The removal of turbid materials from AMD using bentonite clay, Fe or Al salt, MgCO3 and flocculent with varying agitations

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 with 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 a low rate of hydrolysis. The DO and ORP of treated effluent does not show a significant changing trend compared to the 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 for inorganic coagulants. The SEM micrographs exhibit slides with dense-sponge like flocs showing high adsorption capacity.

Efficiency of a flocculent consisting of bentonite clay and fly ash for the removal of pollutants in AMD

“…The removal of sulphate was coupled with the formation of gypsum incorporated into Al, Fe-oxyhydroxysulfates. Such a formation enabled easy sorption by the flocculent-C, particularly by intercalation and adsorption attributed to bentonite clay (Ntwampe 2020b).…”

Facile fabrication of low-cost activated carbon bonded polyethersulfone membrane for efficient bacteria and turbidity removal

“…Different methods, e.g., adsorption (Aghababaei et al 2021;Aragaw 2021) and membrane filtration (Davari et al 2021;Mahmoud & Kochameshki 2021) have been used for the water treatment process. In terms of adsorption, adsorbents for wastewater treatments are made of many materials, such as activated carbon (Belhamdi et al 2020), hydroxyapatite (Hariyanto et al 2020), polymers (Lou et al 2021), zeolites (Konale et al 2020), and clay (Ntwampe 2020). Due to the large surface area, low fabrication cost, and materials in use, activated carbon commonly become adsorbents for removing pollutants in contaminated water (Vargas & Lopes 2020;Ashiqa et al 2021;Mueanpun et al 2021;Sidiqua & Priya 2021).…”