Solution For Heavy Metals Decontamination in Produced Water / Case Study in Southern Tunisia

摘要

Oil industry often generates liquid and solid wastes, whichrnrequire a pre-treatment before their discharge in the receivingrnenvironment. Given their toxicity, among the identifiedrnwastes, heavy metals are the most dangerous contaminants andrnpushed the National Agency of the Environment Protection tornset up a very strict regulation.rnThis paper presents the study and the characterisation of thernpolluting metals concentrated in produced water from anrnoilfield situated in southern Tunisia and describes arnmethodology to decontaminate this produced water. It alsornpresents the specific norms and standardised proceduresrnapplied in this study.rnAnalysis of water produced from the studied oilfield revealedrnthat it contained a high concentration of some heavy metalsrnand especially Zinc, Lead, Manganese, Iron and Barium.rnThese elements are essentially concentrated as particles in thernsolid fraction rather than in a dissolved state, whereas thernother well-known heavy metals pollutants like Cadmium;rnChromium; Nickel; Vanadium and Copper exhibit only lowrnamounts, which are less than the defined standards.rnIt is evident that the considered solutions for the separation ofrnthese heavy metals from water have been founded on naturalrnevaporation principle of produced waters in basins especiallyrnconceived for this effect. However due to the increasing watercut,rnthis technique is efficient only during the summer time.rnIn order to remedy to this latter problem, laboratory tests havernbeen conducted to develop other technique Improvements,rnwhich are the use of spillsorb, calcite and lime. Tests showedrnthat the best results have been obtained with the lime, efficientrnand economic (efficiency > 95 % for most studied metals).