Search

The unprecedented use of fossil fuels necessitates the research community to find clean, safe, renewable and sustainable energy source. One such promising source is microalgal biofuel, which can mitigate the environmental concerns and energy crisis due to its closed carbon cycle. Selection of proper strain and optimization of the culture conditions to maximize the lipid productivity is very important for successful economical biodiesel conversion process. One such robust halophilic species identified was Aphanothece halophytica with rich lipid productivity. They were cultivated in different media and optimized on lab scale as well as in large scale using raceway ponds to produce sufficient biomass for algal oil extraction. The biodiesel conversion process parameters were then optimized by multi-variant response surface methodology (RSM). The free fatty acid (FFA) content of the raw algal oil was only 0.51% which enables direct conversion by transesterification. Eco-friendly, natural white clam shell was calcinated to obtain CaO, which was recovered and reused for three times effectively. The maximum biodiesel yield of around 99 vol% was obtained for the oil/methanol ratio of 0.32(v/v) using calcinated CaO for 6 wt% of raw feed while stirring at 400 rpm at a temperature of 70 °C for 85 min. The GC–MS analysis of the algal biodiesel confirmed the presence of saturated and unsaturated fatty acids in balanced proportion to provide better oxidation stability and good combustion characteristics. Other biodiesel properties were analyzed and found to be within the standards specified by EN and ASTM for automotive application without any engine modification. [ABSTRACT FROM AUTHOR]

The environmental and culture conditions of a potential microalgae Euglena sanguinea were optimized for maximizing the biomass productivity. It was found that the organic macronutrient from poultry litter and organic micronutrient of seaweed extract are very effective to enhance the lipid production. Complementing, these organic nutrients with commercial NPK fertilizer, boost up the lipid productivity by 30.9% in comparison with the established standard Euglena medium. The fatty acid profile of the extracted oil by GC–MS reveals its conformity with commercial diesel. [ABSTRACT FROM AUTHOR]

Algal biofuels have caught worldwide attention, due to the success of first and second generation biofuels on combing environmental concerns in spite of many challenges. Microalgae are the potential and sustainable fuel source with carbon neutrality, where selection of promising strain is crucial for effective biofuel generation. Euglena sanguinea one such robust freshwater species with high lipid productivity was explored on laboratory scale as well as in mass scale in raceway pond. The extracted oil’s fatty acid value was only 3.8 mg KOH g −1 and had 93% triglycerides. Acid value was reduced to ∼0.3 mg KOH g −1 by esterification and the optimized parameters obtained were: methanol/oil ratio: 0.36, H 2 SO 4 : 10 vol.%, time: 42 min. In the subsequent transesterification process natural, recoverable and eco-friendly white mussel shell was used. Maximum yield of ∼98% was obtained at 6 wt.% of calcinated CaO for the reaction time of 80 min at 0.35 methanol/oil ratio. The GC-MS analysis of the algal biodiesel showed the presence of saturated fatty acids: C16:0, C18:0, C22:0, C24:0 and monounsaturated fatty acids C18:1 at appropriate level to provide better oxidation stability and combustion properties to use it for automotive application without any major engine modifications. [ABSTRACT FROM AUTHOR]

The choice of precise strain is a crucial parameter to the success of algal oil industry. A novel halophilic microalgae, Aphanothece halophytica is selected as a potential source to satisfy the enormous energy needs. This species is highly resilient to environmental changes and can effectively utilize both organic and inorganic nutrients. Commercialization of biodiesel production is hindered by its production cost which necessitates advances in quantitative and qualitative microalgae cultivation. In this work, the salinity and major nutrient sources such as nitrogen, phosphorous and potassium of the standard Jaworski’s medium are replaced with commercial agricultural fertilizers like urea (N), single super phosphate (P) and muriate of potash (K) respectively and its concentrations optimized for the growth rate. The result showed maximum growth at 60 ppt salinity, 0.05 g l −1 (N), 0.5 g l −1 (P) and 0.5 g l −1 (K). Then a novel attempt is made to identify a low cost media, involving organic–inorganic (seaweed extract + NPK), inorganic (micronutrients + NPK), organic (vermicompost medium) for maximizing growth rate and lipid productivity, which is then compared with the standard Jaworski’s medium. A. halophytica gave the highest cell density of 21.6 × 10 6 ± 0.17 cells ml −1 on the 20th day with a lipid content of 29 ± 0.1% by dry weight in seaweed extract + NPK medium. It’s potentiality for biodiesel production is further confirmed by the gas chromatography analysis of the lipid. [ABSTRACT FROM AUTHOR]