"over 50% water loss" would apply only to brines (extremely high levels of salt) and to poorly designed-operated-maintainedRO systems. Instead we develop, design and realize tailored high grade water reuse systems with overall over 90% water recovery = less than 10% water loss. Knowing that TDS = total dissolved solids, the first step is to remove all non-mineral solids by advanced biological treatment (without adding any chemicals other than nutrients if/as required). This results in ultra-low TOC, COD, BOD, TSS, turbidity (NTU) and SDI (silt density index) which minimizes irreversible fouling and power consumption of NF/RO membranes and doubles their economic lifetime. In the second step, some of the minerals could be removed by precipitation and/or air stripping. Finally after UF/cartridge pre-filtration and conditioning, the remaining TDS is retained by partial or full RO filtration as needed. I would like to add that some minerals such as sulfates, nitrates, ammonia, ... can also be removed in the first step by advanced biological treatment.
I will be interested to have the commercial details for such a system providing 1000 LPH with 70-80% of TDS reduction. You may write to water_india2005@yahoo.com