ENHANCED PROCESS FOR SELECTIVE SALT RECOVERY FROM WASTEWATER AND BRINES.

摘要

A process for treating wastewater or waste brines that include sodium, sulfate and chloride ions. In one embodiment, the waste brine is concentrated in a brine concentration unit (24) and thereafter directed to a Mirabilite crystallizer (28) that produces hydrated sulfate salt crystals and a first solution (29). The hydrated crystals are melted in a mirabilite melter (30) to form an aqueous sulfate solution that is directed to a sodium sulfate crystallizer (32) which produces sodium sulfate salt crystals. The first solution (29) produced by the Mirabilite crystallizer (28) is directed to a nanofiltration device (36) which produces a permeate stream and a reject stream (31) containing sulfate removed by the nanofiltration device (36). The permeate stream is directed to a sodium chloride crystallizer (40) that produces sodium chloride salt crystals. The reject stream (31) is recycled to the Mirabilite crystallizer (28). The waste brine may be produced by a coal to chemical or coal to liquid process.