Constructed wetland treating mine drainage wastewater: Performance and microbial mechanisms

Abstract

To explore the possibility of using constructed wetlands to treat mine drainage wastewater, a lab- and pilot-scale constructed wetland with different filler units were built to study its effects on pollutants removal performances and microbial characteristics. The results showed that the removal efficiencies of ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3-−N) and chemical oxygen demand (COD) in the mine drainage wastewater were 65.37 %, 77.92 % and 69.00 %, respectively, and ceramic filler functional unit showed better treatment performance. Achromobacter, Arthrobacter, and Pedobacter were the dominant microbial communities, in which Pedobacter would form Fe autotrophic denitrification process with Fe2+ in the mine drainage wastewater to further promote the removal of nitrogen. Besides, the highest abundance of denitrification-related genes (narG, nosB, nosZ), multifunctional genes (napA, napB), and the related enzymes in the N cycle and the TCA cycle ([E.C.1.7.2.4], [EC: 1.1.1.41], [EC: 1.2.7.3]) were formed by microorganisms on the surface of ceramic filler in the constructed wetland. This study could provide theoretical support for the treatment of mine drainage wastewater with constructed wetlands, and also provide a new idea for this field.