Riverbank Sediment Characterization & Preliminary Treatment Results
Riverbank Sediment Characterization & Preliminary Treatment Results 1 Carol Ptacek and David Blowes
University of Waterloo Students: Krista Desrochers, M.Sc. Candidate Peng Liu, Ph.D. Candidate Blair Gibson, Ph.D. Candidate Ou Wang, B.Sc. Candidate 1
Objectives of Study
• Characterize solid-phase composition and forms
of Hg in the bank sediments
• Assess variability in the release of Hg from bank
leaching vs. bank erosion
• Identify potential
geochemical approaches to decrease the release of Hg from the sediments
2
Site Location
3
Site Location
South River RRM 0.1
Bank Stabilization Pilot Site
4
Sediment Studies Sediment Characterization Bulk chemistry Chemical
extractions Mineralogy XRF & XANES
Resuspension Experiments Sediment ratio
variations Colloid
characterization
Bank Filtration Experiments Flow rate
fluctuations & stagnation Colloid
characterization
XRD & clay
speciation
5
Sediment Digestion
• •
Sediment Characterization
Large variation in total Hg in sediment Hg correlated to Cu 6
Carbon & Sulfur
Low C & S (SR) compared to other sites (LS) with elevated Hg 1.4
30
1.2
25
1.0
20
0.8
15
0.6
10
0.4
5
0.2
0
0.0
SR 1 SR 2 SR 3 SR 4 SR 5 S R 53 7-9 6 SW 1(A) 53 20(B 7-2 ) 73 SW (C) -12 SW (D) -1 53 3(E) 753 76(F 7-2 ) 2 8 53 7-3 (G) 3 53 9(H) 7-2 53 41(I ) 7-2 67 (J)
35
% Total Sulfur
% Total Carbon
•
Sediment Characterization
SR Total Carbon Lake Seds Total Carbon
SR Total Sulfur Lake Seds Total Sulfur
7
Chemical Extractions •
Hg speciation highly variable in South River bank sediment Extraction Solution
Target Hg Species
F1
Deionized Water
Water Soluble (HgCl2, HgSO4)
F2
0.01M HCl + 0.1M CH3COOH
Human Stomach Acid Soluble (HgSO4, HgO, Hgads)
1M KOH
Organo-chelated (Hgchel, Hg2Cl2)
F3
Sediment Characterization
A B C D E F(1) F(2) G H I J(1) J(2) SR1 SR2 SR3 SR4 SR5 SR6
SR
0 F4
F5
12M HNO3
Elemental Hg (Hg0, thiol-Hg, Hgamal)
Aqua Regia
Mercuric Sulfide (HgS, HgSe, HgAu)
20
40
60
80
100
% Hg Extracted • •
~2-9% of Hg mass extracted by DI water Greatest mass in “sulfide fraction 8
Sediment Characterization
SR6 Synchrotron Characterization Micro X-ray Fluorescence (XRF) Mapping and X-ray Absorption Near Edge Structure (XANES) Analysis of South River Sediment
9
XRF
Sediment Characterization
10
XANES
Sediment Characterization
All Hg XANES spectra from sediment are similar Implies same form of Hg at each location
11
XANES
Sediment Characterization
Spectra are very similar to spectrum for metacinnabar,
implying HgS formation
12
Sediment Resuspension Tests
Resuspension Tests
Purpose: What is the variability in Hg release due to riverbank erosion? What portions are “dissolved” and “colloidal”?
