Isolation, biomass estimation and characterization of the biofuel potential of diatom Navicula Sphaerophora

Abstract

Navicula Sphaerophora was isolated from a fresh water reservoir in Arunachal Pradesh, India. N. Sphaerophora was grown on two different culture media, chu13 medium and Miracle Gro-medium. The maximum yield was obtained by using culture medium chu13(5.08 g/100ml of culture media). Microalgae crude oil was extracted using soxhlation method with three different solvents n-hexane, iso-propanol and hexane/ iso-propanol mixture. The maximum crude oil was obtained using n-hexane as a solvent (13.8% of dry weight biomass). The crude oil was converted into biodiesel using single stage transesterification process with sodium hydroxide (NaOH) as a base catalyst. Fuel properties of algae biodiesel satisfied biodiesel standard ASTM D6751 and use of this fuel should be comparable with petroleum diesel. Further short term engine test was conducted on single cylinder direct injection diesel engine at four different load (25%,50%,75% and 100%). Three different petroleum diesel and Microalgae Biodiesel blends (10%, 20% and 30%) were prepared. The influence of biodiesel blends on BSFC (brake specific fuel consumption), BTE (brake thermal efficiency), oxides of nitrogen (NOx), UBHC (unburnt hydrocarbons), carbonmonoxide (CO) and smoke opacity was studied and compared with petroleum diesel. Microalgae methyl ester 50% blend (B50) had lowest brake thermal efficiency (BTE) and highest Brake specific fuel consumption (BSFC) as compared to diesel; this may be due to Lower calorific value. HC, CO emission and smoke opacity reduces significantly with microalgae methyl ester. However, the NOx emission increases with all blends when compared to petroleum diesel. 10% microalgae blend with petroleum diesel showed the closet performance to petroleum diesel. Results obtained from present investigation confirmed the biofuel potentiality of Navicula Sphaerophora.