Simultaneous microalgal biomass production and CO₂ fixation by cultivating Chlorella sp. GD with aquaculture wastewater and boiler flue gas

A microalgal strain, Chlorella sp. GD, cultivated in aquaculture wastewater (AW) aerated with boiler flue gas, was investigated. When AW from a grouper fish farm was supplemented with additional nutrients, the microalgal biomass productivity after 7 days of culture was 0.794 g L⁻¹ d⁻¹. CO₂ fixation efficiencies of the microalgal strains aerated with 0.05, 0.1, 0.2, and 0.3 vvm of boiler flue gas (containing approximately 8% CO₂) were 53, 51, 38, and 30%, respectively. When the microalgal strain was cultured with boiler flue gas in nutrient-added AW, biomass productivity increased to 0.892 g L⁻¹ d⁻¹. In semi-continuous cultures, average biomass productivities of the microalgal strain in 2-day, 3-day, and 4-day replacement cultures were 1.296, 0.985, and 0.944 g L⁻¹ d⁻¹, respectively. These results demonstrate the potential of using Chlorella sp. GD cultivations in AW aerated with boiler flue gas for reusing water resources, reducing CO₂ emission, and producing microalgal biomass.