5000 MWCO Filter Fraction
13
Ratio Variations
Resuspension Tests
-1
Total Hg (g L )
• Large variability in Hg release • Possible Hg solubility control 90 85 80
SR2
SR1
SR3
SR4
SR6
SR5
20 15 10 5 0 12
pH
10 8 6 4
Eh (mv)
700 600 500
Alkalinity (mg L-1 CaCO3)
400 300 160 120 80 40 0 0
10
20
30
40
0
10
20
30
40
0
10
20
30
40
0
10
20
30
40
0
10
20
30
40
0
10
20
30
40
14 Mass of Sediment per 160 g SRW (g)
Filter Fractions
Resuspension Tests
-1
Total Hg (g L )
• Large variability in filter-size fractions • Greatest variation for SR3, SR5 & SR6 samples 90 85 80
SR2
SR1
SR3
SR5
SR6
15 10 5 0 12
pH
10 8 6 4
Eh (mv)
700 600 500
Alkalinity (mg L-1 CaCO3)
400 300 160 120 80 40 0 0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
0.3
0.4
15 Filter Pore Diameter (m)
Dynamic Leaching Experiments
Slow flow of river water
through bank sediments to simulate advectivediffusive transport Fluctuate velocity to
evaluate: mass transfer limitations colloid-facilitated transport
16
Control Columns
SR5 1000 0.45 m Filtered 0.2 m Filtered 0.1 m Filtered 5000 MWCO Filtered 3X Flow Increase
Total Hg (ng L-1)
800
600
SR5
SR3
SR6
Total Sed Hg (g g-1)
45.25
25.00
386.10
H2O Soluble Hg (g g-1)
3.16
1.15
33.10
400
200
0 0
10
20
30
40
Pore Volumes
PV/ week
2.7 0.95
2.85 2.85
• Large fluctuations in Hg concentrations • Release of Hg not correlated to extraction and resuspension results • Increases in effluent Hg observed after flow stagnations SR3
SR6 8000
6000 5000 Total Hg (ng L-1)
Total Hg (ng L-1)
6000
4000 3000 2000
4000
2000
1000 0
0 0
10
20
30
0
40
10
1.5
30
Pore Volumes
Pore Volumes
PV/ week
20
4.5
4.5
PV/ week
1.0
3.0
3.0 17
Control Column H2O Chemistry SR5 Control Column
Control Columns SR3 Control Column
SR6 Control Column
Note very high concentrations of Hg in SR3 effluent
-1
Total Hg (ng L )
8000 6000 4000 2000
Alkalinity -1 (mg L CaCO3)
12
600
11
500
10
400
9
300
8
200
7
100
6
0
Eh (mv)
Eh (mv)
pH
0
pH 3X Flow Increase
300 250 200 150 100 50
20
2-
-1
SO4 (mg L )
0
15
Note decline in SO4 concentrations
10 5 0 0
10
20
30
40
Pore Volumes
50
0
10
20
30
40
50
Pore Volumes
60
0
10
20
30
Pore Volumes
40
18
Filter Comparison
Control Columns
• Resuspension experiments ‐ substantial differences in aqueous Hg for different filter sizes • Transport experiments ‐ less pronounced variations in Hg for different filter sizes Resuspension Tests
Total Hg (ng L-1)
10000
3000 0.45 m Filter 0.2 m Filter 0.1 m Filter 5000 MWCO Filter
2500
Total Hg (ng L-1)
80000
Saturated Control Columns
8000 6000 4000
0.45 m Filter 0.1 m Filter 5000 MWCO Filter
2000
1500
1000
500
2000 0
0 SR1
SR2
SR3
SR5
SR6
SR3
SR5
SR6
19
Treatment Studies
Static Screening Experiments
Dynamic Treatment Experiments
Hg-spiked South River water
Treatment of column effluent water
Stabilization additions
