compounds
are endocrine disruptors
(EDCs), but many are not…
So, what is an endocrine
disruptor?
What is an endocrine disrupting compound?
“An endocrine disruptor is an exogenous
substance or mixture that alters function(s) of the
endocrine system and consequently causes
adverse health effects in an intact organism, or its
progeny….”
From: “Global Assessment of the State-of-the-Science of Endocrine
Disruptors.” International Programme on Chemical Safety,
World Health Organization (2002)
Yeast estrogen screen (YES) bioassay
E
R
R
E
Cytoplasm
hER
lac z
CPRG
CPRG
yellow
red
b-gal
Cytoplasm
=Estrogens
E =Estrogen
R
= Receptor
17- Ethinylestradiol
3.5
A570 nm - A630 nm
3.0
• In vitro reporter gene bioassay
EC50 =1.1 x 10-10 M
• Utilizes human estrogen receptor
2.5
2.0
• →Total estrogenic activity
reported as equivalent
concentration of EE2, based on
comparison to standard curve
1.5
1.0
0.5
0.0
1.E-13
1.E-12
1.E-11
1.E-10
1.E-09
1.E-08
Molar concentration in well
1.E-07
1.E-06
Fate of Estrogenic Activity during Conventional
Wastewater Treatment (trickling filter)
Wastewater
Influent (biotower)
Where did it go?
influent
Wastewater
Effluent
(biotower)
Two possibilities:
~50%
removal
effluent
0.0
2.0
4.0
6.0
8.0
10.0
Estrogenic Activity EEQ (nM)
12.0
14.0
– compound destruction
(biodegradation)
– mass transfer
(adsorption to the sludge)
Estrogenic Activity: Comparison of Arizona WWTPs
Oxidation ditch
Membrane bioreactor
Influent
Activated Sludge + BNR
Effluent
Activated Sludge (pure O2)
Biotower #1 (shorter SRT)
Biotower #2 (longer SRT)
Sludge
Comparison of six Arizona WWTPs
Influent
Effluent
Estrogenic activity remaining in effluent (%)
Estrogenic activity remaining in solid (sludge) (%)
Raw Influent
Oxidation Ditch
Chlorination
2° Clarifier
Sludge
Final Effluent to
Storage Pond
Sludge
Drying Beds
Bar Screen
(RAS)
2° Sludge
(WAS)
Sludge
Holding Tanks
Final
Sludge
Oxidation Ditch
1% <0.01%
Raw
Influent
1° Clarifier
Activated
Sludge
Final Effluent
2° Clarifier
Membrane Bioreactor
<0.01% <0.01%
Raw
Influent
Trickling Filters
1° Clarifier
Bar Screen
Grit Chamber
<0.01% <0.1%
Final Effluent
2° Clarifier
RAS
Act. Sl. + BNR
2° Sludge
2° Sludge
(WAS)
1° Sludge
(WAS)
Bar Screen
1° Sludge
Thickener
Effluent
Thickener
Effluent
Thickener #3 Thickener #2
Digester
Supernatant
Anaerobic
Digested
Sludge
Activated Sludge
24% 18%
Thickener #3 Thickener #2
Digester
Supernatant
Anaerobic
Digested
Sludge
Biotower #1
Biotower #2
63% 16%
3% 14%
Fate of Estrogenic Compounds During
Municipal Sludge Stabilization & Dewatering
WERF Project 04-HHE-6
Beverley Stinson, PhD
Kathleen Esposito
Mohammed Abu-Orf, PhD
Edward Furlong, PhD
James Gray, PhD
Dana Kolpin
Patrick Phillips
David Quanrud, PhD
Wendell Ela, PhD
Sondra Teske
Dave Newman
Alan Hais, PE, BCEE
Analytical Methods
• Chemical analysis
• In vitro bioassay
– yeast estrogen screen (YES)
WERF Project 04-HHE-6
Wastewater Treatment Processes
Primary
Treatment
Secondary
Treatment
Aerobic
Digestion
Anaerobic
Digestion
mesophilic
Lime
Addition
(Plant A)
(Plant B)
(Plant C)
Settling
Anaerobic
Digestion
thermophilic
(Plant D)
WERF Project 04-HHE-6
Most Important Contributors to Estrogenicity
WERF Project 04-HHE-6
Compound
Name
Abbr.
