The Effect of the Bentonite Clay Constituents in a Flocculent of FeCl3 and CaMg.2(OH)2 during AMD Treatment Ntwampe OI1, Waanders FB2 and Bunt JR2

Abstract

Abstract: Two sets of experiments were conducted by pouring 200 mL of the acid mine drainage (AMD) decant from Krugersdorp (South Africa) into five 500 mL beakers (mixing) and Erlenmeyer flasks (shaking) and dosed with 20- 60 mL of FeCl3, Fe2(SO4)3, CaMg.2(OH)2 and a combination of FeCl3 with CaMg.2(OH)2 (af-PFCl) respectively. The samples were placed in a flocculator and a shaker and stirred at 250 rpm for 2 minutes respectively, settled for 1 hour and the pH, conductivity and turbidity were measured. A third similar set of experiments was conducted without mixing settled for 1 hour and the same measurement taken. The fourth and fifth sets of experiments were conducted with CaMg.2(OH)2 and afPFCl flocculent respectively. The novelty of this study is to determine the turbidity removal efficiency using FeCl3 and CaMg.2(OH)2 in a form of unprocessed polymers. The results showed that the pH and residual turbidity in the samples with Fe3+ salts, CaMg.2(OH)2 is relatively identical to those in the samples with af-PFCl dosages. The turbidity removal efficiencies exhibited by the Fe salts, CaMg.2(OH)2 and af-PFCl were optimal. The pH and residual turbidity in the AMD samples with mixing, shaking and without mixing indicate that destabilization-hydrolysis is influenced by the physico-chemical properties of the solution, whereas mechanical agitation mainly disperses the reagent(s). Optimal turbidity removal of the samples without mixing also indicates that perikinetic flocculation is a predominant process during aggregation/flocs formation