Leaching from coblended reactive media/sediment mixtures
20
Treatment Treatment of Hg-spiked South River water Blended biochar and Hg-spiked water
Mushroom Soil (B-MS)
Pine Woodchips (B-PW)
Poultry (B-PO)
Preliminary Treatment of Bank Sediment (SR4 Sample) Clays, chars and activated carbon, strong reductants, complexing agents
21
Biochar as a Reactive Media for Hg
Desirable physical properties Large particle size distribution, macroporosity, nano-porosity
Desirable chemical properties High charge density, hydrophilic, hydrophobic, acidic, basic
Concerns High nutrient and trace element content Microbial habitat & substrate
Potential applications Soil amendment, ex-situ reactors, in-stream reactors, in-situ reactive
zones …
22
Biochar Functionalities (1) O (2)
O
OH
CH3
(10)
O
O
Treatment
O
OH
(1 2 )
H N
(1 )
O (8)
N
N
H N
(1 1 ) O
CH3 O
(9)
O R
O
O
(1 3 )
HN
O
(2 )
O
(1 0 ) NH2
N
H3C
(3)
OH
N N
(9 )
HO
(3 )
(8 )
H3C
(4)
N
N
HN
O CH3 H3C
O
(5)
O
+
(7)
(7 )
CH2
N
CH3
O
N
O
(6)
O
(4 )
CH3
O
O
NH2 N
H3C
Oxygen-containing
N
-
(5 )
(6 ) CH3
+
O
Nitrogen-containing
(2) SH
(1)
SH SH
(1)
S
SH 2 (3)
S
S
S
(1)
CH3
HO
O P
O
CH3
(3)
O
P
HO
S
(1)
O
(1)
O
O
O
(1)
HO
P
O
OH OH S
S
S
(6)
(4)
O
P
O O
O S O
(5)
Sulfur-containing
(1)
OH O
P OH
O
O
P
(2)
OH O
O P HO
O
Phosphorus-containing
23
Biochar Physical Properties A
Treatment
B
Silica mineral
C
D
24
Biochar Physical Properties element C O F Na Mg Al Si
wt % 75.73 6.72 0.29 0.2 0.36 0.18 0.07
element C O Na Mg Al
element P S Cl K Ca Fe
wt % 0.44 0.63 0.7 0.54 2.21 1.07
wt % element wt % 74.76 Si 0.08 16.95 P 0.32 0 K 0.67 0.22 Ca 0.67 0.19
A
C
Treatment element C O F Na Mg Al Si
wt % 29.17 37.55 0.22 0.13 0.13 0.78 25.23
element P S Cl K Ca Fe
element wt % element C 63.19 P O 23.88 S Na 0.2 Cl Mg 0.38 K Al 0.25 Ca Si 0.81 Fe
wt % 0.1 0.04 0 0.24 0.72 0.2
wt % 0.53 1.52 0.23 2.64 2.45 0.27
B
D
25
Biochar Batch Test Experiments
Treatment
Evaluate
Hg removal Nutrient and trace element release
NW
SRW
B‐MS
Hg
Hg
B‐PW
B‐PO
Hg
Hg
Experiments
Hg-spiked SRW 9000 ng L-1 Hg
SRW
B-MS
B-PW
B-PO
26
Biochar Batch Test Experiments (Unwashed)
8000
7000
7000
20 10 0
20 10 0
8000
8000
7000 2000 1000 0
7000 2000 1000 0
SRW B-MS B-PW B-PO
2 weeks
8000
SRW B-MS B-PW B-PO
Hg Spiked Experiments
THg ng L -1
Control Experiments
T Hg ng L -1
48 hours
Treatment
Greater than 95% removal of Hg from South River water at 2
weeks for all biochar samples 27
Biochar Batch Test Experiments (unwashed) B-MS
SRW
B-PW
Treatment
B-PO
pH
10 7 4
Eh [mv]
700 500
as CaCO3 mg L -1
Alkalinity
300 600 300 0 0
8
16 0
8
16 0
8
Time [Days]
16 0
8
16
Control Experiments Spiked Hg Experiments
Water Chemistry 28
Biochar Batch Test Experiment (unwashed)
NH3-N mg L -1
PO4-P mg L -1
SRW
B-MS
B-PW
Treatment
B-PO
12
Elevated phosphate, sulfate, chloride
