Continuous Electrocoagulation Processes for Industrial Inorganic Pollutants Removal: A Critical Review of Performance and Applications

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper presents a comprehensive review published over the past 5 years on the development of Continuous Electrocoagulation Processes (CEP) for the treatment of industrial inorganic pollutants. Standalone electrocoagulation systems and combined CEP systems were described. The advantages and challenges of the CEP systems were revealed. Overall, it is a nice review that may benefit society. I recommend the publication     of it in this Journal.

 

Nevertheless, the typography of this manuscript needs be carefully improved

Author Response

Response to Reviewer 1

Dear Reviewer,

On behalf of all co-authors, I would like to sincerely thank you for your valuable time and constructive feedback on our manuscript entitled “Continuous Electrocoagulation Processes (CEP) for Industrial Inorganic Pollutants Removal: A Critical Review of Performance and Applications” (Manuscript No. water-3839049). We are truly grateful for your encouraging comments regarding the comprehensiveness of our review and its potential societal benefits.

Comment: This paper presents a comprehensive review published over the past 5 years on the development of Continuous Electrocoagulation Processes (CEP) for the treatment of industrial inorganic pollutants. Standalone electrocoagulation systems and combined CEP systems were described. The advantages and challenges of the CEP systems were revealed. Overall, it is a nice review that may benefit society. I recommend the publication of it in this Journal. Nevertheless, the typography of this manuscript needs be carefully improved.

Response: We sincerely thank the reviewer for the positive and encouraging feedback on our work. We are pleased that you found the review both comprehensive and beneficial to society. We also highly appreciate your constructive observation regarding typography. In response, we have subjected the manuscript to careful proofreading and thorough formatting improvements in order to enhance readability, clarity, and overall presentation. We believe these revisions have significantly improved the quality of the manuscript and ensured that it now fully meets the journal’s editorial standards.

Reviewer 2 Report

Comments and Suggestions for Authors

Overall assessment: Congrats on the great work! The review paper's topic is of academic and industrial significance and could attract the readers. It is well-written, a sufficient number of documents were reviewed, and the reviewed literature was analyzed well. The topic is relevant to the journal and within Water's scope. It is suitable for publication but requires major revisions. Please see the list of comments below.

List of comments:

Comment (1): The authors, please concisely add your perspective and viewpoint regarding the future outlook and research trends in the abstract section.

Comment (2): The authors referred to electrode passivation as one of the key challenges in the abstract. However, there is no in-depth discussion on the matter in the body of the paper. Please also specify what the interpretation of passivation is in this context. The word "passivation" could be interpreted broadly across disciplines. So, specifying its definition is essential to avoid confusion in the readers.

Comment (3): It is recommended to avoid using acronyms in the title of the paper.

Comment (4): In the last paragraph of the introduction section, please state the significance and novelty of this review compared with other reviews.

Comment (5): The language should be polished.

Comment (6): It is recommended that the authors read the following 2025 reference relevant to the topic and, if you see fit, use those publications to enhance your article: Water 17 (2025), Issue 15, 2351; iScience 28 (2025), Issue 3, 111965; Water 17 (2025), Issue 2, 173; Chemical Engineering and Processing-Process Intensification 209 (2025) 110150;

Comment (7): Please make sure that copyright permission is granted for all images borrowed from the literature.

Comment (8): Figures and Tables are very rich in content, prepared sufficiently, and explained. Well done!

Comment (9): Numerous acronyms and abbreviations have been used in the paper. Please provide a list of acronyms and abbreviations at the end of the paper to help readers easily find the definition of those terms and to avoid possible confusion.

Comment (10): Please prepare a SWOT chart (Strengths, Weaknesses, Opportunities, and Challenges, and summarise the key takeaways and add it to the paper as the last figure.

Comment (11): As it is a relatively long paper with multiple sections and numerous sub-sections, it is recommended to have a table of contents at the beginning of the paper to make it more organized.

Comment (12): Please further elaborate on the research trends and knowledge gaps in the conclusion section.

Comment (13): The Circular economy section of the paper requires more analysis of the literature, and please provide further explanations and discussion in sub-sections of this part.

Author Response

Responses to Reviewer 2

 

 

 

We have revised the manuscript by taking into consideration all your comments, and the responses are itemized for each reviewer. We believe that they have greatly enhanced the quality of the manuscript. All comments were addressed point-by-point and highlighted as follows:

Comment-1: The authors, please concisely add your perspective and viewpoint regarding the future outlook and research trends in the abstract section.

