Author
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Ippolito, James |
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Submitted to: Proceedings of the Idaho Nutrient Management Conference
Publication Type: Proceedings Publication Acceptance Date: 2/16/2010 Publication Date: 3/9/2010 Citation: Ippolito, J.A. 2010. Copper sequestration using local waste products. Proceedings of the Idaho Nutrient Management Conference, March 9, 2010, Shoshone, Idaho. p. 33-34. Interpretive Summary: Technical Abstract: Dairies utilize copper sulfate foot baths to control hoof infections. Typical solutions are 5 or 10% copper sulfate (pH ~6), equal to 12,500 or 25,000 parts per million copper, respectively. When spent, hoof bath solutions are usually disposed of in waste lagoons and subsequently utilized for irrigation. In the Magic Valley, this practice appears to be causing soil copper concentrations to increase. The goal of our research was to use local waste products to sequester copper from a simulated hoof bath solution and to use waste products to adsorb excessive copper from copper-affected soils. We utilized lime waste and fly ash from the Amalgamated Sugar Company, LLC (Twin Falls, ID) to identify copper sorption maximum as a function of pH. In triplicate, solutions containing one gram of material and increasing copper concentrations (0, 2500, 5000, 12500, 25000 parts per million copper) were shaken for one month buffered at either pH 6, 7, 8, or 9. Materials shaken at pH 6 adsorbed the greatest amount of copper, but concentrations up to 25000 parts per million did not maximize all adsorption sites. Thus, additional solutions containing waste materials and copper concentrations of 75000 and 100000 parts per million copper were shaken for one month at pH 6. Results showed that at pH 6 lime waste and fly ash adsorbed a maximum of ~ 45000 and 26000 parts per million of copper. The use of lime waste to sequester copper from spent dairy copper sulfate hoof baths appears to be a viable option. Because lime waste adsorbed a greater quantity of copper as compared to fly ash, we investigated the ability of lime waste to sequester copper from copper-affected soils. A soil from the Logan Soil Series which had received 0, 250, 500, or 1000 parts per million copper approximately one year earlier was utilized. Using a completely randomized design with four replicates, lime waste was applied at 0, 0.5, 1, and 2% by weight (~0, 10, 20, and 40 tons per acre), thoroughly incorporated, and allowed to incubate at 90% of field capacity moisture content for 3 months, after which 15 alfalfa seeds were planted in each pot. Plants were allowed to grow for 2.5 months, and then were harvested at ½” above the soil surface, oven dried at 60 degrees C for 72 hours, ground, weighed, and analyzed for total copper content. Soils were air-dried, ground to pass a 1/16” screen, and then plant-available copper was measured. Soils were also subjected to a sequential metal extraction procedure which identified copper associated with a) soluble species, carbonates, and cation exchange sites, b) iron and manganese oxyhydroxides, c) organic matter and sulfides, and d) residual phases. Increasing soil copper application rate decreased alfalfa yield, but increasing lime waste application rate had no effect on improving alfalfa yield. Increasing soil copper application also increased plant copper concentration, while increasing lime application rate caused a decrease in plant copper concentration. Increasing soil copper application increased plant-available copper content, while increasing lime application rate did not affect extractable soil copper content. Increasing copper application rate increased copper bound in all soil phases. Lime waste significantly affected copper associated with most soil metal phases, but the changes were not large enough to help decrease soil copper concentrations to below levels that would affect alfalfa growth and copper accumulation. The use of lime waste to sequester copper from copper -affected soils, unlike from solution, does not appear to be a viable treatment process. |
