of Fluoride Adsorbent Teshome L. Yami Advisors: Elizabeth C. Butler - - PowerPoint PPT Presentation

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2015 OU International WaTER Conference September 22, 2015 Norman, Oklahoma

Chemically Activated Cow Bone for Increased Fluoride Removal in the Context of Life Cycle Assessment (LCA)

• f Fluoride Adsorbent

Teshome L. Yami Advisors: Elizabeth C. Butler (Dr.), David A. Sabatini (Dr.) CEES, University of Oklahoma

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Outline

 Introduction  Objectives  Methods  Results and discussion  Conclusions

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 Elevated fluoride concentration affects human health.  Bone char has been widely evaluated for fluoride removal; low capacity needs further enhancement.  Chemical activation of biomaterials produces higher specific surface areas than thermal activation; has not been studied for cow bone.

Introduction

Bone char Cow bone Bone charring

 Production of fluoride adsorbents can cause

negative environmental impacts; Life Cycle Assessment (LCA) can evaluate environmental impacts.

Bone deformation

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Objectives

 Improve the fluoride adsorption capacity of cow bone using

chemical activation in place of thermal activation.

 Evaluate environmental impacts of fluoride adsorbents;

identify life cycle stage with greatest negative environmental impacts. Methods

 Cow bones were exposed to varying concentrations of

chemical activating agents:

KOH ZnCl2

H3PO4 acid H2SO4 acid

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Methods

 CAB was evaluated in batch tests and

characterized to explain increased fluoride removal capacity.  Quantity of CAB regained after chemical activation and their associated production cost was evaluated  Field column studies were conducted to evaluate the performance of the adsorbents.  Environmental impacts of fluoride adsorbents were evaluated using LCA.

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Results and discussion: Batch isotherms of CAB

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A B

Adsorbent 30% HSCB 30% HPCB 30% ZnCB 30% KCB 50% KCB Bone char Q1.5 (mg/g) 6.1 + 1.6 5.4 + 1.3 0.5 + 0.2 3.3 + 1.4 3.8 + 0.3 1.4 + 0.5

 Chemical activation using sulfuric and phosphoric acid achieved four fold higher fluoride

adsorption capacity than bone char  Potassium hydroxide activation produced three fold adsorption capacity than bone char

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 Conducted column study using two ground waters in Rift Valley, Ethiopia

 Field test result – same as the laboratory (four fold

higher fluoride removal capacity than bone char)

Note: Co = 10 mg/L RW1- Well # 1 RW2 – Well # 2

Media Bed volumes BC-RW1 100 BC-RW2 140 50% KCB- RW1 400 50% KCB- RW2 600

Results and discussion: Field testing of CAB

WHO Guideline value – 1.5 mg/L

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Results and discussion: Effects of chemical activation

 Chemical activation of cow bone:

• Did not increase SSA
• Did not change PZC (same as bone char)
• However, it increased fluoride adsorption capacity of

cow bone (four fold) than bone char

Adsorbent 30% HSCB-540 30% ZnCB-500 30% KCB-540 50% KCB-540 Bone char Q1.5 (mg/g) 6.3 + 1.1 2.2 + 0.7 3.2 + 0.8 3.6 + 0.9 1.4 + 0.5

 Combined chemical and thermal activation:

Results and discussion: Effect of chemical activation

• Increased fluoride adsorption capacity compared to bone char
• Had similar results (four fold increase) as chemical activation alone

 One step chemical activation is preferred

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Results and discussion: Effect of chemical activation

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 Observed new minerals:

• Bassanite and monetite

 These minerals are thought to be responsible for increased F- removal capacity; subject of

• ngoing research.
• These minerals were not

present in bone char

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Results and discussion: Adsorbent mass recovery and production cost

 Chemical activation produces higher mass of adsorbent per unit

mass of starting material than thermally activated cow bone (Table 1).  The total costs of production of chemically and thermally activated cow bone were found to be $0.30/ kg and $0.83/ kg, respectively.

Table 1 Quantity of material retained

Adsorbent Mass before activation (g) Mass After activation (g) Percentage of mass retained (%) 30% HSCB 30% HPCB 30% KCB 50% KCB Bone char 70 20 70 70 70 48 14 49 52 15 69 71 70 70 22

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Results and discussion: LCA

 Aluminum oxide amended wood char (AOWC) had the highest overall negative environmental impact in all impact categories due to its low fluoride adsorption capacity (Table 2.)  Bone char and treated alum waste had the lowest environmental impact due to their higher adsorption capacity compared to AOWC (Table 2.)

Sujana et al., 2005

253 3.4 Treated alum waste

Brunson and Sabatini, in review

6538 0.13 Amended wood char

Brunson & Sabatini, 2009

496 1.71 Bone char

Brunson, unpublished

1063 0.8 Activated alumina Ref. Total mass of adsorb- ent (kg) Q1.5 (mg/g) Adsorbents Table 2 Adsorbent mass required to meet the functional unit (kg)

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Results and discussion: Process contribution

• Raw materials acquisition is the

life cycle stage that contributed most to negative environmental impact of AOWC to human health, ecosystems quality, and resources.  Damage assessment of adsorbents conducted considering raw materials acquisition, adsorbent manufacturing, and waste management, life cycle stages indicated that:

• For activated alumina (AA), adsorbent manufacturing life cycle stage

contributed most to negative environmental impact to human health, and resources.

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Results and discussion: LCA

 For activated alumina,

transportation by ship had lower impact than aircraft transport for respiratory inorganics impact categories

Respiratory inorganics

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 CAB had four-fold higher capacity than

thermally activated bone char; batch and field.

 Formation of monetite and bassanite during

chemical activation of cow bone is thought to be responsible for the four- fold increase in fluoride adsorption.

 CAB achieved a higher mass of adsorbent

per unit starting material due to less fines lost than thermal activation.

Conclusions

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Conclusions

 CAB was found to be a cost-effective

production process.

 Higher fluoride adsorption capacity

reduces environmental impacts

 Transportation of adsorbents from

abroad produced higher impacts; locally produced high efficiency adsorbents are desirable

 Regeneration could mitigate the

impacts for human health and ecosystems.

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Acknowledgements

 This work was funded by the WaTER Center, Sun Oil Company

Endowed Chair, Ken Hoving Graduate College Fellowship and the National Science Foundation (NSF) (CBET-1066425).

 Special thanks to Junyi Du, Laura R. Brunson (Dr.) and Jim F.

Chamberlain (Dr.) for their collaboration on the LCA work.

 I would also like to thank Anisha Nijhawan for her in put on this work.

References

Amini M, Kim M, Karim CA, Thomas R, Majid A, Klaus NM, Mamadou S, and CJ Annette (2008) Statistical modeling of global geogenic fluoride contamination in groundwaters. Environ Sci Technol 42 (10):3662- 3668 Apambire WB, Boyle DR, & Michel FA (1997). Geochemistry, genesis, and health implications of fluoriferous groundwaters in the upper regions of Ghana. Environmental Geology, 33(1), 13-24. Ayoob S Gupta, AK & Bhat VT (2008). A conceptual overview on sustainable technologies for the defluoridation of drinking

• water. Critical Reviews in Environmental Science and Technology, 38(6), 401-470.

Brunson LR, Sabatini DA (2009) An evaluation of fish bone char as an appropriate arsenic and fluoride removal technology for emerging regions. Environ Eng Sci 26(12):1777-1784 Jagtap S, Yenkie MK, Labhsetwar N & Rayalu S. Fluoride in drinking water and defluoridation of water. Chem Rev 2012; 112(4), 2454-2466.

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Questions?