Model-based optimization of microalgae areal productivity in flat-plate gas-lift photobioreactors

Pfaffinger, Christina Evi; Schöne, Dennis; Trunz, Sascha; Löwe, Hannes; Weuster‐Botz, Dirk

doi:10.1016/j.algal.2016.10.002

Cited by 44 publications

(19 citation statements)

References 43 publications

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“…where µ is the specific growth rate, µ max is the maximum specific growth rate and I K is the light saturation constant. It is worth noting that the range of light intensities used in this work is far away from photo-inhibition phenomena [14], so that Monod's law can be applied without any limitation.…”

Section: Mathematical Modellingmentioning

confidence: 99%

“…Polishchuk et al found that Nannochloropsis oculata grown in a saline medium has a maximum growth rate of 0.365 day −1 [23], while Huesemann et al found that Nannochloropsis salina has a maximum specific growth rate of about 1.0 day −1 when cultivated at 26 • C under a photon flux density of 250 µE s −1 m −2 [24]. In the literature, the only work showing the specific growth rate (µ) in the exponential phase as a function of the mean integral photon flux density in cultures of Nannochloropsis gaditana reports a maximum growth rate µ max of about 0.0370 h −1 (about 0.89 day −1 ) and a saturation constant I k of 43 ± 6 µE s −1 m −2 [14]. The small differences in the values found by these authors may be due to different growth conditions, experimental set-up and light distribution inside the reactor.…”

Section: Kinetic Parametersmentioning

confidence: 99%

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Modelling Nannochloropsis gaditana Growth in Reactors with Different Geometries, Determination of Kinetic Parameters and Biochemical Analysis in Response to Light Intensity

et al. 2022

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Microalgae are unicellular and photosynthetic microorganisms which grow thanks to inorganic salts, CO2 and light, and find applications in several fields thanks to their variety. The industrial application of microalgae has not often been fully exploited because of a lack of information about how microalgae respond to inputs and to different growth environments. In the present work a model able to predict the microalgae growth in reactors with different geometries was developed. We combined a Monod-like model for the specific growth rate with the Lambert-Beer law of homogeneous light distribution in thick photobioreactors. Kinetic parameters related to the cultivation of the microalga Nannochloropsis gaditana were obtained, for the first time through batch cultivation under different photon flux densities inside a quasi-isoactinic photobioreactor, in order to obtain a practically homogeneous light distribution. The maximum specific growth rate and saturation constant resulted, respectively as µmax = 0.0256 h−1 and Ik = 15.28 µE m−2 s−1. These parameters were applied to the model to obtain data on microalgae growth in different geometries. Model simulation results are presented and discussed. Furthermore, biochemical analysis was performed on the biomass obtained at the end of each batch cultivation, grown both under different light intensities and in reactors with different configurations. Results indicated that lipid content increases with increasing average photon flux density. The fatty acid and carotenoids profiles markedly shift when the average light intensity varies: the PUFA content decreases and the SFA content increases when the average light intensity rises, and an accumulation of carotenoids at lower photon flux densities is observed. In conclusion, the model resulted in a useful tool, able to predict the growth of the microalga Nannochloropsis gaditana in reactors with different configurations.

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Section: Mathematical Modellingmentioning

confidence: 99%

Section: Kinetic Parametersmentioning

confidence: 99%

Modelling Nannochloropsis gaditana Growth in Reactors with Different Geometries, Determination of Kinetic Parameters and Biochemical Analysis in Response to Light Intensity

et al. 2022

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“…, 1.03 g X l −1 ) are within a typical range for both, lab-scale and outdoor production of Nannochloropsis sp. in tubular photobioreactors (Olofsson et al, 2012;Pfaffinger et al, 2016;Pereira et al, 2018). The experimental variability regarding c X,0 is rather high within the investigated small pilotscale experiments.…”

Section: Resultsmentioning

confidence: 90%

Experimental and Model-Based Analysis to Optimize Microalgal Biomass Productivity in a Pilot-Scale Tubular Photobioreactor

Weise

Grewe²,

Pfaff

2020

Front. Bioeng. Biotechnol.

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A dynamic coarse-grained model of microalgal growth considering light availability and temperature under discontinuous bioprocess operation was parameterized using experimental data from 15 batch cultivations of Nannochloropsis granulata in a pilot-scale tubular photobioreactor. The methodology applied consists of a consecutive two-step model parameter estimation using pooled, clustered and reorganized data to obtain initial estimates and multi-experiment fitting to obtain the final estimates, which are: maximum specific growth rate µ max = 1.56 d −1 , specific photon half-saturation constant K S,ph = 1.89 mol ph g X −1 d −1 , specific photon maintenance coefficient m ph = 0.346 mol ph g X −1 d −1 and the cardinal temperatures T min = 2.3 • C, T opt = 27.93 • C and T max = 32.59 • C. Biomass productivity prediction proved highly accurate, expressed by the mean absolute percent error MAPE = 7.2%. Model-based numerical optimization of biomass productivity for repeated discontinuous operation with respect to the process parameters cultivation cycle time, inoculation biomass concentration and temperature yielded productivity gains of up to 35%. This optimization points to best performance under continuous operation. The approach successfully applied here to small pilot-scale confirms an earlier one to lab-scale, indicating its transferability to larger scale tubular photobioreactors.

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“…Furthermore combining this simulation with a model for light attenuation over layer thickness and microalgal growth it will be possible to design a reactor for specific microalgal strains and biomass densities to support optimal growth. In an existing reactor, the expected growth rates with different algal strains can be calculated from this simulation.…”

Section: Reactor Unit Models: Results and Applicationsmentioning

confidence: 99%

Validated numerical fluid simulation of a thin‐layer cascade photobioreactor in OpenFOAM

Severin

Brück

Weuster‐Botz

2018

Engineering in Life Sciences

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Recently, microalgae have been considered as a promising alternative for the production of biofuels from CO2. For the efficient cultivation of these microalgae, several types of photobioreactors have been designed and Pilot scale photobioreactors have been used to assess the performance of these reactors. Therein the primarily investigated reactor type is the Raceway Pond. However, the less researched Thin‐Layer Cascade Photobioreactor (TLC) shows a high potential for efficient production processes. Unfortunately, for low‐value products like biofuels costs must be kept to a minimum for an economic operation. To facilitate this, 3D Computational Fluid Dynamic simulations can be employed to estimate performance of reactor variants e.g. with respect to power input and mixing. Since up to now little effort has been put into the modelling of TLC reactors, this report aims to present a simulation approach for these reactors types that allows simple adaptation to different geometric or operational boundary conditions. All models have been generated for a two‐phase mixture in OpenFOAM. To demonstrate its applicability, validation measurements with a physical unit have been performed and were compared to the simulation results. With errors in the order of 10 % a successful simulation of the reactor geometry could be proven.

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Model-based optimization of microalgae areal productivity in flat-plate gas-lift photobioreactors

Cited by 44 publications

References 43 publications

Modelling Nannochloropsis gaditana Growth in Reactors with Different Geometries, Determination of Kinetic Parameters and Biochemical Analysis in Response to Light Intensity

Modelling Nannochloropsis gaditana Growth in Reactors with Different Geometries, Determination of Kinetic Parameters and Biochemical Analysis in Response to Light Intensity

Experimental and Model-Based Analysis to Optimize Microalgal Biomass Productivity in a Pilot-Scale Tubular Photobioreactor

Validated numerical fluid simulation of a thin‐layer cascade photobioreactor in OpenFOAM

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