Greywater as an Alternative Solution for a Sustainable Management of Water Resources—A Review

Round 1

Reviewer 1 Report

This article reviews the processes for treating greywater. In this paper
indicate that the characteristics of greywater depend essentially on the
quality of water uses for the initial supply. I think that including the quality of the water used
as a supply would improve the article.



Table 1 includes limit values ​​established by the legislation, in the case of
Spain, for agricultural irrigation 3 qualities of water are collected
depending on the crop in which it is going to be used, and in table 1
this aspect is not indicated , only limit values ​​corresponding to quality
are included for: a) Irrigation of products for human consumption with a water application
system that does not prevent direct contact of the reclaimed water with
the edible parts, but the consumption is not fresh but with a subsequent
industrial treatment. b) Irrigation of pastures for consumption of milk or meat producing animals. c) Aquaculture.  

Author Response

We thank to reviewers for their precious time and invaluable comments. We have carefully considered all of the comments. The modifications are summarized in our responses below an in the text (in yellow).

Rev. This article reviews the processes for treating greywater. In this paper, indicate that the characteristics of greywater depend essentially on the quality of water uses for the initial supply. I think that including the quality of the water used as a supply would improve the article.

Thank you for your response and the reader's effort. you are totally right. We have added a new paragraph and a table (table 1) about the quality of used water from sources.

Rev. Table 1 includes limit values established by the legislation, in the case of Spain. For agricultural irrigation 3 qualities of water are collected depending on the crop in which it is going to be used, and in table 1 this aspect is not indicated , only limit values corresponding to quality are included for: a) Irrigation of products for human consumption with a water application system that does not prevent direct contact of the reclaimed water with the edible parts, but the consumption is not fresh but with a subsequent industrial treatment. b) Irrigation of pastures for consumption of milk or meat producing animals. c) Aquaculture.

This table has been revised an all values established by the legislation for agricultural irrigation (for the 3 sections) has been added.

Reviewer 2 Report

The authors provided a good review on the current issue of greywater reuse. The composition of the water was given, special attention was paid to the epidemiological danger of the use of grey water, which is especially important in the context of the Covid-19 pandemic. The characteristic of various methods of purification of greywater was given.

Some remarks:

63. 57-63. Repeat the text, you need to edit
64. 110. FILALI et al – CapsLk!

L.318. DCO: apparently the authors mean COD

The article contains only one table. It will be nice to present some of the descriptive information in the form of graphs, diagrams. 

The article contains several self-citations.

The article is actual, informative, and may be interesting to readers

Author Response

We thank to reviewers for their precious time and invaluable comments. We have carefully considered all of the comments. The modifications are summarized in our responses below an in the text (in yellow).

Rev. 57-63. Repeat the text, you need to edit

Thank you for your response and the reader's effort. We have edited the text

“Reuse of treated wastewater (TWW) is a strategic choice focused on the conservation of Tunisia's limited water resources [10].In fact, the number of the wastewater treatment plants in Tunisia, increased from 83 in 2005 to 122 in 2017. Likewise, the length of the sanitation network increased from 14799 km in 2010 to 16337 in 2017. The collected wastewater presented around 260 millions m3 and 80% of the collected treated water was used in agricultural sector [10] “

 Rev. 110. FILALI et al – CapsLk!

All the references that are part of the sentence have been corrected.

Rev. L.318. DCO: Apparently, the authors mean COD.

We agree with this comment and we have modified the text

Rev. The article contains only one table. It will be nice to present some of the descriptive information in the form of graphs, diagrams. 

Thank you for your remark, we have added tables (in total 5 tables) and figure.

Reviewer 3 Report

The aim of this study is very good. The manuscript has been well referenced.  However, the entire paper is not well-written and presented in a convincing manner. The following comments may further enhance the quality of this paper:

1. Some of the keyword selections (greywater, sustainable management) duplicates the same as in the paper title. Other selections should be re-chosen.
2. Many sentences are written in not easy to understand English.
3. What is “high indicator” in Line 39?
4. All acronym names, such as TWW, Ct, CI, should be defined when first appear.
5. What is “them” in Line 63?
6. The objective is focused in “Tunisia”. Why not include this study area in the paper title? Are most of the literature review concentrated in this country? In the last section, “Germany” is included in the discussion. Why?
7. What is “L/p/d”? Please define.
8. Reference “FILALI et al.” should not be in all capital form.
9. Section 3 should be in “bold” letter.
10. Format for literature citations should be uniform throughout the entire text. The form “Sanae Kholtei et al. 2007 [31]” (Line 133) should be modified as “Sanae et al. [31]” or “Kholtei et al. [31]”. Unfortunately, reference #31 is listed under a different author’s name in the reference section. Please do check the consistency of the reference citations on the entire text.
11. “Risk of SARS…” should be assigned a section number such as “3.3”.
12. Lots of reviewed results may be better presented in tabular form instead of in words (such as in section 4).
13. Many spacing errors have been detected (such as in Line 202).
14. What is “1log10”? Please explain.
15. Many quantitative comparisons may be converted into percentage comparisons.
16. Since “cost has been mentioned in Line 360, why not include some review on this matter?
17. What is “minimalist” in Line 464?
18. Are the conclusion remarks aimed for Tunisia or any other countries?
19. What is the heading or meaning of the fourth column in Table 1?

