Copper from Waste Printed Circuit Boards Was Effectively Bioleached Using Newly Isolated Microorganisms and Subsequently Recovered by Microbial Fuel Cell
Round 1
Reviewer 1 Report
MS: Sustainability-2389982
Title: Copper from waste printed circuit boards was effectively bioleached using newly isolated microorganism and subsequently recovered by microbial fuel cell has been proposed by the authors. This study enriches the two newly isolated bacterial strains were isolated from activated sludge and identified as Coniochaeta fodinicola (C. fodinicola) and Talaromyces barcinensis (T. barcinensis) by 16S rDNA. This article can be included in “Sustainability” after some revisions.
1. This study is incorrect in writing format. Please check the format at “Sustainability”.
2. The format of brackets, en dash, hyphen, comma (、), and tilde (~) did not follow the common usage of journal.
3. The styling of Tables and writing using track change is messy.
4. The resolution of most Figures are too low to print for publisher.
5. Some Figures should include the reference.
6. To make Tables more understandable, I advise the authors to rebuild them.
7. On section 3.1, the description of methods and study area is relatively lacking. It is recommended to add such as features or other references.
8. It is recommended to confirm the results of the simulation to ensure the accuracy of the results.
9. A few grammatical and typo mistakes are still there in your manuscript. Please thoroughly check and revise the manuscript carefully.
10. All units should be adopted according to consistent units.
11. Literature writing format of this article is confused.
12. The content is plentiful, but some part of the reference literatures is kind of obsolete (in 5 years). Key publications should be cited as completed as possible. Please also clarify the novelty and application implication of your work in this section. I suggest authors refer to the latest literatures from “Sustainability”, “MDPI”, and other related journals. But please do not exceed 30% of all citations from Sustainability. Authors may see the following reference while revising. https://doi.org/10.1016/j.jlp.2023.105030; https://doi.org/10.1016/j.jlp.2023.104977; https://doi.org/10.1007/s10973-023-12012-8; https://doi.org/10.1007/s10973-022-11898-0
Author Response
Title: Copper from waste printed circuit boards was effectively bioleached using newly isolated microorganism and subsequently recovered by microbial fuel cell has been proposed by the authors. This study enriches the two newly isolated bacterial strains were isolated from activated sludge and identified as Coniochaeta fodinicola (C. fodinicola) and Talaromyces barcinensis (T. barcinensis) by 16S rDNA. This article can be included in “Sustainability” after some revisions.
Point 1: This study is incorrect in writing format. Please check the format at “Sustainability”.
Response 1: Thank you very much for your kind comment. The modification parts were displayed with the "Track Changes" function.
Point 2: The format of brackets, en dash, hyphen, comma (、), and tilde (~) did not follow the common usage of journal.
Response 2: Thank you very much for your kind comment. The modification parts were displayed with the "Track Changes" function.
Point 3: The styling of Tables and writing using track change is messy.
Response 3: Thank you very much for your kind comment. The styling of Tables has been revised. The modification parts were displayed with the "Track Changes" function.
Point 4: The resolution of most Figures are too low to print for publisher.
Response 4: Thank you very much for your kind comment. Figure 1, Figure 3, Figure 5(C) have been replaced with clearer images. To make the image clearer, the Figure 6 has been enlarged. The modification parts were displayed with the "Track Changes" function.
Point 5: Some Figures should include the reference.
Response 5: Thank you very much for your kind comment. The Figures in the manuscript were drawn from experimental data and the software used was shown in Materials and Methods.
Point 6: To make Tables more understandable, I advise the authors to rebuild them.
Response 6: Thank you very much for your kind comment. The Tables have been reconstructed. The modification parts were displayed with the "Track Changes" function.
Table 1. Copper leaching rate by C. fodinicola.
|
Microorganisms |
Leaching time/(d) |
Copper leaching rate (%) |
||||
|
1% (w/v) |
2% (w/v) |
3% (w/v) |
4% (w/v) |
5% (w/v) |
||
|
C. fodinicola |
1 |
3.9±0.2 |
4.1±0.2 |
4.3±0.4 |
4.9±0.3 |
4.0±0.1 |
|
2 |
4.1±0.3 |
5.0±0.2 |
5.1±0.3 |
5.6±0.2 |
4.7±0.3 |
|
|
3 |
8.8±0.3 |
21.28±0.1 |
35.3±0.1 |
86.4±0.2 |
75.5±0.3 |
|
|
4 |
20.0±0.1 |
27.28±0.2 |
64.5±0.2 |
88.8±0.1 |
81.9±0.3 |
|
|
5 |
26.7±0.4 |
36.9±0.2 |
67.6±0.2 |
89.2±0.3 |
88.3±0.3 |
|
Table 2. Copper leaching rate by T. barcinensis.
