Abstract
The contributions of the cement industry to climate change and global warming are important global issues that require immediate attention. The utilization of coccoliths produced by coccolithophores in biocement production is a promising solution. In this study, the potential to enhance the production of Chrysotila carterae coccoliths by optimizing extracellular Ca2+, PO43-, NO3-, and the cultivation period was investigated. Increasing extracellular Ca2+ concentration from 14.4 to 57.6 mM was shown to significantly enhance CaCO3 production, from 5.2 % to 41.1 % after 14 days. Whereas the effects of PO43- and NO3- limitation were insignificant. In addition, the optimum cultivation period was found to be 20 days, at which the C. carterae biomass growth and CaCO3 were the maximum. The growth conditions were optimized using statistical modeling, which showed the optimal Ca2+, PO43-, and NO3- concentrations to be 57.6, 0.036, and 0.882 mM, respectively, at which the CaCO3 content was 44.5 % achieved after 18 days of cultivation. The CaCO3 productivity were also investigated using Emiliania huxleyi and Chlorella sp. The CaCO3 contents were lower in both strains, as compared C. carterae reaching 39.4 % and 30.0 %, respectively under control conditions. This study provides promising results for calcium carbonate production utilizing microalgae for the biocement industry.