Here we describe a circular three-step process for the treatment of PAIWW. The first step involves ED with monovalent selective cation-exchange membranes, with this being followed by RO and precipitation (Figure ). In the ED process, most divalent cations (e.g., Ca 2+ and Mg 2+ ) remain in the diluate stream while the monovalent cations (e.g., H + and Na + ) migrate to the concentrate stream. This selective monovalent separation prevents scaling (mainly by gypsum, CaSO4.2H2O) in downstream RO processes. After the ED step, the diluate stream continues to RO filtration, while the ED concentrate comprising mainly H2SO4 is used for PA production. The low-SO4 2-ED diluate is further treated high recovery RO, producing high-quality water while significantly concentrating the WW. In the final step, the RO concentrate is further neutralized with mined phosphate rock, enabling the recovery of process water. The overall process significantly reduces WW volumes and associated environmental risks, land footprints, and cost. The process also recovers clean water, H2SO4, and P, thus contributing to the economy and sustainability of the plant.