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Wood-based vs. Coal-based GAC a LCA comparison

Wood-based vs. Coal-based GAC a LCA comparison. Manatee County Water Purification Plant Carolina Bianco, John Friary, Rick Loftis. Outline. Background LCA Levels Results Impact Assessment Conclusion. Background- MCWPP. Sarasota and Manatee Counties

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Wood-based vs. Coal-based GAC a LCA comparison

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  1. Wood-based vs. Coal-based GACa LCA comparison Manatee County Water Purification Plant Carolina Bianco, John Friary, Rick Loftis

  2. Outline • Background • LCA Levels • Results • Impact Assessment • Conclusion

  3. Background- MCWPP • Sarasota and Manatee Counties • Capacity: 24.9 MGD surface water, 12.7 MGD groundwater in 2000 • Current treatment process for surface water • PAC • Coagulation • Sedimentation • Filtration • Disinfection

  4. Background- MIB • MIB: methyl•iso•borneol, metabolite of some blue-green algae & bacteria • MIB causes musty taste and odor in water, odor threshold: (5-7 ppt) • Current MIB concentration (10 to 100 ppt) • Desired concentration: (<5 ppt) • TOC concentration: (12 ppm)

  5. Background - MIB removal • Current method: PAC (~800lb/MG) • Possible Alternatives: Ozonation, chlorination, copper sulfate & other algal inhibitors, GAC • Ozonation & ChlorinationDBP • Copper Sulfate, et. al.heavy metals in water!! • Proposed method: GAC

  6. Background – Activated Carbon • 2000 BC • 300,000+ tons per year worldwide • Wood, coal, lignite, coconut shell, peat… • Any cheap, high carbon compound with low inorganics • Powdered or Granular • 500 to 3,000 m2/g (~1,000 m2/g) (100+ac/lb) • Giant Filter

  7. Background: GAC structure

  8. PAC Diameter: <0.1mm Water treatment Cost: ~$0.45/lb CUR: ~800lb/MG Not reusable* GAC Diameter: 1.2 to 1.7 mm Gas treatment Cost: $0.70 to $1.15+/lb CUR: ~300lb/MG Reusable Background – PAC VS GAC

  9. Background – Volume of GAC • MGD: 29.4 • Length of Regeneration Cycle: 183 days • CUR: 300 lb/MG • Density of Wood-Based GAC: 21.84 lb/ft3 • GAC Volume = MGD*Cycle Days*CUR/density • Volume = 29.4 * 183 * 300 / 21.84 = 73,000 ft3 (20 beds, 10ft*19ft*19ft)

  10. Coal Conversion from raw material: 35% Density: 31.2 lb/ft3 Cost: $0.70/lb CUR: 429 lb/MG CUR-vol: 13.75ft3/MG % lost during regeneration: 12.5% Wood Conversion from raw material: 50% Density: 21.84 lb/ft3 Cost: $1.15/lb CUR: 300lb/MG CUR-vol: 13.75ft3/MG % lost during regeneration 20% LCA: Coal- vs Wood-Based

  11. LCA: Functional Unit Cubic Feet of GAC per year to reduce MIB concentrations below 5 ppt.

  12. LCA: Level 1.0 Phosphoric Acid Raw materials (wood or coal) Ammonia Phosphoric Acid (wood) Water, CO2 Removal of MIB by Activated Carbon Carbon fines Water Formaldehyde MIB, TOC Formic Acid, Methanol Energy Metallic compounds Binders

  13. Level 2.0 for Coal or Wood Raw Material Extraction Waste Energy Coal or Wood Manufacturing (Activation) Waste Energy Reactivation Activating agents, Binders GAC Waste gas Energy GAC Filter Beds Water Solids to landfill Drinking water MIB, TOC

  14. Level 2.1.2-A Manufacturing of Wood-based GAC To Atmosphere Off-Gas Treatment Activation Kiln Mixer Sawdust water Wash Acid Recovery Unit water Acid Make Up (H3PO4) Drying Kiln To Atmosphere Screen Dust Collector Granular Activated Carbon

  15. Results (per ft3/yr)

  16. Coal Total Emissions: lower Total Human Risk from chemicals: lower Cost: lower Worker Deaths: 30-40 GWP: higher Impact on Ecology: higher Wood Total Emissions: higher Total Human Risk from chemicals: higher Cost: higher Worker Deaths: 0 GWP: lower Impact on Ecology: lower Conclusion – Coal vs Wood

  17. Acknowledgments • Dr. Mazyck • Dr. Lindner • Dr. Kirmse • Julee MacKenzie • Brandy Smith

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