Abstract

A series of experiments was conducted using 200 mL of acid mine drainage (AMD) collected from Krugersdorp, South Africa to determine turbid materials removal efficiency of a combination of bentonite clay, Fe or Al salt and MgCO3. The sample was poured into five 500 mL glass beakers using bentonite clay, FeCl3, AlCl3 and MgCO3 dosage respectively. The samples were treated in jar test at rapid and slow mixing, allowed to settle for 1 hour, then the pH, conductivity, TSS, DO and ORP were measured (exp A). A Second and third similar sets of experiments were conducted with a combination of bentonite clay and MgCO3 (flocculent) dosage (exp B), and FeCl3 slow mixing only (exp C). Experimental results revealed that the pH of treated effluent with bentonite clay does not exhibit significant increasing trend because of insignificant hydrolysis, whereas the pH of samples with FeCl3, AlCl3 and MgCO3 exhibit a slight decreasing trend, showing low rate of hydrolysis. The DO and ORP of treated effluent does not show significant changing trend compared to untreated AMD sample. Residual TSS of the AMD samples treated with a flocculent is lower than the samples treated with bentonite clay, FeCl, AlCl3 and MgCO3. Residual turbidity of the samples with rapid mixing is identical to that of the corresponding samples with slow mixing. TSS removal efficiency of a flocculent is higher compared to other reagents. The results show that synthetic flocculent is an ideal replacement of inorganic coagulants. The SEM micrographs exhibit slides with dense-sponge like flocs showing high adsorption capacity.

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Supplementary data