Strategies for a Sustainable Economy: Optimizing Processes for BOD, COD and TSS Removal from Wastewater
Round 1
Reviewer 1 Report (Previous Reviewer 2)
Comments and Suggestions for AuthorsThe manuscript is subjected to some improvement before being accepted for publication:
1. Did author check which operating parameter has more effect for optimization such as BOD, COD or TSS?
2. The author have only checked BOD, COD and TSS, but there are other operating parameters which can affect the process efficiency.
3. The author shave performed optimization by manual method. There are software’s/models which can perform better optimization such as RSM.
4. The objectives and novelty of current study should be presented in detail and more clear way.
5. Figure 2 should be replaced with better quality image and font size, same for other figures.
Author Response
THE ANSWER FOR THE REVIEWER 1
Thank you for your comments, which have the role of increasing the value of our article. The answers to your comments are marked in the paper, as follows:
- Comments 1:The manuscript is subjected to some improvement before being accepted for publication. Did author check which operating parameter has more effect for optimization such as BOD, COD or TSS?
Response 1: In the presented article, the highest efficiency of the purification process, for the BOD, COD or TSS parameters, were visualized in figures 9-11. According to the conclusions, the best efficiency is found for the TSS parameter.
- Comments 2: The author have only checked BOD, COD and TSS, but there are other operating parameters which can affect the process efficiency.
Response 2: In the context of the presented article, only the BOD, COD and TSS parameters are subject to analysis. The authors have also published a series of articles in which other parameters were analyzed for the same period of time. From the other articles it is clear that the dosage of ferric chloride is effective for other water quality indicators as well.
https://www.mdpi.com/2073-4441/16/11/1585
- Comments 3:The author shave performed optimization by manual method. There are software’s/models which can perform better optimization such as RSM.
Response 3: Indeed, in this study, a manual optimization method was applied, given the context and objectives of the research. However, there are advanced optimization methods, such as RSM (Response Surface Methodology), which can provide more efficient and accurate solutions, based on the analysis and modeling of the relationships between process variables.
Currently, we use a SCADA system to monitor and control the process parameters, but the integration of such statistical methods and optimization algorithms within the SCADA would allow for automatic adjustment of the parameters in real time, leading to better operational performance and continuous optimization of the process. Implementing such a model could contribute to reducing human errors, saving resources and improving the overall efficiency of the treatment system.
- Comments 4: The objectives and novelty of current study should be presented in detail and more clear way.
Response 4: changes have been made in text, the lines 71-77 and 91-97 (in red color).
- Comments 5: Figure 2 should be replaced with better quality image and font size, same for other figures.
Response 5: Figure 2 has been redrawn
Author Response File: 
Author Response.pdf
Reviewer 2 Report (New Reviewer)
Comments and Suggestions for AuthorsThe abstract is very repetitive, I would strongly suggest adding the results of the study to it.
2. The introduction is very poorly written. I suggest a complete rewrite to add the hypothesis, literature gaps, novelty, and why you have chosen this work. Add the following literature https://doi.org/10.1016/j.ijbiomac.2024.137049
3. Why have authors only used 40% of ferric chloride? Why other percent have not been used must be discussed.
4. The characterization part is also missing. Authors must provide the FTIR and SEM images of the coagulant which will give an idea about the functional groups and surface morphology of the coagulant.
5. The effect of pH must be studied.
Author Response
Thank you for your comments, which have the role of increasing the value of our article. The answers to your comments are marked in the paper, as follows:
- Comments 1: The abstract is very repetitive, I would strongly suggest adding the results of the study to it.
Response 1: Repetitive paragraphs from the abstract have been removed. Information about the research results has also been added to the abstract (lines 23-31, in green color).
- Comments 2: The introduction is very poorly written. I suggest a complete rewrite to add the hypothesis, literature gaps, novelty, and why you have chosen this work. Add the following literature https://doi.org/10.1016/j.ijbiomac.2024.137049
Response 2: Additions have been made to the introductory part (lines 53-77 and lines 91-97, in red). The recommended bibliographic reference has been added (references 32). Other bibliographic references related to the introductory parts have also been added (references 29, 30, 31, 33).