Response 1:   Thank you for your valuable suggestion. As recommended, we have revised the abstract to include a brief statement outlining our perspective on the future outlook and emerging research trends relevant to this study. This addition aims to provide readers with a clearer understanding of the broader implications and potential directions for future work. The abstract has been fully rewritten. It now highlights:

1. Current developments in continuous electrocoagulation (CEP).
2. The novelty of this review including critical assessment and comparative insights.
3. Key findings with advantages, limitations, and future opportunities for CEP.

Comment-2: The authors referred to electrode passivation as one of the key challenges in the abstract. However, there is no in-depth discussion on the matter in the body of the paper. Please also specify what the interpretation of passivation is in this context. The word "passivation" could be interpreted broadly across disciplines. So, specifying its definition is essential to avoid confusion in the readers.

Response 2: We thank the reviewer for highlighting this important point. In the revised manuscript, we have provided a clear definition and detailed discussion of electrode passivation. Specifically, we inserted a new paragraph (last paragraph) in Section 3.1 (Standalone CEP processes)

 “On the other hand, electrode passivation has emerged as the most frequently reported operational challenge in numerous studies on continuous electrocoagulation processes (CEP). This phenomenon involves the gradual accumulation of insulating layers—typically composed of metallic hydroxides, precipitated salts, or sludge particles—on the surface of the electrodes. Such deposits reduce the effective electroactive area, increase electrical resistance, and diminish the rate of coagulant generation, ultimately compromising the overall efficiency of pollutant removal. Passivation poses a significant challenge because it directly impacts energy consumption, process stability, and the long-term scalability of the treatment system. Various mitigation strategies have been proposed, including periodic polarity reversal, mechanical or chemical cleaning of the electrodes, hydrodynamic optimization to reduce sludge buildup, and pretreatment to lower suspended solid concentrations. The selection of electrode material is also critical, as aluminum and iron differ in their susceptibility to fouling depending on the wastewater composition. Effectively addressing electrode passivation is essential for maintaining optimal reactor performance and ensuring the sustainable industrial application of CEP.”

The added paragraph explains that, in the context of continuous electrocoagulation processes (CEP), electrode passivation refers to the progressive accumulation of insulating layers (e.g., metallic hydroxides, precipitated salts, or sludge particles) on electrode surfaces. This phenomenon reduces the electroactive area, increases electrical resistance, and lowers the rate of coagulant generation, which collectively diminishes pollutant removal efficiency. We also discuss its operational implications (higher energy demand, reduced stability, limited scalability) and summarize mitigation strategies such as polarity reversal, electrode cleaning, optimized hydrodynamics, pretreatment to reduce solids, and electrode material selection. This addition ensures consistency between the abstract and the body of the paper and clarifies the interpretation of “passivation” for readers across disciplines.

Comment-3: It is recommended to avoid using acronyms in the title of the paper.

Response 3: Thank you for your helpful recommendation. In accordance with your suggestion, we have revised the title to avoid the use of acronyms, aiming to improve clarity and accessibility for a broader readership.

Comment-4: In the last paragraph of the introduction section, please state the significance and novelty of this review compared with other reviews.

Response 4: Thank you for the valuable suggestion. As recommended, we have revised the last paragraph of the introduction to clearly state the significance and novelty of this review in comparison to existing literature. Specifically, we have highlighted how this review addresses [insert unique aspects—e.g., a comprehensive comparison of recent strategies, a focus on a specific application, inclusion of emerging technologies, etc.], which are either not covered or only briefly mentioned in previous reviews. This addition aims to clarify the distinct contribution of our work and its relevance to current research needs. The novelty of this review is clarified in the last part of the Introduction as:

“To the best of the authors' knowledge, literature lacks a comprehensive and critical review addressing the latest innovations in using CEP for removing inorganic pollutants from water and wastewater. This review seeks to fill that gap by systematically evaluating CEP’s performance in treating inorganic contaminants, highlighting recent advancements, assessing the effectiveness of different system configurations, exploring underlying mechanisms, and identifying knowledge gaps and future research directions to support the development of CEP as a sustainable and efficient industrial wastewater treatment technology.”

Comment-5: The language should be polished.

Response 5: Thank you for your comment. We have carefully revised the manuscript to improve the language, grammar, and overall readability. A thorough proofreading has been conducted to ensure the text is more polished and professional. We believe these improvements enhance the clarity and presentation of our work.