Log
Kow
Mol.
Wt.
Potency,
relative to EE2
[g/mol]
[molEE2/mol]
17α-ethinylestradiol
EE2
4.15
296.39
1.000000
17α-estradiol
E2a
3.67
272.37
0.840000
17β-estradiol
E2
3.94
272.37
0.840000
Estrone
E1
3.43
270.35
0.319000
Estriol
E3
2.81
288.37
0.002000
4-n-Octylphenol
4nOP
5.50
206.33
0.000360
4-tert-Octylphenol
4tOP
5.28
206.33
0.000360
4-Octylphenol monoethoxylates
OP1EO
250.36
0.000010
4-Octylphenol diethoxylates
OP2EO
294.42
0.000010
4-Nonylphenol
NP
5.92
220.34
0.000010
4-Nonylphenol monoethoxylates
NP1EO
4.17
264.39
0.000001
4-Nonylphenol diethoxylates
NP2EO
4.21
290.43
0.000001
Diethylstilbestrol
DES
5.07
268.34
0.924000
Bisphenol A
BPA
3.64
228.28
0.000563
benzoph
3.15
182.22
0.000168
DEHP
8.39
390.56
0.000021
Benzophenone
Diethylhexyl phthalate
(total masses of estrogenic activity per day)
Plant B
(Activated sludge)
Mesophilic
anaerobic
digestion
Liquid phase:
– Estrogenic activity reduced by ~85%
– Hormones are responsible for most of the estrogenic activity in effluent
Solid phase:
– Estrogenicity increased during anaerobic digestion of sludge
– Alkylphenols are converted into more estrogenic metabolites (e.g. NP)
WERF Project 04-HHE-6
(total masses of estrogenic activity per day)
Plant D
(Activated sludge)
Thermophilic
anaerobic
digestion
Liquid phase:
– Estrogenic activity reduced by ~95%
– Hormones are responsible for most of the estrogenic activity in effluent
Solid phase:
– Estrogenicity increased during anaerobic digestion of sludge
– Alkylphenols are converted into more estrogenic metabolites (e.g. NP)
WERF Project 04-HHE-6
Summary Observations
WERF Project 04-HHE-6
• Liquid phase:
– Estrogen hormones account for majority of estrogenic
activity in effluent of WWTPs
– Most estrogenic compounds are efficiently removed
during conventional activated sludge treatment
• Solid phase—anaerobic digestion:
– Estrogenicity increases
– Alkylphenols are converted into more estrogenic
metabolites (e.g. nonylphenol)
– Important to consider the ECs present in biosolids
(e.g. what happens during land application?)
Examples of trace organic compounds
present in municipal wastewater
Log Kow: a measure of how hydrophilic ("water-loving") or how
hydrophobic ("water-fearing") a chemical substance is
Compound
Use
Log Kow
Iopromide
PFOS (Scotchgard)
Sucralose
PFOA
Primidone
Sulfamethoxazole
Trimethoprim
TCEP
Fluoxetine (Prozac)
DEET
Carbamazepine
Tonalide (synthetic musk)
X-ray contrast agent
Surfactant
Artificial sweetener
Surfactant
Anti-convulsant
Antibiotic
Antibiotic
Flame retardant
Anti-depressant
Mosquito repellent
Anti-convulsant
Fragrance
-2.30
-1.08
-1.00
-0.90
0.11
0.48
0.91
1.63
1.80
2.18
2.45
5.90
(None of these compounds are currently regulated in USA)
hydrophilic
(waterloving)
(waterfearing)
hydrophobic
Possible removal
mechanisms
for ECs
during WWT
Significant
Sorption to solids
— Dependent on
hydrophobicity
Biodegradation
— Aerobic
— Anoxic
— Anaerobic
Not Significant
Volatilization
— Low Henry’s constants
Chemical transformations
— Hydrolysis
— Acid base
— Photocatalytic
Generalizing on
EC Fate during
Wastewater Treatment
Hydrophobicity (log KOW)
Biodegradability
ibuprofen
alkylphenols
& lots of others
(maybe not
much reason
for concern)
(e.g. NP)
(may survive
in sludges)
Compounds of
greatest concern:
• Long half lives
• High toxicity
iopromide, PFOS,
carbamazepine,
sulfamethoxazole
PBDEs, triclosan,
PFCs
(concern in
treated WW)
(concern in land
applied biosolids)
Examples of compounds most
susceptible to removal during
conventional WWT
•
•
•
•
•
•
•
•
•
•
•
•
Ibuprophen
Thymol
Estrone
Aspirin
Bezafibrate
Fenoprofen
Salicylic acid
Estriol
Acetaminophen
Cortisol
Prednisone
Dexamethasone
Examples of compounds least
susceptible to removal during
conventional WWT
•
•
•
•
•
Carbamazepine
Diclofenac
Metoprolol
Iopromide
Sotalol
Oulton et al. 2010. Pharmaceuticals and personal care products in effluent matrices: a survey of
transformation and removal during wastewater treatment and implications for wastewater management.
