Efficient microalgae harvesting mediated by polysaccharides interaction with residual calcium and phosphate in the growth medium. (10th October 2019)

• Record Type: Journal Article
• Authors: Rashid, Naim; Nayak, Manoranjan; Lee, Bongsoo; Chang, Yong-Keun
• Is Part Of: Journal of cleaner production. Volume 234(2019)
• Page Start: 150
• Page End: 156
• Publication Date: 2019-10-10
• Subjects: Microalgae -- Harvesting -- Auto-flocculation -- PSAs -- Calcium -- Phosphate; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2019.06.154
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: This study sets out to harvest microalgae through auto-flocculation by manipulating the interactive effect of calcium, phosphate, and polysaccharides (PSAs). The harvesting efficiency (H.E) of 91 ± 2.7% was achieved for Ettlia sp. through auto-flocculation. The H.E was attributed to the chelation of calcium and PSAs present in microalgae medium. In the absence of PSAs, the H.E reduced to 64 ± 05% only. The addition of phosphate (34 ± 0.13 mg L −1 ) increased the H.E to 73 ± 1.5%. Zeta-potential measurements showed that the harvesting was induced by charge neutralization and inter-particle bridging. The PSAs-based auto-flocculation was tested for Chlorella sp. too but it turned out the H.E of 51 ± 1.3% only. The flocculation did not take place when the co-harvesting of Ettlia sp. and Chlorella sp. was carried out. It is concluded that each microalgae specie shows different auto-flocculation mechanism due to variation in their PSAs characteristics. It triggers up the need for setting up a distinct protocol for different microalgae species to assess their auto-flocculation potential. Graphical abstract: Image 1 Highlights: Ettlia sp. showed the harvesting efficiency (H.E) of 91% through auto-flocculation. The interaction of calcium and polysaccharides (PSAs) prompted auto-flocculation. The provision of excess phosphate decreased the H.E. The presence of PSAs facilitated Ettlia sp. auto-flocculation but inhibited Chlorella sp. auto-flocculation.