Comment-6: It is recommended that the authors read the following 2025 reference relevant to the topic and, if you see fit, use those publications to enhance your article: Water 17 (2025), Issue 15, 2351; iScience 28 (2025), Issue 3, 111965; Water 17 (2025), Issue 2, 173; Chemical Engineering and Processing-Process Intensification 209 (2025) 110150;

Response 6: We sincerely thank the reviewer for suggesting these recent and relevant references. We have carefully reviewed the suggested publications. Where appropriate, we have incorporated insights and citations from these works to strengthen our discussion and ensure the review reflects the latest advancements in the field. Accordingly, the following actions have been taken to the suggested references:

• Water 17 (2025), Issue 15, 2351 (Inserted to the manuscript-Ref. 98)
• iScience 28 (2025), Issue 3, 111965 (Inserted to the manuscript-Ref. 113)
• Water 17 (2025), Issue 2, 173 (Not related to the topic of the manuscript)
• Chemical Engineering and Processing – Process Intensification 209 (2025), 110150. (Inserted to the manuscript-Ref. 114)

Comment-7: Please make sure that copyright permission is granted for all images borrowed from the literature.

Response 7: Thank you for raising this important point. We have thoroughly reviewed all figures and images included in the manuscript. For any images borrowed or adapted from previously published literature, we have ensured that proper copyright permissions have been obtained from the respective publishers. Appropriate attributions have also been added to the figure captions in accordance with the copyright requirements

Comment-8: Figures and Tables are very rich in content, prepared sufficiently, and explained. Well done!

Response 8: We sincerely thank the reviewer for the positive feedback regarding the quality and clarity of the figures and tables. We appreciate your recognition and are glad that the visual content effectively supports the discussion in our manuscript.

Comment-9: Numerous acronyms and abbreviations have been used in the paper. Please provide a list of acronyms and abbreviations at the end of the paper to help readers easily find the definition of those terms and to avoid possible confusion.

Response 9: Thank you for your thoughtful suggestion. In response, we have added a comprehensive list of acronyms and abbreviations at the end of the manuscript. This list is intended to help readers easily reference the definitions of commonly used terms and minimize any potential confusion.

Comment-10: Please prepare a SWOT chart (Strengths, Weaknesses, Opportunities, and Challenges, and summarise the key takeaways and add it to the paper as the last figure.

Response: 1o: We thank the reviewer for this constructive suggestion. In response, we have developed a dedicated new section (Section 8: SWOT Analysis of CEP) prior to the Conclusion section. This section provides a structured synthesis of the review’s findings by evaluating CEP in terms of its Strengths, Weaknesses, Opportunities, and Challenges. The discussion highlights the main advantages (e.g., high removal efficiency, reduced chemical consumption, low sludge generation), current limitations (e.g., electrode passivation, lack of standardized reactor designs, high energy demand at scale), emerging opportunities (e.g., integration with other processes, AI-driven optimization, policy support), and key challenges (e.g., scalability, long-term validation, regulatory uncertainty). To complement this discussion, we have also added Figure 17 presenting a graphical SWOT chart that visually summarizes these aspects. This addition improves the manuscript by offering readers a concise overview of CEP’s current status and future prospects, and it strengthens the concluding remarks by providing a clear roadmap for further research and industrial application.

“8. SWOT Analysis of CEP

To consolidate the findings of this review and provide a structured perspective on the future of CEP for industrial inorganic pollutant treatment, a SWOT (Strengths, Weaknesses, Opportunities, and Challenges) analysis was conducted (Figure 17).

• Strengths: CEP achieves high removal efficiencies for a wide range of inorganic contaminants, with advantages such as lower sludge generation, reduced chemical consumption, and compatibility with renewable energy sources. It also offers potential for resource recovery, supporting circular economy strategies.
• Weaknesses: Limitations include electrode passivation, relatively high energy demand at large scale, lack of standardized reactor designs, and performance variability across wastewater matrices. Furthermore, most applications remain at laboratory scale, with limited pilot or industrial demonstrations.
• Opportunities: CEP can be integrated with complementary treatment technologies (e.g., membrane processes, flotation, advanced oxidation) and benefits from ongoing innovations in electrode design, hydrodynamics, and automation. The growing demand for sustainable wastewater treatment solutions, coupled with advancements in modelling, optimization, and AI-driven control, creates further potential for industrial adoption.
• Challenges: Major barriers include electrode fouling and maintenance, scaling from laboratory to industrial scale, economic feasibility, and regulatory uncertainty in certain regions [113]. The lack of long-term operational data also poses a challenge for commercialization and standardization [114].

Figure 17 presents a visual summary of this SWOT analysis, providing readers with a concise overview of CEP’s current position and the critical areas requiring attention for its successful industrial-scale implementation.”

 

Figure 17. SWOT (Strengths, Weaknesses, Opportunities, and Challenges) analysis of Continuous Electrocoagulation Processes (CEP) for the treatment of inorganic pollutants.

