Research Article Open Access

BIOLOGICAL REMOVAL OF COPPER AND SULFATE FROM THE DRAINAGE OF SUNGUN COPPER TAILINGS BY SULFATE-REDUCING BACTERIA IN A DOWN-FLOW FLUIDIZED BED ANAEROBIC REACTOR

Abstract

Copper (Cu) mine drainage contains large amounts of heavy metal and sulfate (SO₄) pollutants that can potentially pose serious risks to human and environmental health. Therefore, it is of particular importance to present practical solutions with minimum cost and maximum efficiency for pollutant removal. Anaerobic bioreactors are considered to be the most suitable methods for the treatment of acidic effluents containing heavy metals due to some advantages such as the possible recycling of precious metals, the need for a small area, easy control, and better process prediction. In this experimental laboratory-scale study, the performance of Sulfate-Reducing Bacteria (SRB) was investigated in a Down-Flow Fluidized Bed (DFFB) anaerobic reactor (2.3 L) for SO₄ and Cu removal from the drainage of Sungun copper tailings. To this end, 800 g of activated carbon granules with an average diameter of 0.63 mm, an apparent density of 0.58 g/cm³, and an effluent volume of 2.5 L were introduced into the reactor in a non-fluid form with a height of 35 cm and 6-600 rpm. To cultivate SRB, 100 g of swampy soil with sand and clay existing near the forest and river was added to 5 L of a liquid culture medium and incubated at 30°C for 7 days. In this experiment, calcium sulfate (1.2 g/L) and sodium lactate (8 mg/L) were used as the final electron acceptor and the energy source, respectively. The pH of the final solution was set to about 7.4 (suitable for SRB growth) using NaOH. The analyzed results indicated that the DFFB reactor was an efficient and suitable method for the treatment of effluents containing large amounts of SO₄ and Cu. The concentrations of SO₄ and Cu in the samples decreased by 99.12 and 99.05%, respectively, after 24 h of retention time.

ENAYAT AFSAR1, AREZOO NEJAEI2*, MOHAMMAD MOSAFERI

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