Recycling of metals from pretreated waste printed circuit boards effectively in stirred tank reactor by a moderately thermophilic culture.
To seek a feasible technique for processing waste printed circuit boards (PCBs), pretreatment of PCBs by table separation and further bioleached by moderate thermophiles in a stirred tank reactor were investigated. The shaking table separation, conducted after grinding and sieving of PCBs, produced two fractions: metal-rich parts (RPCBs), which is more suitable for pyrometallurgy process than untreated PCBs, and metal-poor parts (PPCBs) with only 8.83% metals was then bioleached by a mixed culture of moderate thermophiles effectively. After adaptation, the mixed culture could tolerate 80 g/L PPCBs. The bioleaching results showed that metals recovery was 85.23% Zn, 76.59% Cu and 70.16% Al in only 7 days. Trace Pb and Sn were detected in the leachate because of precipitating. The microorganism community structure was analyzed by amplified ribosomal DNA restriction analysis. Two moderately thermophilic bacteria species were identified as Leptospirillum ferriphilum and Acidithiobacillus caldus. Furthermore, uncultured Thermoplasmatales archaeon was also detected in the leaching system. It was also shown that moderate thermophiles revealed best bioleaching ability when compared with mesophiles and the mixture of mesophiles and moderate thermophiles. Finally, we designed a two-stage process model according to the present study to achieve semi-industrial waste PCBs recycling and economic feasibility analysis indicated that the process was profitable.
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
Ming-Chen
MC
Xia
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
Ya-Ping
YP
Wang
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
Tang-Jian
TJ
Peng
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Biometallurgy, Ministry of Education, Changsha 410083, China.
Li
L
Shen
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Biometallurgy, Ministry of Education, Changsha 410083, China.
Run-Lan
RL
Yu
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Biometallurgy, Ministry of Education, Changsha 410083, China.
Yuan-Dong
YD
Liu
CSIRO Process Science and Engineering, Clayton, Victoria 3168, Australia.
Miao
M
Chen
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Biometallurgy, Ministry of Education, Changsha 410083, China.
Jiao-Kun
JK
Li
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Biometallurgy, Ministry of Education, Changsha 410083, China.
Xue-Ling
XL
Wu
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Biometallurgy, Ministry of Education, Changsha 410083, China; CSIRO Process Science and Engineering, Clayton, Victoria 3168, Australia. Electronic address: zengweimin1024@sina.com.
Wei-Min
WM
Zeng
D042763:Acidithiobacillus / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D059029:Electronic Waste; D008670:Metals / Q000302:isolation & purification / Q000378:metabolism*; D059027:Recycling; D013696:Temperature
D008670:Metals
Amplified ribosomal DNA restriction analysis; Bioleaching; Community structure; Moderate thermophiles; Table separation; Waste printed circuit boards