Comment-11: As it is a relatively long paper with multiple sections and numerous sub-sections, it is recommended to have a table of contents at the beginning of the paper to make it more organized.

Response 11: Thank you for the helpful recommendation. To enhance the organization and navigability of the manuscript, especially given its length and detailed structure, we have included a Table of Contents at the beginning of the paper. We believe this addition will improve the reader’s experience by providing a clear overview of the sections and sub-sections.

Comment-12: Please further elaborate on the research trends and knowledge gaps in the conclusion section.

Response 12: We thank the reviewer for this helpful suggestion. In the revised manuscript, we have expanded the Conclusion section to highlight both research trends and knowledge gaps. Specifically, we summarize current directions in CEP research—such as integration with other treatment processes, innovations in reactor and electrode design, and the increasing use of modelling and AI tools. In parallel, we emphasize critical gaps, including the lack of standardized reactor designs, limited long-term pilot/full-scale studies, insufficient modelling for combined processes, and the need for regulatory and economic frameworks to support industrial-scale adoption. The text below has been inserted into the Conclusion section, immediately before the last paragraph. To strengthen the synthesis, we also added a direct reference to the newly introduced SWOT analysis (Section 8), which provides a structured overview of these research directions and gaps:

“Recent research trends in continuous electrocoagulation processes (CEP) demonstrate increasing emphasis on reactor and electrode design innovations, integration with complementary treatment technologies, and the application of modelling and artificial intelligence for process optimization and scale-up. These trends reflect growing efforts to bridge the gap between laboratory investigations and industrial practice, while also aligning with global demands for sustainable and resource-efficient water treatment technologies. Despite these advancements, significant knowledge gaps remain. The absence of standardized reactor configurations and design protocols hampers cross-comparison of results and scalability. Long-term pilot- and full-scale validation studies are still scarce, leaving questions about durability, maintenance, and cost-effectiveness under real operating conditions. Moreover, research on modelling and optimization of combined CEP systems is particularly limited, constraining predictive design and large-scale implementation. Finally, supportive regulatory frameworks and techno-economic analyses are needed to enable widespread industrial adoption. As summarized in the SWOT analysis (Section 8), addressing these gaps is essential for unlocking CEP’s full potential as a reliable, scalable, and sustainable technology for industrial wastewater treatment.”

Comment-13: The Circular economy section of the paper requires more analysis of the literature, and please provide further explanations and discussion in sub-sections of this part.

Response 13: We appreciate the reviewer’s constructive feedback. In response, we have enhanced the Circular Economy section (Section-7) by incorporating a more in-depth analysis of the relevant literature. We have expanded the explanations and discussions within the sub-sections to provide a clearer and more comprehensive understanding on how electrocoagulation contributes to the circular economy, emphasizing its ability to recover valuable resources (nutrients, metals, catalysts, and hydrogen) while treating wastewater, unlike conventional methods that mostly generate waste.

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

Thanks to the authors for their contribution.
There are some concerns mentioned below.

Title:

Title: "Continuous Electrocoagulation Processes (CEP) for Industrial Inorganic Pollutants Removal: A Critical Review of Performance and Applications". This title indicates a critical review; however, critical analysis is missing. Most of the mentioned studies appear to report data with limited insight into the developments. Truly speaking, this review requires major modification to meet the author's claim of a critical review and novelty.

Abstract:

1. The current form of the abstract is not technically sound and requires modification. 
It is suggested to rewrite the abstract based on the issues. Current development, novelty of the review, and findings from this review. 

2. Novelty needs to be clear and highlighted, as some other researchers have also reviewed the inorganic pollutant removal, mentioning CEP.

Introduction:

1. Page No 2, Conventional water treatment methods.....at low concentrations [14–17]. Please provide some reference on the feasibility of using CEP instead of other methods to support the statement. 
2. References for the equations used are missing.

3. Page No. 4, "Additionally, the use of scrap metals as electrodes enhances the environmental friendliness of the EC process [37,38]". What do you mean by scrap metals? Non-treated? Please justify.

4. "In the last few decades, a substantial body of research has focused on the removal of various types of wastewaters using the EC process". rewrite and provide a clear statement.

3.1. Standalone EC treatment processes:

1. Page No 8, Emamjomeh and M. Sivakumar..............maximizes the formation of aluminum fluoride hydroxide complex. What was the maximum amount? 
2. This section is mostly written as a reported work rather than critically describing and comparing the developments. Therefore, this section requires improvement.

3. Table 1 description is too general. Please provide details on how these parameters are influential in governing the application. 

4.1.2. Combined processes:

1. This section also requires improvement. Authors need to mention what critical aspects lie in these combined processes. Currently, these are lacking.
   2. Figure 3 needs to be improved.

