Technical Studies


Application of seawater desalination brine in microalgae cultivation

Microalgae cultivation has been an emerging filed for research in recent years, and the
popular discussed topics including their application in greenhouse gases reduction, biodiesel
production, and nutrients extraction. The studied species of microalgae with different
halophilism live in freshwater, marine, or other saline lake. Although the cultivation of
marine microalgae has higher technical requirements, lower land demand and higher species
diversity make them have more application potential. However some microalgae preferred
higher salinities than seawater, therefore the usage of nature seawater for cultivation will
limit the growth efficiency of algae cells and their byproducts. How to gain the higher
salinity water has become an important factor to cost decision. Therefore this research tries
to combine the usage of seawater desalination brine and microalgae cultivation. The water
pretreated during the desalination process, would help to reduce the microbial contamination
during microalgae cultivation. Furthermore, the most worthy thing is to gain biodiesel and
other byproducts from the waste brine. Dunaliella sp. has been studied since 1960, and they
included species living in freshwater, marine, or other saline lake. D. salina and D. viridis
are the typical high halophilic microalgae and both of their cultivations are worthy to be
developed. The major byproducts of D. salina are microalgae oil and β-carotene. The
suitable parameters for growth of D. salina are 25℃~30℃, pH 7~9, and salinity between
60‰ to 70 ‰. However the water quality of desalination brine are 25℃~35℃, pH 8~8.5,
and salinity between 50‰ to 60 ‰. The brine quality could match the growth requirement of
D. salina. Utility of brine on D. salina’s. cultivation should make the cost down and upgrade
the application value of pumped seawater from the sea.