Application of Sustainable Remediation Techniques for Heavy Metal Reduction in Polluted Rivers in Mining Zones: Study Area Ponce Enriquez

Abstract

Abstract Mining activity in Ecuador is primarily artisanal and small-scale. Rivers near the mining county of Camilo Ponce Enriquez have been severely affected by this type of mining. A field study was conducted encompassing 29 sites on the rivers Siete, Fermin, and Pagua during sampling campaigns that took place in both dry (December) and wet seasons (February). Physio-chemical parameters and heavy metal concentrations were measured to enable environmental characterization of the rivers. Results revealed that most of the sampled sites had bad water quality and exceeded the environmental limits of heavy metal concentrations set by the Ecuadorian government. A parallel pilot investigation was performed for reducing the heavy metal concentrations in water ecosystems polluted by mining activities using bioremediation techniques. The bioremediation technique applied in the study used bacteria from a wastewater digestor and sugarcane bagasse as a carbon source to support the bacterial community. Sulfide was measured to monitor bacterial activity in experimental bioreactors containing local acid mine drainage (AMD). The results obtained were encouraging, as a significant decrease in heavy metal concentration was observed to nearly the level of Ecuadorian environmental regulations for Al, Cd, Cu, Fe, Pb, and Zn concentrations in freshwater in a set of bioreactors.

Keywords

• acid drainage, artisanal mining, bioremediation, heavy metals, pollution.