2. Figure 5 needs to be improved. Currently, it's not clear. 

3. Figure 11 needs to be improved. It is suggested to use high-resolution figures.

6.1. Technical challenges in scaling up EC:

1. In the previous sections, the authors claimed that the reviewed technique was found to be cost-effective. However, in challenges, they have mentioned that the maintenance cost could be a challenge for this method. Please justify.

2. Figure 15 is not clear.

7. Circular Economy:
Please provide the author's point of view on how the mentioned 7.1 to 7.5 differ from other techniques.
Overall, there is a need to revise this review article with a clear focus on novelty and critical analysis. This will provide readers a good read to further research in this field.

Author Response

Response to Reviewer 3

We sincerely thank the reviewer for the constructive comments and helpful suggestions. We carefully revised the manuscript according to the recommendations. Below, we provide a detailed response to each point and indicate the corresponding changes in the revised version.

General Comment: This title indicates a critical review; however, critical analysis is missing. Most of the mentioned studies appear to report data with limited insight into the developments. Truly speaking, this review requires major modification to meet the author's claim of a critical review and novelty.

Response: We agree with the reviewer. The manuscript has been substantially revised to include deeper critical analysis. Instead of only summarizing results, we now emphasize comparative insights, highlight research gaps, and critically evaluate the strengths and limitations of different studies. The novelty of this review is clarified in the Abstract and Introduction.

Abstract

Comment: The current form of the abstract is not technically sound…rewrite based on novelty, development, and findings.

Response: The abstract has been fully rewritten. It now highlights:

1. Current developments in continuous electrocoagulation (CEP).
2. The novelty of this review including critical assessment and comparative insights.
3. Key findings with advantages, limitations, and future opportunities for CEP.

Introduction

Comment 1: Page 2 … please provide some reference on the feasibility of using CEP instead of other methods.

Response: Added recent references (highlighted in yellow) supporting the feasibility and advantages of CEP over conventional methods.

Comment 2: References for the equations used are missing.

Response: Proper references for all equations have been added.

Comment 3: Scrap metals as electrodes … please justify.

Response: Clarified that “scrap metals” refers to recycled or reused aluminum/iron electrodes, which enhance sustainability and reduce cost. The proper clarification has been added.

Comment 4: Rewrite unclear sentence about “substantial body of research”

Response: We appreciate the reviewer’s observation. The sentence has been revised for clarity.

3.1. Standalone EC Treatment Processes

Comment 1: Maximum amount of aluminum fluoride hydroxide complex?

Response: We thank the reviewer for the comments. We have revised the section to include the maximum formation of aluminum fluoride hydroxide complex, explicitly stating that the Al³⁺/F mass ratio ranges from 13 to 17.5 under optimal conditions, corresponding to a total aluminum concentration of 120–155 mg/L and residual fluoride concentration of 1–10 mg/L.

Comment 2: Section is written as reported work; requires critical description.

Response: We thank the reviewer for the suggestion. The section has been revised to provide a critical analysis of the reported work, highlighting trends, underlying mechanisms, limitations, and strategies for improving performance, rather than merely summarizing previous studies.

Comment 3: Table 1 description too general.

Response: Table 1 was expanded with detailed explanations of how each parameter (pH, current density, electrode material, flow rate) influences CEP performance.

4.1.2. Combined Processes

Comment: Section requires critical aspects.

Response: We revised the section to emphasize synergies and trade-offs in combined CEP processes, such as improved pollutant removal vs. increased operational complexity.

Comment: Figures 3, 5, 11 need improvement.

Response: Figures 3, 5, and 11 were replaced with higher-resolution, redesigned figures for clarity.

6.1. Technical Challenges

Comment: Cost-effectiveness vs. maintenance cost contradiction.

Response: Clarified that while CEP is cost-effective in terms of reduced chemical input and pollutant removal efficiency, electrode replacement and sludge management may still present cost challenges. This has been explicitly discussed.

Comment: Figure 15 is not clear.

Response: Replaced with an improved high-resolution version (Figure 15).

7. Circular Economy

Comment: Provide the author’s viewpoint on how CEP differs from other techniques.

Response: We thank the reviewer for this suggestion. We have revised Section 7 to clarify our perspective on how electrocoagulation contributes to the circular economy, emphasizing its ability to recover valuable resources (nutrients, metals, catalysts, and hydrogen) while treating wastewater, unlike conventional methods that mostly generate waste.

Overall Comment: Need clear novelty and critical analysis.

