Validated innovative approaches for energy-efficient resource recovery and re-use from municipal wastewater: From anaerobic treatment systems to a biorefinery concept

The development of innovative technologies in wastewater treatment create the concept of biorefinery in wastewater treatment plants (WWTPs), placing anaerobic processes in the highlight. Starting from the conventional anaerobic treatment processes to 'closing the loop' scheme, next generation WWTPs are ready to serve for water, energy and materials mining. While bioenergy is still dominating the resource recovery, recovery of value-added materials (i.e. struvite, biopolymers, cellulose) are receiving significant attention in recent years. So, what are the state-of-the-art approaches for energy-efficient resource recovery and re-use from municipal wastewater? This paper follows a critical review on the validated technologies in operational environment available and further suggests possible market routes for the recovered materials in WWTPs. Considering the development and verification of a novel technology together with the valorization of the obtained products, biorefinery and resource recovery approaches were gathered in this review paper from a circular economy point of view. General currently-faced barriers were briefly addressed to pave the way to create to-the-point establishments of resource recovery facilities in the future.