|
Microorganisms |
Leaching time/(d) |
Copper leaching rate (%) |
||||
|
1% (w/v) |
2% (w/v) |
3% (w/v) |
4% (w/v) |
5% (w/v) |
||
|
T. barcinensis |
1 |
20.6±0.1 |
32.32±0.3 |
34.0±0.2 |
44.0±0.3 |
45.0±0.3 |
|
2 |
32.0±0.2 |
40.0±0.4 |
45.1±0.3 |
47.0±0.2 |
50.2±0.3 |
|
|
3 |
36.8±0.3 |
48.0±0.1 |
55.0±0.4 |
60.0±0.3 |
78.0±0.1 |
|
|
4 |
44.2±0.2 |
55.0±0.2 |
60.0±0.3 |
67.0±0.1 |
89.0±0.3 |
|
|
5 |
24.1±0.3 |
44.64±0.3 |
45.2±0.1 |
54.0±0.2 |
60.2±0.4 |
|
Point 7: On section 3.1, the description of methods and study area is relatively lacking. It is recommended to add such as features or other references.
Response 7: Thank you very much for your kind comment. The main thrust of this study was to screen out special microorganisms that efficiently leach copper from WPCBs powder and use MFC to recover copper from bioleaching solution. For the sake of brevity, other physiological characteristics of C. fodinicola and T. barcinensis were not shown in the manuscript.
The colony morphology of C. fodinicola and T. barcinensis was shown in Figure S1.
|
(A) |
(B) |
Figure S1. The colony morphology. (A) C. fodinicola. (B) T. barcinensis.
The cell morphology of C. fodinicola and T. barcinensis was shown in Figure S2.
|
(A) |
(B) |
Figure S1. The cell morphology. (A) C. fodinicola. (B) T. barcinensis.
Point 8: It is recommended to confirm the results of the simulation to ensure the accuracy of the results.
Response 8: Thank you very much for your kind comment. Experimental results have been confirmed.
Point 9: A few grammatical and typo mistakes are still there in your manuscript. Please thoroughly check and revise the manuscript carefully.
Response 9: Thank you very much for your kind comment. The modification parts were displayed with the "Track Changes" function.
Point 10: All units should be adopted according to consistent units.
Response 10: Thank you very much for your kind comment. The units of the horizontal coordinate in Figure 5 have been changed from V to mV, in line with the units of the output voltage in the previous section. The modification parts were displayed with the "Track Changes" function.
Point 11: Literature writing format of this article is confused.
Response 11: Thank you very much for your kind comment. The writing format of the references has been changed in accordance with the formatting requirements of the journal. The modification parts were displayed with the "Track Changes" function.
Point 12: The content is plentiful, but some part of the reference literatures is kind of obsolete (in 5 years). Key publications should be cited as completed as possible. Please also clarify the novelty and application implication of your work in this section. I suggest authors refer to the latest literatures from “Sustainability”, “MDPI”, and other related journals. But please do not exceed 30% of all citations from Sustainability. Authors may see the following reference while revising. https://doi.org/10.1016/j.jlp.2023.105030; https://doi.org/10.1016/j.jlp.2023.104977; https://doi.org/10.1007/s10973-023-12012-8; https://doi.org/10.1007/s10973-022-11898-0
Response 12: Thank you very much for your kind comment. Some obsolete (in 5 years) references have been replaced. The recommended references have been appropriately cited in the manuscript. Some references, although obsolete (in 5 years), were more classic in content and therefore retain key publications. The modification parts were displayed with the "Track Changes" function.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Please find the below opinions:
It would be beneficial to begin the introduction with references to waste management in general and globally in order to enhance the value of the study.
Two newly isolated bacterial strains. Barcinensis were used to bioleach the copper from the waste printed circuit boards 15 (WPCBs) powder, which was obtained by crushing and sorting the printed circuit board substrate 16 following component removal.
I consider the topic original and relevant in the field. It address a specific gap in the field.
This paper presents a framework for industrial and sustainable waste printed circuit boards management.
It would be beneficial to begin the introduction with references to waste management in general and globally in order to enhance the value of the study.
The conclusions are consistent with the evidence and arguments presented. They address the main question posed.
The references are appropriate.
Author Response
Point： It would be beneficial to begin the introduction with references to waste management in general and globally in order to enhance the value of the study.
Two newly isolated bacterial strains. Barcinensis were used to bioleach the copper from the waste printed circuit boards 15 (WPCBs) powder, which was obtained by crushing and sorting the printed circuit board substrate 16 following component removal.
I consider the topic original and relevant in the field. It address a specific gap in the field.
