| Evaluating the performance of an acid mine drainage treatment system, and the biogeochemical processes that occur within it, can be vital for improving the performance and longevity of the treatment system, and in designing new effective long-term treatment systems. In this study, the performance of the Tab-Simco treatment system and the biogeochemical processes that occur within it, were investigated by analyzing water samples from the site. The Tab-Simco treatment system comprises an anaerobic sulfate-reducing bioreactor and an oxidation pond. Results indicated that the treatment system increased the pH of the acid mine drainage (AMD) from 2.8 to 6.3 and decreased the mean acidity from 3,386 to 74 mg/l, SO42- from 4,589 to 2,021 mg/l, Fe from 884 to 3.5 mg/l, Al from 207 to 2 mg/l and Mn from 34.5 to 26.4 mg/l. The average delta34S value of the SO 42- in the untreated AMD was 7.3‰. This value was similar to the delta34S values of the pyrite in the coal seams, indicating that the oxidation of the pyrites was the cause of the AMD. In the bioreactor, delta34S value of dissolved SO42- increased from an average of 6.9 to 9.2‰, confirming the presence of bacterial sulfate reduction processes. Alkalinity production calculations for the bioreactor revealed that roughly about 60% of the alkalinity was produced by bacterial sulfate reduction whereas, the remaining 40% was produced by limestone dissolution. |
