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TRANSCRIPT
GOVERNING EXPONENTIAL GROWTH RATES OF HIGH-DENSITY MICROALGAE CULTURES BY AUTOMATED ADJUSTMENT OF AERATION IN FLAT PANEL AIRLIFT PHOTOBIOREACTORS (POSTER 336)
Subitec GmbH | Sustainable Biotechnology | Stuttgart | Germany Steffen Welzmiller | [email protected] | www.subitec.com
! Subitec GmbH – who we are and what we do
! Motivation
! Limits of mass cultivation – Light
! Experimental layout
! Light saturation and aeration rate
! Conclusion / outlook
Content
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SUBITEC GMBH – WHO WE ARE AND WHAT WE DO
> Spin-off from the Fraunhofer-Institute for Interfacial Engineering
and Biotechnolgy (IGB) in Germany Stuttgart
> Foundation of the enterprise in 2000
> Holding two patent families regarding the Flat-Panel-Airlift
Photobioreactors (FPA)
> First pilot plants in 2008
> Since 2013 design and construction of scale-up and production
plants
> Employees: 14
Subitec: We have evolved from a Spin-off of a R&D organization into a Plant Manufacturer
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! Design addresses inhibitive effects of
photolimitation and photoinhibition
! High Productivityvol. (up to 2 gDW L-1 d-1)
! High biomass concentration (up to 20 gDW L-1)
! No chemical/gaseous gradients
! Straightforward process control
! Modularity
! Low CAPEX and OPEX
The Technology: The Flat-Panel-Airlift Photobioreactor (FPA) allows efficient light utilization
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Light
What We Offer
! Systems for the cultivation of microalgae based on 6 L, 28 L and 180 L FPA-
PBRs
! Laboratory applications, pilot- and large scale plants
! Indoor and outdoor
! Engineering, construction and commissioning of plants
! R&D partner for microalgae based projects
! Development, optimization and adaptation of microalgal cultivation and product
formation processes
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Subitec is building Industrial-Scale Plants For example the following project:
Market segment: Industrial-scale plant for the production of Astaxanthin
Dimension: approx. 700 photobioreactors with a volume of around 130 m3 (= 130.000 l ~ 34.000 gal) installed on a surface equivalent to a soccer field
Scope of Services: > Conceptional study regarding business model and local setting on
site
> Research and technological development
> Basic und Detailed Engineering
> Construction and commissioning of the plant
> Training and support 7
Visual Impressions
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MOTIVATION
Motivation
! Make microalgae biotechnology commercially viable and competitive
▸ OPEX reduction of the cultivation process
! Improve light utilization
! Minimize energy demand
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LIMITS OF MASS CULTIVATION – LIGHT
Light Attenuation ! Absorption (self shading)
! Surface reflection
! Water reflection
! Bubble reflection
! Typical growth phases (lag, log, declining growth,
stationary, death)
▶ Increase photon flux density (PFD)
▶ Increase convective mass transfer
(turbulence, in FPA-PBR = aeration rate)
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EXPERIMENTAL LAYOUT
Experimental Layout
! Thermosynechococcus elongatus BP-1
! Temperature: 55°C / 130°F
! HPS lamps
! Modified BG11 (3-fold conc.)
! Light saturation experiments: ! Fixed air: 180 L h-1 air (6% v/v CO2) ! Variations in light: 120..1020 µmol m-2 s-1
! Aeration rate experiments: ! Fixed light: 780, 405 and 180 µmol m-2 s-1
! Variations in airation: 40..300 L h-1 air (6% v/v CO2)
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LIGHT SATURATION AND AERATION RATE
Solely increase in PFD can not cope with light attenuation affects
! N = 5
! Light saturation at around 500 µmol m-2 s-1 (given set-up)
! During bright sunlight 75% of PAR is not used
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Increase in PFD and aeration rate copes with light attenuation affects
! 780 µmol m-2 s-1 (> 500 µmol m-2 s-1 )
! N = 3..7
! Coordinate translation + fit
! Allows for profitability assessment
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In other words: At intense light increasing the aeration rate is useful
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780 µmol m-2 s-1
Productivity Course over Dry Weight:
At bad light conditions high aeration rates are wasted energy
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780 µmol m-2 s-1
High aeration rates are useful
405 µmol m-2 s-1
Aeration rates > 180 l/h are wasted energy
180 µmol m-2 s-1
Aeration rates > 40 l/h are wasted energy
Energy reduction of at least 45 % is possible
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45 % Energy reduction 60 % Energy reduction
Estimation of Energy Reduction by Adjusted Aeration:
CONCLUSIONS / OUTLOOK
Summarized Conclusions
! Light attenuation is evident
! Light attenuation can partially be coped with by adapted aeration rate
! Control parameters of the aeration rate should be the light intensity and the biomass concentration
! Adjustment allows for
! increased productivity at intense light and high biomass concentration
! low-energy cultivation during dim light or low biomass concentration
! Energy reduction of at least 45 % is possible
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Outlook
▶ Increase the cost effectiveness of cultivating microalgae by using the effects pointed
out
▶ Automation by instrumentation, control and automation (ICA) technologies
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! Non-invasive technology
! Precise online measurement
! Automate feeding / dilution
! Powerful tool in connection with day courses
(photolimitation, photoinhibition, respiration)
Note: Online DW Measurement at High Concentrations is a powerful tool in connection with day courses
(Correllation factor DW/OD = 0.28)
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THANKS TO PETER BERGMANN AND THE TEAM
THANK YOU FOR YOUR ATTENTION [email protected]