12. Evaluation of an Integrated Approach Involving Chemical and Biological Processes for the Detoxification of Gold Tailings Effluent in Ghana

Abstract

Chemical and bio-remediation measures for the detoxification of pollutants such as cyanide and heavy metals in mine tailings effluent have been developed over the years. The study sought to evaluate the decrease in the concentrations of Cu, Zn, Fe, Cd, As and Pb through the integration of the processes involving photo-oxidation, activated carbon, hydrogen peroxide and bacterial degradation to decontaminate wastewater from the gold ore treatment plant until release into the environment in Ghana. The levels of trace metals Cu (0.345 mg l^-1), Zn (0.07 mg l^-1) and Fe (0.146 mg l^-1) in treated effluent released into natural water bodies after bacterial degradation was generally within international and local standards for effluent discharges. Except for As, the levels of Cd and Pb which are hazardous heavy metals that may pose adverse health and environmental effects were within acceptable limits. The toxicity of these metals were in the increasing order Pb < Cd < As. The anthropogenic source of As in the chemically processed arseno-pyritic rock ores of the study area and the marginal 14–49% efficiency of As of the different detoxification processes could have contributed to the high levels of As in the effluent. If optimal conditions are attained for the decontamination processes used, the multi-remediation approach could be an effective solution for the decontamination of mine tailings effluent.