Coupled electrochemical methods for nitrogen and phosphorus recovery from wastewater: a review

Declining mineral resources, high fertilizer production cost and widespread eutrophication are calling for the recovery of nitrogen and phosphorus from wastewaters in the context of the circular economy. Among the currently available methods for nitrogen and phosphorus recovery from water, electrochemical coupling technologies with synergistic effects hold great promise. Here, we review the recovery of nitrogen and phosphorus from water by electrochemical coupling technologies with focus on separate recovery of nitrogen, separate recovery of phosphorus and concurrent recovery of nitrogen and phosphorus. Limitations of traditional methods are presented. We observed that air stripping and membrane stripping are the main electrochemically coupling techniques for nitrogen recovery, while chemical precipitation and electrochemical induced precipitation are the main electrochemically coupling techniques for phosphorus recovery. We detail the coupling reasons, purposes, mechanisms, performance, as well as limitations of these electrochemical coupling systems.