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Methane Adsorption by Different Biochars

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  1. Methane Adsorption by Different Biochars YaminiSadasivam & 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, CH4concentration, 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: In addition to biochars, GAC was obtained from Fisher Scientific and tested for its methane adsorption capacity

  8. Batch Adsorption Testing – Material characteristics 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 - 1210C (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 Objectives 1 Characterize more biochar types in the lab for their physical-chemical and geotechnical properties Test the effects of biochar properties, MC, temperature & biochar amendment ratio on CH4 adsorption & oxidation capacity 2 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!