Phosphorus removal from wastewater by microalgal cultivation in photobioreactors: a systematic literature review and multivariate analysis

Microalgae cultivation in photobioreactors efficiently removes phosphorus (P) from wastewater, which is a key factor in eutrophication of aquatic ecosystems. This study systematically reviewed the literature on microalgae cultivation in photobioreactors to determine the best configurations, species, and operational conditions for P removal from wastewater using multivariate analysis. A Scopus database search was performed using the terms “photobioreactor,” “microalgae,” “wastewater treatment” OR “anaerobic digestion effluent” OR “digestate” OR “centrate,” “nutrient recovery” OR “phosphorus recovery” for articles published between 2016 and 2024. The highest P removal efficiencies (> 90%) were obtained in the zigzag microalgae biofilm bioreactor, stirred tank, and hybrid tubular. However, “flat plate photobioreactor” was the most frequently used, with 61 observations and moderate P removal (71%). It is recommended to prioritize energy-efficient photobioreactors and those that do not have undesirable consequences, such as plastic reactors that can release micro and nanoplastics into the environment. Among the microalgae, Chlorella vulgaris has been shown to be more stable, with a P removal efficiency of approximately 87%. The optimal operational configuration had an average hydraulic retention time of 6.67 ± 4.64, a pH range of 7–9, light intensity of 253 ± 265 µmol photons m⁻² s⁻¹, and a temperature range of 16–30 °C. This study enhances the understanding of P removal from wastewater by microalgae cultivation in photobioreactors, providing a robust foundation for future experimental research.`