6 0 0.80 0.40 0.00
SO4 mg L
-1
850
Anions and Nutrients
425 0
NO3 mg L
-1
-1 Cl mg L
160 80 0 5.0 2.5 0.0 0
8
16 0
8
16 0
Time [Days]
8
16 0
8
16
Control Experiments Spiked Hg Experiments
29
Biochar Batch Test Experiment (unwashed) SRW
B-MS
B-PW
Treatment
B-PO
-1
5
-1
Pb ng L
0.5 0.0 4.50
Pb ng L
-1
0 1.0
Cu g L
-1
Pb g L
Elevated As, Pb
As ng L
10
-1
-1 As g L
15
2.25 0.00 0
8
16 0
8
16 0
8
Time [Days]
16 0
8
16
Control Experiment Spiked Hg Experiment
Trace Elements 30
Comparison of Unwashed and Washed Biochar (Hg Removal)
Treatment
2 weeks
Control Experiments
THg ng L -1
10
Washed biochars Unwashed biochars
5
300 150 0
100 50 0 SRW B-MS B-PW B-PO
THg Removal%
9000 4500
SRW B-MS B-PW B-PO
Hg Spiked Experiments
T Hg ng L -1
0
Greater than 92% Hg removed from South River for all washed
biochar samples at 2 weeks
31
Initial Reactive Media Batch H2O Chemistry Treated SR4 Sediment
Controls - no sediment
4
8
8
6
6
pH
0 10
4 2
0 500
0 500
400
400 Eh (mv)
2
300 200
200
0 400
0 400
100 0
Alkalinity (mg L-1 CaCO3)
100
200
4.0
300
100
300
Treated SR4 Sediment
0.9 0.6 0.3 0.0 0.40 0.30
300
0.20
200
0.08
100 0
0.04 0.00
SR4 Control Thiol I ATP B-MS B-WC Thiol II GAC MRM GI S ATP+Thiol I ATP+Thiol II GI+ATP GI+S S+ATP
4
•Thiol I has elevated NH3 •B‐MS & Thiol II have elevated PO43‐
2
0 10
SR4 Control Thiol I ATP B-MS B-WC Thiol II GAC MRM GI S ATP+Thiol I ATP+Thiol II GI+ATP GI+S S+ATP
Eh (mv) Alkalinity (mg L-1 CaCO3)
6
•Thiol I control ~ 100 g L‐1 •Thiol II control pH
University of Waterloo Students: Krista Desrochers, M.Sc. Candidate Peng Liu, Ph.D. Candidate Blair Gibson, Ph.D. Candidate Ou Wang, B.Sc. Candidate 1
Objectives of Study
• Characterize solid-phase composition and forms
of Hg in the bank sediments
• Assess variability in the release of Hg from bank
leaching vs. bank erosion
• Identify potential
geochemical approaches to decrease the release of Hg from the sediments
2
Site Location
3
Site Location
South River RRM 0.1
Bank Stabilization Pilot Site
4
Sediment Studies Sediment Characterization Bulk chemistry Chemical
extractions Mineralogy XRF & XANES
Resuspension Experiments Sediment ratio
variations Colloid
characterization
Bank Filtration Experiments Flow rate
fluctuations & stagnation Colloid
characterization
XRD & clay
speciation
5
Sediment Digestion
• •
Sediment Characterization
Large variation in total Hg in sediment Hg correlated to Cu 6
Carbon & Sulfur
Low C & S (SR) compared to other sites (LS) with elevated Hg 1.4
30
1.2
25
1.0
20
0.8
15
0.6
10
0.4
5
0.2
0
0.0
SR 1 SR 2 SR 3 SR 4 SR 5 S R 53 7-9 6 SW 1(A) 53 20(B 7-2 ) 73 SW (C) -12 SW (D) -1 53 3(E) 753 76(F 7-2 ) 2 8 53 7-3 (G) 3 53 9(H) 7-2 53 41(I ) 7-2 67 (J)
35
% Total Sulfur
% Total Carbon
•
Sediment Characterization
SR Total Carbon Lake Seds Total Carbon
