“…Indeed, particular processing is necessary to recover useful nutrients and obtain treated water (final effluent) preferably appropriate for reuse/recycling or safe disposal [ 17 ], thus avoiding secondary pollution [ 13 , 18 , 19 ]. Significant R&D efforts have been made for testing/application of various treatment processes, including chemical precipitation, air and steam stripping [ 20 , 21 , 22 , 23 , 24 , 25 ], evaporation, ion exchange, adsorption [ 25 ], and membrane processes [ 23 , 26 , 27 ]. The efficiency, technology readiness level, and economic feasibility of these processes are discussed in several recent reviews [ 7 , 15 , 17 , 19 , 28 , 29 ], which indicate that significant R&D work lies ahead to develop such sustainable processes for various types of digestates.…”