This paper presents a framework for industrial and sustainable waste printed circuit boards management.
It would be beneficial to begin the introduction with references to waste management in general and globally in order to enhance the value of the study.
The conclusions are consistent with the evidence and arguments presented. They address the main question posed.
The references are appropriate.
Response: Thank you very much for your kind comment. The description of waste management has been added to the introduction section. The sentence “Developed countries generally follow the "3R" (reduce, reuse, recycle) principle and follow the "resource-product-renewable resource" and the "circular economy" development model. Implement an "extended producer responsibility system" and form joint producer associa-tions or authorised civil society organisations. Legislation to ensure the smooth flow of WEEE logistics and finance, so as to achieve comprehensive recycling of WEEE.” has been added.
Author Response File: Author Response.docx
Reviewer 3 Report
1.line 104: The rpm unit is wrong and should be reported in g.
2. line 111: Explain why titanium wire and 75 Ω resistance was used
3. line 126: Mention the sequence of primers and PCR conditions.
4. line 129: Mention the MEGA software version.
5. It is necessary to write the accession number of the sequences registered in GenBank.
6. It is necessary to perform a statistical analysis in Table No. 1, under which conditions copper leaching is significantly better. Based on the percentage, it is not possible to check whether the results are significant or not
7. line 181: Penicillium chrysogenum should be in italics. The names of organisms should be italicized. This principle is not observed in the figures either.
8. In the conclusion, the role of this study in preserving the environment should be mentioned.
Author Response
Point 1: line 104: The rpm unit is wrong and should be reported in g.
Response 1: Thank you very much for your kind comment. The authors discussed that the unit g is generally used for the speed of a centrifuge and that the speed in the manuscript refers to the speed of the oscillatory incubator, which is generally expressed in rpm.
Point 2: line 111: Explain why titanium wire and 75 Ω resistance was used
Response 2: Thank you very much for your kind comment. Titanium wire, which is corrosion resistant, can be used as a conductor in microbial fuel cells to connect the anode material to the cathode material. We have also used titanium wire as a conductor in our previous studies [1, 2]. The external resistance of 75 Ω used in this study was to improve the electrical production performance, and it has been reported that when external resistance was increased, the power decreased [3]. Moreover, in an MFC, electrogenic bacteria were enriched under higher current densities, i.e., low external load, and were able to sustain better current [4].
[1] Yin X, Li X, Wang X, et al. A spontaneous electric field membrane bioreactor with the innovative Cu‐nanowires conductive microfiltration membrane for membrane fouling mitigation and pollutant removal [J].Water Environment Research, 2019, 91: 780-787.
[2] Yin X, Li X, Hua Z, et al. The growth process of the cake layer and membrane fouling alleviation mechanism in a MBR assisted with the self-generated electric field [J].Water Research, 2020, 171: 115452.
[3] González del Campo A, Caizares P, Lobato J et al. Effects of External Resistance on Microbial Fuel Cell's Performance [J]. Environment, Energy and Climate Change II, 2014, 34: 175–197
[4] Katuri K P, Scott K, Head I M, et al. Microbial fuel cells meet with external resistance [J]. Bioresource Technology, 2011, 102(3): 2758-2766.
Point 3: line 126: Mention the sequence of primers and PCR conditions.
Response 3: Thank you very much for your kind comment. According to the report provided by the testing company, the sequence of primers and PCR conditions were shown as follows.
DNA extraction was performed using the E.Z.N.A™ Mag-Bind Soil DNA Kit, followed by two rounds of PCR amplification.
For the first round of PCR amplification, the amplification system was as follows:
Table 1 PCR amplification system
|
Component |
Volume |
|
2×Hieff®RobustPCRMasterMix |
15 µL |
|
Bar-PCR primerF |
1 µL |
|
PrimerR |
1 µL |
|
PCR products |
10~20 ng |
|
H2O |
9~12 µL |
|
Total volume |
30 µL |
Mix gently by pipetting or shaking and centrifuge briefly to bring the reaction solution to the bottom of the tube. Place the PCR tube in the PCR instrument for amplification. PCR reaction conditions:
Table 2 PCR reaction conditions
|
Temperature |
Time |
|
95°C |
3 min |
|
94°C |
20 sec |
|
55°C |
20 sec |
|
72°C |
30 sec |
|
72°C |
5 min |
|
10°C |
∞ |
For the second round of amplification, Illumina bridge PCR compatible primers were introduced into sterile PCR tubes (200 µL) and the reaction system shown in the following table was prepared:
Table 3 PCR amplification system
|
Component |
Volume |
|
2×Hieff®RobustPCRMasterMix |
15 µL |
|
PrimerF |
1 µL |
|
Index-PCR PrimerR |
1 µL |
|
PCR products |
20~30 ng |
|
H2O |
9~12 µL |
|
Total volume |
30 µL |
Mix gently by pipetting or shaking and centrifuge briefly to bring the reaction solution to the bottom of the tube. Place the PCR tube in the PCR instrument for amplification. PCR reaction conditions:
Table 4 PCR reaction conditions
|
Temperature |
Time |
|
95°C |
3 min |
|
94°C |
20 sec |
|
55°C |
20 sec |
|
72°C |
30 sec |
|
72°C |
5 min |
|
10°C |
∞ |
For the sake of brevity, the above content was not displayed in the manuscript.
