Use of photosynthetic microorganisms in wastewater treatment: a systematic review on nutrient removal

Abstract

The accumulation of nitrogen and phosphorus in water bodies is one of the main drivers of eutrophication and environmental degradation, a problem that conventional treatments do not always solve due to their high costs and energy requirements. In this context, this review analyzes the potential of microalgae and cyanobacteria as a sustainable alternative for wastewater purification. A systematic search was conducted in SCOPUS up to September 2025, following the PICO methodology and the PRISMA flow diagram, identifying 235 studies, of which 36 met the inclusion criteria as original research published between 2020 and 2025 with experimental data on nutrient removal. The findings show that these microorganisms can remove more than 90% of nitrogen and phosphorus, with species such as (Chlorella) and (Scenedesmus) standing out. Additionally, microalgae–bacteria consortia outperform single cultures due to their metabolic cooperation. Optimal operational conditions reported include pH between 7–8.5, temperatures of 22–28 °C, and minimum photoperiods of 12 hours. Although the technology is promising, challenges remain, such as the lack of methodological standardization, scale limitations since most studies are conducted at laboratory level, and the costs associated with biomass recovery.