Challenges in Designing Electrochemical Disinfection Systems for Reducing Microbial Contamination in Drinking Water Distribution Networks

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

This is an important article that contains necessary criticism of recent publications in the field of electrochemical water disinfection. This completely justified criticism will help to improve research in this field. Therefore, this article should be published in the journal in its current form.

Author Response

Comments and Suggestions for Authors. This is an important article that contains necessary criticism of recent publications in the field of electrochemical water disinfection. This completely justified criticism will help to improve research in this field. Therefore, this article should be published in the journal in its current form.

I thank the Reviewer for taking the time to read my contribution and for his/her very positive opinion. I would like to point out that, in an attempt to further improve the form and the English, I decided to slightly modify the title and to rewrite both the Abstract and the Conclusions. If contacted for further opinion, I hope that the Reviewer will approve these changes.

Reviewer 2 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

It can be accepted for publication

Author Response

Comments and Suggestions for Authors. It can be accepted for publication

I thank the Reviewer for taking the time to read my contribution and for his/her very positive opinion. I would like to point out that, in an attempt to further improve the form and the English, I decided to slightly modify the title and to rewrite both the Abstract and the Conclusions. If contacted for further opinion, I hope that the Reviewer will approve these changes.

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Problems with designing an electrochemical disinfection approach to reduce microbial contamination of drinking water distribution systems

This manuscript about analyzing the problems in reducing the microbial contamination in an electrochemical disinfection approach. This idea is very good and it’s focusing the real world problem, but I have found the following flaws

1.                  This manuscript discussing the very limited publication.

2.                  This is not contains challenges & future perspectives.

3.                  Need to be included illustrations, schematics and more tables

 

4.                  It is not well organized for publication.

Author Response

Comments and Suggestions for Authors. This manuscript about analyzing the problems in reducing the microbial contamination in an electrochemical disinfection approach. This idea is very good and it’s focusing the real world problem, but I have found the following flaws

1. This manuscript discussing the very limited publication.
2. This is not contain challenges & future perspectives.
3. Need to be included illustrations, schematics and more tables
4. It is not well organized for publication.

 

I thank the Reviewer for taking the time to read my contribution. As for the comments raised, the aim of the contribution was to comment on the works published in the last 2 years, regarding approaches theoretically suitable to perform an electrochemical disinfection of drinking water. I agree with the Reviewer that the number of publications can be considered "limited"; however, this has allowed the detailed analysis of each work, and I believe that the result is an original and motivated criticism, which I hope will help to improve the research activity on the topic.

In an attempt to further improve the form and English, I have completely revised the manuscript and have also decided to slightly change the title. Both the Abstract and Conclusion sections have been rewritten, and I hope the Reviewer will appreciate the changes; the conclusion section now contains explicit reference to challenges & future perspectives. 

Also, a new paragraph has been added at the beginning of Section 4 to briefly discuss the disinfection mechanisms.

Tables 1 and 2 present the list of works published in the last 12 months, and in the previous 12 months, respectively. Considering the Reviewer’s request, I have revised the tables, adding a column to include the main disinfection approach discussed in each work. I hope the Reviewer will approve these changes.

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

Comments for Editor and Authors

A review article has been prepared by the authors about the problems with designing an electrochemical disinfection approach to reduce microbial contamination of drinking water distribution systems. The study is well planned. After considering the suggestions given below, it is appropriate to publish it in the journal Water.

1. The abstract should be improved to reflect the importance of the study.
2. The studies discussed in the review article were accessed from which database and using which keywords? Providing this information would enhance the transparency and credibility of the research process. The study includes published works from the last two years, which ensures a focus on recent developments. However, expanding the search to include studies from the last five years could have provided a more comprehensive perspective, capturing broader trends and deeper insights. A more extensive literature review would strengthen the study’s impact and contribute to a more well-rounded discussion.
3. In line 72, 73 “Wen et al. [9]” This reference does not belong to Wen et al. It should be checked and corrected.
4. In line 332, “…unregulated contaminants are listed in Table 4.1”. Table 4.1 is not included in the manuscript. It should be checked.

