The invention presents innovative methods to de-scale sulfate-rich saline streams such as seawater and the like in conjunction with desalination processes. The effective de-scaling of such streams by the inventive methods: (1) enhances the performance, efficiency and cost effectiveness of desalination processes; and (2) allows the viable use of the de-scaled reject brine from desalination processes, for example, as a suitable saline water for oil-gas field's water injection operations to improve hydrocarbons recovery and/or as a feed stock for chlor-alkali industries.