erm, i know this post will be "out of step" with the others but... Ponds , and
aquaculture .... but must be stepped (various stages) as for broad-acre , grow salt tolerant plants and use their biomass in a concentrated area to improve the humus and water retention ... most salt tolerant plants filter it out before it enters the plant through it's
roots , use this to do the work for you....secondly, sunlight kills chlorine.. use it in ponds that fill with algae that produces C02 this will change the state of the carbonates , there are many brackish water fish that can be used that are
vegetarian / omnivorous ... then transfer the water from this stage to a second stage water filtration ... many different types of reeds and trees can be used here , find ones that suit your climate, this should sufficiently filter water
enough for normal aqua-culture and farming small scale with an intensive system making you a lot more self-sufficient ... in arid area's with less than 20 inches annually i wouldn't recommend broad acre food farming without a lot of previously installed infrastructure, (trees with
canopy and farming between the rows) or large expensive equipment on a "hit and miss" crop cycle ...i hope some of this info may help you , but good luck on your adventure, who know's 10 years from now you might be pakistans largest inland prawn/shrimp farmer
P.S. i think in essence your rebuilding a new ecology, this is a long term and frustrating process , will need a lot of inputs, i do think activated carbon and zeolite will be needed to treat the water to be potable, and may include distilation too