Nutrient recovery in effluents from the energy sectors for microalgae and cyanobacteria biomass production: A review

Since the Industrial Revolution, human activities in the various energy sectors have led to the production of large amounts of wastewaters and effluents that are rich in dissolved compounds and organic matter and that can lead to negative effects on the environment if they are not well managed. A large diversity of effluents is produced in the various energy sectors, with wastewaters from Oil and Gas activities, as well as biomass-to-energy processes. These effluents are available for use as water and/or nutrient sources for photosynthetic microorganisms cultivation. In the past two decades, the use of these wastewaters for microalgae and cyanobacteria cultivation has increased exponentially. These photosynthetic microorganisms can assimilate the dissolved nutrients to produce biomass, thereby fixing carbon dioxide responsible for climate change. Owing to their highly variable physical-chemical compositions, each effluent has to be studied on a case-by-case basis to investigate their potential for growing microalgae and cyanobacteria, using them as culture media. This bibliographic review provides an overview of the literature regarding the use of wastewaters and effluents from the various energy sectors for microalgae and cyanobacteria cultivation, as well as their bioremediation efficiencies (mainly nitrogen and phosphorous). In recent years, the usability of each effluent for microalgae growth has been proven by many culture and bioremediation studies performed in batch mode and at small scale, up to 1 m3. In coming years, pilot and industrial studies should appear concerning the combination of effluents to limit the high use of dilution water.