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

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Uses of Metals

Metals

Images from: Google Images

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Declining Ore Grades

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

Year 3

What Are Biosolids?

Edmonton Waste Management Centre-Clover Bar

Image: https://reducedimpactfamily.wordpress.com/2010/03/01/our-visit-edmonton-waste-management-center/

Biosolids are defined as wastewater sludge destined for beneficial use (Mangory et al). Main components: water, organic matter, trace elements…

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Incorporation of Biosolids into LTH Technology for Production of Biofuel

Lipids Hydrolysis Reactor Water Aqueous Waste

Free Fatty Acids

Pyrolysis Reactor Hydrocarbons By-products Two-step Thermal Lipid To Hydrocarbon Technology

Biosolids

Solid phase & Aqueous Phase

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

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Recovery of Metal Values from Biosolids?

• Toxicity

Pb, Cu, As Cr, Hg, Ni Pb, Cu, As Cr, Hg, Ni Pb, Cu, As Pb, Cu, As Pb, Cu, As Cr, Hg, Ni

Image modified from: http://2015.igem.org/Team:Bielefeld-CeBiTec/Project/HeavyMetals

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Results

• Settling of hydrolyzed biosolids

0 min 5 min 24 h

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Results

• Metal distribution after thermal hydrolysis(280oC, 60 min)

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

Solid Phase

Acids Bases

Metal leachates Metals

Electrowinning

Proposed Scheme of Metal Recovery Concentrated Pure Metal Solutions

Purification

Results

• Leach metals with sulfuric acid (3h, 200rpm, 25 oC, solid(g):

sulfuric acid(mL)=1(g):10 (mL) )

Recovery Percentage of Metals (%)

H2SO4 Al Ti Cr Fe Mn Cu Zn 0.5 M 31.6 ± 0.6 20.1 ± 5.9 42.5 ± 1.6 40.4 ± 0.5 43.6 ± 0.9 18.4 ± 10.8 44.0 ± 1.0 1 M 60.9 ± 4.2 25.4 ± 11.0 65.3 ± 3.4 70.8 ± 2.5 73.6 ± 1.3 9.4 ± 0.6 73.4 ± 3.8 1.5 M 68.4 ± 13.2 28.4 ± 11.6 70.7 ± 11.8 77.3 ± 13.4 77.9 ± 11.7 10.3 ± 1.8 77.8 ± 13.4 2 M 66.7 ± 8.1 29.3 ± 13.7 69.1 ± 7.3 75.0 ± 8.9 75.8 ± 8.4 10.4 ± 1.6 74.7 ± 8.9 11

Future Plans

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

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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