The microalga Tetraselmis suecica is significant in aquaculture due to its high nutritional content , including proteins , essential fatty acids , and vitamins , making it an ideal food source for rotifers , copepods , cladocerans, Artemia , and green water systems . Although NaOH has been reported as an effective flocculant for this microalga, it is costly , commercially restricted , and requires careful handling . This study aims to optimize the flocculation process , a crucial step for efficient microalgae harvesting , by comparing the efficacy of two flocculants (sodium hydroxide and calcium hydroxide ) and evaluating their impact on rotifer culture. The microalga T. suecica was cultivated in a batch system until reaching a volume of 60 L in a flat photobioreactor with a 10 cm optical path , with CO2 injection controlled by pH. A modified f/2 medium , 25 PSU salinity , 23°C temperature , and constant illumination were used . The microalgal biomass was harvested and subjected to flocculation treatments upon reaching a density of 1 g L-1 . The flocculated biomass was used in a rotifer culture experiment , where density was recorded daily . The paste flocculated with commercial hydrated lime showed insoluble whitish precipitates ; however , no significant differences (p<.05) were found in the rotifer culture fed with both types of flocculated biomass (Fig. 1). Compared to sodium hydroxide , hydrated lime has fewer commercial restrictions , is easier to handle , and is more economical , making it a simple and cost-effective strategy for harvesting this microalgal species , facilitating its use in aquaculture for rotifer production.
Keywords: Microalgal paste, hydrated lime, rotifers, culture.