A long-term pilot-scale algal cultivation on power plant flue gas - Cultivation stability and biomass accumulation

A long-term culture of a selected freshwater microalgal assemblage on power plant flue gas was realized using a pilot-scale photobioreactor. Different culture conditions of light cycle, harvesting amount, pH stabilization, and sulfur addition were tested during a 12-month continuous operation at a natural gas fired power plant. The results concluded that the daily harvesting amount of 60% with no light-cycle and NH4NO3 as the nitrogen source and pH stabilization agent, resulted in optimal cultivation performance. Biomass concentration and biomass productivity reached 1.07 +/- 0.23 g L-1 and 0.43 +/- 0.14 g L-1 d(-1), respectively. During the year-long cultivation period, the algal assemblage was relatively stable with average abundances of 88 +/- 4% and 12 +/- 4% for algae and bacteria, respectively, and no significant differences between individual case scenarios. The stable culture fostered a stable biomass composition. Protein, carbohydrate, and lipid contents of the algal biomass were 58.60 +/- 2.41%, 19.5 +/- 2.44%, and 9.70 +/- 1.68%, respectively.