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

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) chemicalquantity (manufactured/imported in US ≥1 million pounds/year)

POHO (Pollutant Of Human Origin) source or origin

Slide credit: Adapted and extended by Daughton from: Renewable Resources Journal, 2005, 23(4):6-23.

Common Contaminant “Lingo”

• many additional categories

• use depends on context, author, audience, date of publication

Target Compounds for USGS National Reconnaissance of Emerging Contaminants in US Streams

Extend list to biosolids?

• 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)

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.

Emerging Contaminants in Biosolids

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

• 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”

Objectives

Available: http://www.epa.gov/nerlesd1/chemistry/pharma/image/drawing.pdf

Concentratedpopulation

Central wastewater treatment facility

Sewage sludge

Effluent

Kill pathogensRemove solids

Biosolids

Landfill orincineration

Land application

IndustryPre-treatment

+

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 land-

applied biosolids is THE question

Some Organic

Contaminants in Biosolids

* Adapted from Xia, 2005; Kinney, 2006; Kester, 2005

Compound Concentration (mg kg-1)

Log Kow Solubility (mg L-1)

Vapor Pressure (mmHg)

Antimicrobial Compounds        

triclosan 10.2 4.53 10  6.45 x 10-7

Human Drugs        

carbamazepine 0.07 2.45 17.7 1.84 x 10-7

Fragrances        

d-limonene 0.63 4.57 13.8 1.98

indole 19.6 2.14 3560 1.22 x 10-2

Sex and Steroidal Hormones        

3b-coprostanol 126 8.82 0.000203 5.47 x 10-10

cholesterol 209 8.74 0.095 7.79 x 10-10

Plasticizers        

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

Polycyclic aromatic hydrocarbons        

anthracene 0.14 4.5 0.0434 6.53 x 10-6

phenanthrene 0.342 4.52 1.15 1.21 x 10-4

Others        

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

0.210.0000131

 4.5 – > 8.0

0.000004 –7.48  7.6 x 10-10 –

0.08

Penta dibrominated diphenyl ethers PBDEs (Sum)

 <0.008 – 4.89 5.74 – 8.27

0.01 - 0.13 2.12 x 10-9 – 1.94 x 10-3

Polychlorinated dibenzodioxins andDibenzofurans (total TEQ)

0.0000333 6.8 0.0000193 7.4 x 10-4

Attitudes Towards Emerging Contaminants in Biosolids

It’s all a bunch of hype!

• “pollutant du jour” syndrome

• WWTPs are very efficient and will degrade organics

• availability in biosolids is so low, and the concentration in biosolids-amended soil is so low, that there’s nothing to worry about

The sky is falling!

• we’re awash in evermore dangerous chemicals

• 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 three-

dimensional movement of water, heat, and multiple solutes in variably saturated media

• considers various soil properties

• 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

• no-cost tool • to be used primarily as a teaching tool

• simulates one-dimensional water movement and chemical fate/transport in vadose zones

• no source or sink terms

• cannot simulate plant uptake

• considers reversible partitioning

• no consideration of partitioning or movement in vapor phase

• no-cost tool

• simplified educational model

• predicts movement and degradation of pesticides in soils

• considers soil, chemicals, daily rainfall and irrigation amounts, and daily evapotranspiration

• 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

• designed to help screen chemicals for persistence (air, water, soil, sediment), bioaccumulation, and aquatic toxicity characteristics when no experimental data are available

• designed to help identify pollution prevention opportunities

• uses quantitative structure/activity relationships (QSARs) to predict risk data

• no-cost tool

• predicts toxicity of industrial chemicals to aquatic organisms such as fish, invertebrates, and algae by using QSARs

• 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