Author Response

Comments for Editor and Authors. A review article has been prepared by the authors about the problems with designing an electrochemical disinfection approach to reduce microbial contamination of drinking water distribution systems. The study is well planned. After considering the suggestions given below, it is appropriate to publish it in the journal Water.

1. The abstract should be improved to reflect the importance of the study.
2. The studies discussed in the review article were accessed from which database and using which keywords? Providing this information would enhance the transparency and credibility of the research process. The study includes published works from the last two years, which ensures a focus on recent developments. However, expanding the search to include studies from the last five years could have provided a more comprehensive perspective, capturing broader trends and deeper insights. A more extensive literature review would strengthen the study’s impact and contribute to a more well-rounded discussion.
3. In line 72, 73 “Wen et al. [9]” This reference does not belong to Wen et al. It should be checked and corrected.
4. In line 332, “…unregulated contaminants are listed in Table 4.1”. Table 4.1 is not included in the manuscript. It should be checked.

I thank the Reviewer for taking the time to read my contribution and for his/her substantially positive opinion. In an attempt to further improve the form and the English, I have completely revised the manuscript and have also decided to slightly change the title. Both the Abstract and Conclusion sections have been rewritten, and I hope the Reviewer will appreciate the changes.

The references cited in lines 72 and 73 (74 and 75 in the revised form of the manuscript) have been corrected: I thank the Reviewer for pointing out these errors.

Line 332 (338 in the revised form of the manuscript) refers to ref. 35; I have added the detail. Table 4.1 in [35] is a very long collection of data, extending from page 43 to page 180.

Finally, the articles discussed in the contribution were identified using the SciFinder database, a resource of the Chemical Abstracts Service (CAS); it is a database of chemical and bibliographic information that covers various scientific and biomedical fields, with an emphasis on chemistry. According to CAS, SciFinder provides access to the world's most comprehensive and authoritative source of references, substances, and reactions in chemistry and related sciences.

The search was performed starting with "drinking water" (304,710 results), limiting the search to articles published since 2023 (31,980 results) and then searching for "electrochemical disinfection" as a filter. This reduced the list to 3,936 results, which were further filtered by limiting the sources to journals and reviews (2,886 results). SciFinder provides the title, abstract, and links to the various works, highlighting the keywords used. Scrolling through the results it was then possible to select the works of interest. If the reviewer feels that any relevant works have been missed, I would greatly appreciate the information to retrieve them.

Reviewer 5 Report (New Reviewer)

Comments and Suggestions for Authors

It is an interesting commentary review article on the aspects of electrochemical disinfection. The author pointed out several points worth noticing in this area, and proposed some possible future directions. I have a few critical comments that would like the author to address before publication.

1. Table 1 listed only the name of the papers without a clear classicfication of mechanism and operating conditions; thus this table is hardly informative. Please use provide more details in Table 1, classification such as electrochemical H2O2 generation, electroporation, electrochlorination, operational parameters such as current density, and performance metrics.
2. Same comment applies to Table 2.
3. Please give a brief introduction of different electrochemical disinfection mechanisms and drinking water regulation limit (part 4), otherwise it is hard to understand the discussion.

Comments on the Quality of English Language

No comments.

Author Response

Comments and Suggestions for Authors. It is an interesting commentary review article on the aspects of electrochemical disinfection. The author pointed out several points worth noticing in this area, and proposed some possible future directions. I have a few critical comments that would like the author to address before publication.

1. Table 1 listed only the name of the papers without a clear classification of mechanism and operating conditions; thus this table is hardly informative. Please provide more details in Table 1, classification such as electrochemical H2O2 generation, electroporation, electrochlorination, operational parameters such as current density, and performance metrics.
2. Same comment applies to Table 2.
3. Please give a brief introduction of different electrochemical disinfection mechanisms and drinking water regulation limit (part 4), otherwise it is hard to understand the discussion.

Comments on the Quality of English Language. No comments.

 

I thank the Reviewer for taking the time to read my contribution and for his substantially positive opinion. Tables 1 and 2 present the list of works published in the last 12 months, and in the previous 12 months, respectively, specifying the publication date (reported in each work, usually in the form "available online"). The works are quite different from each other: most of them are articles, but there are also some reviews; furthermore, not all the works are of an electrochemical nature (I could have excluded them, but I preferred not to do so, because it seemed interesting to me to keep them). Considering the above, and the Reviewer’s request, I have revised the tables, adding a column to include the main disinfection approach discussed in each work. I hope the Reviewer will approve these changes.

