6/20/2019 1 Evaluating biochar in sustainable stormwater treatment of heavy metals: characteristics, mechanisms, and barriers Sarah Burch Jeffrey Nason Motivation for copper remediation • Copper present in stormwater runoff • brake pad wear • Pipes, fungicide, algaecide • Low concentration of copper toxic to some aquatic organisms • Concentrations as low as 2 parts per billion (ppb) inhibit olfactory system in juvenile coho salmon • Current BMPs reduce copper to as low as 5 ppb http://static.ddmcdn.com/gif/brake-pads-4.jpg McIntyre et al. 2012
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characteristics, mechanisms, and barriers Sarah Burch ... · Motivation for Biochar/Bioenergy production Lehmann (2007) ... • Identify questions in biochar supply, production, and
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6/20/2019
1
Evaluating biochar in sustainable stormwater
treatment of heavy metals: characteristics, mechanisms, and barriers
Sarah Burch
Jeffrey Nason
Motivation for copper remediation
• Copper present in stormwater runoff
• brake pad wear• Pipes, fungicide, algaecide
• Low concentration of copper toxic to some aquatic organisms
• Concentrations as low as 2 parts per billion (ppb) inhibit olfactory system in juvenile coho salmon
• Current BMPs reduce copper to as low as 5 ppb
http://static.ddmcdn.com/gif/brake-pads-4.jpg
McIntyre et al. 2012
6/20/2019
2
Motivation for Biochar/Bioenergy production
Lehmann (2007)
Biochar for water treatment
http://www.aqsolutions.org/
Objectives/Approach
• Relate physical and chemical biochar properties to metals sorption performance
• Characterization
• Batch Performance Evaluation
• Evaluate mechanisms for removal of metals
• Electrostatic Modelling
• Potentiometric Titration
• pH Sorption Edge
• Evaluate barriers to field‐scale implementation
• Column performance evaluation and prediction
• Identify questions in biochar supply, production, and applications preventing advancement
Performance
Biomass Source
Pyrolytic Temperature
Characterization
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Production of thermally altered biomass
• Feedstock
• Douglas Fir chips (debarked)
• Hazelnut Shells
• Pre‐treatment• Coarse Grinding
• Pyrolysis Conditions
• T = 300, 500 and 700 ˚C• Time = 1 hour
• N2 atmosphere
• Post‐treatment• Grinding and sieving to 40 ×50 mesh size
determined as best indicators of copper removal performance
• Biochar exceeds performance in copper removal of industry standard, GAC, in batch and fixed-bed column experiments in SSW and performs similarly to GAC copper removal in river water and metals competition
• DLM predicted RSSCTs results which are scaled to predict field scale capacity under variable field solution conditions
• FTIR‐ATR results show no identifiable peaks that would correspond to surface functional groups
In attenuated total reflectance (ATR) mode:
• The detection depth is generally 1‐2μm deep, but varies based on material. Black, highly absorbing materials have smaller sampling depths and sometimes provide too weak a signal as a result. (Anderson Materials Evaluation, Inc.)
FTIR‐ATR GAC Results
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 1000 2000 3000 4000
Absorbance (a.u.)
Wavenumber (1/cm)
Proton Binding
→ ;
→ ;
→ ;
• Proton binding constants determined via titration data by graphical extrapolation or
objective curve fitting routines (MINEQL+ and MINFIT)
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• Hazelnut > Doug Fir
• ↑ pHfinal with ↑ T
Role of adsorbent pH on final equilibrium batch pH
5.0
5.5
6.0
6.5
7.0
7.5
8.0
D300 D500 D700 H300 H500 H500SRNOM
H700 H700SRNOM
GAC
Final Batch Equilibrium pH
Methods: Potentiometric Titration
• Proton Binding
• Titrant additions vs. pH
• 1 and 10 mM ionic strength
• pH 3 to 10
• Point of Zero Salt Effect (PZSE) determined as intersection of titrations at 2 ionic strengths
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Potential for Release of Adsorbed Copper
0
10
20
30
40
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Concentration (ppb)
Elapsed Time (Days)
Influent H700 2/17 Effluent H700 2/17
• Agrees with proximate carbon analysis
• Most mass is lost between approximately 250‐350 ˚C
Thermogravimetric Analysis (TGA)
0
20
40
60
80
100
0 200 400 600 800
Weight Remaining (%
)
Temperature (°C)
Hazelnut Shells
Douglas Fir
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pKa of Functional Groups
FTIR Detection
• In attenuated total reflectance (ATR) mode, the detection depth is generally 1‐2μm deep, but can be much less or a bit more dependent upon the material. Black, highly absorbing materials tend to have smaller sampling depths and sometimes provide too weak a signal as a result. [Anderson Materials Evaluation, Inc.]