- Comments 3: Why have authors only used 40% of ferric chloride? Why other percent have not been used must be discussed.
Response 3: The determinations were made based on a standard procedure that assumes a ferric chloride concentration of 40%.
The 40% concentration (standard concentration) was used:
-it is stable, easy to store and transport.
-it ensures a balance between chemical efficiency and risks associated with handling.
-it is a standardized value in many industries, which simplifies applicability.
This concentration is frequently used, as it represents an optimal compromise between chemical efficiency and handling safety. It is also considered ideal for drinking and industrial water treatment applications, due to the balance between performance and ease of use.
- Comments 4: The characterization part is also missing. Authors must provide the FTIR and SEM images of the coagulant which will give an idea about the functional groups and surface morphology of the coagulant.
Response 4: In this study, we did not include FTIR and images of the coagulant, since the main purpose of the research was focused on evaluating its performance in the coagulation process and analyzing the efficiency of the treatment plant, in relation to the quality indicators of the treated water. Our focus was on measuring performance parameters such as BOD, COD, TSS reduction, which are essential for evaluating the efficiency of the treatment process.
We agree that FTIR and SEM analyses would provide valuable additional information about the chemical and morphological structure of the coagulant, which could better explain the coagulation mechanisms and its efficiency. We will consider performing these analyses in future studies, to complete the characterization of the material used and to provide a deeper understanding of the processes involved.
- Comments 5: The effect of pH must be studied.
Response 5: The effect of pH was also studied. According to the NTPA 001 standard, pH falls within the discharge limits in the outfall, between 6.5 and 8.5. This is presented in row 1 of table 1 (blue color).
Author Response File: Author Response.pdf
Reviewer 3 Report (New Reviewer)
Comments and Suggestions for AuthorsManuscript by Eniko Gaspar et al on Strategies for a sustainable economy: Optimizing processes for BOD, COD and TSS removal from wastewater conducted research on efficiency of 40% ferric chloride in the purification of wastewater by measuring pollution indicators BOD5, CODCr and TSS. Authors put good effort to improve the treatment process for Dumbraveni domestic wastewater using rotating biological contractor method.
Comments:
Ferric chloride is a well known coagulant used in the wastewater treatment process. What is the novelty of this research compared to the existing research which involved ferric chloride for wastewater treatment?
Authors haven't discussed anything about ferric chloride in their introduction (rationale behind the selection of ferric chloride).
Authors used 40% ferric chloride for this particular research, authors should discuss why they chose this number?
Abstract: line 19 to 24-repitition of the same sentence about effect of 40% ferric chloride on BOD5, CODcr and TSS. Authors should avoid the repetition.
Figure 3: X and Y axes labels were missing. What is EPD on x-axis
Line 113 and 115: From figure 3, it is understandable that increasing the dose of ferric chloride 40% coagulant resulted in decreasing the turbidity. It is hard to understand why authors mentioned (line 115) the turbidity is favored by increasing the dose of coagulant agent FeCl3 40%. Authors should explain clearly?
Results & discussion: line 126 to line 135: Authors made hypothesized summary. If these comments are from the existing literature, authors should clearly cite the corresponding references that support the mentioned comments. If these comments are from the current research-authors should present the results.
Figure 4, 5,6,7,8 and table 2 represents the same results. Authors should avoid repetition of figures. For example figure 4 can be omitted.
Authors should clearly discuss why 40% ferric chloride led to improved removal efficiency of BOD5, CODCr and TSS.
Author Response
THE ANSWER FOR THE REVIEWER 3
Thank you for your comments, which have the role of increasing the value of our article. The answers to your comments are marked in the paper, as follows:
- Comment 1: Ferric chloride is a well known coagulant used in the wastewater treatment process. What is the novelty of this research compared to the existing research which involved ferric chloride for wastewater treatment?
Response 1: The novel aspects of the study were presented in lines 91-97 (in red color).
- Comment 2: Authors haven't discussed anything about ferric chloride in their introduction (rationale behind the selection of ferric chloride).