SR Total Sulfur Lake Seds Total Sulfur
7
Chemical Extractions •
Hg speciation highly variable in South River bank sediment Extraction Solution
Target Hg Species
F1
Deionized Water
Water Soluble (HgCl2, HgSO4)
F2
0.01M HCl + 0.1M CH3COOH
Human Stomach Acid Soluble (HgSO4, HgO, Hgads)
1M KOH
Organo-chelated (Hgchel, Hg2Cl2)
F3
Sediment Characterization
A B C D E F(1) F(2) G H I J(1) J(2) SR1 SR2 SR3 SR4 SR5 SR6
SR
0 F4
F5
12M HNO3
Elemental Hg (Hg0, thiol-Hg, Hgamal)
Aqua Regia
Mercuric Sulfide (HgS, HgSe, HgAu)
20
40
60
80
100
% Hg Extracted • •
~2-9% of Hg mass extracted by DI water Greatest mass in “sulfide fraction 8
Sediment Characterization
SR6 Synchrotron Characterization Micro X-ray Fluorescence (XRF) Mapping and X-ray Absorption Near Edge Structure (XANES) Analysis of South River Sediment
9
XRF
Sediment Characterization
10
XANES
Sediment Characterization
All Hg XANES spectra from sediment are similar Implies same form of Hg at each location
11
XANES
Sediment Characterization
Spectra are very similar to spectrum for metacinnabar,
implying HgS formation
12
Sediment Resuspension Tests
Resuspension Tests
Purpose: What is the variability in Hg release due to riverbank erosion? What portions are “dissolved” and “colloidal”?
5000 MWCO Filter Fraction
13
Ratio Variations
Resuspension Tests
-1
Total Hg (g L )
• Large variability in Hg release • Possible Hg solubility control 90 85 80
SR2
SR1
SR3
SR4
SR6
SR5
20 15 10 5 0 12
pH
10 8 6 4
Eh (mv)
700 600 500
Alkalinity (mg L-1 CaCO3)
400 300 160 120 80 40 0 0
10
20
30
40
0
10
20
30
40
0
10
20
30
40
0
10
20
30
40
0
10
20
30
40
0
10
20
30
40
14 Mass of Sediment per 160 g SRW (g)
Filter Fractions
Resuspension Tests
-1
Total Hg (g L )
• Large variability in filter-size fractions • Greatest variation for SR3, SR5 & SR6 samples 90 85 80
SR2
SR1
SR3
SR5
SR6
15 10 5 0 12
pH
10 8 6 4
Eh (mv)
700 600 500
Alkalinity (mg L-1 CaCO3)
400 300 160 120 80 40 0 0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
0.3
0.4
0.0
0.1
0.2
0.3
0.4
15 Filter Pore Diameter (m)
Dynamic Leaching Experiments
Slow flow of river water
through bank sediments to simulate advectivediffusive transport Fluctuate velocity to
evaluate: mass transfer limitations colloid-facilitated transport
16
Control Columns
SR5 1000 0.45 m Filtered 0.2 m Filtered 0.1 m Filtered 5000 MWCO Filtered 3X Flow Increase
Total Hg (ng L-1)
800
600
SR5
SR3
SR6
Total Sed Hg (g g-1)
45.25
25.00
386.10
H2O Soluble Hg (g g-1)
3.16
1.15
33.10
400
200
0 0
10
20
30
40
Pore Volumes
PV/ week
2.7 0.95
2.85 2.85
• Large fluctuations in Hg concentrations • Release of Hg not correlated to extraction and resuspension results • Increases in effluent Hg observed after flow stagnations SR3
SR6 8000
6000 5000 Total Hg (ng L-1)
Total Hg (ng L-1)