Journal of Environmental Monitoring. 12. 1956-1978.
What are the options to increase removal
of ECs during WWT?
1. Optimize biological treatment conditions
– Increase SRT
– Add BNR
2. Incorporate advanced treatment processes
–
–
–
–
Activated carbon adsorption
Ozonation
Advanced oxidation processes (AOPs)
Membranes (NF, RO)
Solids Retention Time
Several studies have shown that increasing the SRT
provides for greater removal of ECs
• Increases the biodegradative capacity of activated sludge
– May promote better adapted microbial populations for EC removal
• Increases the sorptive capacity of activated sludge
– May Improve hydrophobic/hydrophilic properties of flocs and their
ability to act as sorbents for ECs
However, other studies have found no correlation of
SRT with removal of ECs, e.g. Joss et al. (2005);
Gobel et al. (2007)
Laboratory simulation of
wastewater treatment
(activated sludge)
Garrett Configuration
Garrett 1958
Pumps
BioStat MD
Control Unit
CMAS Reactor
Synthetic
Wastewater
Clarified Effluent
/Clarifier
Effect of increasing sludge age
on EDC removal during
activated sludge treatment
Influent
Effluent
Sludge
EC removal can be improved by increasing the sludge age
General consensus on effect of SRT
• A majority of studies have shown a positive correlation between
increased SRT and increased percentage removal of ECs
•
As sludge age increases, EC removal efficiency also increases
• Other factors may also be important…
– Temperature, pH, seasonal variations
– Microbial populations may vary among WWTPs
• BNR: removal efficiency of ECs increases with higher rates of
nutrient removal
However…
What is an appropriate MCL for
estrogens in effluent?
• Environment Agency of England and Wales suggests a
predicted no-effect concentration (PNEC) of 1 ng/L total
estrogens to protect aquatic wildlife
• British Columbia has set an environmental guideline at 0.5 ng/L
EE2
• Australia and Norway have used a PNEC of 0.1 ng/L EE2 for risk
assessment
(1 ng/L = 1 part per trillion = 1 penny in 10 billion dollars)
Question: Can AS be sufficiently optimized to achieve
these guidelines?
Effluent estrogen concentration vs. SRT
Sum of E1 and E2 in effluent
EE2 in effluent
Credit: Linda Gaulke, EAWAG
• Even with long SRT, conventional WWT cannot achieve
<1 ng/L of total estrogen hormones in effluent
• Future regulation may necessitate use of advanced
wastewater treatment?…
Advanced Wastewater Treatment
EC destruction processes
• Ozone
• Advanced oxidation processes (AOPs)
EC removal (separation) processes
• Membranes (e.g. RO, NF)
• Activated carbon
Advanced treatment can provide complete to near
complete removal of most ECs, but at a high cost
Comparison of PPCP Removal efficiencies
by different WWTP technologies
Oulton et al. 2010. Pharmaceuticals and personal care products in effluent matrices: a survey of
transformation and removal during wastewater treatment and implications for wastewater management.
Journal of Environmental Monitoring. 12. 1956-1978.
Incidence of intersex in fish (Roach)
Testis
(control)
Ovary
(control)
male
female
intersex
(after 6 months exposure to different effluent treatment streams)
SF = sand filtration; ASP = activated sludge process
Intersex
Intersex
Testis
Testis
(6 mo ASP) (12 mo ASP)
Testis of Roach fish exhibited intersex
characteristics after 6 and 12 months
exposure to ASP effluent
Conclusion: based on the in vivo fish intersex assay, tertiary SF provides
equivalent benefits to more expensive advanced WWT options
Baynes et al. 2012. Additional treatment of wastewater reduces endocrine disruption in wild fish—a comparative study of tertiary
and advanced treatments. Environmental Science and Technology. 46. 5565-5573.
