Determination of Electrogenic Potential and Removal of Organic Matter from Industrial Coffee Wastewater Using a Native Community in a Non-Conventional Microbial Fuel Cell
Round 1
Reviewer 1 Report
Extending MFC research from municipal to agro-industrial wastewater treatment is certainly interseting and valuable. Unforetunetly this publication is substandard.
Examples of major problems:
The title of the manuscript is inaccurate and also lowers the value of this work. It would be more accurate to state: "Comparing enriched vs. non enriched EAB cultures for coffee production wastewater treatment"
This is also refelected in the introduction, which could be summarised with: "In a previous publication MFC for treating CWW were developed and tested." I.e. the introduction is very generic and has little to do with presenting/establishing the required backround to discuss the results.
This statement in the disccusion: "However, there [are] no reports of the application of these techniques in native microbial communities obtained directly [from] the specific wastewater used as substrate in anodic chamber" is not true at all. There are an increasing number of publications which have dealt with this for e.g. domestic waste water as well as the cross-adaptation of mixed cultures to other functionalities.
This "The cyclic voltammetry analysis with reference electrodes and the experimental electrodes was evidence of the system ability to transfer electrons (energy generation) in the non-conventional MFCs used in this study. The behavior exhibited in the tests carried out through a The CV analyzes show the same current peaks for the oxidation of 0.3 mA and -0.3 mA for the reduction of the reference electrolyte (Fe(CN)6) in the tests carried out on the reference electrodes and the carbon electrodes used to the unconventional MFC. These results shown a similar magnitude of redox current indicating that MFC electrodes fabricated with carbon felt have electric charge transfer properties suitable for energy recovery without limitations in this BES." at the beginning of the results, is pointless, since you did not account for internal resistances and differences between EAB and Fe(II)/Fe(III) reaction kinetics.
Your use of the term "treatment" is not good. Either use experiment (i.e. set of conditions), or batch depending on what it is exactly you mean.
Calling your reactors: "non-conventional microbial fuel cells", when there are hundreds of studies where carbon felt/cloth were used for the electrodes is bad and even more so when this is not followed up with a comparison of your reactors to others...
The formating of this manuscript is poor:
- Disjointed results & discussion make it hard to read and follow your train of thought. Please adhear to the standard of text results, figure/table results and then discussion there of, next for next set of results, and then discussion of meta results.
- Unformated screenshots (e.g. figure 12 and 13) from measurement and calculation software, generally doesn't belong in a publication, especially when the formating has a y-axis showing only 0,00000 A.
- The abreviation for current density is [j], the abreviation for voltage is [U] or [deltaE] when determined from two potentials [E], power density doesn't have an abreviation and you should adhear to international naming conventions, making section 3.3 unnecessary.
- The description of structure of the experments needs to be improved. How many reactors were used, two for each set of experimental conditions? How many bactches (last 3 of each duplicate? All for each duplicate?) were statistically analysed?
I hope this helps you make improvements to this publication and your future ones.
Author Response
Dear reviewer,
thank you for your comments and observations, we send you a document with the considerations and corrections. Additionally, we will send the document to correct it in the language review service of the journal to improve description and redaction of the content.
Best regards.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors were demonstrated the information in a systematic way with good number of citation. This representation of the topic is very basic. It is also necessary to critically evaluate and do not make hasty conclusions, which may lead to misinterpretations. Several points are important to be addressed before going to possible publication in this high-quality journal. In addition, the authors need to address all points in the revision stage for broad range readers understanding.
1. Abstract: Please keep in mind that this section is completely different from the Introduction section. Authors are suggested to mention the novelty of the study clearly. The authors need to consider these points in the revision stage.
2. The Introduction section needs to be extended with describing the cause, fatality, novelty of the work, advantages and disadvantages of the present study, which is clearly missing.
3. Therefore, the abstract and introduction needs to be improved.
4. The Fig 1: should be the schematic diagram and the experimental set up and should be placed in the material and methods section.
5. The description of material and methods section is little complicated. Please update.
6. There is no proper representation of material and methods section; like Experimental set up, Analysis etc.
7. Missing of wastewater characterization.
8. Basic format for submission paper is missing. Confusion in fig with title.
9. Graphs could be better. Please modify.
1 Missing of error bar, control study and the replication of analysis.
Comments for author File: Comments.docx
Author Response
Dear reviewer,
thank you for your comments and observations, we send you a document with the considerations and corrections. Additionally, we send the document to correct its wording and content in the language review service of the journal. In this way, we will deepen the topics exposed in items 1-3 and 5.
