You can use a successive RO ...

You can use a successive RO process where in the first stage you can set a higher level of flux of reject, using the reject for the second phase RO, and use the reject form second for third stage.   After the direct membrane filtration of wastewater, a typical phases of recovery can be 65%, 10% and 5%.  Based on the feed water quality you can increase or decrease the flux on rejects.  I hope that helps.