In an attempt to further improve the form and English, I have completely revised the manuscript and have also decided to slightly change the title. Both the Abstract and Conclusion sections have been rewritten, and the conclusion section now contains explicit reference to challenges & future perspectives. To address the Reviewer’s request, a new paragraph has been added at the beginning of Section 4 to briefly discuss the disinfection mechanisms.

Regarding the regulatory limits for drinking water, the reference to NSF standards 61 and 600 is already reported at the beginning of Section 4. Following the format changes introduced, I hope that the Reviewer will find the discussion easier to understand.

Round 2

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

The current format of this manuscript is much improved and need to check spell, type errors by the author.

Reviewer 5 Report (New Reviewer)

Comments and Suggestions for Authors

I have no further comments.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a very good and important article that critically examines recently published scientific articles on the subject of electrochemical water disinfection. This is also urgently needed because many works in this field are characterized by a lack of practical relevance. In addition, some of the current research works use and investigate materials or structures that cannot be used in practice. It is therefore to be hoped that this article will improve the quality of research in the field of electrochemical water disinfection. In my view, the manuscript can be published as it is now.

Author Response

I sincerely thank the Reviewer for his/her comments and appreciation for the contribution under discussion. I obviously agree with him/her that most of the works published on the subject are devoid of practical relevance, representing a problem both from a scientific and health points of view.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript provides a valuable critique of the current state of electrochemical disinfection research. It highlights significant gaps and emphasizes the importance of regulatory compliance.

1.       The abstract is well-written but could elaborate on key findings or recommendations.

2.       Abstract line 11, “This review provides comments……” should be rephrased in correct English, such as “This review highlights the key areas where researchers should focus more closely and outlines the critical features a disinfection system must possess for successful application in real-world settings”.

3.       Include specific findings or conclusions drawn from the review in the abstract.

4.       Line 30-33, “In most cases, the accountability…………before reaching the water outlets”. This is a very lengthy and awkward sentence. It must be broken into 2 to 3 meaningful sentences. Similarly, the next sentence “This is the case of……..” should also be rephrased.

5.       There is no reference in the first two paragraphs of introduction. Kindly start the introduction with some general sentences such as “Groundwater, a vital source of drinking water, has been exposed to numerous pollution risks over time. As manufacturing technologies have advanced, new categories of pollutants have emerged, entering the environment and being detected across various water bodies, including groundwater, as reported in https://doi.org/10.1016/j.seppur.2024.129566 ” Kindly add the following in references.  

https://doi.org/10.1016/j.jece.2024.113920

6.       Line 41-50, add some references to these paragraphs please.

 

Comments for author File: Comments.pdf

Author Response

Reviewer 2

The manuscript provides a valuable critique of the current state of electrochemical disinfection research. It highlights significant gaps and emphasizes the importance of regulatory compliance.

I sincerely thank the Reviewer for his/her comments and appreciation for the contribution under discussion. I obviously agree with him/her that most of the works published on the subject have significant gaps as they do not consider regulatory compliance.

1. The abstract is well-written but could elaborate on key findings or recommendations.

The abstract is short, since it does not seem possible to say much more, based on the works discussed in the review. However, thanks to the Reviewer’s contribution, the sentence “The importance of proposing systems that comply with current regulations is also emphasized” has been added. As the Reviewer will certainly have noticed (reading the contribution), all the works related to the topic and published in the last 24 months are substantially irrelevant, either due to conceptual errors, or inappropriate choices, which would preclude a practical application.

2. Abstract line 11, “This review provides comments…” should be rephrased in correct English, such as “This review highlights the key areas where researchers should focus more closely and outlines the critical features a disinfection system must possess for successful application in real-world settings”.

The original version of the sentence has been replaced with the one proposed by the Reviewer.

3. Include specific findings or conclusions drawn from the review in the abstract.

Please see my response to comment #1.

