The effect of saw dust in a flocculent with bentonite clay and FeSO4 in AMD treatment without addition of a neutralizer

Abstract

Abstract 200 mL of synthetic acid mine drainage (AMD) was poured into five 500 mL glass beakers and treated in a jar test. The samples were dosed with 1.0–2.5 g bentonite clay, 20–60 mL of 0.025 or 0.05 M FeSO4 and 1.0–2.5 g saw dust respectively. The samples were mixed at 250 rpm for 2 minutes and reduced to 100 rpm for 10 minutes. The samples were allowed to settle for 1 hour, after which the pH, oxidation-reduction potential (ORP) and turbidity were measured (exp. A). Two other similar sets of experiments were conducted by dosing the samples with a combination of bentonite clay and FeSO4 with and without saw dust, similar treatment and measurements (exp. B and exp. C), similar treatment and measurements were conducted. The pH and the efficiencies of the flocculants containing 0.025 and 0.05 M Fe3+ in FeSO4 are similarly identical. The removal of turbid materials from the samples with FeSO4 is the lowest, followed by a combination of bentonite clay and FeSO4, whereas a combination of bentonite clay, FeSO4 and saw dust the highest. Comparative removal efficiencies between the two flocculants show that the presence of FeSO4 is relatively insignificant. The removal efficiency of a combination of bentonite clay, FeSO4 and saw dust from AMD sample is low with for Cu2+, and optimal for both Ni2+ and Fe2+ ions.