Removal of Hg (Ⅱ) Ions from Industrial Wastewaters Using Aluminum Sulfate

摘要

The main purpose of this study was first to investigate the removal of Hg(II) ions from industrial wastewaters by coagulation-flocculation with aluminum sulfate, secondly to understand the contribution of some parameters including the coagulant dose, pH, and the addition of adjuvant (activated carbons and lime). Jar-test experiments were carried out on wastewater samples containing mercury from the industrial area of Biskra (BIWW: Biskra industrial wastewater, C_(0)= 1.01 mg/L) and Tizi Ouzou (TOIWW: Tizi Ouzou industrial wastewater, C_(0)= 1.81 mg/L).The maximum elimination of mercury at ambient temperature was 49% and 58% that were obtained with concentrations of 180 mg/L and 200 mg/L of aluminum sulfate at a pH close to 7 for both Tizi Ouzou and Biskra samples, respectively. The obtained results showed that the removal efficiency of mercury ions is improved by the addition of adjuvant (activated carbon and lime). The removal efficiency of Hg (II) ions increased with increasing lime and activated carbon masses, experiments results indicated that the yield increased with the increase in the dose of the adjuvant to reach a maximum of 82.89% (TOIWW) and 83.38% (BIWW).The experiments were conducted to test the ability of coupling coagulation-flocculation to adsorption. It was verified that coupling was more efficient in the removal of Hg(II) ions from industrial wastewater than coagulation-flocculation alone. Almost complete removal (99.42) of Hg was obtained by coupling coagulation-flocculation and adsorption on powdered activated carbon.Accordingly, it is believed that coupling coagulation-flocculation and adsorption are practical for utilization in industrial wastewater treatment for mercury removal.