Copper Sequestration Using Local Waste Products Jim Ippolito Research Soil Scientist USDA-ARS Kimberly, ID

Presentation Outline Why worry about Cu in Idaho? Waste materials –Beneficial use Laboratory solution sorption studies Greenhouse soil sorption studies Conclusions

Why Worry About Cu in Idaho? (nass.usda.gov/QuickStats/)

Local Wastes Can we beneficially reuse Amalgamated Sugar Co: Spent Lime Waste? –274,000 tons/year Coal Ash? –19,000 tons/year Goal is to sequester Cu

Laboratory Solution Sorption Study Fly ash or Lime waste –1g into 50mL centrifuge tubes Add 50mL of increasing Cu solutions in pH buffers –Rates equivalent to 2500, 5000, 12500, 25000, 75000, mg Cu/kg –pH: 6, 7, 8, 9 Shake for 1 month and analyze solution for Cu Replicated 3 times

Next Question Can lime waste sorb excess soil Cu? Healthy AlfalfaCu-Affected Alfalfa

Greenhouse Soil Cu Sorption Soil received: –0, 250, 500, 1000 mg Cu/kg –Incubated for ~9 mo Lime waste –0, 0.5, 1.0, 2.0% by weight (0,10,20,40 tons/ac) –Incubated for 3 months Alfalfa –15 seeds/pot –2.5 months of growth

Greenhouse Soil Cu Sorption Measured: –Plant yield –Plant Cu content –DTPA extractable soil Cu –Soil phases that Cu could be associated with: Soluble species/carbonates/cation exchange sites Fe/Mn (hydr)oxides Organics Residuals

0% Lime Waste % Lime Waste % Lime Waste % Lime Waste Soil pH = 7.9; biochar pH = 8.5 Cu added = 0, 250, 500, 1000 mg kg -1 Lime Waste added = 0, 0.5, 1, 2% by wt

Sequential Soil Cu Extraction

Conclusions Lime waste and fly ash sorb solution Cu –Decreasing pH increases sorption –Fly Ash: ~26,000 mg Cu/kg –Lime Waste: ~45,000 mg Cu/kg Lime waste addition to Cu-laden soil –No improvement in alfalfa yield Decreased alfalfa Cu content –No effect on extractable (i.e. DTPA) soil Cu –No major discernable differences in soil Cu phases

Conclusions The use of lime waste: –Appears to be a viable option for sequestering solution copper. –Would not be recommended for alkaline soils containing excess copper.

Thank you Questions? Jim Ippolito, Ph.D. Research Soil Scientist USDA-Agricultural Research Service Northwest Irrigation and Soils Research Laboratory Kimberly, Idaho Phone: (208)