16-19 June 2013, Montreal 10 Annual World …...CO2 Capture Extraction Dewatering Harvesting...
Transcript of 16-19 June 2013, Montreal 10 Annual World …...CO2 Capture Extraction Dewatering Harvesting...
16-19 June 2013, Montreal 10th Annual World Congress on Industrial
Biotechnology and Bioprocessing
Serge R. Guiot [✉[email protected] ☏ +1 (514) 496-6181],
J.-C. Frigon, F. Matteau-Lebrun, B. Tartakovsky
Bioengineering Laboratory, NRC Energy, Mining & Environment
P.J. McGinn, S.J.B. O’Leary
NRC Aquatic & Crops Resource Development
Algal Carbon Conversion
Algal Carbon Conversion Program
2/16
CO2 Capture
Extraction
Dewatering
Harvesting
Photobioreactor
Energy
Light
Waste Water
Algae
Soil Amendment
BYPRODUCTS
BIO-OIL
Biodiesel
Animal Feed
RESIDUAL
Biojet
Pyro Syngas
AD Methane
High Value
Other
Monitoring
FEEDSTOCKS
ALGAE
CULTIVATION
SYSTEMS
Economic Pain Points
Algal Carbon Conversion
Algal Biorefinery Value Chain
Algal Carbon Conversion 3/16
Bioengineering Laboratory Energy, Mining & Environment Portfolio 4/16 ©S.R. Guiot 2013
AD, a must in an algal biorefinery
• Whole-cell perspective:
• microalgae blooms cultivated in open ponds, often for wastewater treatment and
environmental protection purposes → typically diluted & low in lipid content => justifying
lower value use and simple processing approach such as AD
• Algal residue perspective:
• as much as 50% of all cultivated solids can be residue, requiring disposal, particularly if
value added approaches for the use of residual proteins, polysaccharides, and other
chemicals cannot find cost effective separation technologies as well as suitably large and
viable markets
• Both → attractive feedstock for AD
• production of energy and/or fuels as compressed gas
• recovery of associated nutrients, mainly nitrogen and phosphorous
• AD ⇒ significant benefits for reducing energy cost and environmental impacts of an
algal bio-refinery
CO2
Formate
Acetate
Monomers (sugar, amino-acids, fatty acids)
hydrolysis
CH4
methanogenesis
3
Acetogenic bacteria
Ethanol
Butyrate
Propionate
Lactate
H2
2
Acidogenic
fermentative bacteria
4 Methanogenic
archaea
Hydrolytic
fermentative bacteria
1 Anaerobic digestion (AD)
Complex organic matter (cellulose, starch, proteins, lipids …)
Theoretical biochemical methane
potential, from elemental formulas :
CARBOHYDRATES : YCH4 = 0.42 Nm3 / kg
Limiting step: hydrolysis / methanogenesis
Limiting step: proteolysis
PROTEINS : YCH4 = 0.51 Nm3 / kg
Limiting step: LCFA acetogenesis
FATS : YCH4 = 1 Nm3 / kg
Broad feedstock
spectrum + CO2
acetogenesis
5/16 ©S.R. Guiot 2013
Limiting step: hydrolysis
OTHERS (nucleic a., glycoproteins,
…) : YCH4 = 0.5 Nm3 / kg
Bioengineering Laboratory Energy, Mining & Environment Portfolio 6/16 ©S.R. Guiot 2013
Algal species screening for biomethane potential (BMP)
Screening of microalgae strains
for methane production was
performed in 500 mL serum
bottles at 35°C and 150 rpm
agitation under optimal conditions
(pH, buffer, nutrients), with
anaerobic sludge as inoculum at
a ratio of 2:1
Bioengineering Laboratory Energy, Mining & Environment Portfolio 7/16 ©S.R. Guiot 2013
Typical biphasic time-
courses
Hypothesis: LCFA
accumulation, first
repressing
methanogenesis, then
after adaptation, higher
productivity resumed
Algal species screening for BMP (2)
Incubation (days)
Cu
mu
lati
ve
me
tha
ne
(LS
TP/k
g T
VS
in)
Bioengineering Laboratory Energy, Mining & Environment Portfolio 8/16 ©S.R. Guiot 2013
Algal species screening for BMP (3)
Bioengineering Laboratory Energy, Mining & Environment Portfolio 9/16 ©S.R. Guiot 2013
Algal species screening for BMP (4)
n=15 n=5
Highest YCH4 with
Scenedesmus sp.-
AMDD, Isochrysis sp.
