Biological nutrient recovery from wastewater for circular economy

The limits of resource availability are currently driving the changes in the world’s production systems, and in turn changing how wastewater is treated. As we now head toward a circular economy, the recovery of nutrients has become an important global strategy in wastewater treatment due to the need for appropriate recycling of key minerals/materials from waste to create a sustainable and viable modern society. It is a promising strategy for reducing the depletion of nonrenewable resources and damage done to the environment which is to their extraction and manufacture. This chapter reviews state-of-the-art technologies that enable nutrients (e.g., nitrogen, phosphorus, and potassium) to be recovered throughout the wastewater treatment cycle, focusing on the latest technological advances. The mechanism, configurations, impact factors, potentials, as well as limitations of different technologies are discussed. These include: the physicochemical processes (e.g., crystallization, stripping, and absorption); anaerobic processes (e.g., anaerobic digestion and anaerobic MBR); photo-bioprocesses (e.g., microalgae-based technologies and photosynthetic bacteria-based technologies); and microbial electrochemical technologies such as microbial electrolysis cells, microbial fuel cells and microbial recycling cells. Although nutrient recovery technologies are still developing, further research is required to make the processes as efficient as possible and investigate the integration of resource recovery methods to enhance the commercial applicability of these technologies. More benchmark enlarged-scale and life cycle studies must be conducted, which will significantly benefit the application of nutrients recovery technologies in wastewater treatment to achieve the ideal of a circular economy.