Effect of heavy metal contamination on microalgae growth ... of heavy metal contamination on microalgae growth and conversion to biofuel through acid catalyzed conversion Derek Hess,

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  • Effect of heavy metal contamination on microalgae growth and conversion to

    biofuel through acid catalyzed conversion

    Derek Hess, Katerine Napan, Brian McNeil, Jason C.

    Quinn

    Mechanical and Aerospace Engineering Utah State University 1

  • Acknowledgements

    2

    Utah Water Research Laboratory

    Joan McLean Tessa Guy Joe Stewart

    Research Students Eric Torres Laura Birkhold Christine Inkley Mike Morgan Hailey Summers

    BioEnergy Center

  • TRANSESTERIFICATION

    Outline

    3

    0% 5%

    10% 15% 20% 25% 30% 35% 40%

    LIPID YIELD

    PRODUCTIVITY

    0%

    20%

    40%

    60%

    80%

    100%

    120%

    As Cd Co Cr FATE OF METALS

    PRODUCTION PROCESS

    RESULTS

    CO2

    PHOTOBIOREACTORS

    ALGAE

    BIOFUEL

    LEA COAL POWER PLANT

    HEAVY METALS &

    ACID CATALYZ

    ED

    SUPERCRITICAL

    METHANOL

  • #

  • Growth Setup

    5

    14 Heavy metals used Nannochloropsis salina 1X

    Element Fly Ash PBR

    (mg metalkg-1) (mg metal * L-1) As 391.0 0.078 Cd 76.0 0.015 Co 79.0 0.016 Cr 651.0 0.130 Cu 655.0 0.131 Hg 49.5 0.010 Mn 745 0.149 Ni 1270.0 0.250 Pb 273.0 0.054 Sb 203.0 0.041 Se 49.5 0.010 Sn 18.8 0.004 V 565.0 0.113 Zn 2200.0 0.440

  • Acid Catalysed Conversion

    Demonstrated on small and medium scale sys.

    6 mL H2SO4, 294 mL methanol, 30 g biomass

    6 hr. reaction at 62 C 6

    H2SO4 + Methanol + Heat

    Microalgae

    Biodiesel & CHCl3 Extraction

    Biodiesel

    in situ Transesterificati

    on

    Chloroform Distillation

    Wahlen et al., Bioresource Technology (2011).

  • Supercritical Methanol Conversion

    Demonstrated on a small scale system

    100 mL methanol, 10 g biomass 1.5 hr. reaction at 250 C 7

    Biodiesel Extraction Supercritical Meth.

    Transesterification Methanol + Heat

    Microalgae

    Chloroform Distillation

  • TRANSESTERIFICATION

    Growth Results

    8

    PRODUCTION PROCESS

    CO2

    PHOTOBIOREACTORS

    ALGAE

    BIOFUEL

    LEA COAL POWER PLANT

    HEAVY METALS &

    ACID CATALYZ

    ED

    SUPERCRITICAL

    METHANOL

    0% 5%

    10% 15% 20% 25% 30% 35% 40%

    LIPID YIELD

    PRODUCTIVITY

    0%

    20%

    40%

    60%

    80%

    100%

    120%

    As Cd Co Cr FATE OF METALS

    RESULTS

  • 0

    5

    10

    15

    20

    25

    30

    35

    0 1 2 3 4 5 6 7

    OD

    750

    Time (days)

    0 1 2 3 4 5 6 7 8 9

    10

    0 1 2 3 4 5 6 7

    Gro

    wth

    den

    sity

    (g/L

    )

    Time (days)

    Biomass Productivity

    Productivity and Lipid Results

    9

    Average productivity: Control: 1.1 g L-1 d-1 Metals : 0.6 g L-1 d-1

    Combined impact: 56% decrease in lipid production

    Lipid Yield: Control: 38.8% 0.59% Metals : 31.58% 0.48%

    0%

    5%

    10%

    15%

    20%

    25%

    30%

    35%

    40%

    Per

    cent

    Lip

    id C

    onte

    nt

    Lipid Yield

  • 0%

    20%

    40%

    60%

    80%

    100%

    120%

    140%

    As Cd Co Cr Cu Hg Ni Pb Sb V

    ICPMS: Fate of Metals Significant sorption of heavy metals to the biomass.

