Spirulina is one of the promising photosynthetic microorganisms as the source for food, cosmetic, and other value-added products such as phycocyanin. However, its production cost associated with cultivation is expensive because of high concentration of bicarbonate (76wt%) in standard Zarrouk medium for Spirulina. Bicarbonate not only acts as a carbon source but also helps maintaining culture medium in alkaline condition, which is essential for growth of Spirulina. The present study demonstrates that bicarbonate (16.8 g/L) in standard Zarrouk medium was completely replaceable by chemical CO2 absorption using 0.2M NaOH and 154.2 mmol CO2 gas could be absorbed in the form of NaHCO3/Na2CO3 into 1 L medium during the process. This process was incorporated into Spirulina cultivation, which enabled us to reduce the total cost of preparation of Zarrouk medium by 34.3% without sacrificing biomass and pigments production. In addition, another important use of NaOH is achievement of cost-efficient and ecofriendly sanitization of culture medium.