Recovery of Metals from Biosolids Treated by Thermal Hydrolysis - PowerPoint PPT Presentation

Recovery of Metals from Biosolids Treated by Thermal Hydrolysis Chengyong Zhu, Mehdi Omidghane, Lin Xia, Michael Chae, David C. Bressler Department of Agricultural, Food and Nutritional Science, University of Alberta 1

Uses of Metals Metals Images from: Google Images 2

Declining Ore Grades Year http://www.csiro.au/en/Research/MRF/Areas/Resourceful-magazine/Issue-07/Producing-more-from-less 3

What Are Biosolids? Edmonton Waste Management Centre-Clover Bar Biosolids are defined as wastewater sludge destined for beneficial use (Mangory et al). Main components: water, organic matter, trace elements… 4 Image: https://reducedimpactfamily.wordpress.com/2010/03/01/our-visit-edmonton-waste-management-center/

Incorporation of Biosolids into LTH Technology for Production of Biofuel Biosolids Water Free Fatty Acids Pyrolysis Hydrolysis Lipids Hydrocarbons Reactor Reactor Aqueous Waste By-products Solid phase & Aqueous Phase Two-step Thermal Lipid To Hydrocarbon Technology Source: Maher, 2007(with modifications) 5

Recovery of Metal Values from Biosolids? • Economic Values Take Al for example: Annual production of biosolids: 25, 000 dry tonnes Content of Al: 30,000 mg/kg Recovery rate: 90% Unit price: 0.72 USD/LB ≈ 1.0 Million USD http://www.edmonton.ca/city_government/utilities/biosolids-management.aspx 6

Recovery of Metal Values from Biosolids? • Toxicity Pb, Cu, As Cr, Hg, Ni Pb, Cu, As Pb, Cu, As Pb, Cu, As Pb, Cu, As Cr, Hg, Ni Cr, Hg, Ni 7 Image modified from: http://2015.igem.org/Team:Bielefeld-CeBiTec/Project/HeavyMetals

Results • Settling of hydrolyzed biosolids 0 min 5 min 24 h 8

Results • Metal distribution after thermal hydrolysis(280 o C, 60 min) Al Ti Cr Fe Mn Cu Zn Ag Y Aqueous 3.69 0.039 0.245 6.66 1.78 0.038 2.91 0.005 0.005 ± ± ± ± ± ± ± ± ± Phase (mg/L) 0.011 0.058 1.14 0.17 0.013 0.11 0.005 0.001 0.89 Solid 3817 1571 298 21922 397 814 1047 3.21 8.64 ± ± ± ± ± ± ± ± Phase 6 ± (mg/kg) 278 37 1645 14 28 38 1.08 0.38 1716 9

Acids Purification Electrowinning Concentrated Bases Solid Metal Metals Pure Metal Phase leachates Solutions Proposed Scheme of Metal Recovery

Results • Leach metals with sulfuric acid (3h, 200rpm, 25 o C, solid(g): sulfuric acid(mL)=1(g):10 (mL) ) Recovery Percentage of Metals (%) H 2 SO 4 Al Ti Cr Fe Mn Cu Zn 0.5 M 31.6 20.1 42.5 40.4 43.6 18.4 44.0 ± ± ± ± ± ± ± 5.9 1.6 0.5 0.9 10.8 1.0 0.6 1 M 60.9 25.4 65.3 70.8 73.6 9.4 73.4 ± ± ± ± ± ± ± 11.0 3.4 2.5 1.3 0.6 3.8 4.2 1.5 M 68.4 28.4 70.7 77.3 77.9 10.3 77.8 ± ± ± ± ± ± ± 13.2 11.6 11.8 13.4 11.7 1.8 13.4 2 M 66.7 29.3 69.1 75.0 75.8 10.4 74.7 ± ± ± ± ± ± ± 13.7 7.3 8.9 8.4 1.6 8.9 8.1 11

Future Plans • Optimize leaching metals with sulfuric acid • Leach metals with other acids • Recovery of metals 12

Acknowledgement This research is funded by BioFuelNet Canada, a network focusing on the development of advanced biofuels. BioFuelNet is a member of the Networks of Centres of Excellence of Canada program. Website: www.biofuelnet.ca. 13