    Media reuse plausible

    10 * Metals Se and Sn did not fall within quality control ** Metals Mn and Zn removed due to contamination

  • TRANSESTERIFICATION

    Acid Catalyzed Results

    11

    PRODUCTION PROCESS

    CO2

    PHOTOBIOREACTORS

    ALGAE

    BIOFUEL

    LEA COAL POWER PLANT

    HEAVY METALS &

    ACID CATALYZ

    ED

    SUPERCRITICAL

    METHANOL

    0% 5%

    10% 15% 20% 25% 30% 35% 40%

    LIPID YIELD

    PRODUCTIVITY

    0%

    20%

    40%

    60%

    80%

    100%

    120%

    As Cd Co Cr FATE OF METALS

    RESULTS

  • Acid Catalysed Results

    12

    Impact of metals on extraction: Control: 80% 7% Metals : 89% 7%

    Impact on Lipid Profile: Change in Profile Metals decrease lipid content

    0%

    20%

    40%

    60%

    80%

    100% Recovery Efficiencies

    0% 5%

    10% 15% 20% 25% 30% 35% 40%

    14:0 16:0 16:1 18:0 18:1 18:2 20:5 FAME

    Lipid Profiles

    Transesterification impact: 9% increase in lipid recovery efficiency Combined impact (productivity & recovery): 51% decrease in lipid

    production

  • ICPMS: Fate of Metals ICPMS analyses of the biodiesel, and all by-

    products

    13 * Metals Mn and Zn removed due to contamination

    0% 10% 20% 30% 40% 50% 60% 70% 80% 90%

    100% 110%

    As Cd Co Cr Cu Ni Pb Se Sb V Biodiesel LEA Methanol / Water Losses Other

    ** Metals Sn and Hg conc. below ICPMS detection limit

    Majority of heavy metals found in LEA and Methanol / Water by-products.

    Minimal Biodiesel Contamination

  • TRANSESTERIFICATION

    Supercritical Methanol Results

    14

    PRODUCTION PROCESS

    CO2

    PHOTOBIOREACTORS

    ALGAE

    BIOFUEL

    LEA COAL POWER PLANT

    HEAVY METALS &

    ACID CATALYZ

    ED

    SUPERCRITICAL

    METHANOL

    0% 5%

    10% 15% 20% 25% 30% 35% 40%

    LIPID YIELD

    PRODUCTIVITY

    0%

    20%

    40%

    60%

    80%

    100%

    120%

    As Cd Co Cr FATE OF METALS

    RESULTS

  • Supercritical Methanol Results

    15

    Impact of metals on extraction: Control: 98% 8% Metals : 100% 3%

    Impact on Lipid Profile: Change in Profile Metals shifted lipid content

    Combined impact (productivity & recovery): 55% decrease in lipid production

    0%

    20%

    40%

    60%

    80%

    100%

    Recovery Efficiencies

    0%

    5%

    10%

    15%

    20%

    25%

    30%

    35%

    14:0 16:0 16:1 18:0 18:1 18:2 20:5

    FAME

    Lipid Profiles

    Transesterification impact: 2% increase in lipid production efficiency

  • Concentrated Growths

    16

    Nannochloropsis salina Scenedesmus Obliquus

    Light intensity: 1000 mol m-2 s-1 Salt water species 14 heavy metals

    Light intensity: 200 mol m-2 s-1 Fresh water species 10 heavy metals

    All metals conc. limit productivity Metals conc. over 1X limit productivity

    0 1 2 3 4 5 6 7 8 9

    10

    Har

    vest

    Den

    sity

    (g/L

    )

    Metals Concentration 0X 1X 2X 5X 10X

    0 1 2 3 4 5 6 7 8 9

    10

    Har

    vest

    Den

    sity

    (g/L

    )

    1X 0X 5X 2X 10X Metals Concentration

  • Conclusion Metals negatively impact system

    Productivity decrease of 56% Acid Catalyzed Biodiesel yield decrease of 51% Supercritical Methanol Biodiesel yield decrease of 55%

    End Fate Biomass sorbes majority of metals Media reuse plausible By-products (LEA and Methanol/Water) contain majority of metals Minimal Biofuel contamination

    Metals impact processes and productivity Metals at any concentration negatively impact productivity Metal impact of biofuel conversion varies with conversion type

    17

  • Future Work

    Supercritical Methanol Fate of Heavy Metals work (ICPMS)

    Downstream Processing Biochemical Methane Potential Testing Fermentation

    Modeling Life Cycle Analysis

    18

  • Thank You

    Contact information: Derek Hess

    derekhess7@gmail.com (208) 206-0371

    19