Review Reports - Wastewater Treatment with Geotextile Filters: The Role in Permeability and Pollutant Control

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The distinction between contributions from geotextile removal and biofilm removal is unclear. The authors should refocus the results and discussion on the primary goal of the study: examining the role of biofilm in permeability and pollutant control. If the aim is solely to compare the performance of two nonwoven geotextiles, this should be clearly stated, and the biofilm aspect should not be included.

Line 165. The authors mention “A small increase in permeability was observed over the 10 cycles” but the next sentence which state “initial average permeability of all permeameters was 2.28 x 10-2 m/s, while the final average was 1.43 x 166 10-2 m/s” shows the permeability is reducing. Is that an error or intentional?

Line 169: “These results suggest that although biological clogging occurred, it is possible that there was also some degree of physical clogging.” Are the authors just making assumptions? Needs to be clearer is that is claimed based on their other result findings.

Line 177: What is Polypropylene, it appears all of the sudden in the discussion and does not make any sense in the context.

Line 174 to Line 181. The paragraph is unclear if the authors are discussing the cause of reduction in permeability as geotextile or is it because of the biofilms.

Line 193 to Line 197: “Overall, the permeability of both types of geotextiles remained virtually unchanged throughout the 20 cycles, indicating that bioclogging was negligible during the approximately 80-day operating period.” This is a very generic statement. How can they claim bioclogging was negligible. The authors should provide results from their experiment to support this.

Section 3.2. Physical-chemical parameters are the authors focusing on general removal efficiency of the geotextile membrane or are the focusing on removal due to biofilm. It is unclear. If it by biofilm then it is not obvious on how they quantifying what is removed by biofilm vs what is removed by physical straining through geotextile membranes. This section need to reorganized to convey the results clearly.

Section 3.3. Measurement of biomass growth would be much of value if it not tied together with section 3.2. So the authors should correlate the results in section 3.2 to section 3.3.

Comments on the Quality of English Language

Line 177: What is Polypropylene, it appears all of the sudden in the discussion and does not make any sense in the context.

Line 174 to Line 181. The paragraph is unclear if the authors are discussing the cause of reduction in permeability as geotextile or is it because of the biofilms.

Section 3.3. Measurement of biomass growth would be much of value if it not tied together with section 3.2. So the authors should correlate the results in section 3.2 to section 3.3.

Author Response

Find the responses in the attached file. Thank you very much!

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Article entitled Wastewater treatment with geotextile filters: the role of biofilm in permeability and pollutant control written by Maria Vitoria Morais, Leonardo Marchiori, Josivaldo Sátiro, Antonio Albuquerque and Victor Cavaleiro and submitted to Applied Sciences journal as a draft no applsci-3392741, deals with an important issue of effective wastewater treatment.

Article is in journal’s scope. Therefore, it could be considered for publication in Applied Sciences journal. As English is not my native language, I am not able to assess language correctness. However, while reading, I found some statements missing, confusing or unclear. Below, I enclose the list of my comments.

I would rewrite the sentences in which publications 6-9 are cited. The citation rule makes the text very difficult to read.

A significant part of the cited literature is quite old - over 10 years old. This, combined with the small number of cited items, causes doubts about the relevance of the literature review. Some of the cited items are not in English, conference materials and diploma theses are cited - this may cause problems with access to original sources. I suggest supplementing the literature review with the latest publications, no older than 5 years.

In the last paragraph of the introduction, the Authors write: “observe the effects of biological clogging, and the treatment processes mediated solely by microorganisms, excluding the influence of physical clogging. This methodology ensures that the findings exclusively reflect biological activity”. I have not found any descriptions in the methodology regarding microbiological control. Similarly in the results. Please supplement this information: what microbiological tests were performed, what microorganisms were identified, how the results were related to the activity of microorganisms.

The figures prepared by the authors are illegible. The Authors use only two colors for each of them, four shapes of points per each color. With small graphs, everything overlaps and you can't see much. I suggest expanding the color palette (as it is on Figures 2 and 3), while reducing the size of the marker defining the individual result (point). This should make the graphs more legible. Alternatively, the Authors can try to solve the problem of graph legibility in a different way. The % scale (Y axis) does not have to be 0-100. Reducing the range should also help. Similarly parameters on Y axis at Fig. 7.

How biomass content was determined?

I don't understand the purpose of figure 9 and what message it conveys. Perhaps this figure can be removed and replaced with a short text description.

Can it be determined with certainty from SEM that what is observed at figures 10-17 is living organic matter? Is there no chance that these are remnants of dead organic matter, organic compounds or material of an inorganic nature?

The material presented is interesting and worth publication. However, some supplementation is needed. Based on my comments and overall impression, I suggest major revision.

Author Response

Find the responses in the attached file. Thank you very much!

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript investigates the use of geotextile filters in wastewater treatment, focusing on the interaction between biofilm formation, permeability, and pollutant removal efficiency. The study evaluates two types of geotextiles with distinct grammages, analyzing permeability changes, nutrient removal, and biomass development over an 80-day experimental period using synthetic wastewater.

1. Could authors expand the introduction to provide a more detailed comparison between geotextile-based systems and conventional wastewater treatment techniques, emphasizing cost, efficiency, and space requirements?

2. Please include recent references (e.g., 2022-2024) to highlight advances in biofilm-supported filtration systems.

3. Please clarify whether the synthetic wastewater composition reflects typical wastewater characteristics in real-world scenarios.

4. Please discuss how the observed differences between GT120 and GT300 could inform material section for specific wastewater treatment applications.

5. Authors can expand on the practical implications of the findings.

6. Could authors briefly outline the potential future research directions in the conclusion?

Author Response

Find the responses in the attached file. Thank you very much!

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

This is my second review of this manuscript. The Authors answered all of my comments. Suggested corrections have been applied. Second version is better than the first one. I suggest to accept this article in its present form.