1. Methane Adsorption by Different Biochars
Yamini Sadasivam & Krishna R. Reddy
University of Illinois at Chicago
Illinois Biochar Group Meeting
04/05/2013

2. Presentation Outline Methane oxidation in landfill cover systems
Biochar as a landfill cover material
Ongoing research at UIC
Batch adsorption testing
Types of biochars used
Physical-chemical properties
Testing protocol
Results
Major conclusions
Future goals & objectives

3. Methane oxidation in landfill covers
LFG emissions are among the major sources of greenhouse gases to the atmosphere
Traditionally soil covers were used to achieve microbial methane oxidation by methanotrophs
Major issues with cracking of soil surfaces
Inefficient performance in the absence of LFG extraction systems
Biocover materials with organic amendments were used to increase methane oxidation efficiency
Major issues with material’s self-degradation
Formation of EPS causing pores to clog & hindering the transport of gases
Cannot contribute to methane adsorption

4. Biochar – A Potential Landfill Cover Material
Biochar can be amended to landfill cover soils to enhance CH4 adsorption and oxidation
Biochar can be used
Biochar is advantageous over current compost biocovers
Enhanced CH4 adsorption
Greater porosity and specific surface area (limits pore clogging due to EPS formation)
Favors growth and CH4 oxidation activity of methanotrophs which can conveniently exist within the highly porous biochar
Enhanced gas transport through the pores
Sustainable and cheap option to mitigate LFG

5. Ongoing Biochar Research Goals
To quantify the physical, chemical and geotechnical characteristics of biochars and biochar-amended soils.
To determine the adsorption and enhanced gas transport properties of biochars and biochar-amended landfill cover soils for CH4 and oxygen.
To characterize the main factors that affect CH4 oxidation.
To investigate adsorption and oxidation of CH4 under various conditions such as biochar composition and size, soil composition, CH4 source strength, CH4 concentration, moisture content, and temperature.
To model the mechanisms of CH4 oxidation within biochars and biochar-amended landfill cover systems and determine kinetic parameters defining these mechanisms.
To conduct a full-scale field demonstration.
To prepare guidance manual to design biochar and biochar-amended landfill cover soil systems for landfill applications.

6. Batch Adsorption Testing – Biochars used
BS : Biochar Solutions Inc.
CK : Char King International
AW : Aztec Wonder, LLC
CE – WP1 : Wood pellets w/ash
CE – WP2 : Wood pellets w/o ash
CE – AWP : Aged wood pellets
GAC : granular activated carbon

7. Batch Adsorption Testing – Biochars used
Feedstock & Production Processes:
Biochar Source
Feedstock
Treatment Process
Treatment Temperature
Residence Time
Post-treatment
Biochar Solutions Inc.
Pine Wood
Slow pyrolysis C
6 hrs
Screened through 3mm mesh
Char-King International
90% pine & 10% fur wood
Fast pyrolysis
> 5000C
< 1 hr
Activated with oxygen
Aztec Wonder, LLC
Aged oak & hickory wood biochar
Pyrolysis – Missouri type concrete kiln
~ 5000C
---
Mixed w/innocula & sieved (1/4”)
Chip Energy Inc.
Wood Pellets
Gasification
5200C
N/A
Not subjected to fine ash filtration
Fine ash separated
In addition to biochars, GAC was obtained from Fisher Scientific and tested for its methane adsorption capacity

8. Batch Adsorption Testing – Material characteristics
Biochar type pH
Moisture Content (% d.w.)
Organic Content (%)
Average Particle Size (mm)
Specific Gravity
Water Holding Capacity (% total mass) BS
8.5
29.2
0.7
1.1
54.66 CK
9.0
5.6
31.3
0.2
1.5
63.94 AW
8.2
49.2 76
0.9
1.2
49.96
CE-WP1
6.4
3.2
96.9
0.8
58.73
CE-WP2
6.9
3.7
96.8
0.6
32.91
CE-AWP
7.2
4.3
82.3
5.8
44.52
GAC
21.3 89
2.9
1.6
49.06
pH of biochars range from 6 – 9; pH values for biochars from Chip Energy are around neutral
MC of sterilized biochars range from 0 – 6% d.w. except for AW & GAC
BS, CK AW & GAC have SG > 1; CE biochars have SG < 1
WHC refers to the amount of moisture the biochars can absorb; WHC of finer grained biochars are higher than coarse grained biochars

9. Batch Adsorption Testing – Material characteristics
D50 of biochars range between 0.2 mm and 7 mm

10. Batch Adsorption Testing – Protocol
Step 1:
Sterilization of biochars C (15 psi);
30 min/cycle for 2 consecutive days
Step 3:
5g material used; controls (no biochar); gas samples stored in 5 ml vials & analyzed within 4 hr using HP 6890 GC w/ FID and GS Carbon plot column
Step 2:
Evacuation of vials – 5 mm glass serum bottles crimped w/ butyl septa & aluminum caps

11. Batch Adsorption Testing -Results

12. Batch Adsorption Testing -Results
CE-WP2 tested at 10% headspace CH4 (v/v)
WHC of Biochar ≈ 50% (d.w.)
MC was varied at 4 levels (25, 50, 75 & 100% WHC)

13. Batch Adsorption Testing -Results
CE-WP2 tested at 10% headspace CH4 (v/v)
Positive heat of adsorption; Qe decreases w/ increasing T

14. Major Conclusions 1
Methane adsorption capacities of biochars are strongly dependent upon their physical-chemical characteristics 2
Generally, methane adsorption capacity of fresh biochars increases with decreasing particle size 4
Presence of moisture negatively affects the methane adsorption capacity of biochars 5
Methane adsorption capacity decreases with increasing temperature 6
Activated – pine & fur wood biochar showed the highest methane adsorption capacity (Qe ≈ 3500 mL/Kg)

15. Future Goals and Objectives1
Characterize more biochar types in the lab for their physical-chemical and geotechnical properties 2
Test the effects of biochar properties, MC, temperature & biochar amendment ratio on CH4 adsorption & oxidation capacity 3
Develop an effective design based on modeling the laboratory results and determine optimum biocover size for field implementation 4
Test the biochar in the field and monitor its performance for LFG mitigation

16. Thank you!