Emerging
Contaminants
in
Biosolids
George O’Connor
Soil and Water Science Department,
University of Florida
20th Annual Biosolids Management Conference
September 9-11, 2007
Contributing author: Liz H. Snyder
Common Contaminant “Lingo”
Chemical Group
Grouping Method
EDC (Endocrine Disrupting Chemical)
toxicological mode of action or endpoint
PBT (Persistent, Bioaccumulative Toxic)
POP (Persistent Organic Pollutant)
environmental properties
OWC (Organic Wastewater Contaminant)
location of occurrence
PPCP (Pharmaceuticals and Personal Care Product)
type of intended usage
Priority Pollutant
regulation
ECC (Emerging Compound of Concern)
novelty, fad, timeliness, or new concern
Xenobiotics
foreign versus endogenous
HPV (High Production Volume) chemical
quantity (manufactured/imported in US ≥1 million
pounds/year)
POHO (Pollutant Of Human Origin)
source or origin
• many additional categories
• use depends on context, author, audience, date of publication
Slide credit:
Adapted and extended by Daughton from: Renewable Resources Journal, 2005, 23(4):6-23.
Target Compounds for USGS National Reconnaissance
of Emerging Contaminants in US Streams
• Human Drugs
• Prescription (13)
• Non-prescription (6)
•Veterinary and Human Antibiotics (21)
•Industrial and Household Wastewater Products
• Insecticides (8)
• Plasticizers (5)
• Detergent Metabolites (5)
• Fire Retardants (2)
• Fossil Fuel and Fuel Combustion Indicators (6)
• Antioxidants (5)
• Others (8)
• Sex and Steroidal Hormones (15)
Extend list to biosolids?
Emerging Contaminants in Biosolids
 Buyuksonmez F, Sekeroglu S. “Presence of pharmaceuticals and personal care products (PPCPs) biosolids and their degradation during composting.” Journal
of Residuals Science and Technology. 2005. 2(1): 31-40
 Cai Q, Mo C, Wu Q, Zeng Q, Katsoyiannis A. “Quantitative determination of organic priority pollutants in the composts of sewage sludge with rice straw by
gas chromatography coupled with mass spectrometry.” 2007. J. Chromatography 1143: 207-214.
 Harrison EZ, Oakes SR, Hysell M, Hay A. "Organic Chemicals in Sewage Sludges." Science of the Total Environment. 2006. 367(2-3):481-497 (review
involving pollutants in general)
 Gomez-Rico MF, Font R, Aracil I, Fullana A. “Analysis of organic pollutants in the sewage sludge of the Valencian community (Spain).” Archives of
Environmental Contamination and Toxicology. 2007. 52: 306-316.
 Heidler J, Sapkota A, Halden, RU. "Partitioning, Persistence, and Accumulation in Digested Sludge of the Topical Antiseptic Triclocarban During
Wastewater Treatment." Environmental Science and Technology. 2006. 40(11): 3634-3639.
 Jones-Lepp TL, Stevens R "Pharmaceuticals and Personal Care Products in Biosolids/Sewage Sludges - The Interface between Analytical Chemistry and
Regulation." Analytical and Bioanalytical Chemistry. 2007. 387(4): 1173-1183.
 Heidler J, Halden RU. "Mass Balance Assessment of Triclosan Removal During Conventional Sewage Treatment." Chemosphere. 2007. 66(2): 362-369.
 Kinney CA, Furlong ET, Zaugg SD, Burkhardt MR, Werner SL, Cahill JD, Jorgensen GR. "Survey of Organic Wastewater Contaminants in
Biosolids Destined for Land Application." Environmental Science and Technology. 2006. 40(23): 7207-7215.
 Kester GB, Borbst RB, Carpenter A, Chaney RL, Rubin AB, Schoof RA, and Taylor DS. “Risk Characterization, Assessment, and Management of Organic
Pollutants in Beneficially Used Residual Products.” Journal of Environmental Quality. 2005. 34:80-90.
 Miao XS, Yang JJ, Metcalfe CD. “Carbamazepine and its metabolites in wastewater and in biosolids in a municipal wastewater treatment plant.”
Environmental Science and Technology. 2005. 39(19): 7469-7475.
 O’Connor G. “Organic compounds in sludge-amended soils and their potential for uptake by crop plants.” The Science of the Total Environment. 1996.
185: 71-81.
 Osemwengie LI. "Determination of Synthetic Musk Compounds in Sewage Biosolids by Gas Chromatography/Mass Spectrometry." Journal of
Environmental Monitoring. 2006. 8(9): 897-903.
 Rogers HR. “Sources, behaviour and fate of organic contaminants during sewage treatment and in sewage sludges.” The Science of the Total Environment.
