Microbiological potential for gold leaching and recovery from E-waste

Intan Nurul Rizki, Tsuyoshi Hirajima, Naoko Okibe

Research output: Contribution to conferencePaper

Abstract

It is believed that production of electronic waste (e-waste) is one of the most rapidly growing problems in the world, about 5-8% of which being exported to developing countries, especially in Asia and Africa. From the viewpoint of its metal composition, e-waste can be a promising source for recycling of a number of valuable metals. Among them, this study focused on recycling of gold (Au). A two-stage biohydrometallurgical process; (i) bio-thiourea (CS(NH2)2; TU) leaching, followed by (ii) precipitation of bio-Au nanoparticles (bio-AuNPs) was set as the final objective of study. Chemical-TU leaching has been performed by a number of studies for Au recovery, yet it is generally considered that its implementation needs further cost-feasibility. Modification of this method was attempted by using the extremely acidophilic Fe-oxidizing archaeon, Acidiplasma sp. strain Fv-Ap, as the tool for microbiological redox potential control during the TU leaching. Several factors (such as TU/Fe(III) ratio and pulp density) were shown to affect Au recovery. Under the optimal condition at 3% pulp density, about 9% of Au was recovered by addition of strain Fv-Ap, while the recovery remained 7% in sterile control. Before attempting microbial Au() recovery from the TU-leached Au(I), fundamental studies were carried out using Au(III) reagent to optimize bio-AuNPs production by using the acidophilic Fe-reducing bacterium, Acidocella aromatica strain PFBC. Different concentrations of formate (as e--donor; 1, 5, 1, and 2 mM) were tested for optimization. Use of higher formate concentrations allowed production of finer particles: 2 mM formate enabled production of the finest AuNPs (12 nm) with the highest density (97 particles/ cell). The possibility to recover Au from the resultant TU leachate was also tested. Au(I) reduction occurred slower compare to synthetic Au(III) reagent. Approximately 9% of Au(I) was reduced from the leachate. The results indicated that Bio-AuNPs method might be an alternative way to recover Au from solutions, yet further reaction optimization is necessary.

Original languageEnglish
Publication statusPublished - Jan 1 2017
Event14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017 - Sapporo, Hokkaido, Japan
Duration: Sep 26 2017Sep 29 2017

Conference

Conference14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017
CountryJapan
CitySapporo, Hokkaido
Period9/26/179/29/17

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gold
leaching
leachate
recycling
metal
redox potential
developing world
bacterium
cost
electronic waste
nanoparticle
pulp
method
particle

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)

Cite this

Rizki, I. N., Hirajima, T., & Okibe, N. (2017). Microbiological potential for gold leaching and recovery from E-waste. Paper presented at 14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017, Sapporo, Hokkaido, Japan.

Microbiological potential for gold leaching and recovery from E-waste. / Rizki, Intan Nurul; Hirajima, Tsuyoshi; Okibe, Naoko.

2017. Paper presented at 14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017, Sapporo, Hokkaido, Japan.

Research output: Contribution to conferencePaper

Rizki, IN, Hirajima, T & Okibe, N 2017, 'Microbiological potential for gold leaching and recovery from E-waste' Paper presented at 14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017, Sapporo, Hokkaido, Japan, 9/26/17 - 9/29/17, .
Rizki IN, Hirajima T, Okibe N. Microbiological potential for gold leaching and recovery from E-waste. 2017. Paper presented at 14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017, Sapporo, Hokkaido, Japan.
Rizki, Intan Nurul ; Hirajima, Tsuyoshi ; Okibe, Naoko. / Microbiological potential for gold leaching and recovery from E-waste. Paper presented at 14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017, Sapporo, Hokkaido, Japan.
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