Assessment of the Combined Use of Basic Oxygen Furnace Sludge and Hydrogen Peroxide in the Treatment of Acid Mine Drainage

Abstract We recently demonstrated the use of basic oxygen furnace sludge (BOFS) to remove arsenic and sulfate from acidic solutions, which was found to be an interesting alternative for the reuse of steel waste. In this study, four systems were evaluated to determine whether BOFS is stable in acidic solutions and capable of removing As, Mn, and sulfate from acid mine drainage (AMD). In the S1 system (BOFS/DEIONIZED WATER pH 2.5), the stability of the residue was evaluated by placing the BOFS in deionized water acidified with H2SO4 until the pH reached 2.5. This system was maintained for 408 h under agitation to evaluate the possible solubilization of metals present in the BOFS. The results showed that only Ca and Mg were solubilized, and the pH increased from 2.5 to 12 after 408 h. The S3 system (BOFS/AMD) evaluated the metal removal capacity by BOFS and achieved 100% removal of As and Mn and 70% removal of sulfate after 648 h. In the first 30 min, the pH increased from 2.5 to 9.0, which was maintained until the end of the experiment. Simultaneously, S4 and S5 systems (BOFS/AMD / H2O2) were also evaluated using the oxidizing agent H2O2 (29% w/w) in the following proportions: 0.5 mM in S4 and 1 mM in S5. The removal of As, Mn, and sulfate in these systems was similar to that in the S3 system, which contained only BOFS. The results demonstrated that the formation of iron oxides was not accelerated by H2O2 and that iron, which is present in high concentrations in BOFS, was not the primary agent influencing metal removal from AMD.