Physicochemical speciation of toxic fractions of wastewaters.

A physicochemical speciation scheme in tandem with bioassays identified the toxic fractions of the wastewater from a base metal refining and fertilizer complex. The toxic fractions were the leachates from suspended solids, purgeables, and bound metals of the dissolved fraction. Most of the metals were bound to macrosolutes of Mr greater than 30,000 and exchangeable by cation- and weak anion-exchange resins. In contrast, total chromium and surfactants were bound strongly to microsolutes of Mr less than 1500, removable only by strong anion-exchange resin.