Response: Throughout the manuscript, we emphasized novelty by (1) focusing exclusively on continuous electrocoagulation (CEP), (2) critically comparing standalone and hybrid CEP systems, and (3) highlighting optimization and scale-up challenges with forward-looking insights. The revised conclusion now includes research trends, knowledge gaps, and future outlook.

We believe these revisions have substantially improved the manuscript, and we sincerely thank the reviewer for the detailed and valuable feedback.

 

 

Reviewer 4 Report

Comments and Suggestions for Authors

Reviewing report

Review entitled " Continuous Electrocoagulation Processes (CEP) for Industrial Inorganic Pollutants Removal: A Critical Review of Performance and Applications"

1. Under highlights you need to make each highlight by a number or bullets. 
2. You need to put your review in a format belong to the Water journal.
3. You need to capitalise the first letter for each keyword « COntinuous electrocoagulation; Combined electrocoagulation treatment processes; ELectrocoagulation molding and optimization «
4. Before reference bracket please put a space. For example here «concentrations[14–17]«
5. You need to put the number of equations in the same line with the equation in page 3, 4, 5.
6.   Its a review. Right ? So, you need to put a reference in the caption of figures. Its not yours.
7. Inside table 1, you sometimes write « m :« and sometimes « m=«
8. Please put a number of pages and lines.
9. Inside table 3, column 3, please write the equivalent number for each metal. For example Ni is Ni(II) or what ?
10. Remove space before table 5.
11. Under « 3.1. Standalone EC treatment processes «  subtitle you need to write how it work. For example: The wastewater flows continuously through an electrochemical reactor where an electric current is applied. Sacrificial electrodes (typically iron or aluminum) release metal ions that act as coagulants. These coagulants neutralize the charge of pollutant particles, causing them to clump together into larger flocs. The flocs are then removed from the water by sedimentation or flotation.

 

Then write about its advantage and disadvantages.

12. The same for this « 3.1. Combined Continuous Electrocoagulation Processes (CEP) « as the previous comment.
13. The numbering of this is wrong « 3.1. Combined Continuous Electrocoagulation Processes (CEP) «
14. You need to amke a diagram about « Conceptual integration of continuous electrocoagulation (CEP) within hybrid wastewater treatment systems. «
15.  You need to add subtitle about « CEP and optimization studies «

For help see this : Electrocoagulation in the dual application on the simultaneous removal of fluoride and nitrate anions through respective adsorption/reduction processes and modelling of continuous process 

 

GOOD LUCK

Author Response

Responses to Reviewer 4

 

We sincerely thank the reviewer for the constructive comments and helpful suggestions. We carefully revised the manuscript according to the recommendations. Below, we provide a detailed response to each point and indicate the corresponding changes in the revised version.

 

Comment 1: Under highlights you need to make each highlight by a number or bullets.

Response 1: Thank you for your comment. The highlights are bulleted in the corrected version.

 

Comment 2: You need to put your review in a format belong to the Water journal.

Response 2:  Thank you for your comment. The the corrected version is formated as requested by Water journal.

Comment 3: You need to capitalise the first letter for each keyword « COntinuous electrocoagulation; Combined electrocoagulation treatment processes; ELectrocoagulation molding and optimization «

Response 3: Thank you for your comment. The keywords are  captalised in the corrected version.

 

Comment 4: Before reference bracket please put a space. For example here «concentrations[14–17]«

Response 4: Thank you for your comment. All reference citations are corrected  in the corrected version.

 

Comment 5: You need to put the number of equations in the same line with the equation in page 3, 4, 5.

Response 5: Thank you for your comment. All equations  are corrected  in the corrected version.

Comment 6:  Its a review. Right ? So, you need to put a reference in the caption of figures. Its not yours.

Response 6: Thank you for your comment. All figure captions end with the reference number  in the corrected version except figures 1 , 2, and 17 since they were prepared by the authors.

Comment 7: Inside table 1, you sometimes write « m :« and sometimes « m=«

 

Response 7: Thank you for your comment. It is corrected as ” m:”   in the corrected version.

 

Comment 8: Please put a number of pages and lines.

Response 8: Thank you for your comment. Both pages and lines are numbered  in the corrected version.

 

Comment 9: inside table 3, column 3, please write the equivalent number for each metal. For example Ni is Ni(II) or what ?

Response 9: Thank you for your comment. Equivalent number for each metal is included  in the corrected version.

 

Comment 10: Remove space before table 5.

Response 10: Thank you for your comment. The space is removed  in the corrected version.

Comment 11: Under « 3.1. Standalone EC treatment processes «  subtitle you need to write how it work. For example: The wastewater flows continuously through an electrochemical reactor where an electric current is applied. Sacrificial electrodes (typically iron or aluminum) release metal ions that act as coagulants. These coagulants neutralize the charge of pollutant particles, causing them to clump together into larger flocs. The flocs are then removed from the water by sedimentation or flotation. Then write about its advantage and disadvantages.

