Carbon source regulation of microalgal-fungal system for the resource recovery of wastewater: A review

Abstract

The integration of microalgal-fungal system (MFS) with wastewater treatment processes presents a promising strategy for the sustainable management of wastewater, offering innovative and eco-friendly solutions to nutrient removal and resource recovery. However, the inadequacy of carbon concentrations in wastewater significantly impedes the growth and stabilization of MFS. Carbon source regulation is a potential solution to enhance the performance of co-cultivation system. However, the exploration of available carbon sources for the co-cultivation systems remains limited, and comprehensive descriptions into the intricate interaction between fungi and microalgae are limited. This review elucidates the structure and interplay within MFS, providing insights into the effects of diverse inorganic, organic and waste carbon sources on MFS performance. First, the formation processes and mechanisms of MFS are comprehensively described, along with the basic mechanisms of microalgal- fungal interactions, including substance exchange and information exchange. Second, the utilization processes and metabolic mechanisms of inorganic carbon sources (ICS) (CO2 and bicarbonate) and organic carbon sources (OCS) (glucose, acetate, glycerol) are summarized, highlighting the effects on microalgae and co-culture systems in terms of biomass productivity, lipid yield and resource recovery efficiency, which provide the basis for large-scale application. Finally, this review also considers the advantages of MFS for the production of biofuels and high value-added products. Overall, this review provides a comprehensive understanding of the role of carbon source regulation in the performance and resource recovery of MFS, offering valuable insights for the development of more economical and effective external carbon sources in the future.