Author Response

We thank to reviewers for their precious time and invaluable comments. We have carefully considered all of the comments. The modifications are summarized in our responses below an in the text (in red).

Rev. Some of the keyword selections (greywater, sustainable management) duplicates the same as in the paper title. Other selections should be re-chosen.

Thank you for you precious remarks and comments; we perform the modification to the keywords.

Rev. Many sentences are written in not easy to understand English.

This paper has been revised by an English-speaking colleague.

Rev. What is “high indicator” in Line 39?

This indicator of water scarcity is determined according to the annual availability per capita in m3 to indicate the water situation of the country. According to the WHO. Water stress begins when the water availability per capita / year is less than 1700 m3. When these availabilities are less than 1000 m3 per capita per year, we are talking about water shortage in the country. Below 500 m3 per capita per year, water becomes a development constraint. the current availability of the annual allocation per capita in m3 per year is equal to 450 (> 1).

Rev. All acronym names, such as TWW, Ct, CI, should be defined when first appear.

All acronym names have been defined.

Rev. What is “them” in Line 63?

The expression “them” has been deleted, and the entire parapgraph has been rewritten

Rev. The objective is focused in “Tunisia”. Why not include this study area in the paper title? Are most of the literature review concentrated in this country? In the last section, “Germany” is included in the discussion. Why?

You are right, most of the review is focused on Tunisia, for that, we adjusted the title by adding "Tunisia”

-  Germany was included in the discussion of section 4, because it was a research work carried out by a group of Tunisian and German researchers, in this work they compared two greywater treatment experiments, one carried out in Tunisia and the other one was carried out in berlin ( as part of a thesis).

Rev. What is “L/p/d”? Please define.

We have mentioned the abbreviation (L/p/d) stands for “Liters per day” in the text.

Rev. Reference “FILALI et al.” should not be in all capital form.

The entire references list have been checked.

Rev. Section 3 should be in “bold” letter.

We changed section 3 to bold text

Rev. Format for literature citations should be uniform throughout the entire text. The form “Sanae Kholtei et al. 2007 [31]” (Line 133) should be modified as “Sanae et al. [31]” or “Kholtei et al. [31]”. Unfortunately, reference #31 is listed under a different author’s name in the reference section. Please do check the consistency of the reference citations on the entire text.

Yes, we added the correction of references  31 and all references was checked.

Rev. “Risk of SARS…” should be assigned a section number such as “3.3”.

Yes, this section has been modified as suggested.

 Rev. Lots of reviewed results may be better presented in tabular form instead of in words (such as in section 4).

Thank you for your precious remark; we have added 3 tables in this section.

Rev. Many spacing errors have been detected (such as in Line 202).

We checked all the text and all spacing errors have been deleted/

Rev. What is “1log10”?  Please explain.

The decimal logarithm is the unit used to evaluate the variation in bacteriological parameters, for example 1 log 10 means that the reduction in total coliform values decreases by one logarithmic unit for water; I have added the explanations in all the text.

Rev. Many quantitative comparisons may be converted into percentage comparisons.

We have tried to improve the presentation of some results in form of tables and percentages.

Rev. Since “cost has been mentioned in Line 360; why not include some review on this matter?

Thank you for your valuable comments, there is a second paper in progress, where we have developed this topic of "cost of cleaning wastewater treatment plants" with more details.

 Rev. What is “minimalist” in Line 464 ?

The expression “minimalist” has been deleted. We replaced this expression with the adequate explanation.

Rev. Are the conclusion remarks aimed for Tunisia or any other countries?

The conclusion remarks addressed to all countries suffering from water scarcity with particular emphasis on Tunisia.

Rev. What is the heading or meaning of the fourth column in Table 1?

Table 1 has changed to Table 5 in the new version of the article. The fourth column of the table represents the Spanish standards for use of treated wastewater in agricultural irrigation; it is the first part of the 3^rd large column which represents Spain.

Round 2

Reviewer 3 Report

Much improved than the original version, especially on the English part. However, there are still a few corrections needed:

1. The keyword "greywater" which is the same in the paper title has not been changed.
2. Reference "FILALI et al." is still in all capital letters.
3. Many spacing errors still can be detected throughout the entire text.
4. Please list out all the authors' name (last name and initials) for all the references under the form "et al." in the reference listing.
5. Have not seen the promised added tables in the revised manuscript.

Author Response

We thank to the reviewer for their precious time and invaluable comments. We considered carefully all recommendations and modifications. 

1. The keyword "greywater" which is the same in the paper title has not been changed.
2. Reference "FILALI et al." is still in all capital letters.
3. Many spacing errors still can be detected throughout the entire text.
4. Please list out all the authors' name (last name and initials) for all the references under the form "et al." in the reference listing.

We perform all the modifications sugested. Thanks again for the recommendations.

Related to point 5 ”Have not seen the promised added tables in the revised manuscript”. We added some tables but during revisions stages there were eliminated. 

 

Author Response File: Author Response.docx