Integration of algae-based resource recovery with wastewater treatment systems

Significant increase in anthropogenic activities over the past decades has resulted in the excessive release of waste to natural water bodies, reducing water quality and damaging the aquatic ecosystem by eutrophication. Efficient and cost-effective remediation technologies are required to avoid these negative impacts by reducing the nutrient load from waste streams. Conventional methods for wastewater treatment are complex, energy-demanding, and result in the emissions of greenhouse gases. The integration of microalgae with conventional wastewater treatment, however, offers a more sustainable, comprehensive, and eco-friendly approach. Microalgae-integrated wastewater treatment processes are based on the removal of suspended solids during primary treatment, followed by the removal of organic and inorganic nutrients by microalgal cultures, or by mixed microalgal and bacterial cultures, during secondary and tertiary treatment stages. During the process of algae-based bioremediation, valuable biomass with a remarkable biochemical composition, including proteins, lipids, and carbohydrates, is also produced. This algal biomass serves as a flexible feedstock for high-value compounds such as biofuels, biofertilizers, and bioactive compounds, while simultaneously increasing the process sustainability within the circular bioeconomy context. This chapter highlights the advantages and mechanisms of integrating algae-based wastewater treatment processes into conventional wastewater treatment systems for enhanced resource recovery and reduced greenhouse gases emissions.