and Scenedesmus
dimorphus: 410, 408
and 397 mLCH4/gVS,
respectively
Degradation efficiency:
72 – 75%
Bioengineering Laboratory Energy, Mining & Environment Portfolio 10/16 ©S.R. Guiot 2013
Anaerobic bioprocessing in continuously-fed digesters (CSTR)
• The strain Scenedesmus sp.-AMDD was
chosen as a model strain for processing
testing in continuously-fed digesters (daily
feeding)
• 10 L completely-stirred tank reactor
(CSTR)
• Mechanical mixing at 80 rpm
• Temperature: 35°C
• Feed: 10-20 g TVS/wet kg
• Hydraulic retention time (HRT): 16 to 58 d
• Organic loading rate (OLR): 0.2 - 0.6 g
TVS/Lrx.d
Bioengineering Laboratory Energy, Mining & Environment Portfolio 11/16 ©S.R. Guiot 2013
HRT (days) 16 58 58
Cin (g TVS/L) 11 11 20
OLR (g TVS/Lrx.d) 0.7 0.2 0.35
AD in continuous CSTR (2)
Bioengineering Laboratory Energy, Mining & Environment Portfolio 12/16 ©S.R. Guiot 2013
Potential factors limiting anaerobic degradation of microalgae
• Hydrolysis limited: cell walls (glycoproteins)
• CSTR : 52% degradation (vs 75% in early BMPs)
• larger portion of recalcitrant organics with the “new” supply of Scenedesmus (modification of the strains, at production, harvesting, storage ?)
255 ± 16 LSTP/g TVSin (46%)
177 ± 43 LSTP/g TVSin(33%)
• inhibition of methanogenic populations by long chain fatty acids (LCFA) • BMP assays with LCFA at concentration of 2.5 and 1.25 g/L showed:
• slow but high yield with palmitic acid (812 ± 10 L/kg),
• strong and permanent inhibition by palmitoleic acid possibly because of transient accumulation
of myristic acid
• fair degradation of eicosapentaenoic acid (EPA) (453 ± 72 L/kg)
• proliferation of sulfate-reducing bacteria
Bioengineering Laboratory Energy, Mining & Environment Portfolio 13/16 ©S.R. Guiot 2013
Algal suspension processed in advanced AD technology
• UASB reactor : 3.5 L useful volume - 35°C
• microbial biomass (granules) in reactor (rxr) : 30-40 g VSS/Lrxr
Anaerobic granule
= aggregate of
bacteria, auto-
immobilization
• Inlet concentration : 4 and 8 g TVS/L
• HRT: 2 and 4 days
• OLR: 2 and 4 g TVS/Lrxr·d
• CH4 productivity : 0.54 L (STP) CH4/Lrxr·d
• TVS degradation efficiency : approaching 50% (based on CH4
production)
Bioengineering Laboratory Energy, Mining & Environment Portfolio 14/16 ©S.R. Guiot 2013
Pretreatment to improve the digestibility of algae
Crude Microwave Alkaline
Crude Microwave Alkaline
Incubation (days)
Cu
mu
lati
ve m
eth
an
e
(LS
TP/k
g T
VS
ad)
Bioengineering Laboratory Energy, Mining & Environment Portfolio 15/16 ©S.R. Guiot 2013
Conclusions
• Target : 20 kg TVS/m3rxr·day; 75% conversion
• Profitable @ FIT $0.15/kWh CHP & C credit $30/t eCO2
• Effective pre-treatment (thermal) combined with advanced AD technology
• Two-stage AD, allowing for targeted optimization 1st stage towards improved hydrolysis, e.g. low pH, high temperature.
Thank you!
Questions – comments ?