1996. 185: 3-26.
 Ying G and Kookana R. “Triclosan in wastewaters and biosolids from Australian wastewater treatment plants.” 2007. 3(2): 199-205.
 Xia K, Bhandari A, Das K. “Occurrence and fate of pharmaceuticals and personal care products (PPCPs) in biosolids.” Journal of Environmental
Quality. 2005. 34(1): 91-104.
PPCPs as “Emerging” Risks?
It is reasonable to surmise that the occurrence of
PPCPs in waters is not a new phenomenon.
It has only become more widely evident in the last
decade because continually improving chemical
analysis methodologies have lowered the limits of
detection for a wide array of xenobiotics in
environmental matrices.
There is no reason to believe that PPCPs have
not existed in the environment for as long as
they have been used commercially.
Slide credit:
Adapted from Christian Daughton, PhD, Environmental Protection Agency
Einstein on:
Environmental Monitoring
“Not everything that can be counted
counts, and not everything that counts can
be counted.“ (oft attributed to Albert Einstein)
corollary for environmental monitoring:
Not everything that can be measured is
worth measuring, and not everything
worth measuring is measurable.
Slide credit:
Adapted from Christian Daughton, PhD, Environmental Protection Agency
Predicting the fate of emerging
contaminants – difficult, but
not hopeless
• Why difficult?
–
–
–
–
Complex compounds and metabolites
Low to very low concentrations
Analytical difficulties
Unknown chemical properties and biological effects
• Why not hopeless?
– Previous experience with similar compounds, e.g.
pesticides, priority pollutants
– Basic chemical principles expected to apply
– Previous risk assessments for other biosolids-borne
organics, e.g. PCBs, dioxins
Objectives
• Identify biosolids-borne emerging
organic contaminants, sources, typical
concentrations, and potential impacts
• Explain the basic principles of organics
reactions/fates in soil/plant systems
• Show how lessons learned can be
applied to modern “emergents”
Available: http://www.epa.gov/nerlesd1/chemistry/pharma/image/drawing.pdf
Concentrated
population
Industry
Pre-treatment
Central wastewater treatment facility
Landfill or
incineration
Sewage sludge
Kill pathogens
Remove solids
Effluent
Biosolids
Land application
In
biosolids
and/or
effluent
+
Contaminant Fate In WWTPs
• Even when removal is efficient, sufficient
chemical can exit in effluent to:
– Affect aquatic organisms
• Low concentrations do not mean “no effect”
– Contaminate surface and ground waters
– Contaminate drinking water supplies
• Organics may accumulate in biosolids
– Removal from aqueous phase does not mean degradation
– Subsequent availability of biosolids-borne organics in landapplied biosolids is THE question
Compound
Concentration
(mg kg-1)
Log Kow
Solubility
(mg L-1)
Vapor Pressure
(mmHg)
10.2
4.53
10
6.45 x 10-7
0.07
2.45
17.7
1.84 x 10-7
0.63
4.57
13.8
1.98
Antimicrobial Compounds
triclosan
Human Drugs
carbamazepine
Fragrances
d-limonene
10-2
19.6
2.14
3560
1.22 x
3b-coprostanol
126
8.82
0.000203
5.47 x 10-10
cholesterol
209
8.74
0.095
7.79 x 10-10
bis(2-ethylhexyl)phthalate
20 - 160
3.98
0.40
6.45 x 10-6
diethylhexyl phthalate
10.5
7.88
0.27
1.42 x 10-7
anthracene
0.14
4.5
0.0434
6.53 x 10-6
phenanthrene
0.342
4.52
1.15
1.21 x 10-4
1,4-dichlorobenzene
5.3
3.52
79
1
phenol
2.1 - 54.7
1.5
82800
0.35
bisphenol A
4.70
3.32
120
3.91 x 10-7
PCBs (Actual concentration – 95th %)
Total toxic equivalent basis (TEQ)–
95th percentile
0.21
0.0000131
4.5 –
> 8.0
0.000004 –
7.48
Penta dibrominated diphenyl ethers
PBDEs (Sum)
<0.008 – 4.89
5.74 –
8.27
0.01 - 0.13
2.12 x
–
1.94 x 10-3
Polychlorinated dibenzodioxins and
Dibenzofurans (total TEQ)
0.0000333
6.8
0.0000193
7.4 x 10-4
indole
Sex and Steroidal Hormones
Plasticizers
Some
Organic
Contaminants
in Biosolids
Polycyclic aromatic hydrocarbons
Others
7.6 x 10-10 –
0.08
10-9
* Adapted from Xia, 2005; Kinney, 2006;
Kester, 2005
Attitudes Towards Emerging Contaminants
in Biosolids
It’s all a bunch of hype!
