Method of reclaiming brine solutions using an organic chelant

A method of reclaiming a well completion brine solution by using an organic chelant that is capable of discriminating between (i) iron and non-zinc heavy metals; and (ii) calcium and zinc. The chelant contains a functional group selected from the group —CO 2 H or —PO(OH)R 20 or a salt or ester thereof, —C(O)—, —OE, —SE, —N═C(R 2 )R 3 , EO—N═C(R 2 )R 3 , —N(R 2 )R 3 , and —N(C(O)R 1 )R 2 group optionally substituted with a —COOH or —PO(OH)R20 or a salt or ester thereof, —SE or —OE group, wherein R 2 and R 3 are independently selected from E or forms, with nitrogen, phosphorous, oxygen or sulfur, a heterocyclic ring; E is R 1 or —H; R 1 is a C 1 -C 30 alkyl or aralkyl group or a derivative thereof and R 20 is —OH or R 1 .