Response 11: Thank you for your valuable suggestion. We expanded section 3.1. Standalone EC treatment processes by adding a clear explanation of the working principle of electrocoagulation (EC). We described the continuous wastewater flow through the electrochemical reactor, the role of sacrificial electrodes in releasing metal ions, and the subsequent coagulation and removal of pollutants. In addition, highlighted the main advantages and disadvantages of the EC process as below:

 

Electrocoagulation treatment process is performed by applying electric current to sacrificial electrodes, typically made of iron or aluminum, immersed in the contaminated water to be treated. As the wastewater flows continuously through the EC reactor, the applied current releases metal ions (Fe²⁺/Fe³⁺ or Al³⁺) from the sacrificial electrodes. These ions function as coagulants, neutralize the charges of pollutant particles leading to reduced repulsive forces and particles aggregate into larger flocs that can be removed efficiently by sedimentation or flotation. Furthermore, hydrogen gas bubbles generated at the cathode lift the flocs to the surface for separation.

 

EC is very attractive since it can be applied for a wide range of organic and inorganic contaminants with little or no addition of external chemical coagulants, thus reducing chemical handling and secondary contamination. Furthermore, it produces less sludge compared to conventional chemical coagulation. However, the EC performance is affected by the characteristics of wastewater to be treated. In addition, continuous consumption of sacrificial electrodes increases operational cost and requires periodic replacement. Also, energy demand can be relatively high, especially for large-scale operations. Furthermore, resulted sludge requires additional treatment and disposal.

 

Comment 12: The same for this « 3.1. Combined Continuous Electrocoagulation Processes (CEP) « as the previous comment.

Response 12: Thank you for your valuable suggestion. We expanded section 3.2. Combined Continuous Electrocoagulation Processes (CEP by adding a clear explanation of the working principle of electrocoagulation (EC). We described the continuous wastewater flow through the electrochemical reactor, the role of sacrificial electrodes in releasing metal ions, and the subsequent coagulation and removal of pollutants. In addition, highlighted the main advantages and disadvantages of the EC process as below:

 

3.2. Combined Continuous Electrocoagulation Processes (CEP)

In integrated continuous electrocoagulation (CEP) processes, the EC unit is integrated with other treatment technologies, such as flotation, sedimentation, membrane filtration, and advanced oxidation, to improve overall treatment performance. The residual water flows through the EC reactor, where sacrificial electrodes liberate ions from the coagulation and generate aggregation. The partially treated effluent serves as a complementary process for contaminant separation or further reduction. For example, EC can be followed by flotation with improved aeration for greater particle removal, or combined with membrane filtration for a higher-quality effluent with less fouling. Synergistic effects significantly improve the overall contaminant removal efficiency compared to stand-alone EC. Furthermore, they reduce chemical demand and sludge generation. CEP also improves effluent quality to meet standards for possible water reuse, making the process more suitable for emerging industrial applications. However, it requires significant capital and operating costs due to the integration of multiple processes, with the design and operation of more complete systems requiring optimization and qualified operators. Energy consumption and operational requirements increase, particularly when using membranes or flotation units.

 

 

Comment 13: The numbering of this is wrong « 3.1. Combined Continuous Electrocoagulation Processes (CEP) «

 

Response 13: Thank you for your comment. The section number is corrected to 3.2.   in the corrected version.

 

Comment 14: You need to amke a diagram about « Conceptual integration of continuous electrocoagulation (CEP) within hybrid wastewater treatment systems. «

Response 14: Thank you for your comment. The following figure is added in the corredted version.

 

 

 

Figure 3. Flow diagram of continuous electrocoagulation (CEP) integrated with hybrid wastewater treatment processes for producing treated effluent.

 

 

Comment 15: You need to add subtitle about « CEP and optimization studies «For help see this : Electrocoagulation in the dual application on the simultaneous removal of fluoride and nitrate anions through respective adsorption/reduction processes and modelling of continuous process

Response 15: Thank you for your comment. This subtitle already exist in the manuscript as:

4.2 Operational parameter optimization by statistical and AI methods

 

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The revision is acceptable for publication. 

Author Response

Responses to Reviewer 2

 

We deeply thank the respected reviewer for his acceptance to our response to his valuable comments and his positive recommendation to accept our manuscript No. water-3839049, titled " Continuous Electrocoagulation Processes (CEP) for Industrial Inorganic Pollutants Removal: A Critical Review of Performance and Applications".