6000
4000 3000 2000
4000
2000
1000 0
0 0
10
20
30
0
40
10
1.5
30
Pore Volumes
Pore Volumes
PV/ week
20
4.5
4.5
PV/ week
1.0
3.0
3.0 17
Control Column H2O Chemistry SR5 Control Column
Control Columns SR3 Control Column
SR6 Control Column
Note very high concentrations of Hg in SR3 effluent
-1
Total Hg (ng L )
8000 6000 4000 2000
Alkalinity -1 (mg L CaCO3)
12
600
11
500
10
400
9
300
8
200
7
100
6
0
Eh (mv)
Eh (mv)
pH
0
pH 3X Flow Increase
300 250 200 150 100 50
20
2-
-1
SO4 (mg L )
0
15
Note decline in SO4 concentrations
10 5 0 0
10
20
30
40
Pore Volumes
50
0
10
20
30
40
50
Pore Volumes
60
0
10
20
30
Pore Volumes
40
18
Filter Comparison
Control Columns
• Resuspension experiments ‐ substantial differences in aqueous Hg for different filter sizes • Transport experiments ‐ less pronounced variations in Hg for different filter sizes Resuspension Tests
Total Hg (ng L-1)
10000
3000 0.45 m Filter 0.2 m Filter 0.1 m Filter 5000 MWCO Filter
2500
Total Hg (ng L-1)
80000
Saturated Control Columns
8000 6000 4000
0.45 m Filter 0.1 m Filter 5000 MWCO Filter
2000
1500
1000
500
2000 0
0 SR1
SR2
SR3
SR5
SR6
SR3
SR5
SR6
19
Treatment Studies
Static Screening Experiments
Dynamic Treatment Experiments
Hg-spiked South River water
Treatment of column effluent water
Stabilization additions
Leaching from coblended reactive media/sediment mixtures
20
Treatment Treatment of Hg-spiked South River water Blended biochar and Hg-spiked water
Mushroom Soil (B-MS)
Pine Woodchips (B-PW)
Poultry (B-PO)
Preliminary Treatment of Bank Sediment (SR4 Sample) Clays, chars and activated carbon, strong reductants, complexing agents
21
Biochar as a Reactive Media for Hg
Desirable physical properties Large particle size distribution, macroporosity, nano-porosity
Desirable chemical properties High charge density, hydrophilic, hydrophobic, acidic, basic
Concerns High nutrient and trace element content Microbial habitat & substrate
Potential applications Soil amendment, ex-situ reactors, in-stream reactors, in-situ reactive
zones …
22
Biochar Functionalities (1) O (2)
O
OH
CH3
(10)
O
O
Treatment
O
OH
(1 2 )
H N
(1 )
O (8)
N
N
H N
(1 1 ) O
CH3 O
(9)
O R
O
O
(1 3 )
HN
O
(2 )
O
(1 0 ) NH2
N
H3C
(3)
OH
N N
(9 )
HO
(3 )
(8 )
H3C
(4)
N
N
HN
O CH3 H3C
O
(5)
O
+
(7)
(7 )
CH2
N
CH3
O
N
O
(6)
O
(4 )
CH3
O
O
NH2 N
H3C
Oxygen-containing
N
-
(5 )
(6 ) CH3
+
O
Nitrogen-containing
(2) SH
(1)
SH SH
(1)
S
SH 2 (3)
S
S
S
(1)
CH3
HO
O P
O
CH3
(3)
O
P
HO
S
(1)
O
(1)
O
O
O
(1)
HO
P
O
OH OH S
S
S
(6)
(4)
O
P
O O
O S O
(5)
Sulfur-containing
(1)
OH O
P OH
O
O
P
(2)
OH O
O P HO
O
Phosphorus-containing
23
Biochar Physical Properties A
Treatment
B
Silica mineral
C
D
24
Biochar Physical Properties element C O F Na Mg Al Si
wt % 75.73 6.72 0.29 0.2 0.36 0.18 0.07
element C O Na Mg Al
element P S Cl K Ca Fe
