Biodiesel production using microalgae Chlorella vulgaris oil and homogeneous, immobilized lipase enzyme and heterogeneous catalysts | |
| Author | Haldar, Arindam |
| Call Number | AIT Thesis no.FB-11-08 |
| Subject(s) | Microalgae Biodiesel fuels |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. no.FB-11-08 |
| Abstract | With the need to reduce carbon emissions, and the dwindling reserves of crude oil, liquid fuels derived from plant material – biofuels – are an attractive source of energy. Biodiesel is an alternative fuel produced from renewable resources like vegetable oils, animal fats and most recently algal oils. Many microalgae naturally have high lipid content (20 – 50% dry weight). Chlorella vulgaris is one of the fastest growing microalgae with high lipid content and carbon dioxide sequestration ability. Growth conditions, oil extraction methods from biomass and transesterification of oil with various catalysts for the above mentioned microalgae needed to be studied and optimized. The main focus of this study was production of oil from microalgae Chlorella vulgaris in lab-scale bioreactor including a study of the growth dynamics of the microalgae, comparison of oil extraction of microalgal biomass using ultrasonic waves and microwave heating and to compare of the efficiency of transesterification reaction by using homogeneous, immobilized enzyme and heterogeneous catalyst. The optimum time period of growth of the cells were also established to be around 20 days at which the exponential growth phase ends. The optimum concentration of CO2 in air delivered into the bioreactor for growth of Chlorella vulgaris cells was found to be 20 ml/min when air is supplied at the rate of 1 l/min. The biomass productivity (mg of biomass/ml of culture) of Chlorella vulgaris for 15 day growth period was found out to be 0.63 mg/ml and that for 20 day growth period was 0.91 mg/ml. The average oil extraction by microwave heating method was 41.07 % while that for ultrasonication treatment method was 41.18 %. The main factor influencing oil extraction from dry biomass by microwave heating and ultrasonication was found to be the treatment time. The optimal treatment times for both the processes were found out to be 8 mins. On basis of power consumption microwave heating method was found out to be economical compared to ultrasonication. Homogeneous KOH catalyst (93.44 %) gave maximum FAME conversion followed by immobilized enzyme Novozyme 435 catalyst (86.15 %) and heterogeneous CaO/Al2O3 solid catalyst (83.85 %). The FAME conversion using mixtures of fresh and recycled catalysts were 81.71% and 76.16% for Novozyme 435 and CaO/Al2O3 catalyst respectively. The density of biodiesel in this study was in the range of 852-854 kg/m3 at 150C, a considerable reduction from the original density 914 kg/m3. Transesterification of algal oil produced biodiesel with viscosity of about 4.5 cSt, a drastic reduction from original value of 32.28 cSt which were within normal specifications. The biodiesel obtained from transesterification of the algal oil can be used only by blending with normal petroleum diesel in lieu of it’s slightly less FAME content or if conversion is further improved by optimization. |
| Year | 2011 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. no.FB-11-08 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Rakshit, Sudip Kumar; |
| Examination Committee(s) | Athapol Noomhorm;Anal, Anil Kumar; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2011 |