A method for sequestering cations that can precipitate from an aqueous composition, the method comprising: adding a multi-dentate ligand to the aqueous composition comprising at least one dissolved component selected from NaCl, KCI, Na 2 SO 4, and Na 2 CO 3 and at least one type of dissolved divalent cation selected from calcium, barium, strontium and magnesium that can precipitate from the aqueous composition to produce scaling; then enabling the multi-dentate ligand to bond with the divalent cation to form a non-scaling ionic complex wherein the cation, absent formation of the ionic complex, is subject to scaling; then filtering the aqueous composition with a membrane having sub-1-μm pores that removes a filtered brine including the ionic complex yet passes a remnant of the aqueous composition; reducing the pH of the filtered brine by adding an acid to the filtered brine to release and remove the divalent cation from the multi-dentate ligand and to produce a composition including the multi-dentate ligand; and after the cation is released and removed, adding a base to the composition including the multi-dentate ligand to neutralize the acid and reintroducing the multi-dentate ligand into additional aqueous composition to form additional non-scaling ionic complex in a predominantly closed loop; characterized in that said method further comprises separating, in a desalination system, purified water from the remnant of the aqueous composition that remains after the filtered brine is filtered out in a process that supplies heat from a source of thermal energy to heat the remnant of the aqueous composition up to a temperature at which the dissolved divalent cation would precipitate if not bonded in the non-scaling ionic complex and previously removed from the aqueous composition and that produces a water output and a solids output. adding a multi-dentate ligand to the aqueous composition comprising at least one dissolved component selected from NaCl, KCI, Na 2 SO 4, and Na 2 CO 3 and at least one type of dissolved divalent cation selected from calcium, barium, strontium and magnesium that can precipitate from the aqueous composition to produce scaling; then enabling the multi-dentate ligand to bond with the divalent cation to form a non-scaling ionic complex wherein the cation, absent formation of the ionic complex, is subject to scaling; then filtering the aqueous composition with a membrane having sub-1-μm pores that removes a filtered brine including the ionic complex yet passes a remnant of the aqueous composition; reducing the pH of the filtered brine by adding an acid to the filtered brine to release and remove the divalent cation from the multi-dentate ligand and to produce a composition including the multi-dentate ligand; and after the cation is released and removed, adding a base to the composition including the multi-dentate ligand to neutralize the acid and reintroducing the multi-dentate ligand into additional aqueous composition to form additional non-scaling ionic complex in a predominantly closed loop; characterized in that said method further comprises separating, in a desalination system, purified water from the remnant of the aqueous composition that remains after the filtered brine is filtered out in a process that supplies heat from a source of thermal energy to heat the remnant of the aqueous composition up to a temperature at which the dissolved divalent cation would precipitate if not bonded in the non-scaling ionic complex and previously removed from the aqueous composition and that produces a water output and a solids output.