Performance evaluation of bubble column photobioreactor along with CFD simulations for microalgal cultivation using human urine

Optimization of microalgae cultivation to reduce the associated costs is one of the major objectives in a biorefinery model. The present study optimized the microalgal cultivation using 4.5-8.5 % v/v of DHU (diluted human urine) as a cost-effective resource, in a bubble column photobioreactor (BCPBR) under real-time conditions. Media with 5.5 % DHU and 4% CO2 showed maximal biomass productivity of 0.14 g L-1 day(-1) with a final concentration of 1.06 g L-1. Phosphate and ammonium removal of 90.70 % and 84.10 % respectively was achieved. The biofixation of CO2 obtained for 6 days, during the cultivation in 5.5 % DHU, by supplying 4% of CO2 enriched air was 0.29 g L-1 d(-1). Computational fluid dynamics (CFD) simulations were used to study the effects of velocity magnitude, shear stress, turbulent kinetic energy, and irradiance on the microalgal growth inside the BCPBR. The developed kinetic model predicted the biomass concentration and phosphate removal up to 98 % and 82 % accuracy respectively. Such studies would aid in comprehending the large scale commercial cultivation and thereby facilitate the application of microalgae in the future.

Automated summary

The study optimized microalgae cultivation using diluted human urine as a cost-effective resource in a bubble column photobioreactor. The results showed maximal biomass productivity and nutrient removal efficiency. Computational fluid dynamics simulations and a developed kinetic model provided insights for large scale commercial cultivation of microalgae.