The potential of a natural biopolymeric flocculant, ε-poly-l-lysine, for harvesting Chlorella ellipsoidea and its sustainability perspectives for cost and toxicity
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The successful production of microalgal biomass requires the precise coordination of many different steps. Cell harvesting is a central process in all methods currently used for the production of microalgal biomass. Therefore, improving the harvesting process itself, and using a harvesting method that is compatible with adjacent steps, is necessary to prevent problems that may occur during downstream processing. This study examined the potential of the cationic biopolymer ε-poly-l-lysine (ε-PLL) for use in the harvest of microalgae (Chlorella ellipsoidea). The effects of ε-PLL concentration and mixing intensity on flocculation efficiency and operating costs were determined. We found that ε-PLL was not toxic to microalgal cells at concentrations of up to 25 mg/L, based on the photosystem II quantum yield. A recovery rate of 95% was achieved using 19 mg/L ε-PLL, and the estimated harvest cost was 20 US$/ton of harvested biomass. Moreover, ε-PLL displayed antimicrobial properties, leaving the harvested biomass intact and pure. Therefore, the use of ε-PLL-induced flocculation appears to be an attractive option when harvesting microalgal biomass for use as low- and high-value commodities for humans or animals.
KeywordsChlorella ellipsoidea ε-Poly-l-lysine Flocculation Biomass harvest Response surface methodology
This study was supported by the Korea Institute of Toxicology (Grant KK-1805).
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Conflict of interest
The authors declare that they have no conflict of interest.
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