Effect of disposal of aluminum recycling waste in soil and water bodies

摘要

This study evaluated environmental contamination by disposal of waste from tertiary aluminum industry in soil and water bodies. The main wastes of this industry are dross, non-metallic waste (product of dross leached with water) and liquid effluent. The water at the bottom of the pond, where the alkaline and saline aluminum effluent is discharged, presented high values of pH (>9) and high concentration of ammonia (N-NH3). However, dross disposal in soil decreased pH (<4) of groundwater and increased concentrations of Al3+, Na+, K+, Ba2+, Ni2+, Pb2+, Cu2+ and Zn2+. The N-NH3 produced from the reaction with water and some components of dross (aluminum nitride) probably promoted the increase of the nitrifying microbial activity in soil, which was responsible for the decrease in pH. In this condition, many components of dross were also easily leached into groundwater. The disposal of non-metallic waste into soil did not change the groundwater pH, but increased concentrations of Mn2+, Ba2+, Pb2+, Fe3+ and Ni2+. The disposal of aluminum recycling wastes without any treatment can change the quality of groundwater and surface waters, mainly due to high level of N-NH3, which modifies the pH of these waters and is very toxic to aquatic organisms.