4. Line 30-33, “In most cases, the accountability…………before reaching the water outlets”. This is a very lengthy and awkward sentence. It must be broken into 2 to 3 meaningful sentences. Similarly, the next sentence “This is the case of…” should also be rephrased.

As suggested, the first sentence was divided into 2 parts. The same was done with the following sentence.

5. There is no reference in the first two paragraphs of introduction. Kindly start the introduction with some general sentences such as “Groundwater, a vital source of drinking water, has been exposed to numerous pollution risks over time. As manufacturing technologies have advanced, new categories of pollutants have emerged, entering the environment and being detected across various water bodies, including groundwater, as reported in https://doi.org/10.1016/j.seppur.2024.129566”

Kindly add the following in references: https://doi.org/10.1016/j.jece.2024.113920

I thank the Reviewer for his/her suggestions; unfortunately, the two suggested works concern the remediation of contaminated groundwater, while this review focuses on the treatment of drinking water, with the aim of providing the end user with water that is more microbiologically safe. Although the Reviewer suggested a paragraph stating that groundwater is an important source of drinking water, it is clear from the suggested works that appropriate purification treatments may be needed before the water is suitable for human consumption. For obvious reasons, these treatments are not among those discussed here, and it seems inappropriate to include the suggested comment.

A new reference ([1] in the updated list) has been added at the end of the first paragraph and towards the end of the second paragraph.

6. Line 41-50, add some references to these paragraphs please.

A new reference ([4] in the updated list) has been added to support the first sentence (lines 42-44 in the revised manuscript).

The following sentence (lines 44-47 in the revised manuscript) is very general in content, since it only provides a list of possible chemicals used to control pathogens in drinking water; however, a new reference has been added here as well ([5] in the updated list).

Reviewer 3 Report

Comments and Suggestions for Authors

Based on the following comments, I think this review article is not complete enough and must be rejected.

 

Although the title highlights “Problems with designing an electrochemical disinfection process”, the author reported no information about the process description of the considered matter and its associated problems.

Following my previous comment, this review article must include some real-world applications of the mentioned process, their associated problems, the potential solution methods for these problems, and so on.

Generally, this document does not follow the standard structure of a review article. The author is advised to read several review articles about water treatment processes and adjust his own article based on.

The abstract is too short and presents limited information. I think the author can pay more attention to modifying the abstract and making it more interesting.

The review article often includes a section focusing on introducing future potential research in the investigated field. Here, the electrochemical disinfection approach to reduce microbial contamination of drinking water.

Where is the conclusions section of the review article?!!!

32 references are not enough for preparing a review article.

Author Response

Reviewer 3

Based on the following comments, I think this review article is not complete enough and must be rejected.

I thank the reviewer for taking the time to read the manuscript; however, I disagree with his judgment, for the reasons detailed below.

Although the title highlights “Problems with designing an electrochemical disinfection process”, the author reported no information about the process description of the considered matter and its associated problems.

I respectfully disagree with the Reviewer: guidance on the most important features of a properly designed drinking water disinfection device can be found starting on the second page of the “general discussion” section. Furthermore, my comments about the published papers point out in a timely and detailed manner the problems of each approach suggested by the works published in the last 24 months. The reviewer may or may not agree with my comments, which clearly express my point of view, but I believe that this is not enough to reject a work (as proof of this, the other reviewers support its publication).

Following my previous comment, this review article must include some real-world applications of the mentioned process, their associated problems, the potential solution methods for these problems, and so on.

Real-world applications exist and are mentioned in the cited website (see lines 405-410); they have not been discussed in detail in this work to limit/avoid criticism on an obvious conflict of interest.

Generally, this document does not follow the standard structure of a review article. The author is advised to read several review articles about water treatment processes and adjust his own article based on.

According to the Instructions for Authors on the Water (MDPI) website, Review manuscripts should comprise:

• Front matter: Title, Author list, Affiliations, Abstract, Keywords.
• Review sections: a literature review organized logically within specific sections and subsections (optional).
• Back matter: Acknowledgments, Author Contributions, Conflicts of Interest, References.

Based on the above, no “standard structure” (e.g., Introduction, Materials and Methods, Results, Discussion, Conclusions) for a review manuscript is required.

