2107460 Introduction to Hazardous Waste
Treatment
Fate and Transport of Contaminants
Manaskorn Rachakornkij, Ph.D. NCE-EHWM
Department of Environmental Engineering Faculty of Engineering
CHULALONGKORN UNIVERSITY
2
3
Some fate and transport processes in
the subsurface and atmospheric
environment.
4
Some fate and transport
processes in the aquatic
environment.
5
Site Investigation
First step: site investigation
What chemicals are present?
How much of these chemicals were deposited at the site?
Where, on the site, are these chemicals located?
6
What Chemicals?
Historical records
What industrial activities occurred at the Site?
What chemicals were used at the Site?
Where were they used?
Were chemicals stored in tanks? Where? Are they still in the tanks?
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Chemical Amounts?
Second step: How much of these chemicals were released?
Records?
Recollection of employees?
Similar industries?
8
Fates of Chemicals
Where do the chemicals go once they are released to the environment? Air
Soils
Groundwater
Surface water
Biota (plants or animals)
Sediments
9
To the Air
Liquid to gas phase (volatilization)
Chemicals that do not want to be in water (hydrophobic)
Chemicals that prefer to be in air (volatile organic chemicals - VOCs)
Chemicals that can move into air, but do so more slowly (semivolatile organic chemicals)
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To the Air
11
Particulates in Air
Very small fragments of material (particulates) can be released into the air
At these sites, particulates would have been discharged from the stacks
The heavy particulates will move down wind and settle on the soil
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Wind Transport
Size of particulate matter
(microns)
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Flowchart for fate and transport assessments of the atmosphere.
14
To the Soil
Sorbed chemicals can move into air or water.
Some chemicals do not want to go into water (hydrophobic).
Chemicals may attach (sorb) to soil particles.
Sorbed chemicals can slowly detach from soils and move into air or water.
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Sources of fluids for the
generation of landfill leachate.
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Soil Particles
Water
Water Table
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Groundwater Contaminants
Aqueous Groundwater
LNAPL (Light Nonaqueous-Phase Liquid)
DNAPL (Dense Nonaqueous-Phase Liquid)
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Contamination from a Landfill
19
Contamination by TCE (trichloroethylene)
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Lead in Soil
At many sites, lead is of concern.
Lead is an insoluble metal.
Lead tends to attach to soil particles
Lead can move if attached to very, very small particles called colloids.
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Lead in Groundwater
Lead on surface
Size of particles exaggerated for illustration
Vertical Movement
Horizontal Movement
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Flowchart for fate and transport assessment for soils and groundwater
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To the Water
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Water Soluble
Chemicals which move into water are referred to as being soluble - these chemicals prefer to be in water (hydrophilic).
Hydrophilic chemicals will tend to migrate far from where they are deposited.
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Flowchart for fate and transport assessment in surface water and sediment.
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In Summary
Chemicals can be in air, soils or water.
Chemicals can move from from one medium to another.
Chemicals can be hydrophilic or hydrophobic, soluble or insoluble in water, volatile, semivolatile or nonvolatile.
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Subsurface Contaminant Transport
Process Type Process
Physical processes Advection, dispersion, diffusion, density stratification, NAPL flow, fractured media flow
Chemical processes Redox, ion exchange, complexation, precipitation, immiscible phase partitioning, sorption
Biological processes Aerobic/anaerobic degradation, cometabolism, biological uptake
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Types of Contaminant
Organic
Natural: Hydrocarbon
Synthetic : Pesticide
Inorganic
Heavy Metals: Cu(II), As(V), As(III), Cr(VI)
Chemistry: what you have learn for environmental chemistry class
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Organic Compounds
Usually containing C and H atoms
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Organic Compounds
Compound/
FamilyFormula
Specific
Gravity
Solubility
(mg/L)Kow
Vapor
Pressure
(mm Hg)
HenrysLaw
(unitless)
Fuels and derivatives
Benzene C6H6 0.879 1750 130 60 0.22
Toluene C6H5CH3 0.866 535 130 22 0.26
Ethylbenzene C8H10 0.867 152 1400 7 0.32
Phenol C6H6O 1.071 93,000 29 0.2 1.89 105
Ketones
Acetone CH3COCH3 0.791 inf 0.6 89 0.00104
Methyl ethyl ketone CH3COCH2CH3 0.805 2.68 105 1.8 77.5 0.00181
Halogenated aliphatics
Tetrachloroethene CCl2CCl2 1.631 150 390 14 1.21
Trichloroethene C2HCl3 1.466 1100 240 60 0.42
cis-1,2-Dichloroethene C2H2Cl2 1.27 3500 5 206 1.33
Vinyl chloride CH2CHCl 0.908 2670 24 266 3.58
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Physical and Chemical Properties
Water Solubility
Henrys Law Constant
Sorption and Partitioning
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Water Solubility
The ability of chemical to dissolve in to the water, usually the maximum reported
Function of Temperature, Pressure, and pH (especially inorganic chemical)
Terms Hydrophobic :
Water Hater
(non-polar molecule)
Hydrophilic :
Water Lover
(polar molecule)
+
+
-
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Inorganic Compounds Solubility
Hydrophilic Molecule
High solubility in water compared with organic molecule
Solubility greatly depending on pH
Can be calculated using the solubility products (Ks0 or Ksp) for each compound
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Mineral Solubility at pH =7
(mg/l)
Gibbsite Al2O3.2H2O 0.001
Quartz SiO2 12
Hydroxylapatite Ca5OH(PO4)3 30
Amorphous Silica SiO2+2H2O=Si(OH)4 120
Fluorite CaF2 17
Dolomite CaMg(CO3)2 480
Calcite CaCO3 500
Gypsum CaSO4.2H2O 2100
Sylvite KCl 264000
Epsomite MgSO4.7H2O 267000
Mirabillite Na2SO4.10H2O 280000
Halite NaCl 360000
Inorganic Compounds Solubility
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Solubilities of metal hydroxides as a
function of pH.
