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 Utah Water Research Laboratory Joan McLean Tessa Guy Joe Stewart Research Students Eric Torres Laura Birkhold Christine Inkley Mike Morgan Hailey Summers BioEnergy Center 2
Outline PRODUCTION PPROCESS HOTOBIOREACT ORS HEAVY METALS COAL POWER PLANT & CO ALGA 2 E TRANSESTERIFICAT BIOFUEL ACID CATALYZ RESUL PRODUCTIVIT Y 4 35% 3 25% 15% 1 5% TS LEA ION SUPERCRITI CAL METHANOL ED 1 10 8 6 4 LIPID YIELD As Cd FATE OF METALS Co Cr 3
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Growth Setup 14 Heavy metals used Nannochloropsis salina 1X Fly Ash PBR Element (mg metal kg-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 5
Acid Catalysed Conversion Microalgae H2SO4 + Methanol + Heat Biodiesel & CHCl3 in situ Extraction Transesterificati on Demonstrated on small and medium scale sys. 6 ml H2SO4, 294 ml methanol, 30 g biomass Wahlen Bioresource 6 ethr.al.,reaction attechnology 62 C (2011). Chloroform Distillation Biodiesel 6
Supercritical Methanol Conversion Microalga e Methanol + Heat Supercritical Meth. Transesterification Extraction Biodiesel Chloroform Distillation Demonstrated on a small scale system 100 ml methanol, 10 g biomass 1.5 hr. reaction at 250 C 7
Growth Results PRODUCTION PPROCESS COAL POWER PLANT HOTOBIOREACT ORS HEAVY METALS & CO ALGA 2 E RESUL 4 35% 3 25% 15% 1 5% PRODUCTIVIT Y TS TRANSESTERIFICAT LEA ION BIOFUEL ACID CATALYZ SUPERCRITI CAL METHANOL ED 1 10 8 6 4 LIPID YIELD As Cd FATE OF METALS Co Cr 8
Productivity and Lipid Results Growth OD750 density (g/l) Biomass Productivity 35 10 309 8 25 7 206 5 15 4 103 2 5 1 0 0 1 2 3 4 55 6 6 7 7 Time (days) Percent Lipid Content 4 35% 3 25% 15% 1 5% Lipid Yield Average productivity: Lipid Yield: Control: 1.1 g L -1 d -1 Control: 38.8% ± 0.59% Metals : 0.6 g L -1 d -1 Metals : 31.58% ± 0.48% Combined impact: 56% decrease in lipid production 9
ICPMS: Fate of Metals Significant sorption of heavy metals to the biomass. Media reuse plausible 14 1 10 8 6 4 As Cd Co Cr Cu Hg Ni Pb Sb V * Metals Se and Sn did not fall within quality control ** Metals Mn and Zn removed due to contamination 10
Acid Catalyzed Results PRODUCTION PPROCESS COAL POWER PLANT HOTOBIOREACT ORS HEAVY METALS & CO ALGA 2 E RESUL 4 35% 3 25% 15% 1 5% PRODUCTIVIT Y TS TRANSESTERIFICAT LEA ION BIOFUEL ACID CATALYZ SUPERCRITI CAL METHANOL ED 1 10 8 6 4 LIPID YIELD As Cd FATE OF METALS Co Cr 11
Acid Catalysed Results 4 Lipid Profiles 10 Recovery Efficiencies 35% 3 8 25% 15% 6 4 1 5% 14:0 16:0 16:1 18:0 18:1 18:2 20:5 FAME Impact on Lipid Profile: Change in Profile Metals decrease lipid content Impact of metals on extraction: Control: 8 ± 7% Metals : 89% ± 7% Transesterification impact: 9% increase in lipid recovery efficiency Combined impact (productivity & recovery): 51% decrease in lipid production 12
ICPMS: Fate of Metals ICPMS analyses of the biodiesel, and all byproducts heavy metals found in LEA and Methanol / Water by- Majority of products. 11 10 9 8 7 6 5 4 3 1 As Cd Co Cr Cu Ni Pb Se Sb V Biodiesel LEA Methanol / Water Losses Other * Metals Mn and Zn removed due to contamination Minimal Biodiesel Contamination ** Metals Sn and Hg conc. below ICPMS detection limit 13
Supercritical Methanol Results PRODUCTION PPROCESS COAL POWER PLANT HOTOBIOREACT ORS HEAVY METALS & CO ALGA 2 E RESUL 4 35% 3 25% 15% 1 5% PRODUCTIVIT Y TS TRANSESTERIFICAT LEA ION BIOFUEL ACID CATALYZ SUPERCRITI CAL METHANOL ED 1 10 8 6 4 LIPID YIELD As Cd FATE OF METALS Co Cr 14
Supercritical Methanol Results 35% Lipid Profiles 10 Recovery Efficiencies 3 25% 8 6 15% 1 4 5% 14:0 16:0 16:1 18:0 18:1 18:2 20:5 FAME Impact on Lipid Profile: Change in Profile Metals shifted lipid content Impact of metals on extraction: Control: 98% ± 8% Metals : 10 ± 3% Transesterification impact: 2% increase in lipid production efficiency Combined impact (productivity & recovery): 55% decrease in lipid production 15
Concentrated Growths 9 8 7 6 5 4 3 2 1 0 Harvest Density (g/l) 10 0X Nannochloropsis salina 1X 2X 5X 10X Metals Concentration Harvest Density (g/l) 10 9 8 7 6 5 4 3 2 1 0 Scenedesmus Obliquus 0X 1X 2X 5X 10X Metals Concentration Light intensity: 1000 µmol m -2 s -1 Salt water species 14 heavy metals All metals conc. limit productivity Light intensity: 200 µmol m -2 s -1 Fresh water species 10 heavy metals Metals conc. over 1X limit productivity 16
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
Supercritical Methanol Future Work 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