Integrated culture and harvest systems for improved microalgal biomass production and wastewater treatment

Microalgae cultivation in wastewater has received much attention as an environmentally sustainable approach. However, commercial application of this technique is challenging due to the low biomass output and high harvesting costs. Recently, integrated culture and harvest systems including microalgae biofilm, membrane photobioreactor, microalgae-fungi co-culture, microalgae-activated sludge co-culture, and microalgae auto-flocculation have been explored for efficiently coupling microalgal biomass production with wastewater purification. In such systems, the cultivation of microalgae and the separation of algal cells from wastewater are performed in the same reactor, enabling microalgae grown in the cultivation system to reach higher concentration, thus greatly improving the efficiency of biomass production and wastewater purification. Additionally, the design of such innovative systems also allows for microalgae cells to be harvested more efficiently. This review summarizes the mechanisms, characteristics, applications, and development trends of the various integrated systems and discusses their potential for broad applications, which worth further research.