36 pH
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Lo
g C
-14
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
H+
OH-
Al+3
Al(OH)4
-
AlOH+2
Al(OH)2
+
Al(OH)3
Al3(OH)
4
+5
Al13
O4(OH)
24
+7
AlTotal
Solubility Diagram for Al(OH)3(s)
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Solubility Diagram for Cr(OH)3(s)
38 pH
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Lo
g C
-14
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
H+OH
-
Fe+3
Fe(OH)4
-
FeOH+2
Fe(OH)2
+
Fe2(OH)
2
+4Fe
Total
Solubility Diagram for Fe(OH)3(s)
39 pH
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Lo
g C
-14
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
H+
OH-
Zn+2
Zn(OH)4
-2
ZnOH+
Zn(OH)2 (aq)
Zn2(OH)
6
-2
ZnTotal
Zn(OH)3
-
Zn2(OH)
+3
Solubility Diagram for Zn(OH)2(s)
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Organic Compounds Solubility
Hydrophobic (non-polar) molecule
Usually low water solubility
Less pH dependent
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Henrys Law Constant
Transfer of contaminant from aqueous phase, directly to gas phase
Equilibrium partitioning similar to octanol-water partitioning
Partitioning equation known as Henrys Law
Hc is the relationship between partial pressure and aqueous concentration of component
Hc
Pc
[C]aq
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Henrys Law Constant
Chemicals that do not want to be in water (hydrophobic)
Chemicals that prefer to be in air (volatile organic compounds - VOCs)
Chemicals that can move into air, but do so more slowly (semi-volatile organic compounds - SVOCs)
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Sorption and Partitioning
Sorption association of dissolved or gaseous contaminant with a solid material
Adsorption surface process
Absorption internal process
Leads to retardation of the contaminant front (slower movement compared to tracer due to sorption)
Desorption reverse of either sorption process
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Soil Grain Sorption
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Linear Sorption Isotherm
Sorption linearly related to aqueous concentration. Partition coefficient is Kd or Kp
Kd is related to Kow
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Partitioning to Solid Phase
Octanol water partition
coefficient
Organic carbon partition
coefficient
Soil water partition
coefficient
water
octanol
C
CowK
aqueous
soil
C
CpK
aqueous
organic
C
CocK
ococp fKK
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Regression Equations for Sorption
Equation (a) No. (b) r2 (c)Chemical Class
RepresentedRef.
log koc = 0.55 log S + 3.64(S in mg/L)
106 0.71Wide variety, mostly
pesticides
Kenaga et al.,
(1978)
log koc = 0.54 log S + 0.44(S in mole fraction)
10 0.94
Mostly a romatic or
polynuclear aromatics;
two chlorinated
Karickhoff et al.,
(1979)
log koc = 0.557 log S + 4.277 (S in moles/L)
15 0.99Chlorinated
hydrocarbonsChiou et al., (1979)
log koc = 0.544 log kow + 1.377 45 0.74Wide variety, mostly
pesticidesKenaga et al, (1978)
log koc = 0.937 log kow 0.006 19 0.95Aromatics, polynuclear
aromatics, triazines and
dinitroaniline herbicides
Brown et al. (1981)
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Kp and foc
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Retarded v. Non-retarded Species
Sorption slows rate of advance of front
Sorbing fronts will eventually get there
Some compounds irreversibly sorb to soil
Relative
Concentration
(C/C )0
0
1
Retarded species
Nonretarded
species
x =v t._
b
ba
x
x =v t/(1+ k )ab
d
n
_.
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Chemical Analysis
Field
Rough situation of chemical contamination
Lab
More precise data and information
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Field Analytical Equipment
PID Analyzer Air sampling VOCs
Portable XRF
Metal Identification
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