Abstract
Wastewater utilization as a medium for microalgal cultivation have copious simultaneous perquisites such as removal of nutrients (80–100%), heavy metal removal, carbon dioxide (CO
2
) sequestration from atmosphere (1.83 kg CO
2
kg
−1
biomass), and high biomass production for biofuel generation (40–50% higher than crops feedstock). Municipal, industrial, domestic, agro-industrial, and several other types of wastewater treatment by coupling microalgal cultivation require two sorts of systems: open pond systems (OPs) and closed photobioreactors (PBRs). Many studies have focused on the utilization of OPs and closed PBRs for microalgal cultivation; however, comprehensive information in context of nutrient removal efficiency and biomass productivity with updated data is not fully addressed. In this review, wastewater treatment coupled microalgal cultivation for biofuel generation is emphasized in OPs and closed PBRs. The limitations of both systems, implementation of different approaches to enhance the biomass productivity, and economic feasibility are also highlighted. Based on the literature analysis, PBRs are more effective in wastewater treatment and biomass/biofuel generation due to contamination control and management of major parameters affecting microalgal growth. However, the implementation of various techniques to reduce the capital investment in PBR reactor designs is required for further use on commercial scale.
Graphical abstract