The sky is falling!
• “pollutant du jour” syndrome
• we’re awash in evermore
• WWTPs are very efficient and will
degrade organics
dangerous chemicals
• availability in biosolids is so low,
and the concentration in biosolidsamended soil is so low, that there’s
nothing to worry about
• unknown toxicity,
mutagenicity, carcinogenicity
The “Correct” Attitude
• Likely that fate of biosolids-borne contaminants is
compound/biosolids/management specific
• Known risks are likely small
• Unknown risks require assessment by those who
appreciate the uniqueness of biosolids-amended
systems
Principles of Organic Contaminant
Behavior in Biosolids-Amended Soils
•
•
•
•
•
•
Retention/Release/Partitioning
Degradation
Volatilization
Photolysis
Plant uptake and metabolism
Leaching and runoff
Retention/Release/Partitioning
Retention/Release
Kd = fraction sorbed to soil / fraction in
aqueous phase
Kd = Soil adsorption/partition coefficient
Koc = adsorption coefficient normalized to
OC content of soil
Koc = Kd / fraction OC
Biosolids addition may increase the OM content of
the soil and, thus, a chemical’s retention
Partitioning, Kow
• Defined as the ratio of the equilibrium concentrations of a
dissolved substance in a two-phase system consisting of two
largely immiscible solvents.
Log Kow = log (Cn-octanol/Cwater)
– Correlated to water solubility, soil/sediment sorption
coefficient, and bioconcentration in biota
– Measurement or estimation of the octanol/water partition
coefficient is an important first step in assessing the fate of
chemicals.
Degradation
Degradation
• Two types: biotic and abiotic
• Half-life (t1/2): time required for ½ of a compound to degrade
– Biological half-life
-Disappearance time
– Chemical half-life
-Pseudo-persistence
• Half-life is one way to categorize contaminant persistence
– <10 days (unlikely to be available for significant plant uptake)
– 10-50 days
– >50 days persistent
• Bound residues may have extended half-lives, but have limited biological
and environmental availability
Volatilization
Volatilization
• The process by which a chemical is lost as a gas
• A chemical’s tendency to volatilize is measured by the
chemical’s Henry's Constant (HC), which is a function of
chemical solubility and vapor pressure.
• The greater a chemical’s HC, the greater the chemical’s
volatility (tendency to volatilize).
• Biosolids and biosolids management practices can affect a
chemical’s volatility
– Strong retention by biosolids reduces volatilization loss
– Volatilization losses from surface-applied biosolids greater than losses
from soil-incorporated biosolids
Photolysis
Photolysis
• Chemical process by which molecules are broken down into
smaller units through the absorption of light
• Biosolids and biosolids management can affect photolysis
– Incorporation of a chemical into biosolids protects the chemical from
photolysis
– Photolytic losses from surface-applied biosolids greater than losses
from soil-incorporated biosolids
– Photolytic losses of biosolids-borne chemical assumed negligible
Plant Uptake and Metabolism
Plant Uptake and Metabolism
• Uptake can occur through multiple processes
– Uptake from soil solution, translocated from roots to shoots
– Absorption by roots or shoots of volatilized compounds
– Partitioning of bound compounds directly into plant tissue
from soil particles or aerosols deposited on leaves
• Compounds can be metabolized (detoxified) and/or deposited
in various non-food chain components of the plant
• Bioconcentration factor (BCF)
– Concentration in plant/concentration in soil
– Want low values (BCF<0.01)
Leaching and Runoff
Leaching and Runoff
• Leaching
– Loss of chemical via vertical movement through the soil with
percolating water: weakly retained chemicals easily lost
– Promoted by preferential and/or facilitated flow
• Runoff
– Loss of chemical in
water or sediment
that runs off the soil:
strongly retained chemicals
lost in sediment
• Biosolids: can reduce both
types of loss
“Hazardous Traits”
• Low log Kow (<-2)
– High solubility, minimal retention, leachable, high bioavailability
• High log Kow (>5)
– Strongly retained , particle runoff, bioaccumulative, persistent
• High t1/2 (>2 months)
– Persistent, long-term effects
• High Henry’s constant (>10-5)
– Volatile, easily transported in wind (world-wide)
• High BCF (>0.01) – contamination of vegetation
• High concentrations and detection frequency
– Likely exposure risk
Applying Principles to Emerging
Organics
• Models
– Transport
– Quantitative structure-activity relationship (QSAR)
– Fugacity
• Inferences
– Similarities in chemical structure, modes of action (MOAs)
– Common sense
• Experience
– Successes/failures of WWTPs and application programs
– Part 503 risk assessment (PCBs and dioxins)
