Enhancing microalgal biomass production in lab-scale raceway ponds through innovative computational fluid dynamics-based electrode deflectors.

The design of novel electrode deflector structures (EDSs) introduced a promising strategy for enhancing raceway ponds performance, increasing carbon fixation, and improving microalgal biomass accumulation. The computational fluid dynamics, based flow field principles, proved that the potency of arc-shaped electrode deflector structures (A-EDS) and spiral electrode deflector structures (S-EDS) were optimal. These configurations yielded superior culture effects, notably reducing dead zones by 9.1% and 11.7%, while elevating biomass increments of 14.7% and 11.5% compared to the control, respectively. In comparison to scenarios without electrostatic field application, the A-EDS group demonstrated pronounced post-stimulation growth, exhibiting an additional biomass increase of 11.2%, coupled with a remarkable 23.6% surge in CO2 fixation rate and mixing time reduction by 14.7%. A-EDS and S-EDS, combined with strategic electric field integration, provided a theoretical basis for promoting microalgal biomass production and enhancing carbon fixation in a raceway pond environment to similar production practices.

Effective removing of rotifer contamination in microalgal lab-scale raceway ponds by light-induced phototaxis coupled with high-voltage pulse electroshock.

Rotifer reproduction control in open microalgae cultivation systems poses a significant challenge for large-scale industries. Conventional methods, such as electric, meshing, and chemical techniques, are often expensive, ineffective, and may have adverse environmental-health impacts. This study investigated a promising control technique through light-induced phototaxis to concentrate rotifers in a specific spot, where they were electroshocked by local-limited exposure dose. The results showed that the rotifers had the most pronounced positive and negative phototropism with phototaxis rates of 66.7 % and -78.8 %, respectively, at blue-light irradiation of 30 µmol∙m-2∙s-1 and red-light irradiation of 22.5 µmol∙m-2∙s-1 for 20 min. The most effective electroshock configuration employed 1200 V/cm for 15 min with a 1-second cycle time and a 10 % duty cycle, resulting in a 75.0 % rotifer removal rate without impacting microalgae growth. The combination of the two light beams could effectively lead rotifers to designated areas where they were electrocuted successfully.

Biomass production of carbohydrate-rich filamentous microalgae coupled with treatment and nutrients recovery from acrylonitrile butadiene styrene based wastewater: Synergistic enhancement with low carbon dioxide supply strategy.

This study attempted to remove acrylonitrile and acetophenone from simulated acrylonitrile butadiene styrene (ABS) based wastewater while recovering nitrogen and phosphorus using the carbohydrate-rich filamentous microalgae Tribonema sp.. Results showed that typical acetophenone and acrylonitrile presented significant inhibitory effect on Tribonema sp. growth and co-metabolism of CO2 improved the tolerance of Tribonema sp. to toxic pollutants. The microalgae biomass increased by 34.47% (3.16 g/L) and 58.17% (3.97 g/L) via supplementing 2% CO2 in the 100 mg/L acrylonitrile and acetophenone groups, respectively. The filamentous microalga was rich in carbohydrates and its productivity was further enhanced by 32.52% and 70.34%, respectively, in 100 mg/L acrylonitrile and acetophenone groups with 2% CO2 supplement. The synergistic CO2 supply strategy effectively enhanced the biomass production of filamentous microalgae, and moreover, improved the treatment efficiency of ABS based wastewater simulated by acetophenone or acrylonitrile addition, while at same time enhanced the recovery of nitrogen and phosphorus nutrients.