An integrated algal membrane photobioreactor as a green-transition technology for the carbon capture and utilization

The harvesting of microalgae strongly affects their effective application as a source of biomass for fuels and chemicals. The aim of this study was the evaluation of the performance of the recently developed Encapsulated Self-Forming Dynamic Membrane (ESFDM) module integrated into a cylindrical photobioreactor (PBR) for the efficient and simultaneous microalgae biomass cultivation and harvesting. The effect of different permeate fluxes was investigated (90-180 L m-2 h-1) obtaining excellent results in terms of harvesting rates (54.23-117.36 g m-2 h-1). Microalgal lipids content was determined under different nutrient regimes, including starvation periods for enhancing the content of lipids. A maximum volumetric biomass productivity of 257 mg L-1d-1 was achieved at a nitrogen content of 15.7 ± 10.6 mg L-1. On the other hand, the highest lipids productivity (42 mg L-1 d-1) was obtained during the starvation phase of nitrogen nutrients. The harvesting rate appeared to be strongly dependent on permeate flux, since the highest permeate flow corresponded in increase of the biomass harvested. The innovative SFDM enormously facilitates microalgae recovery. Indeed, the utilization of the SFDM has been demonstrated as an effective solution to increase the biomass harvesting rate while maintaining biomass concentration inside the photo-bioreactor below 1 g L-1 with a view at ensuring an efficient penetration of light into the membrane photobioreactor (mPBR) and consequently boosting the photosynthetic activity. The simultaneous implementation of the nitrogen starvation strategy can further increase the energy recovery potential from the biomass to address an algal biorefinery approach, besides reducing resources consumption.