Response 2: Introductory aspects about ferric chloride and related research in the field have been introduced in lines 53-71. Also, the related bibliographic references have been introduced (References 29-33).
- Comment 3: Authors used 40% ferric chloride for this particular research, authors should discuss why they chose this number?
Response 3: The determinations were made based on a standard procedure that assumes a ferric chloride concentration of 40%.
The 40% concentration (standard concentration) was used:
-it is stable, easy to store and transport.
-it ensures a balance between chemical efficiency and risks associated with handling.
-it is a standardized value in many industries, which simplifies applicability.
This concentration is frequently used, as it represents an optimal compromise between chemical efficiency and handling safety. It is also considered ideal for drinking and industrial water treatment applications, due to the balance between performance and ease of use.
- Comment 4: Abstract: line 19 to 24-repitition of the same sentence about effect of 40% ferric chloride on BOD5, CODCr and TSS. Authors should avoid the repetition.
Response 4: Repetitive paragraphs from the abstract have been removed. Information about the research results has also been added to the abstract (lines 23-31, in green color).
- Comment 5: Figure 3: X and Y axes labels were missing. What is EPD on x-axis
Response 5: Figure 3 was made and changes were made to the text with the correct notations (lines 145-151)
- Comment 6: Line 113 and 115: From figure 3, it is understandable that increasing the dose of ferric chloride 40% coagulant resulted in decreasing the turbidity. It is hard to understand why authors mentioned (line 115) the turbidity is favored by increasing the dose of coagulant agent FeCl3 40%. Authors should explain clearly?
Response 6: Thank you, it was a mistake of expression. I have made the necessary corrections (lines 155-156, in blue color).
- Comment 7: Results & discussion: line 126 to line 135: Authors made hypothesized summary. If these comments are from the existing literature, authors should clearly cite the corresponding references that support the mentioned comments. If these comments are from the current research-authors should present the results.
Response 7: additions were made with bibliographical references (line 169, in blue color)
- Comment 8: Figure 4, 5,6,7,8 and table 2 represents the same results. Authors should avoid repetition of figures. For example figure 4 can be omitted.
Response 8: Figure 4 cannot be omitted because it is the graphic representation of the values corresponding to the studied parameters while in table 2 and figures 5, 6, 7 and 8 the efficiency of the process is presented. In fact, the values from table 2 are repeated in figures 5, 6, 7 and 8 which is why TABLE 2 has been eliminated.
- Comment 9: Authors should clearly discuss why 40% ferric chloride led to improved removal efficiency of BOD5, CODCr and TSS.
Response 9: recommended additions were made in lines 108-115 in blue.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report (Previous Reviewer 2)
Comments and Suggestions for AuthorsThe authors have revised accordingly.
Author Response
Comments: The authors have revised accordingly.
Response: Thank you very much for the review!
Reviewer 2 Report (New Reviewer)
Comments and Suggestions for Authorssatisfactory revision
Author Response
Comments: satisfactory revision
Response: Thank you very much for the review!
Reviewer 3 Report (New Reviewer)
Comments and Suggestions for AuthorsThe manuscript has improved significantly through revision.
Table 2: since table 2 has been removed from the manuscript. All the table numbers should be renamed from Table 1 to 8 .
Author Response
Comments 1: The manuscript has improved significantly through revision.
Response 1: Thank you very muck for the review.
Commentes 2: Table 2: since table 2 has been removed from the manuscript. All the table numbers should be renamed from Table 1 to 8 .
Response 2: Thank you for the correction. I have renumbered the tables and changed the numbering in the text. The changes are highlighted in yellow color (lines 231, 235, 246, 267, 318).
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
The manuscript has lots of grammatical, and technical errors. Both language and the presentation need to be improved extensively.
Some glaring mistakes:
Abstract: The statements do not read well. BOD & COD are not organic compounds. They are used to measure the strength of contaminants in the water. Though 40% FeCl₃ solution improve coagulation performance, it can pose challenges such as increased corrosion risk, pH reduction, higher sludge production, and potentially higher costs.
