Method for treating effluent waste from a cation-exchange column regeneration cycle, including backwashing the column; regenerating the column using rinse water and a regenerant brine having a temperature warmer than room temperature, thereby forming a waste effluent containing divalent cations; precipitating the divalent cations in a precipitation reactor at a temperature warmer than room temperature; filtering the precipitation effluent; optionally, adjusting the filtered precipitation effluent pH; concentrating the filtered precipitation effluent via membrane-based water recovery, thereby forming separated concentrated salt and pure rinse water; and recirculating the separated concentrated salt and pure rinse water back to the column for a subsequent regeneration cycle. Also, a system including an exhausted cation-exchange column; a chemical precipitation reactor; a filtration unit; an optional pH adjustment unit; and a membrane-based water recovery unit, wherein the system is a closed-loop through which s
