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Emerging Contaminants in Biosolids George O’Connor Soil and Water Science Department, University of Florida 20 th Annual Biosolids Management Conference September 9-11, 2007 Contributing author: Liz H. Snyder. Common Contaminant “Lingo”.

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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”

  • 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
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

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
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

Predicting the fate of emerging contaminants – difficult, but not hopeless
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”








Central wastewater treatment facility

Landfill or


Sewage sludge

Kill pathogens

Remove solids



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 land-applied biosolids is THE question

Contaminant Fate In WWTPs

Some Organic Contaminants in Biosolids

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

attitudes towards emerging contaminants in biosolids
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
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




Plant uptake and metabolism

Leaching and runoff

Principles of Organic Contaminant Behavior in Biosolids-Amended Soils
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 k ow
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.

Partitioning, Kow
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

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

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
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)

Plant Uptake and Metabolism
leaching and runoff

Loss of chemical via vertical movement through the soil with percolating water: weakly retained chemicals easily lost

Promoted by preferential and/or facilitated flow


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

Leaching and Runoff
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

“Hazardous Traits”
applying principles to emerging organics


Quantitative structure-activity relationship (QSAR)



Similarities in chemical structure, modes of action (MOAs)

Common sense


Successes/failures of WWTPs and application programs

Part 503 risk assessment (PCBs and dioxins)

Applying Principles to Emerging Organics


Chemical Movement in Soils (CMIS)


Chemflo 2000

  • 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


Persistent, Bioaccumulative, Toxin Profiler

Ecological Structure Activity Relationships (ECOSAR)

  • 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
  • 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


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
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

Knowns and Expectations

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



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?


Unknowns and Potential Surprises



logKoc = 3.7 Half-life = 100 days

logKoc = 3.7 Half-life = 5 days


logKoc = 3.1 Half-life = 30 days

logKoc = 1.8 Half-life = 60 days

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  • 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