Modelling of light and temperature influences on cyanobacterial growth and biohydrogen production

D Zhang,P Dechatiwongse,E.A Del Rio-Chanona,G.C Maitland,K Hellgardt,V.S Vassiliadis

doi:10.1016/j.algal.2015.03.015

D Zhang, P Dechatiwongse + Show 4 more

Open Access

https://doi.org/10.1016/j.algal.2015.03.015

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Abstract

Dynamic simulation is a valuable tool to assist the scale-up and transition of biofuel production from laboratory scale to potential industrial implementation. In the present study two dynamic models are constructed, based on the Aiba equation, the improved Lambert–Beer's law and the Arrhenius equation. The aims are to simulate the effects of incident light intensity, light attenuation and temperature upon the photo-autotrophic growth and the hydrogen production of the nitrogen-fixing cyanobacterium Cyanothece sp. ATCC 51142. The results are based on experimental data derived from an experimental setup using two different geometries of laboratory scale photobioreactors: tubular and flat-plate. All of the model parameters are determined by an advanced parameter estimation methodology and subsequently verified by sensitivity analysis. The optimal temperature and light intensity facilitating biohydrogen production in the absence of light attenuation have been determined computationally to be 34°C and 247μmolm−2s−1, respectively, whereas for cyanobacterial biomass production they are 37°C and 261μmolm−2s−1, respectively. Biomass concentration higher than 0.8gL−1 is also demonstrated to significantly enhance the light attenuation effect, which in turn inducing photolimitation phenomena. At a higher biomass concentration (3.5gL−1), cyanobacteria are unable to activate photosynthesis to maintain their lives in a photo-autotrophic growth culture, and biohydrogen production is significantly inhibited due to the severe light attenuation.

Highlights

Carbon dioxide, CO2, is the major source of environmental concern for causing global warming and it is mainly released by burning carbon-based energy resources such as petrol, coal and natural gas [21]
Because of this severe light extinction, even when the incident light intensity is high, photoinhibition may only appear in a small area close to the light source of PBRs, while the major part is controlled by photolimitation
Since the effects of light attenuation on cell growth and hydrogen production are very similar, the current study focuses on cyanobacterial growth rate as an example for detailed explanations

Summary

Introduction

CO2, is the major source of environmental concern for causing global warming and it is mainly released by burning carbon-based energy resources such as petrol, coal and natural gas [21]. To reduce the production of CO2 and fulfil the increasing demand for energy, novel sustainable and environmentally friendly energy sources are being sought. Biofuels such as biodiesel, biohydrogen, and ethanol are expected to provide new opportunities to replace conventional fossil fuels and diversify sustainable energy sources [22]. Lipids are usually used to generate biodiesel, while starch and sugars are always converted to ethanol, hydrogen and other biofuels [30]. Cyanobacterial growth rate is strongly influenced by various factors such as nutrient concentration, temperature and light intensity. In the Monod model, as shown in Eq (1), the maximum specific growth rate μmax is treated as a constant, but in reality it is a function of light intensity and temperature. When nutrients are in excess, the growth rate is independent of nutrient concentration and the term of

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Conclusion