Potential Use of Wastewater Treatment Plant Sludge in Fabrication of Burnt Clay Bricks

Round 1

Reviewer 1 Report

The article is interesting, the investigation provides a study about various properties for the characterization of burnt clay bricks produced using different dosages of Water treatment plant sludge. They varied the percentages of WTS were 5%, 10%, 15%, 20%, 30%, and 40%), so they partly replace conventional clay in bricks. The article could be published but there are some points that must be corrected before publication.

Line 24: Are percentages by weight?

Line 125-127: please, correct the numbers of the chemical formulas to subscripts

Line 148: please, put parenthesis in C.

Line 211: Light, lowercase L

Line 223-224: Why after 20% of WTS, is there a decrease in compressive strength? To what is it attributed?

Line 293: Lesser, lowercase L

Line 326: Sulphate, S lowercase

Line 438: You must adjust the references as requested by the Journal and you must consider at least 2 articles from this journal in relation to the subject of the article.

When this has been done the article can be published.

Author Response

Please find the attached file with point by point answer to reviewer comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

1. Water treatment plants produce a huge amount of sludge, which is discharged into nearest watercourse leading to harmful effects - Is it applicable to all countries or in a specific country?
2. "Water treatment plants produce a huge amount of sludge" any data on quantity?
3. "The clay and water treatment plant sludge (WTS) used  for brick manufacturing have similar chemical composition." I beg to differ, even I worked on few projects in this domain, I am sure clay has different content, what was done here is an assumption, please check. WTP waste content is derived from which unit it comes from, what process is adopted in that particular unit.
4. "5%, 10%, 15%, 20%, 30% and 40%" how this percentages were determined, is it based on some prior work or DOE?
5. Line 28-30: All bricks with or without WTP waste will show porous structure, that does not indicate because of this addition weight is reduced, wrong interpretation.
6. Line 26: Why flexural strength is evaluated for a brick, which country code specifies it?
7.  Line 31: 20% is not high dosage, also dosage is a word used for liquid mixture in solids
8. Line 36: this work is based on water treatment plant sludge, why here waste water treatment plant data provided?
9. Line 35-42 belongs to waste water which is irrelevant to this work, remove it add content related to water treatment plant
10. Line 83-85 without any data dont promote this statement everywhere, rather write clear points.
11. Introduction transition is really poor, content flow is dragging.
12. Remove section 2, this is about water treatment plant it is not hazardous in any country classification, if I am not correct, this work is on Wastewater, then change title properly.
13. "Bricks produced for this study were obtained from a local brick kiln" line 103: is it correct sentence? Are you producing bricks or obtained bricks, if obtained how this is a valid work?
14. Section 3 change it to materials and methods
15. I doubt the data of Table 1 and 2, also add both data and present in one table. If it is clay which clay is tested here, many clay varieties exist.
16. Table 3 shows all leaching is within limits then how its hazardous and what is the use of this work?
17. Table 3 title is wrong, leaching toxicity is meaningless, please alter.
18. Why authors compared clay with WTS, it is not the focus point of this work, what authors wish to convey is not clear to me.
19. Section 5: Which country code is used for this testing procedure, please provide that information, since international readership is expected it will help them to really understand through that code.
20. Line 176: How many cycles of this done, also this is not explained in materials and methods section, there is lot of dragging exists in the content flow, authors need to be clear, crisp and on point.
21. Line 194: How much percentage lighter?
22. Line 201: Why this comparison is required, its purely out of scope of this work, if this to be taken authors need to rewrite materials and methods section incorporating all this information.
23. Line 210: If specific gravity varies how the composition of those materials is similar and in nearby percentage of mixing is really confusing to me.
24. Fig 9(b) I dont understand what is the real use here
25. Section 6.4: convey the need since its a compression material, why flexure is needed?
26. Line 245: Is this R² value comparable and correlating? Poor interpretation. The same for all places where this is equation is placed, please check the interpretation
27. Section 6.9: Sulphate attack test
28. Line 349: Is influenced by....
29. 6.10: How many cycles done is not clear
30. I dont understand the need of section 7 here in this work
31. Many references are not in proper format, check ref1 etc, change them please.

Please perform the corrections and resubmit for evaluation.

Author Response

please find attached response to reviewer comments. 

Author Response File: Author Response.pdf

Reviewer 3 Report

The topic addressed is of practical significance and practicability and the experimental process and results are described in detail, while the research content is not innovative and concise enough. This paper cannot be accepted in its current form. Some suggestions are as followed.

1. The abstract does not coverall the researchand conclusions.
2. The introduction should be more logical and targeted. For example, the literature review offered in the introduction does not come up to a clear conclusion as for the contribution of the paper.
3. Some properties of brick samples are studied in this paper, but no relevant research at the test piece or structural level has been carried out, and the conclusion of "bricks fabricated with high dosage of WTS (i.e.20%) will minimize the environmental burden and lead to more durable and economical masonry construction" mentioned in the abstract cannot be drawn.
4. The research ofthis paper has been studied many times in published articles and relevant data and conclusions have been drawn, it is not enough to compare experimental results with empirical formulas derived from experimental data. It is suggested to compare the results of this paper with the experimental results of other papers.
5. How do SEM images confirm the porous structure of bricks made with WTS? Figure 4 shows very little information.
6. Although the workload of the paper is adequate, the lack of mechanism analysis makes the papermore like an experimental report.
7. The data is very comprehensive, but the description is sometimes inconsistent. For example, not all indicators are optimal when the replacement rate is 20%.
8. There are several typos in the document. For example, in Figure 5, …A)> …a), …d)> …b)
9. What is the relationship between the 5th reference and the research content of the paper? Is the authorserious about quoting the 8th reference?

Author Response

please find the attached file with point by point response to reviewer comments. 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear Authors,

Now the article is in acceptable format, I recommend its inclusion

Author Response

Please find the attached file for reviewer response reply

Author Response File: Author Response.pdf

Reviewer 3 Report

The relevant literature and data comparisons with other papers have been supplemented, and the language logic and discussion of the results have been further improved. However, if ' lead to more durable and economical masonry construction' mentioned in the paper can be confirmed, it is necessary to increase the research at the component and structure level, so it is recommended to add this part in the follow-up research. Overall, the current rigor and completeness of the paper are relatively good.

Author Response

Please find the attached file for reviewer response reply

Author Response File: Author Response.pdf