Chemical precipitation of lead from lead battery recycling plant wastewater

The 1,3-benzenediamidoethanethiol dianion (BDET2-) binds soft heavy metals from aqueous stock solutions as highly stable metal-ligand compounds. In the present study, the potassium salt of this ligand was applied to field samples collected from an operating lead battery recycling site (LBRS) which generates wastewaters containing concentrations of lead from 2 to 300 ppm at an average pH of 1.5. Goals of this study were to reduce lead concentrations to below 0.5 ppm and produce stable Pb-BDET precipitates. It was found that more than 99.4% removal of lead from an average initial concentration of 3.61 ppm could be accomplished within 15 min using an equimolar dose of the BDETK2 ligand. Moreover, the precipitates remained stable during 30-day leaching tests.