Anaerobic Sulfate-reducing Bacteria in a Copper Filter Treatment System

Abstract

Remediation technologies involve any operation that decrease toxicity, volume, or mobility of hazardous waste or pollutants by the use of physical, chemical and / or biological processes. Bioremediation has advantages over conventional treatments, allowing mineralization or conversion into harmless substances of a variety of contaminants; also, it can be applied at the affected site, has low installation and operating costs, is easy to use and technologically effective. Different microorganisms, viable or not, and / or cellular components may be used in these processes. The metallurgical and mining industries are the main source of heavy metal pollution of rivers and lakes. It is imperative to remove metals from their effluents. Microorganisms can change the redox state of metals such as Cu, by direct (enzyme) or indirect processes (through reduction of iron sulfate reduction / sulfur or sulfur oxidation), therefore, a key factor that decides applying bioremediation strategies is the bioavailability of an electron donor that can be used in metal reduction. Sulfate reducing bacteria are able to catalyze, under anaerobic conditions, the sulfate reduction using organic compounds as electron donors, producing the bioprecipitation of metal as sulfides, which generally are stable solids. However, this process is influenced by the presence of other pollutants, metals or organic, in watercourses, which affect the acidity of the medium. In addition, sulfate-reducing bacteria are strictly anaerobic and usually are very sensitive to environmental oxygen, dying after exposition. In oxygenated environments, like the surface of water bodies and neighboring sediments, aerobic microorganisms can be used to complement the process. Actinobacteria are aerobic prokaryotic organisms. Their metabolic diversity and particular growth characteristics, mycelial form and relatively rapid colonization of selective substrates, indicate them as well suited agents for bioremediation of metal and organic compounds. They can reduce or uptake metals. A combination of treatments will ensure a successful process.