Membrane technology in microalgae harvesting for biofuel production
Microalga has emerged as one of the most promising alternatives sources of lipid for use in biodiesel production because of their high growth rates and productivity to produce biomass compared to other generations of biodiesel feedstocks. In this study, Chiorella vulgaris was selected as the m...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2014
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| Subjects: | |
| Online Access: | http://umpir.ump.edu.my/id/eprint/8776/1/NUR%20HIDAYAH%20BINTI%20MAT%20YASIN.PDF |
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| Summary: | Microalga has emerged as one of the most promising alternatives sources of
lipid for use in biodiesel production because of their high growth rates and
productivity to produce biomass compared to other generations of biodiesel
feedstocks. In this study, Chiorella vulgaris was selected as the model microalga.
The most important issue to be addressed is the recovery process of Chiorella
vulgaris biomass that can be substantially more expensive than the culturing of the
microalgae. Therefore, Chiorella vulgaris harvesting is an important research area in
order to develop an appropriate and economical process for microalgae species so
that the production of this biodiesel is competitive. Detailed studies on the
effectiveness of membrane filtration for the separation of Chiorella vulgaris biomass
from the culture medium had been carried out. The hydrophilic cellulose acetate
membrane with pore diameter of 1.2 pm exhibited the best performances among four
membranes tested (cellulose nitrate, polypropylene and polyvinylidenefluoride) in
terms of permeation flux. The optimal conditions achieved were 1.5 bar of
transmembrane pressure (TMP) and 0.4 ms -1 of crossflow velocity (CFV). In
addition, 0.75% sodium hypochloride (NaOC1) at 60 °C was performed as the
membrane cleaning process. The concentration polarization (CP) thickness was
found to be strongly depended on the membrane surface charge and the number of
membrane cleaning cycles. The microalgae-membrane interaction was successfully
achieved by XDLVO approach. Finally, the microfiltration method was compared with
c entrifugation and coagulation method to determine the most efficient method for separating
Chiorella vulgaris biomass from the culture medium. Of the three harvesting methods described in this work, it was found that the membrane
microfiltration was more effective in harvesting process because it allowed the
handling of large volumes of culture at a low energy costs. Similar fatty acid
(FAME) profiles were obtained for all of the harvesting methods, indicating that the
main components were palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid
(C18:2). However, the amounts of the individual FAME were higher for
microfiltration than for centrifugation and coagulation; coagulation performed the
most poorly in this regard by producing the smallest amount of FAME (41.61 ± 6.49
mgfg dw). The unsaturated FAME (C 16:1, C 18:1, C 18:2, C 18:3) were predominant
in the FAME profile (>70%) for all harvesting methods applied and thus making
Chiorella vulgaris biomass a good species for biodiesel production. |
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