Evaluation of Efficiencies of Locally Available Neutralizing Agents for Passive Treatment of Acid Mine Drainage

Abstract

Acid mine drainage (AMD) generated from the mining industry elevates environmental concerns due to the pollution and contamination it causes to bodies of water. Over the years, passive treatment of AMD using alkalinity-generating materials have been widely studied with pH neutralization as its commonly observed mechanism. During the treatment process, heavy metal removal is also promoted by precipitation due to pH change or through adsorption facilitated by the mineral component of the materials. In this study, four materials were used and investigated: (1) a low grade ore (LGO) made up of goethite, calcium oxide, and manganese aluminum oxide (2–3) limestone and concrete aggregates (CA) composed of calcite, and (4) fly ash consisting of quartz, hematite, and magnetite. The performance of each alkalinity-generating agent at varying AMD/media ratios was based on the change in pH, total dissolved solids (TDS), oxidation reduction potential (EH); and heavy metals (Fe, Ni, and Al) removal and sulfate concentration reduction. Concrete aggregate displayed the most significant effect in treating AMD after raising the pH to 12.42 and removing 99% Fe, 99% Ni, 96% Al, and 57% sulfates. Afterwards, the efficiency of CA at various particle sizes were evaluated over 1 h. The smallest range at 2.00–3.35mm was observed to be most effective after 60 min, raising the pH to 6.78 and reducing 94% Fe, 78% Ni, and 92% Al, but only 28% sulfates. Larger particles of CA were able to remove higher amounts of sulfate up to 57%, similar to the jar test. Overall, CA is an effective treatment media for neutralization; however, its performance can be complemented by a second media for heavy metal and sulfate removal.

Propose the surface flow constructed wetland in the treatment of acid drainage in the closure of a tailings deposit

“…In the tests it was observed that the concrete aggregate showed efficiency in the treatment, which resulted in the removal of 99% iron, 99% nickel, 96% aluminum and 57% sulfates. In addition, the concrete aggregate was evaluated, which resulted in the removal of 94% iron, 78% nickel, 92% aluminum and 28% sulfate [32].…”

Effect of Particle Character and Calcite Dissolution on the Hydraulic Conductivity and Longevity of Biosand Filters Treating Winery and Other Acidic Effluents

“…In this study, more of the smaller sand particles were composed of calcite, as discussed in more detail in Section 3.3. This may also be beneficial in terms of dissolution kinetics because the overall reaction surface area is larger with smaller particles [10].…”

“…Operational results from a pilot horizontal flow system as well as a more advanced vertical flow system with a novel hydraulic design have shown that the systems are also effective in neutralizing acidic WWW while increasing the sodium adsorption ratio (SAR) of the effluent [8,9]. The neutralization mechanism has been attributed to abiotic dissolution of calcite present in the sand [8,9] and may be applicable to other forms of acidic WW, similar to passive systems for treatment of acid mine drainage [10,11].…”