Some people are using ...

Some people are using evaporation bonds. they are made of concrete. But they require a very large spaces. Other solutions is to dispose the reject to the groundwater via a borewell, but you have to get a permission from the government and keep the reject well away from the feed wells. These two solutions are economic.

Finally other solutions like demineralization plants and zero liquid discharge systems are used, but they cost. However they have a better environmental impact.