Simultaneous removal of heavy metals from wastewaters [articol]

Abstract

Heavy metals have become a major concern in last decades. They are frequently detected in the aquatic environments due to anthropogenic activities and industrial and urban wastes discharge into water bodies. Although some of these metals are necessary, at low doses, for growth of biological life, the presence of heavy metals in the environment, in large concentrations, can be detrimental to a variety of living species, including man. The aim of this study was to explore the possibility of simultaneous removing Cr(III), Fe(II) and Fe(III) from wastewaters by precipitation with NaOH. The effects of NaOH dose, mixing time, mixing intensity, settling time and solution temperature were investigated. The optimum conditions of the precipitation process, which resulted from this study, are: NaOH dose: 500 mg/L, mixing time: 5 minutes, mixing intensity: 50 rpm, settling time: 30 minutes, solution temperature: 14°C.