Effect of solar and artificial lighting on microalgae cultivation and treatment of liquid digestate

A comparative study was carried out to assess the effect of two light sources on microalgae cultivation and the treatment of liquid digestate. The R1 photobioreactor operated with LED lightning allowed to achieve moderate nutrient removal rates whereas soluble COD (Chemical Oxygen Demand) was reduced in 90%. After switching this reactor into sunlight, the removal rate of phosphates increased to 66%. However, the greatest removal rate of both nutrients and sCOD of up to 93% was observed in the R2 photobioreactor operated only under sunlight. Microglena sp. was the dominant algae growing in the R1 reactor, and the main bacteria families detected were Chitinophagaceae, Sphingomonadaceae and Xanthobacteraceae. In contrast, Tetradesmus obliquus dominated in the R2 reactor and Rhodanobacteraceae, Chitinophagaceae and A4b were predominant bacteria in this run. Furthermore, much greater biomass productivity as well as overall biomass density was observed in the R2 photobioreactor cultivated exclusively with solar lightning.

Automated summary

A comparative study was conducted to evaluate the influence of two light sources on microalgae cultivation and liquid digestate treatment. The R1 photobioreactor operated with LED lighting achieved moderate nutrient removal rates, while soluble COD was reduced by 90%. Upon switching to sunlight, the phosphate removal rate increased to 66%. However, the R2 photobioreactor, exclusively operated under sunlight, exhibited the highest removal rate of both nutrients and sCOD up to 93%. Microglena sp. dominated in the R1 reactor, with Chitinophagaceae, Sphingomonadaceae, and Xanthobacteraceae as the main bacteria families detected. In contrast, Tetradesmus obliquus dominated in the R2 reactor, with Rhodanobacteraceae, Chitinophagaceae, and A4b as the predominant bacteria.