wt % 0.44 0.63 0.7 0.54 2.21 1.07
wt % element wt % 74.76 Si 0.08 16.95 P 0.32 0 K 0.67 0.22 Ca 0.67 0.19
A
C
Treatment element C O F Na Mg Al Si
wt % 29.17 37.55 0.22 0.13 0.13 0.78 25.23
element P S Cl K Ca Fe
element wt % element C 63.19 P O 23.88 S Na 0.2 Cl Mg 0.38 K Al 0.25 Ca Si 0.81 Fe
wt % 0.1 0.04 0 0.24 0.72 0.2
wt % 0.53 1.52 0.23 2.64 2.45 0.27
B
D
25
Biochar Batch Test Experiments
Treatment
Evaluate
Hg removal Nutrient and trace element release
NW
SRW
B‐MS
Hg
Hg
B‐PW
B‐PO
Hg
Hg
Experiments
Hg-spiked SRW 9000 ng L-1 Hg
SRW
B-MS
B-PW
B-PO
26
Biochar Batch Test Experiments (Unwashed)
8000
7000
7000
20 10 0
20 10 0
8000
8000
7000 2000 1000 0
7000 2000 1000 0
SRW B-MS B-PW B-PO
2 weeks
8000
SRW B-MS B-PW B-PO
Hg Spiked Experiments
THg ng L -1
Control Experiments
T Hg ng L -1
48 hours
Treatment
Greater than 95% removal of Hg from South River water at 2
weeks for all biochar samples 27
Biochar Batch Test Experiments (unwashed) B-MS
SRW
B-PW
Treatment
B-PO
pH
10 7 4
Eh [mv]
700 500
as CaCO3 mg L -1
Alkalinity
300 600 300 0 0
8
16 0
8
16 0
8
Time [Days]
16 0
8
16
Control Experiments Spiked Hg Experiments
Water Chemistry 28
Biochar Batch Test Experiment (unwashed)
NH3-N mg L -1
PO4-P mg L -1
SRW
B-MS
B-PW
Treatment
B-PO
12
Elevated phosphate, sulfate, chloride
6 0 0.80 0.40 0.00
SO4 mg L
-1
850
Anions and Nutrients
425 0
NO3 mg L
-1
-1 Cl mg L
160 80 0 5.0 2.5 0.0 0
8
16 0
8
16 0
Time [Days]
8
16 0
8
16
Control Experiments Spiked Hg Experiments
29
Biochar Batch Test Experiment (unwashed) SRW
B-MS
B-PW
Treatment
B-PO
-1
5
-1
Pb ng L
0.5 0.0 4.50
Pb ng L
-1
0 1.0
Cu g L
-1
Pb g L
Elevated As, Pb
As ng L
10
-1
-1 As g L
15
2.25 0.00 0
8
16 0
8
16 0
8
Time [Days]
16 0
8
16
Control Experiment Spiked Hg Experiment
Trace Elements 30
Comparison of Unwashed and Washed Biochar (Hg Removal)
Treatment
2 weeks
Control Experiments
THg ng L -1
10
Washed biochars Unwashed biochars
5
300 150 0
100 50 0 SRW B-MS B-PW B-PO
THg Removal%
9000 4500
SRW B-MS B-PW B-PO
Hg Spiked Experiments
T Hg ng L -1
0
Greater than 92% Hg removed from South River for all washed
biochar samples at 2 weeks
31
Initial Reactive Media Batch H2O Chemistry Treated SR4 Sediment
Controls - no sediment
4
8
8
6
6
pH
0 10
4 2
0 500
0 500
400
400 Eh (mv)
2
300 200
200
0 400
0 400
100 0
Alkalinity (mg L-1 CaCO3)
100
200
4.0
300
100
300
Treated SR4 Sediment
0.9 0.6 0.3 0.0 0.40 0.30
300
0.20
200
0.08
100 0
0.04 0.00
SR4 Control Thiol I ATP B-MS B-WC Thiol II GAC MRM GI S ATP+Thiol I ATP+Thiol II GI+ATP GI+S S+ATP
4
•Thiol I has elevated NH3 •B‐MS & Thiol II have elevated PO43‐
2
0 10
SR4 Control Thiol I ATP B-MS B-WC Thiol II GAC MRM GI S ATP+Thiol I ATP+Thiol II GI+ATP GI+S S+ATP
Eh (mv) Alkalinity (mg L-1 CaCO3)
6
•Thiol I control ~ 100 g L‐1 •Thiol II control pH
