Application of Phanerochaete chrysosporium for enhancing gold recovery via bio-oxidation of refractory sulfidic ores in a circumneutral environment

Hein, Guillermo; Mahandra, Harshit; Ghahreman, Ahmad

doi:10.1016/j.psep.2023.07.095

Cited by 1 publication

(12 citation statements)

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“…Finally, experiments were scaled up in a 2 L reactor, and sulfide oxidation and Au recovery were evaluated employing a replenishing strategy for three cycles (14 d bio-oxidation per cycle). In replenishing tests, once a bio-oxidation cycle was finished, the residual spent liquid was replaced with a new microbial culture, continuing with the treatment for the next cycle [6].…”

Section: Experimental Design Of Bio-oxidation Testsmentioning

confidence: 99%

“…The choice of 7 d for the pre-growth stage is based on the time required to reach robust microbial growth, which is frequently observed after 5 d to 8 d of incubation [12,18]. In order to maintain consistency and comparison with our previous investigation, 7 d of incubation was maintained in this research [6]. After the growing stage, bio-oxidation tests were begun using a 5% w/v PD (pulp density) sulfidic ore, setting the agitation speed at 150 rpm for 14 d. Control runs were also carried out using identical experimental conditions, excluding microbial inoculation.…”

Section: Experimental Design Of Bio-oxidation Testsmentioning

confidence: 99%

“…The enzyme activity of LiP and MnP was determined by spectrophotometrically measuring the absorbance of the culture filtrate under specific assay conditions using the oxidation of veratryl alcohol (310 nm) and Mn 2+ (240 nm), correspondingly [6,25]. One unit (U) of a particular enzyme activity is designated as the amount of enzyme needed to form 1 µmol of its specific product per min per liter (U/L).…”

Section: Enzyme Assaysmentioning

confidence: 99%

“…However, the use of these types of microorganisms to catalyze the oxidation of sulfidic ores in biomining has been barely investigated in comparison to acidophilic bacteria [2,4]. Recent investigations have shown a limited capacity of neutrophilic bacteria to oxidize solid matrices, while fungi have exhibited a more significant potential to assist the oxidation of sulfidic ores [5,6]. The oxidative capacity of the fungus Phanerochaete chrysosporium (P. chrysosporium) has been chiefly investigated in a pH range of 4.0 to 5.0, catalyzing the oxidation of sulfidic concentrates and pyrite [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…The oxidative capacity of the fungus Phanerochaete chrysosporium (P. chrysosporium) has been chiefly investigated in a pH range of 4.0 to 5.0, catalyzing the oxidation of sulfidic concentrates and pyrite [7,8]. In our previous investigation, a low-grade sulfidic ore was bio-oxidized at a circumneutral pH, showing the capacity of P. chrysosporium at this pH range [6]. The fungal action of P. chrysosporium is based on the secretion of ligninolytic enzymes, including lignin peroxidase (LiP) and manganese peroxidase (MnP), which are mainly responsible for the alteration of different substrates [9].…”

Section: Introductionmentioning

confidence: 99%

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Assessment of Modified Culture Conditions for Fungal Bio-Oxidation of Sulfidic Gold Ores Performed at Circumneutral pH

Hein,

Mahandra,

Ghahreman

2023

Sustainability

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The significant neutralization of waste streams required after the acidic bio-oxidation of sulfidic gold ores could be avoided by performing a novel treatment at circumneutral pH with an in situ neutralization. For the first time, the white-rot fungus Phanerochaete chrysosporium was incubated in a modified culture medium containing corn steep, an industrial waste product, to support microbial activity and, subsequently, the oxidation of a sulfidic ore at an initial circumneutral pH environment. In this investigation, the concentration of the native culture medium ingredients was first evaluated with response surface methodology to attain maximum sulfide oxidation. The statistical analysis proposed a modified culture medium composed of 12.86 g/L glucose, 2.20 g/L malt extract, 1.67 g/L yeast extract, and 0.49 g/L MgSO4·7H2O to reach a maximum of 28.7% sulfide oxidation after 14 d-bio-oxidation. pH-controlled batch cultures showed that an increase in initial pH in the range of 5.8 to 7.0 reduced the microbial activity, affecting sulfide oxidation. In addition, the modified culture medium at which yeast extract was substituted with 1.67 g/L corn steep produced comparable microbial activity and sulfide oxidation after 14 d, attaining 21.6% at 5% w/v with a maximum 39 U/L lignin peroxidase and 116 U/L manganese peroxidase. A 40.6% sulfide oxidation and 43.8% gold recovery were obtained after 42 d three-cycle replenishing bio-oxidation and 24 h cyanidation, respectively. Overall, corn steep waste showed the potential to substitute more expensive culture medium ingredients, supporting microbial activity and oxidation of sulfidic gold ores at an initial circumneutral pH and contributing to circularity of waste management.

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Section: Experimental Design Of Bio-oxidation Testsmentioning

confidence: 99%