Line 125-129: “The coagulant ferric chloride 40% was added to each container, container 1 = 0.5 mg/L, container 2 = 1 mg/L, container 3 = 5 mg/L, container 4 = 7.5 mg/L, container 5 = 10 mg/L by mixing for about one minute at 100 rpm, the influence of the amounts of coagulant on turbidity and on the quality indicators followed was observed. The rapid mixing step helps to disperse the coagulant in each container” what are these concentrations 0.5 mg/L, 1 mg/L etc.,?
Figure 1. The turbidity variation throughout the Jar test procedure: What is Y-axis title? Is it turbidity (NTU)?. What are the initial solution turbidities? Mention all experimental conditions in the figure label. What is EPD? Explain the x-axis labels.
Figure 2. Comparison of the evolution of COD, BOD and TSS concentrations between the year without ferric chloride dosing and the years with dosing.
Here the y-axis title shows mg O2/L, whereas the figure ligands indicate BOD, COD & TSS. How to read and interpret these figures?
Line 166. “three pollutants” – BOD, COD and TSS are not pollutants themselves. They are only measurements.
Figures 3 & 4. Efficiency is misspelled in y – axis title, chart titles.
Figure 6. Correct the legends. “Efficiency in BOD removal” make it “BOD removal efficiency”
Table 3. is it one “sample” test
Tables 4, 5 & 6. “df” normally capital letters are used “DF”. What is “Subiects”? subject?
Figure 7. COD- TSS correlation is not strange
None of the figures has error bars
FeCl3 is a common coagulant used for sewage treatment. The work is routine and does not add any additional knowledge to the society.
Unfortunately, though the work has been done extensively over a period of three years, I am not able to recommend this paper for publication due to the reasons cited above. Authors are strongly recommended to completely revise the entire paper.
Comments on the Quality of English Language
English has to be improved a lot.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript is subjected to some improvement before being accepted for publication:
1. The novelty of the current study is not clear, as the related studies were already conducted.
2. Abstract Line #13, the statement and meaning are not clear, author needs to rewrite it.
3. Line #21, The abbreviation should be corrected such as Biochemical Oxygen Demand (BOD) etc.
4. Line # 26, the mathematical model name/detail should be written here.
5. The introduction section, many references are outdated such as 2004, 2006, 2009 etc. Author should replace with appropriate recent references.
6. Line # 59, the wastewater treatment plant city name and country detail should be provided.
7. Line # 121, the schematic diagram of wastewater treatment plant should be provided for better understanding.
8. Conclusion is too long; author should discuss the main findings and results of the study.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe work entitled “Strategies for sustainable economy in optimizing the processes for removal of the bod, cod 3 and tss from the wastewater” has the purpose of demonstrating that the use of ferric chloride had a significant impact on the removal efficiency of COD, BOD and TSS pollutants in wastewater treatment processes. The observed efficiency of the ferric chloride treatment method suggests that this technique could be a viable and effective solution for improving water quality in wastewater treatment systems. The work is interesting but needs major revisions that essentially facilitate its reading and understanding by the reader. English needs improvement.
Abstract
Improve English. For example, there are too many repetitions (e.g. Use, used...).
Introduction
In my opinion, the introduction should be completely rewritten. There are, for example, too many historical references that are not very important, while the current state of the art should be explored in depth.
Specific suggestions:
1- lines 70-85: "move into the “result and discussion" section.
2- lines 87-93: move into "materials and methods" section.
Materials and methods
1- Introduce bibliographic references for "Jar Test method".
2- lines 133-139: move into the “result and discussion" section.
Results and discussion
This session should be rewritten in a more concise form to better highlight the experimental results. There are, in general, too many graphs and tables.
Specific suggestions:
1- figure 2: the graphs must have the same scale to appreciate the differences between the various experimental results.
2- show table 2 or figures 3, 4 and 5. There are too many.
3- merge tables 4, 5 and 6 into a single table.
4- merge tables 7, 8 and 9 into a single table.
5- merge tables 10, 11 and 12 into a single table.
Comments on the Quality of English LanguageEnglish needs to be improved. For example, there are many repetitions
