Citation:
Ahmed M.D. Al Ketife, Simon Judd and Hussein Znad. Optimization of cultivation conditions for combined nutrient removal and CO2 fixation in a batch photobioreactor. Journal of Chemical Technology and Biotechnology, Volume 92, Issue 5, May 2017, pp. 1085-1093
Abstract:
The application of Chlorella vulgaris for simultaneous CO2 biofixation and nutrient removal
has been optimised using response surface methodology (RSM) based on Box Behnken
design (BBD). Experimental conditions employed comprised CO2 concentrations (Cc,g) of
0.03-22% CO2, irradiation intensities (I) of 100-400 μE, temperatures of 20-30°C and
nutrient concentrations of 0-56 and 0-19 mg/L nitrogen and phosphorus respectively, the
response parameters being specific growth rate μ, CO2 uptake rate Rc and %nutrient removal.
Results
Over 10-days the biomass concentration reached almost 3 gL-1 for Cc,g of 5% CO2, with
corresponding values of 0.74 g L-1 d-1 and 1.17 day-1 for Rc and μ respectively and 100%
nutrient (N and P) removals. At 22% CO2 the Rc and μ decreased by around an order of
magnitude, and nutrient removal also decreased to 79% and 50% for N and P respectively.
Conclusion
Optimum values 5% CO2, 100 μE and 22°C were identified for Cc,g, I and T respectively,
with μ and Rc reaching 1.53 day-1 and 1 g L-1 d-1 respectively along with associated nutrient removal of 100%. Regression analysis indicated a good fit between experimental and model
data.