Suspended filamentous algal cultures for wastewater treatment: A review

More than 50 years have passed since the first studies of microalgae treating effluents were published. Suspended growth of filamentous algae in wastewater ponds has been considered in several publications for over a decade. However, despite all the research efforts and the knowledge generated, the technology is far from being adopted. This review compiles all the publications identified in different databases, which used filamentous algal ponds to remediate varied wastewaters, with the aim of identifying the research needs to allow the technology’s application. The experimental methods and results obtained were extracted and compiled for comparison from 28 relevant studies, in which municipal wastewater and Oedogonium spp. were most used. Most of the studies were performed at a small laboratory scale and for short time periods. There was a remarkable use of effluents with a high degree of pretreatment and more studies focused on the biomass productivity than the treatment performance. It is recommended that future research use wastewater, with minimum intervention, rather than defined nutrient solutions, to assess the potential for wastewater treatment. Transitioning from laboratory to outdoor systems at scale should be a primary aim to further adopt this technology.