Anaerobic digestion is widely employed in wastewater treatment plants (WWTPs) for sludge management. Dewatering filtrate of digested sludge (i.e., dewatering sidestream) is rich in nutrients (e.g., ammonium and phosphate) released from the biomass, offering potential for resource recovery. Bipolar membrane electrodialysis (BMED) is a matured electrochemical technique that enables simultaneous nutrient separation and acid/base production, which is scalable and operates at a lower voltage than conventional water electrolysis. To recover nutrients effectively, BMED must be coupled with other recovery processes. However, a holistic understanding of their interplay within an integrated process remains limited, along with the effect of wastewater composition on operational performance and maintenance requirements. The goal of this project is to validate a pilot-scale system comprising a crystallizer, BMED, and membrane contactor for nutrient recovery from the dewatering sidestream under relevant conditions at a collaboration facility. Each unit provides essential functionalities for nutrient recovery, including precipitation for phosphate recovery and alkalinity reduction, NH4+ separation and acid/based production, and ammonia recovery to produce a concentrated liquid. These recovered nutrients can be converted into marketable fertilizers, enhancing resource efficiency, generating revenue, and reducing reliance on synthetic fertilizers to promote a circular economy.
