https://www.massey.ac.nz/~ychisti/Biodiesel.pdf

Biodiesel from microalgae.

Sustainability is a key principle in natural resource management, and it involves operational efficiency, minimisation of environmental impact and socio-economic considerations; all of which are interdependent. It has become increasingly obvious that continued reliance on fossil fuel energy resources is unsustainable, owing to both depleting world reserves and the green house gas emissions associated with their use. Therefore, there are vigorous research initiatives aimed at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. However, alternate energy resources akin to first generation biofuels derived from terrestrial crops such as sugarcane, sugar beet, maize and rapeseed place an enormous strain on world food markets, contribute to water shortages and precipitate the destruction of the world's forests. Second generation biofuels derived from lignocellulosic agriculture and forest residues and from non-food crop feedstocks address some of the above problems; however there is concern over competing land use or required land use changes. Therefore, based on current knowledge and technology projections, third generation biofuels specifically derived from microalgae are considered to be a technically viable alternative energy resource that is devoid of the major drawbacks associated with first and second generation biofuels. Microalgae are photosynthetic microorganisms with simple growing requirements (light, sugars, CO 2 , N, P, and K) that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and valuable co-products. This study reviewed the technologies underpinning microalgae-to-biofuels systems, focusing on the biomass production, harvesting, conversion technologies, and the extraction of useful co-products. It also reviewed the synergistic coupling of microalgae propagation with carbon sequestration and wastewater treatment potential for mitigation of environmental impacts associated with energy conversion and utilisation. It was found that, whereas there are outstanding issues related to photosynthetic efficiencies and biomass output, microalgae-derived biofuels could progressively substitute a significant proportion of the fossil fuels required to meet the growing energy demand.

/pdf/biofuels-from-microalgae-a-review-of-technologies-for-1t1wwr5e69.pdf

Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products

https://www.massey.ac.nz/~ychisti/EPA%20Review.pdf

Recovery of microalgal biomass and metabolites: process options and economics

http://www.unece.lsu.edu/biofuels/documents/2008oct/bf08_15.pdf

Biodiesel from microalgae beats bioethanol.

Heterotrophic cultures of microalgae: Metabolism and potential products

A 20 L gas-agitated slurry bubble column bioreactor was used to investigate the effects of nonmechanical low-intensity agitation on development of broth rheology and fungal pellet morphology during production of lovastatin by the filamentous fungus Aspergillus terreus Fermentations were carried out under elevated dissolved oxygen levels (400% of air saturation) at gassing rates that ranged from 05 to 15 vvm Various initial concentrations of the growth limiting nitrogen source were used to attain different total biomass concentrations, to observe the effect of this variable on development of pellets and the rheology of the fermentation broth The non-Newtonian rheology of the fermentation broth was influenced both by the biomass concentration and the size of the fungal pellets The stable pellet diameter ranged from ∼2300 to ∼2900 μm Too low turbulence (gassing rate of 05 vvm) and low dissolved oxygen levels adversely affected lovastatin production The best biomass specific production of lovastatin 

/pdf/aspergillus-terreus-broth-rheology-oxygen-transfer-and-4so1vqvm8v.pdf

Aspergillus terreus Broth Rheology, Oxygen Transfer, and Lovastatin Production in a Gas-Agitated Slurry Reactor

Lovastatin suppresses its own synthesis in the microfungus Aspergillus terreus. The inhibitory effect was documented by spiking identical batch cultures with pure lovastatin (0, 50, 100 and 250 mg/l) 24 h after initiation from spores.

/pdf/lovastatin-inhibits-its-own-synthesis-in-aspergillus-terreus-4hjf6fec1m.pdf

Lovastatin inhibits its own synthesis in Aspergillus terreus

Cost-effective production of 13C, 15N stable isotope-labelled biomass from phototrophic microalgae for various biotechnological applications

Eicosapentaenoic acid (EPA) volumetric productivity from an outdoor chemostat culture ofPhaeodactylum tricornutum UTEX 640 in a 50-l tubular photobioreactor varies with dilution rate, reaching a maximum of 47.8 mg l−1 d−1 at D=0.36 d−1. Continuous culture at high dilution rates' is proposed as the most adequate operating mode to maximize polyunsaturated fatty acid production.

Effect of dilution rate on eicosapentaenoic acid productivity of Phaeodactylum tricornutum UTEX 640 in outdoor chemostat culture

The growth yield of the PUFA-producing marine microalgaIsochrysis galbana ALII-4 grown in a light limited chemostat, was measured under a wide variety of conditions of incident irradiance (I
 O
 ) and dilution rates (D). The experiments were conducted under laboratory conditions at 20 °C under continuous light. D ranged from 0.0024 to 0.0410 h−1 at three intensities of Io (820, 1620 and 3270 µmol photon m−2 s−1) close to those found in outdoor cultures. A maximum efficiency Ψ
 max
 = 0.616 g mol photon−1 was obtained at I
 O
 = 820 µmol photon m−2 s−1 and D = 0.030 h−1 and the maximum capacity of the biomass to metabolize the light harvested was found to be 13.1 µmol photon g−1 s−1. Above this value, a significant drop in the system efficiency was observed. A new approach based in the averaged irradiance is used to assess the photon flux absorbed by the biomass.

J. M. Fernández Sevilla

Papers

Aspergillus terreus Broth Rheology, Oxygen Transfer, and Lovastatin Production in a Gas-Agitated Slurry Reactor

Lovastatin inhibits its own synthesis in Aspergillus terreus

Cost-effective production of 13C, 15N stable isotope-labelled biomass from phototrophic microalgae for various biotechnological applications

Effect of dilution rate on eicosapentaenoic acid productivity of Phaeodactylum tricornutum UTEX 640 in outdoor chemostat culture

Growth yield determination in a chemostat culture of the marine microalga Isochrysis galbana