91勛圖

Abstract

Spirulina is a photosynthetic cyanobacterium rich in protein, and Dunaliella salina is reach in beta-carotenoid, polyunsaturated fatty acids, minerals and vitamins. Spirulina spp. are produced in fresh water, although freshwater shortages and the highcost of feed stock carbon limit Spirulina production. Dunaliella salina cultivation requires high saline water which needs adding of NaCl. Thus, use of seawater with low-cost carbon and less amount of NaCl should be evaluated for growing S. maxima and D. salina, respectively. Conversely, Ca2+ and Mg2+ of natural seawater (NSW) cause milky turbidity and nutrient precipitation when PO4-P is added to prepare culture media for both species. Here, NSW was pretreated with bituminous coal and NaOH to sediment Ca2+ and Mg2+ and obtain total organic carbon (TOC)-enriched pretreated seawater supernatant (PSWS), which was used to formulate S. maxima and D. salina culture media. We devised formulae for calculating bituminous coal and NaOH concentrations required for adequate sedimentation of Mg2+ and Ca2+ in NSW of any salinity level. The precipitation rate of Ca2+ and Mg2+ was 32.52% and 99.91%, respectively, while TOC increased 6.97-fold in PSWS compared to NSW.

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