Abstract
For biomass recovery of tropic ocean oleaginous microalgae strain Desmodesmus sp. WC08, eight flocculation methods (pH adjustment, Al2 (SO4)3, polyacrylamide, AlCl3, Ca (OH) 2, FeCl3, alum and chitosan) were evaluated and optimized. The results indicated that ferric chloride, aluminum sulfate, aluminum chloride and chitosan exhibited high flocculation ability and their flocculation efficiency were all beyond 94% at the optimal dosage (0.15, 0.4 and 0.03 gL-1, respectively). Chitosan displayed the most tremendous potential for biomass recovery from culture broth based on its feasibility and safety. Acetic acid and hydrous chloride, used to dissolving chitosan, had no significant difference in the flocculation efficiency. And when the pH of culture broth was set 5 or 6, the flocculation efficiency of chitosan was higher and the required flocculation time was less. More dose chitosan was needed to harvest the biomass following the cell growth stage. Overall, the optimal flocculation reagent for harvesting biomass of Desmodesmus sp. WC08 is chitosan, and its optimal flocculation conditions are: just when the pH of the culture broth was set to 6 and the dosage of chitosan was 0.03 g/L at the end of microalgae cultivation, more than 110g of algal biomass can be recovered just by per 1 g of chitosan. Meanwhile, there is little residual chitosan found in the final flocculation supernatant which can be reused to some extent.
Highlights
In recent decades, microalgae have become more and more attractive because of a wide range of applications
In this work we have explored the harvesting potential of tropic ocean microalgae strain Desmodesmus sp
Determination of flocculation efficiency: 45 cm3 of algal culture broth was placed in a 50 cm3 test jar
Summary
Microalgae have become more and more attractive because of a wide range of applications. Microalgal cells harvesting is a bottleneck technology all the time for all kinds of miroalgal applications based on algal biomass, due to their small size (5-20 μm), low culture concentration (0.5-5 gL-1) in culture medium, and high cost (about 20-30% of total production cost) [3,4]. There are several available techniques for microalgae harvesting, such as centrifugation, filtration, air floatation, gravity sedimentation, flocculation and so on. In contrast, flocculation is most popular among these methods Because it is effective, convenient and low-cost for harvesting microalgae from large quantities of culture broth [7]. Convenient and low-cost for harvesting microalgae from large quantities of culture broth [7] It can largely improve harvesting efficiency of other separation technology by pretreatment
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