Microalgae for C02 Fixation

The problem of climate change arising mainly from C02 emission is currently a critical
environmental issue. Biofixation using microalgae has recently become an attractive
approach to C02 capture as algal species naturally use C02 for photosynthesis.
Nannochloropsis sp., Chaetoceros sp., Pavlova lutheri, and /sochrysis galbana were
cultivated in 1 L vessels to determine the best microalgal strain. Cell density of each
microalgae culture Nannochloropsis sp., Isochrysis galbana, Pavlova lutheri and
Chaetoceros sp. yield result of 35.0xl06
, 7.0xl06
, 2. 75x106
, and l.Oxl06 ce!ls/ml,
respectively. Maximum biomass formation rate, Xmax (mg L "1d"1
) and and lipid content
of selected microalgal strain, Nannochloropsis sp. were 22 and 46, respectively.
Nannochloropsis sp. cells were further cultured in 5 L working volume of bioreactor.
Microalgal strains were grown under different temperatures and different air flow rates
to fmd out optimum range. The effects of C02 concentration on growth and lipid
content were also investigated. Nannochloropsis sp. was considered the best species
among all other species with maximum biomass formation rate, Xmax (mg L"1d"1
) and
and lipid content of 22 and 46 mg/L, respectively. Optimum temperature and C02
fixation rate (mg/L) was 25°C and 488.8, respectively. C02 supply with continuous
aeration gave a significant difference in result, culture with C02 supply lead to higher
biomass productivity of 420 mg/L. Air flow rate of 2 L/min gives better result
compared to I Llmin aeration, with 520 mg/L dry weight and 110 mg/L lipid content;
the higher flow provides more C02, thus accelerate growth. Maximum specific growth
rate of5 L cultivation was higher than 1 L cultivation of39 x 106 and 35 x 106 cells d"1
,
respectively. While doubling time was 8.8 and 10.8 day for l L cultivation and 5 L
cultivation, respectively.