Transport
Hydrus
Chemflo 2000
Chemical Movement
in Soils (CMIS)
• simulates one-, two-, and threedimensional movement of water,
heat, and multiple solutes in
variably saturated media
• no-cost tool
• considers various soil properties
• simulates one-dimensional
water movement and chemical
fate/transport in vadose zones
• predicts movement and
degradation of pesticides in
soils
• no source or sink terms
• considers soil, chemicals, daily
rainfall and irrigation amounts,
and daily evapotranspiration
• accounts for water uptake by plant
roots
• both adsorbed and volatile solutes
(such as pesticides) can be
modeled
• quantifies degradation and
production of solutes
• considers transport of viruses,
colloids, and/or bacteria
• new model created to address
constructed wetlands
• to be used primarily as a
teaching tool
• cannot simulate plant
uptake
• considers reversible partitioning
• no consideration of partitioning or
movement in vapor phase
• no-cost tool
• simplified educational model
• displays two soils side by side to
enable comparisons
• simple interpretation of water
movement, solute transport,
solute degradation, and solute
distribution
QSAR
Persistent, Bioaccumulative,
Toxin Profiler
Ecological Structure
Activity Relationships
(ECOSAR)
• no-cost tool
• no-cost tool
• designed to help screen chemicals for
persistence (air, water, soil, sediment),
bioaccumulation, and aquatic toxicity
characteristics when no experimental data are
available
• predicts toxicity of industrial chemicals to
aquatic organisms such as fish, invertebrates,
and algae by using QSARs
• designed to help identify pollution prevention
opportunities
• uses quantitative structure/activity relationships
(QSARs) to predict risk data
• considers only industrial chemicals discharged to
the aquatic environment
• estimates a chemical's acute (short-term) toxicity
and, when available, chronic (long-term or
delayed) toxicity
Fugacity
Biosolids-Amended Soil: Level 4
(BASL 4)
• no-cost tool
• simple assessment of the fate of biosolids-borne compounds applied to soil
• considers chemical, soil, and biota properties
• accounts for time, biosolids application, and soil plowing
• considers leaching, volatilization, degradation, bioturbation
• estimates plant uptake and bioaccumulation
• incorporates effects of changing organic matter content with biosolids addition
• addresses equilibrium, steady-state, and dynamic scenarios
Inferences
Inferences Continued
Knowns and Expectations
•
Concentrations of most organics in biosolids are low
•
Amended soil concentrations can be 200-fold lower than in biosolids
– 10,000 lbs (5 T/A) of biosolids diluted in ~ 2,000,000 lbs of soil
•
“PBTs” expected to be strongly retained by biosolids
•
Organic chemicals in biosolids may be slow to degrade, but likely are of
limited bio- and environmental availability
•
Soluble organic chemicals are expected to be more of a problem in the safe
disposition of effluents than biosolids
•
Lessons (e.g., risk assessments) learned with better-studied chemicals with
similar properties are probably extendable to “emerging” contaminants
Unknowns and Potential Surprises
• Even low concentrations of an emerging organic could affect
organisms in ways we haven’t considered
–
–
–
–
–
–
Antibiotic resistance in humans/animals
Changes in soil microbes and reactions they mediate
Chronic hormone exposure
Cumulative and synergistic effects of various chemicals
Cancer
?
• Risk due to prolonged human and environmental exposure at
low concentrations largely unknown
• Effects of various biosolids preparation processes on chemical
structure, behavior, persistence, bioavailability unknown?
• And
?
Chemical Movement in Soils (CMIS)
Exercise 1
logKoc = 3.7
Half-life = 100 days
logKoc = 3.7
Half-life = 5 days
Chemical Movement in Soils (CMIS)
Exercise 2
logKoc = 3.1
Half-life = 30 days
logKoc = 1.8
Half-life = 60 days
Thumbs Up / Thumbs Down
• When biosolids are applied at typical agronomic rates, organic
contaminant concentrations can be “diluted” 100-200 fold
• Kow (octanol/water partition coefficient) can be used to predict Koc
(organic carbon partition coefficient), as well as how a compound
will partition into a living organism
• An organic compound with a t1/2 > 50 days will always be available
for plant uptake
• Adding biosolids to a sandy soil will improve the retention capacity
of the soil for emerging organics
• Organic compounds that partition out of wastewater influent and
onto sewage sludge solids are likely to have low log Koc and log Kow
values
• A large log Koc can act to extend the half-life of a biosolids-borne
compound
• Highly volatile organics can not be taken up by plants
• “Emerging Contaminants” have come into use within the last 10
years