TREATMENT OF ACID EFFLUENTS FOR THE REMOVAL OF MANGANESE AND HEAVY METALS ASSOCIATED WITH EFFLUENTS FROM THE COAL MINING THROUGH THE PROCESSES OF FLOCULATION AND FLOTATION BY DISSOLVED AIR

Abstract

This study was developed with the objective of evaluating the effluent treatment processes from coal mining, as well as the efficiency in removing manganese and other heavy metals. The procedures consisted of applying mining wastewater treatment methods through the neutralization processes, followed by Flocculation and Sedimentation (NFS) and Dissolved Air Flotation (FAD) on a bench scale. The test via NFS showed an efficiency of 99.58% in the removal of the manganese dissolved in the effluent, with an increase in
pH up to 9.95. For the FAD tests, the average manganese removal efficiency was 97.12% and with pH 9.4. For other metals, NFS showed 99.79% removal for Total Aluminum, 99.32% for Zinc and 97.79% for Soluble Iron, while FAD had an average removal of 96.33% for Total Aluminum, 97.02% for Zinc, and 97.26% for Soluble Iron. All tests fell within the limits established by environmental legislation with respect to the concentration in toxic metals, this proves that the process of treating the effluent from a coal company under study showed an efficiency for the removal of the analyzed metals, especially  iron, zinc, and manganese. There remained the need for adjustments in future research work to adapt manganese to pH values below 9.0. It was also found that, in addition to the NFS, the FAD treatment technique constitutes an alternative for the treatment of acid mine effluents, corroborating with previous works and justifying a possible future reintroduction in the systems of treatment of acid mine drainage in the region.