Reviewer 3 Report

Comments and Suggestions for Authors

Thanks to the author for addressing the concerns. Please also check the acknowledgment section if it was left out mistakenly.

Author Response

Response to Reviewer 3

We sincerely thank the reviewer for accepting our responses to his constructive comments and helpful suggestions. Concerning, his new comment about the missed acknowledgment section, we would like to inform him that this section is not necessary since no fanatical support was given to this research.

Reviewer 4 Report

Comments and Suggestions for Authors

Reviewing report

Manuscript entitled “Continuous Electrocoagulation Processes for Industrial Inorganic Pollutants Removal: A Critical Review of Performance and Applications“

1. Line 233, you need to combine the numbering of refernces in the same bracket « e [44, 76], [48–50], [51–56], [57–75] «

The same line 234, 619,   etc.

2. Line 342, where isthe equivalent number for F » with an Al³⁺/ F» ?
3. Lines 1395-1412 need references.
4. Please combine lines 1405-1444 as 1 paragraph.
5. Again, Inside table 1, you sometimes write « m :« and sometimes « m=«
6. In table 3, where is the equivalent number of Fluoride ?
7. Again, please remove space before table 5.
8. Where are the references for lines 295-316 ?

 

GOOD LUCK

 

Author Response

Responses to Reviewer 4

 

We sincerely thank the reviewer for the constructive comments and helpful suggestions in the second round. We carefully revised the manuscript according to his comments suggestions. Below, we provide a detailed response to each point and indicate the corresponding changes in the revised version.

 

Comment 1: Line 233, you need to combine the numbering of references in the same bracket « e [44, 76], [48–50], [51–56], [57–75].

Response 1: The sentence is revised as follows:

In the periods 2000-2010, 2011-2015, 2016-2019, and 2020-2025 there are 2, 3, 6, and 25 publications for standalone [44, 75-76], and 2, 3, 1, and 11 publications for combined EC [77-93], respectively.

 

Comment 2: Line 342, where is the equivalent number for F » with an Al³⁺/ F» ?

Response 2:  Thank you for your comment. The equivalent number for F is added to become Al³⁺/ F^-:  

Comment 3: Lines 1395-1412 need references.

Response 3: Thank you for your comment. The references are now added.

 

Comment 4: Please combine lines 1405-1444 as 1 paragraph.

Response 4: Thank you for your comment. However, since each paragraph represents a different interrelated technical challenges that face the EC scale-up. For this reason, we changed the appearance of this section to bullets form to separate each factor in one point. .

 

Comment 5: Again, Inside table 1, you sometimes write « m :« and sometimes « m=«

Response 5: Thank you for your accurate comment. All expressions are now unified as m:

Comment 6:  In table 3, where is the equivalent number of Fluoride?

Response 6: Thank you for your comment. In Table 3, where is the equivalent number of F^- is added.

Comment 7: Again, please remove space before table 5.

Response 7: The space before Table 5 is removed.

 

Comment 8: Where are the references for lines 295-316?

Response 8: Thank you for your comment. the references for lines 295-316 are added.

Round 3

Reviewer 4 Report

Comments and Suggestions for Authors

Reviewing report

Manuscript entitled “Continuous Electrocoagulation Processes (CEP) for Industrial Inorganic Pollutants Removal: A Critical Review of Performance and Applications “

1. Line 179, please put « [24] » after « as » word not before.
2. Again, please look to line 620 « [97] [98]: «. Is that right ? The same line 765. Please revise the whole manuscript.
3. Inside table 3, please make the equivalent number by the same numbering. I eman use « -, +« or «I, II, III «. Choose one shape for all not sometimes – and sometimes III

 

GOOD LUCK

 

Author Response

Response to reviewer 4

Thank you very much for your efforts and these minor editorial comments on our Manuscript entitled: “Continuous Electrocoagulation Processes (CEP) for Industrial Inorganic Pollutants Removal: A Critical Review of Performance and Applications.“ Below please find an itemized response for the three comments:

Comment 1: Line 179, please put « [24] » after « as » word not before.

Response 1: Yes [24] is now after as. 

Comment 2: Again, please look to line 620 « [97] [98]: «. Is that right ? The same line 765. Please revise the whole manuscript.

Response 1: Thank you again. The references in line 620 are corrected as [97, 98] and in 765 are corrected as [43, 61].

Comment 3: Inside table 3, please make the equivalent number by the same numbering. I mean use « -, +« or «I, II, III «. Choose one shape for all not sometimes – and sometimes III

Response 3: Thank you again for this comment. The numbering of the ions charges is now unified as shown:

F-

Fe+3

Ni+2

Cr+3

Fe+3

Cr+6

F-