The abstract is too short and presents limited information. I think the author can pay more attention to modifying the abstract and making it more interesting.

The abstract is short, since it does not seem possible to say much more, based on the works discussed in the review. However, the sentence “The importance of proposing systems that comply with current regulations is also emphasized” has been added. As the Reviewer will certainly have noticed (reading the contribution), all the works related to the topic and published in the last 24 months are substantially irrelevant, either due to conceptual errors, or inappropriate choices, which would preclude a practical application.

The review article often includes a section focusing on introducing future potential research in the investigated field. Here, the electrochemical disinfection approach to reduce microbial contamination of drinking water.

Where is the conclusions section of the review article?!!!

As previously commented, the Reviewer's request is not supported by the Journal's editorial decisions, as Water does not provide any “standard structure” (e.g., Introduction, Materials and Methods, Results, Discussion, Conclusions) for a review manuscript. Since no general conclusions can be drawn from the review of the discussed articles (other than perhaps a generic "let's start over, paying attention to the details"), the contribution includes a concluding paragraph (and not a conclusions section) before the references (lines 411-413).

32 references are not enough for preparing a review article.

This review discusses all the works related to the topic and published in the last 24 months.
To increase the number of references, it would be necessary to consider works published in a wider time frame; however, it seems worrying that the only contribution (in my opinion) worthy of note dates back to 2008. I fear that widening the time frame of the published works would mean criticizing a greater number of works, without adding useful indications.

Reviewer 4 Report

Comments and Suggestions for Authors

Title: Problems with designing an electrochemical disinfection approach to reduce microbial contamination of drinking water distribution systems

Recommendation: Major revisions needed as noted.

1. Please Improve the ABSTRACT, e.g identifying flaws, proposing solutions, or setting a research agenda.

2. Conclusion is missing, please add conclusion.

3. Careful revision of English grammar or typographical errors are need.

4. The language used is mostly clear, but there are some areas where sentence structure can be simplified for readability.

5. It is necessary to incorporate clear reasoning and establish strong connections between sentences and paragraph to enhance the overall flow and coherence of the article.

6. Include diagrams or schematics of typical electrochemical disinfection setups and the proposed improvements. A flowchart comparing current methods versus ideal system designs would help readers visualize the gaps and solutions.

7. Please discuss some articles about the cost implications of system, including material selection and system design adjustments, as well as the lifecycle analysis.

8. Incorporate particular indicators, such as energy usage, contaminant removal rates, and chlorine generating efficiency, to assess the effectiveness and safety of disinfection systems.

 

 

Comments on the Quality of English Language

need improvement. 

Author Response

Reviewer 4

Title: Problems with designing an electrochemical disinfection approach to reduce microbial contamination of drinking water distribution systems

Recommendation: Major revisions needed as noted.

I thank the reviewer for taking the time to read the manuscript; however, I disagree with his judgment (major revisions needed), for the reasons detailed below.

1. Please Improve the ABSTRACT, e.g. identifying flaws, proposing solutions, or setting a research agenda.

The abstract is short, since it does not seem possible to say much more, based on the works discussed in the review. However, the sentence “The importance of proposing systems that comply with current regulations is also emphasized” has been added. As the Reviewer will certainly have noticed (reading the contribution), all the works related to the topic and published in the last 24 months are substantially irrelevant, either due to conceptual errors, or inappropriate choices, which would preclude a practical application.

As for a possible research agenda, commercial systems are now available (see lines 405-410), indicating that research has reached an acceptable level. As with all things, improvements are desirable, but this is sensitive information.

2. Conclusion is missing, please add conclusion.

According to the Instructions for Authors on the Water (MDPI) website, Review manuscripts should comprise:

• Front matter: Title, Author list, Affiliations, Abstract, Keywords.
• Review sections: a literature review organized logically within specific sections and subsections (optional).
• Back matter: Acknowledgments, Author Contributions, Conflicts of Interest, References.

Based on the above, no “standard structure” (e.g., Introduction, Materials and Methods, Results, Discussion, Conclusions) for a review manuscript is required.

