Role of Actinomycete sp. in Bio-extraction of Copper from Electronic Waste

Abstract

Copper is bioleached from printed circuit boards (PCBs) using Actinomycete sp. It was identified by 16S rRNA, called Streptomyces graminofaciens. The tolerance of S. graminofaciens towards copper showed that it couldn’t live in the presence of copper sulfate. The process was carried out by culturing 3.09×103 CFU of S. graminofaciens in 50 ml of modified starch nitrate medium for three days at 200 rpm and 30C and then 0.5% e-waste was added for other 5 days. Glucose (0.01 g/ml) and ammonium sulfate (0.002g/ml) were the best carbon and nitrogen sources. At pH 5, the leached copper was 88.1%. The bio-dissolution mechanism was investigated via the production of enzymes of S. graminofaciens metabolites, which showed that the higher dissolution has occurred in an un-denatured sample (non-heating) than the denatured one (heating). FTIR spectra confirmed the action of S. graminofaciens through the disappearance and appearance of some peaks. SEM showed that the e-waste gained more pores as a result of bio-treatment, which refers to the liberation of metals in solution.