Cost comparison for tertiary and
advanced wastewater treatments
treatment Total Cost
CO2
option ($/pe/yr) (kg/pe/yr)
GAC
ClO2
Ozone
SF
5.53
2.91
2.25
1.69
13
6
<3
-
(from Baynes et al., 2012)
Sand filtration (SF) provided an effluent equivalent in
quality to GAC, at about 1/3 of the total financial cost
(based on in vivo fish intersex assay)
Economic ranking of options for
reducing ECs in effluent discharge
High cost
1. Advanced treatment
― Membranes, activated carbon
― Ozone, advanced oxidation processes
2. Tertiary treatment
― BNR
― Sand filtration
3. Optimize conventional WWT
— Increase SRT
Low cost
4. Source control
— (Effectiveness is uncertain)
Will there be regulations pertaining to ECs?
Regulating ECs is problematic…
– ECs can exert biological effects at very low doses (ng/L)
– Measuring ECs accurately is challenging and expensive
– ECs occur as complex mixtures in wastewater; are biological
effects multiplied by mixtures?
– Should a biological test (bioassay) be used to assess ECs?
(in vitro? in vivo?)
– in vivo: what biological endpoint should be used?
(reproduction? intersex?)
– In the end, a combination of chemical and bioassay-based
tests may be implemented to assess ECs in effluent
Summary
1. EC fate during conventional WWT is dependent on overall
biological process efficiency
2. The majority of estrogenic activity in effluent is due to estrogen
hormones
3. It is important to recognize ECs are also present in the solid phase
4. EC removal can be improved by increasing SRT
5. Additional biological treatment (SF, BNR) is effective
6. Advanced WWT is most effective and most expensive
7. Some type of future regulation of ECs is possible and may include
a combination of chemical and bioassay-based parameters
Questions?
Lower Santa Cruz River
Tucson, AZ
quanrud@email.arizona.edu
Sweetwater Recharge Facilities (Tucson, AZ)
Soil aquifer treatment (SAT)
(Courtesy of Tucson Water)
EC Removal during Soil Aquifer Treatment
(Sweetwater Recharge Facilities, Tucson, AZ)
Occurrence of selected EDCs in treated
biosolids in the U.S.
Published in: Joel A. Citulski; Khosrow Farahbakhsh; Environ. Sci. Technol. 2010, 44, 8367-8376.
Land Application of Biosolids:
Long Term Fate of Trace Organics?
Biosolids
Field
Marana, AZ
Marana Agricultural Center (MAC)
NW ~20mi
• Twenty years of biosolid application
Tucson, AZ
• Soil analyzed for:
estrogenic activity
Nonylphenol
 PBDEs
Land Application of Biosolids: Fate of TOrCs?
UA Marana Ag. Center
Biosolid plots
Total PBDEs
0
concentration (ug PBDE/kg soil)
20 40 60 80 100 120 140
depth (ft)
0.5
1.5
2.5
3.5
4.5
3x
1x
control
• Estrogenic activity
• Polybrominated diphenyl
ethers (PBDEs)
• Nonylphenol
• Estrogenic activity and nonylphenol
are removed under aerobic
conditions and do not accumulate
over time
• PBDEs accumulate in soil over time
and degrade very slowly, if at all
Plant B:
Activated sludge
Mesophilic
anaerobic
digestion
(Model of Concentration Addition)
Plant D:
Activated sludge
Thermophilic
anaerobic
digestion
Definition (USGS)
http://toxics.usgs.gov/regional/emc/
“Emerging contaminants can be broadly defined as
any synthetic or naturally occurring chemical or any
microorganism that is not commonly monitored in
the environment but has the potential to enter the
environment and cause known or suspected adverse
ecological and/or human health effects.”
Fate of Ecs in the environment?
• ECs are not uniquely special--they have measurable physical
properties just like contaminants we’ve dealt with in the past,
e.g. pesticides and others
• ECs can be expected to follow similar behaviors as “legacy”
pollutants that have similar physical properties….