Point 4: line 129: Mention the MEGA software version.
Response 4: Thank you very much for your kind comment. The MEGA software version was V7.0.26. The modification parts were displayed with the "Track Changes" function.
Point 5: It is necessary to write the accession number of the sequences registered in GenBank.
Response 5: Thank you very much for your kind comment. We are sorry that we are not registered in GenBank. The C. fodinicola and T. barcinensis were just deposited in China General Microbiological Culture Collection Center. In subsequent studies, we will take care to register in Genbank.
Point 6: It is necessary to perform a statistical analysis in Table No. 1, under which conditions copper leaching is significantly better. Based on the percentage, it is not possible to check whether the results are significant or not
Response 6: Thank you very much for your kind comment. To make the results easier to understand, the Tables have been reconstructed.
Table 1. Copper leaching rate by C. fodinicola.
|
Microorganisms |
Leaching time/(d) |
Copper leaching rate (%) |
||||
|
1% (w/v) |
2% (w/v) |
3% (w/v) |
4% (w/v) |
5% (w/v) |
||
|
C. fodinicola |
1 |
3.9±0.2 |
4.1±0.2 |
4.3±0.4 |
4.9±0.3 |
4.0±0.1 |
|
2 |
4.1±0.3 |
5.0±0.2 |
5.1±0.3 |
5.6±0.2 |
4.7±0.3 |
|
|
3 |
8.8±0.3 |
21.28±0.1 |
35.3±0.1 |
86.4±0.2 |
75.5±0.3 |
|
|
4 |
20.0±0.1 |
27.28±0.2 |
64.5±0.2 |
88.8±0.1 |
81.9±0.3 |
|
|
5 |
26.7±0.4 |
36.9±0.2 |
67.6±0.2 |
89.2±0.3 |
88.3±0.3 |
|
Table 2. Copper leaching rate by T. barcinensis.
|
Microorganisms |
Leaching time/(d) |
Copper leaching rate (%) |
||||
|
1% (w/v) |
2% (w/v) |
3% (w/v) |
4% (w/v) |
5% (w/v) |
||
|
T. barcinensis |
1 |
20.6±0.1 |
32.32±0.3 |
34.0±0.2 |
44.0±0.3 |
45.0±0.3 |
|
2 |
32.0±0.2 |
40.0±0.4 |
45.1±0.3 |
47.0±0.2 |
50.2±0.3 |
|
|
3 |
36.8±0.3 |
48.0±0.1 |
55.0±0.4 |
60.0±0.3 |
78.0±0.1 |
|
|
4 |
44.2±0.2 |
55.0±0.2 |
60.0±0.3 |
67.0±0.1 |
89.0±0.3 |
|
|
5 |
24.1±0.3 |
44.64±0.3 |
45.2±0.1 |
54.0±0.2 |
60.2±0.4 |
|
It could be seen from Table 1, the maximum leaching rate of 89.2 % was achieved at a 4% (w/v) dosage of WPCBs and a leaching time of 5 d for copper leaching with C. fodinicola. Table 2 showed that the maximum leaching rate of 89.0 % was achieved at a 5% (w/v) dosage of WPCBs and a leaching time of 4 d for copper leaching with T. barcinensis.
Point 7: line 181: Penicillium chrysogenum should be in italics. The names of organisms should be italicized. This principle is not observed in the figures either.
Response 7: Thank you very much for your kind comment. We have made modifications. The modification parts were displayed with the "Track Changes" function.
Point 8: In the conclusion, the role of this study in preserving the environment should be mentioned.
Response 8: Thank you very much for your kind comment. The sentence “The process does not require the consumption of hazardous chemicals such as sulphuric acid, and the leaching process does not produce secondary pollution, which effectively reduces the pollution of the environment. In addition, the current generated by the MFC replaces the conventional power supply in the electrolytic process for the reduction of Cu2+, which effectively reduces treatment costs.” has been added. The modification parts were displayed with the "Track Changes" function.
Author Response File: Author Response.docx
