Furthermore, as the RO concentrate comprises mainly phosphoric acid (>40 g P L -1 ) it can be recovered by different methods. Reaction of synthetic RO concentrate with natural phosphate rock results in higher P/Ca ratio in the rock and a neutralized concentrate. The results highlight the potential of the new process as an economically viable pathway toward more sustainable PA production. Processes targeting other acidic wastewaters may benefit from the high monovalent permselectivity at low pH.