Exploring the combined effects of bicarbonate, NPK fertilizers, and salinity on Chlorella vulgaris growth

Abstract

In recent times, the microalga Chlorella vulgaris has attracted significant attention due to its multifaceted applications in diverse disciplines. Nonetheless, discrepancies in growth rates and biomass yield are observed across freshwater and saline environments. This research was designed to elucidate the impacts of varying concentrations of NaHCO₃, NPK fertilizer, and NaCl on the proliferation of Chlorella vulgaris cultivated in 288L plastic bottle bioreactors, ensuring optimal light exposure and aeration for algal propagation. Biomass quantifications were executed tri-weekly, utilizing metrics such as optical density (OD) and biomass concentration (mg/L). Post a 30-day cultivation period, the findings revealed that optimal biomass was attained with an augmentation of 30 mg/L NaHCO₃ and 100 mg/L NPK. Remarkably, the alga manifested resilience to escalating salinity levels, recording a peak biomass of 1036 mg/L upon the introduction of 20 g/L NaCl. Moreover, the research underscored a robust correlation between optical density (OD) and biomass concentration (mg/L) amidst diverse salinity regimes, underscoring the criticality of these parameters in the proliferation of Chlorella vulgaris.