Microalgae culture in RAS post-culture water

A diatom strain belonging to the genus Amphora, isolated from the biofilm formed in the post-culture water, and a strain of green algae from the waters of the high-salinity graduation tower (60 PSU) were selected for further research from the pre-selected strains for cultivation in the post-culture waters (RAS),

The result of the collected observations on the growth of selected strains are the currently ongoing, two-stage experimental cultures. Independent growth stages eliminate the inhibitory effect of RAS effluent on algae growth, while providing a source of concentrated biomass that can be used for purification of RAS waters.

The first stage was a mass culturing of strains in conditions already defined as optimal, i.e. in environmental waters enriched with macro and microelements with salinity selected for the strain, and the addition of a growth surface in the form of broken glass for the benthic strain, diatoms. The aim of this stage was the optimization of cell growth and division to obtain the right amount of biomass in good physiological condition. In the second stage, the biomass from the first stage, after concentration by centrifugation and removal of the supernatant, was transferred to the RAS post-culture water and control conditions in order to observe further growth, biochemical changes in the biomass and the rate of absorption of biogenic substances from the water.

The preliminary analysis of the results shows the assimilation of about 50% of macroelements (nitrates, phosphates) from RAS waters during the 10-day cultivation, in the second stage in a mixed culture, i.e. green alga with diatom. At the present stage, further breeding variants are being prepared in order to increase the efficiency of assimilation of macroelements by supplementing RAS water with microelements, which is potentially a factor limiting the growth of algae.

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