3. Careful revision of English grammar or typographical errors are need.

This is a very general observation, which could be responded to by saying "Thank you, I have revised the English and corrected any typos"; if the Reviewer found something that needs correction, I would appreciate a specific comment or at least the line number to look for (by the way, the Reviewer’s sentence should read “Careful revision of English grammar or typographical errors is needed”)

4. The language used is mostly clear, but there are some areas where sentence structure can be simplified for readability.

As also pointed out by Reviewer #2, a couple of paragraphs at the beginning (lines 31-41 I the revised manuscript) have been revised for readability.

5. It is necessary to incorporate clear reasoning and establish strong connections between sentences and paragraph to enhance the overall flow and coherence of the article.

Again, this is a very general observation and of little use. Reviewer #1 commented "In my opinion, the manuscript can be published as it is now", so it's a bit difficult to improve something without knowing what's wrong (but others say is fine as is).

6. Include diagrams or schematics of typical electrochemical disinfection setups and the proposed improvements. A flowchart comparing current methods versus ideal system designs would help readers visualize the gaps and solutions.

A comment has been added towards the end of the contribution (see lines 409-410), to guide the reader through the ebooster.com.au website and find directions on how a system can be installed. Unfortunately, I am unable to add further details in the paper in order to limit/avoid criticism on an obvious conflict of interest.

7. Please discuss some articles about the cost implications of system, including material selection and system design adjustments, as well as the lifecycle analysis.

A rough indication of the costs of a system was provided in my previous contribution (ref. [23] in the updated list); as the Reviewer will surely understand, the cost of a system depends on the specific application (reactor size, number of reactors, management mode, accessory instrumentation, etc.)

The expected lifetime depends on the operating conditions: the higher the current fed into the electrochemical reactor, the shorter the expected lifetime of the electrodes. An estimate can be obtained by dividing 2,000,000 by the applied current density; for example, if a system operates at an average current density of 200 A/m2, its expected lifetime is about 10,000 hours.

8. Incorporate particular indicators, such as energy usage, contaminant removal rates, and chlorine generating efficiency, to assess the effectiveness and safety of disinfection systems.

For guidance on operating parameters and/or energy consumption, the Reviewer is invited to look at the case studies/installation examples on the website (https://ebooster.com.au/case-studies-main and related subpages). Considering that most of the systems have been installed in public hospitals supervised by the Queensland Health Authority, their effectiveness and safety is evidenced by the fact that they are currently/still operational.

To avoid arguments, the Reviewer should keep in mind that this technology is relatively new and market acceptance is slow if references cannot be provided.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The author had a golden chance in the revision stage to at least resolve/address some of my concerns/comments. Unfortunately, no modifications are made based on my comments. So, I cannot support publishing this manuscript in the Water Journal.

Author Response

Reviewer #3 originally provided opinions on the manuscript that I did not agree with: he complained that the structure of the work was not what he/she had envisaged, and I explained that Water does not provide any pre-established structure for review articles (it does not matter if other reviews available in the literature have a structure more in line with the Reviewer's expectations).

The Reviewer also complained about the lack of a "Conclusions" section, and I explained the reasons for its absence in the present contribution.

The criticism about the number of bibliographical references also seems out of place: many reviews have a greater number of references, but certainly not a detailed analysis of their content.

Ultimately, I did not consider it necessary to make substantial changes to my work, also in light of the positive judgment of other Reviewers, who evidently approached the task with fewer prejudices.

The above clearly focuses on the form of the contribution, rather than on its substance.

Based on the above, from which it appears quite evident that the Reviewer's judgment is based more on the form of the contribution than on its substance, I respectfully reiterate that the comments received in round 1 were not (in my opinion) such as to require changes to the work.

Reviewer 4 Report

Comments and Suggestions for Authors

it is up to the editor to decide whether to accept or reject the manuscript.

Author Response

As the Editor may appreciate from the original comments of Reviewer 4 and my responses, the criticisms were mainly directed at the form of the contribution, rather than its substance. Contrary to the Reviewer’s expectations, Water does not provide/impose a pre-established structure for review papers; since my contribution is in line with the indications provided by Water, I did not feel it necessary to make any particular changes to the manuscript. The positive comments expressed by other Reviewers helped to support my decision.