This may not answer you question, but our report does discuss a system incorporating a distillation system to enhance water recovery.

https://www.researchgate.net/publication/269874822_Laboratory_Study_for_Evaluating_Performance_of_Unit_Processes_to_Treat_the_Electrodialysis_Reversal_EDR_Reject_Stream_for_the_Proposed_Fort_Irwin_Water_Treatment_Plant_Environmental_Laboratory

Technical Report Laboratory Study for Evaluating Performance of Unit Processe...

RO can produce a concentrate containing 30000 ppm total dissolved solids

(TDS). Two problems with RO are that organics can seriously foul RO systems and that RO requires a feed stream that is free of suspended solids. Because of this it is advisable to  remove organics from wastewater before it enters the RO, so extensive front-end filtration equipment is required. Some membranes are pH and temperature sensitive, so pH control and feed equalization may be necessary.

Yes, RO can be adopted when you have TDS of 7000 ppm as a feed. I can cite an example used in treating tannery effluent.

The ZLD system for tanneries  comprises the following:  proper collection of effluent, primary treatment, secondary treatment, further preparatory treatment for ZLD system,

Reverse Osmosis for reducing effluent quantity for evaporation, reuse of the

recovered RO permeate in tanneries’ process, evaporation of the RO concentrate

in evaporator, reuse of the recovered condensate in tanneries process, recovery of

crystallised salt, recycle of un-crystallised salt for evaporation with RO

concentrate, and storage of the recovered salt in safe impervious covered storage facility. For details you may visit  http://www.iwma.in/Guidelines%20on%20ZLD.pdf

I agree with answer Biswas above:

Reverse Osmosis for reducing effluent quantity for evaporation, reuse of the

recovered RO permeate in tanneries’ process, evaporation of the RO concentrate

in evaporator, reuse of the recovered condensate in tanneries process, recovery of

crystallised salt, recycle of un-crystallised salt for evaporation with RO

concentrate, and storage of the recovered salt in safe impervious covered storage facility. For details you may visit http://www.iwma.in/Guidelines%20on%20ZLD.pdf