In response:
4. We have changed the fig. 1 to show a more detailed view of the MFC.
6. We complement the description of materials and methods with subtitles to further detail this section.
7. In this document, we only present the organic matter craterization of the substrates.
8. We use a journal template to upload the document.
9-10. We adjusted the nomenclature of the graphs and presented the error bars in the diagrams.
Best regards.
Author Response File: Author Response.docx
Reviewer 3 Report
Title: -Determination of electrogenic potential and removal of organic matter from industrial coffee wastewater using a native community in a no-conventional Microbial Fuel Cell.
Manuscript ID: processes-2055898
In general, this work is so interesting and has value added results for future large scale applications towards industrial wastewater treatment. The author focused on generating renewable energy removal of organic matter from industrial coffee wastewater using a native community in a no-conventional Microbial Fuel Cell. However, the report of this work has some significant drawbacks and therefore, I suggest accepting this work after minor corrections. However, to fulfill the insufficient justification and analysis of data in this present work, the following comments should be incorporated.
1. Given the topic and scope of the paper, some recently MFC work (Frontiers in Nanotechnology, 4 (2022) 1–16; Chemical Engineering Journal Advances, 10 (2022) 100283; Sensing and Bio-Sensing Research, 36 (2022) 100484; Journal of Chemical Reviews, 2021 3(4) 320–344; Journal of Nanomaterials, 2021 (2021) 1–21; Nano-Structures & Nano-Objects, 25 (2021) 100663; All Life, 14 (2021) 541–568; Materials Science for Energy Technologies, 3 (2020) 136–149; Journal of Science: Advanced Materials and Devices, 4 (2019) 353–369) should be highlighted in the introduction and discussion part to broaden the readership.
2. Please carefully check the sentences again. I strongly encourage the authors to ask a native English speaker to brush up English.
3. Why you choose Conventional Titanium wire other than commonly used copper wire? Justify?
4. Since commercially available activated carbon is not recommended to use a supporting conductor due to its expensiveness and non-renewability of its precursor. So, to scale up the cell, such constraints limit the wide applications of activated carbon. Therefore, what is your future recommendation on this?
5. Since you use a factorial experimental design to optimize all the possible factors. Why not you choose response surface methodology? Because it is gives more accurate result than factorial experimental design. So, justify why you choose factorial experimental design?
6. What is your evidence to choose a mixed inoculum?
7. Line 152 it says…”The internal resistances of the systems that oscillated in the range of 1000 – 3800 Ω. This resistance is too much bigger and reduce the performance of energy production and treatment efficiency. So, would you please revise it?
8. What was the real distance between anode and cathode electrode on your MFC?
9. Line 169… COD removal rates between 400 – 600 mgO2 L-1 day-1 were reached, the results are shown… did you mean 400 – 600 mg L-1?
10. Does your MFC assembly fulfills the minimum standard cell set up performance?
Comments for author File: Comments.docx
Author Response
Dear reviewer,
thank you for your comments and observations, we send you a document with the considerations and corrections.
In response:
1-2. We send the manuscript to the journal for language review and we are evaluating the actualization of references.
3. We have chosen Ti wire as a cost-effective alternative to Pt wire and Cu wire could have an antimicrobial activity.
4. For scale-up MFC with activated carbon cathod compunds we should recomend and evaluate other carbon derivatives (including mineral and natural carbon).
5. The factorial experimental design was chosed to complement this explorative/descriptive investigation. Surface response design should be the next step to imporve and optimice the application of MFCs.
6. We evaluated the Mixed Inoculum in order to evaluate a more complete wastewater native microbial community present in both substrates.
7. We have checked the internal resistance sentence.
8. The distance between electrodes were 4 mm, we have changed the fig. 1 to show a more detailed view of the MFC.
9. We have changed the mgO2.L-1 notation to mg.L-1.
10. The MFCs configurantion and performance were tested in previos experimentation so they fullfill minimum standard cell set up.
Best regards.
Author Response File: Author Response.docx
