Optimization of Biodiesel Production by a High Oil Content Algae Chlorella pyrenoidosa Using Different Substrates

Abstract

newline xi newlineABSTRACT newlineBiodiesel has been reported as a renewable, green fuel with better engine-emission properties to combat the issues of global warming, depleting oil reserves, and foreign exchange savings etc. The present investigation was an effort to standardize the use of Fog s medium and alternative substrates for the growth of Chlorella pyrenoidosa algae. These growth substrates were also examined in terms of methylesters produced with the help of transesterification for the algal lipids. In this study, dairy wastewater (DWW), rice straw hydrolysate (RSH) and chemically formulated Fog s medium were analyzed as growth media for C. pyrenoidosa algae. It has been reported that C. pyrenoidosa algae contains a huge amount of lipids suitable for conversion into biodiesel by transesterification reaction. RSH was prepared by enzymatic hydrolysation as well as non-enzymatic methods. Algae biomass yield was examined highest 3.12 g/L in DWW medium, followed by 2.15 g/L RSH (acidic/autoclave) medium, 1.68 g/L RSH (cellulase method) and least 0.92 g/L in Fog s medium. The produced biodiesel from algae grown in each medium was analyzed from the entire alga harvested by each medium and compared with fossil fuel diesel, wherein the performances of physical, engine and emission parameters were examined. The best performance has been found for B20 blend at 80 % engine load for all the three biodiesel samples. It was biodiesel produced from algae grown in DWW medium (having brake thermal efficiency of 42.23 %, brake power of 39.99 KW, calorific value of 41.865 MJ/Kg and flash point of 188º C) which showed higher value of all performance parameters in comparison to the biodiesel produced from algae grown in RSH and Fog medium. The fatty acid analysis (GC-MS) and TLC of all the three produced biodiesels proved to be quite similar. The engine based, emission based and various other parameters were according to ASTMD 6751 and EN 14214 standards. The produced biodiesel from C.pyrenoidosa grown in DWW may be act as good feedstock among the other growth media in terms of yield, engine and emissions performance. newlineKey words: Chorella pyrenoidosa, Fog s medium, dairy wastewater, rice straw hydrolysate and biodiesel.