Acid mine drainage treatment using chicken eggshell waste

Abstract

Acid mine drainage (AMD) is a source of soil and water resources pollution. Calcite is a mineral constituted of calcium carbonate (CaCO3). The AMD interaction with calcite drives their natural neutralization. Calcite is the main component of the chicken eggshell (ES). This work aimed to evaluate the use of ES waste as a material to treat raw AMD. Five treatments (T1, T2, T3, T4, and T5) were carried out with concentrations of 1, 2, 3, 4, and 5 ES g/L AMD, respectively. Each treatment was performed for 3 h at room temperature without agitation. The response variables analyzed were pH, redox potential (Eh), electrical conductivity (σ), chlorides (Cl–), alkalinity, sulfates (SO42–), nitrates (NO3–, and potentially toxic heavy metals and metalloids (PTHMM). Also, the removal efficiencies of SO42–, NO3–, and PTHMM were analyzed. Additionally, the chemical and mineralogical composition of ES and precipitates were determined. The initial pH for AMD was 2.50 and it reached a final value of 5.50, 5.60, 5.80, 5.93, and 6.12 in T1, T2, T3, T4 and, T5, respectively. Moreover, the different treatments granted alkalinity to the treated effluents, reaching a maximum value of 124 CaCO3 mg/L in T5. Finally, Al and Fe were completely removed from AMD, whereas Cu reached > 95 % removal, especially in T3, T4, and T5. Ba, Cr, and Pb showed an average removal of ~65 %. The ES concentration that showed the best results of neutralization and PTHMM removal efficiency was 5 ES g/L. The results showed that ES is a biocompatible waste material with an added value because it can be used as a sustainable material to treat raw AMD.

Heavy Metal Dispersion in a Hydrological Sub-Basin as Consequence of Mining Activity in Taxco, Guerrero (Southern Mexico)

“…The AMD is continuously incorporated into the surface drainage near the mining complexes. For instance, sample S2 stood out as a generating point for AMD [35,36]. This sampling site is in the northern part of the hydrological recharge zone of the Taxco-Cocula sub-basin.…”

“…The differences between the chemical facies are due to the geology in which the springs are located as their hydrogeochemical characteristics in the dry and rainy seasons do not vary significantly, in congruence with the physical-chemical parameters measured in situ. The geology of the zone plays a key role in diminishing the hazardous effects of AMD [36,41] (Table 3, Figure 1).…”