| Energy crisis is becoming to hit almost every part of the world due to the popula-tion growth and rapid industrialization, since the last few decades, fossil fuels have become an indispensable part of human daily lives. However, fossil fuels are non-renewable source which are limited in supply and will be exhausted one day. In addition, burning fossil fuels have brought numerous environmental concerns, in-cluding green house gas (GHG) effects which significantly contribute to global warming.So searching for renewable energy sources has become the key challenge in this century, in order to stimulate a more sustainable energy development for the fu-ture. Biodiesel is currently being recognized as a green and alternative renewable diesel fuel which has attracted vast interest from governments, researchers, and local and international traders. At present,biodiesel is produced mainly from cereal crops, such as corn, canola, soybeans and so on. Increasing biofuel production on arable land could have severe consequences for global food supply.Microalgae grow extremely rapidly and many are exceedingly rich in oil, which can utilize salt and waste water streams,and also alkaline land, they also can couple CO2-neutral fuel production with CO2sequestration. In recent years the researchers focused on the cultivation of microalgae and the photobioreactors. In this paper, we design a new photobioreactor on the basis of the theory for reaction engineering. We have taken some endeavors as below:1. A laboratory-scale batch reactor was established to investigate the influence of temperature, light, pH and the concentration of carbon dioxide on the growing of nan-nochloropsis maritime. The results show that:the specific growth rate of microalgae is different at different pH. The specific growth rate of algae was maximum when pH was8.0. But the growth would be inhibited blow7.0, and completely inhibited when carbon dioxide was saturation in the medium,pH=4.92. In this instance, the cells were not damaged.they will restore vitality with the increasing of pH. The biomass of mi-croalgae can increase by62.1%, within24hours when the light intensity was30001ux,and the photoinhibition will happen when the light intensity is higher than30001ux.The optimal temperature is27℃.2、A set of oscillatory flow-photobioreactor has been designed and established, with65mm in diameter and1500mm in height. The device is consisted by two parts:vibration and photobioreactor. The fluid mode in chamber is come ture by ad-justing the frequency and amplitude.It is also an internal radiation photobioreactor.3、We cultivated maritime chlorella in oscillatory flow-photobioreactor with continuous culture method. We investigated the pH value, initial concentration and multi-level mixed model parameters on the impact of microalgae culture. The results showed that the maximum specific growth rate was occurred at pH=7.5, which is lower than the early reported. The initial concentration is the key factor for the spe-cific growth rate of microalgae. The multi-level mixed model parameter is9when St=2.430, Reo=1427.8. In the case, the specific growth rate was drop with the increase of the initial concentration, but the productivity increased. Then ad-justed the amplitude and frequency, the multi-level mixed model parameter was16, the maximum specific growth rate was0.563d-1at the initial concentration0.142g/L,and the productivity was95mg/(L·d).With these all above results, the oscillatory flow-photobioreactor is conducive to the growth of maritime Chlorella. The whole system also covers less area, so the pro-ductivity per unit area can be very high. We think oscillatory flow-photobioreactor is a certain prospect reactor, but needs further study. |
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