• Properties:
– Hydrophobicity
– Volatility
– Biodegradation potential
Reduction of Estrogenic Activity
(based on YES bioassay)
Plant
Solid Stabilization Process
Reduction
A
Aerobic Digestion
18%
B
Mesophilic Anaerobic Digestion
-31%
C
Lime addition to dewatered sludge
-312%
D
Thermophilic Anaerobic Digestion
-135%
Factors affecting removal efficiency of ECs
during biological treatment processes
• SRT, HRT
• pH, temperature
• BNR--nitrification/denitrification
What are the variables we can
manipulate to enhance the
removal of ECs during WWT?
• HRT
• SRT
• Additional unit processes
• Nutrient removal
• What else?
Can we improve EC removal during
conventional WW treatment?
Hypothesis: increasing the solids retention time
(sludge age) can improve EC removal during
conventional activated sludge wastewater
treatment
Sources of Emerging Contaminants
epa.state.oh.us
Which treatment parameter(s)
influence removal of ECs?
Helbing et al. 2012. Micropollutant biotransformation kinetics associate with WWTP process parameters and
microbial community characteristics. Environmental Science and Technology. 46. 10579-10588.
How to proceed w.r.t. ECs?
• First, optimize existing (biological) treatment processes for EC
removal (SRT, HRT, etc.)
• Second, plan for flexibility in long-term WWTP design to take
into account potential for future regulation of ECs
• Third, incorporate advanced WWT processes as needed
Sum of E1 and E2 in effluent
Is there a correlation between
SRT and effluent concentrations of estrogens?
(compilation of data from 8 research studies)
Credit: Linda Gaulke, EAWAG
EE2 in effluent
Less data and lower concentrations; no apparent trend
due to low values at both high and low SRT
(compilation of data from 5 research studies)
Credit: Linda Gaulke, EAWAG
Economics of advanced wastewater treatment
Hypothetical comparison of total costs of advanced wastewater treatment
options for three WWTP sizes (adapted from Jones et al., 2007).
Treatment
Option
Activated
sludge with
GAC + ozone
Activated
sludge with
MF + RO
Pop.
Size
Capital
Capital
Cost
Cost
(Standard) (Advanced)
($ million) ($ million)
Operating
Cost
(Standard)
($ million)
Operating
Cost
(Advanced)
($ million)
Total
Cost
(per m3)
($)
5,000
3.25
1.12
0.30
0.03
4.91
50,000
11.1
4.32
0.22
0.22
2.48
200,000
33.1
12.8
0.99
0.86
1.87
5,000
3.25
2.08
0.30
0.19
6.22
50,000
11.1
15.3
0.22
1.50
3.85
200,000
33.1
35.5
0.99
5.77
2.64
(1,000 gal = 3.79 m3)
Cost comparison for tertiary and
advanced wastewater treatments
Treatment
Option
Activated
sludge with
GAC + ozone
Pop.
Size
Total
Cost
(per m3)
($)
5,000
4.91
50,000
2.48
200,000
1.87
treatment
option
GAC
ClO2
Ozone
SF
Total Cost
($pe/yr)
CO2
(kg/pe/yr)
5.53
2.91
2.25
1.69
13
6
<3
-
(from Baynes et al., 2012)
Activated
sludge with
MF + RO
5,000
6.22
50,000
3.85
200,000
2.64
(from Jones et al., 2007)
(1,000 gal = 3.79 m3)
SF provided equivalent effluent
quality as GAC, based on in
vivo fish intersex tests, at
about 1/3 of the total cost
Why are we more aware of ECs now?
Improved analytical techniques
– parts per billion (ppb) (µg/L)
– parts per trillion (ppt) (ng/L)
– parts per quadrillion (ppq) (pg/L)
Our understanding of toxicity has
not caught up with our ability to
measure these compounds….
Economics of advanced wastewater treatment
Summary findings:
Capital Costs: advanced WWT can exceed conventional WWT
Operating Costs: advanced WWT (membranes) can greatly
exceed (up to 6x) conventional WWT (along with increased
energy consumption and CO2 emissions)
Modifying existing conventional WWT (increase SRT, add
nutrient removal processes) may be almost as effective in
removing ECs, but with much lower capital and operating
costs
2007. Jones et al. Questioning the excessive use of advanced treatment to remove organic
micropollutants from wastewater
Chemical vs. bioassays
• Some studies have shown