Recovery by Aspergillus oryzae of Gold from Waste Water from Gold Plating

Abstract

Strain SUT 30218 was selected from 60 strains of mold as the organism that most efficiently removed gold from gold-plating baths with a nutrient. The nutrient was composed of yeast extract, malt extract, peptone and glucose. The strains were cultured with shaking in a test tube for 3 to 4 days at 27°C before being screened. The selected strain was identified as Aspergillus oryzae based on its morphological characteristics. The strain removed 87 to 93% of gold from yeast-malt medium (pH 6.0) containing waste water from gold plating (gold, 71 ppm) during shaking culture in a Sakaguchi flask for 5 days at 27°C. Gold could be obtained from the gold-laden cells of Aspergillus oryzae by washing of the cells with a mixture of thiourea (0.1m) and oxidizing agents (0.02M).