Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors tested the effect of activated carbon on hydrogen sulfide removal from landfill gas and tested activated carbon samples. The research is conducive to the development of zero greenhouse gas emissions. The manuscript can be approved after minor revisions. The main things that need to be changed are shown below:

 

Point 1: It is suggested to add the research content, purpose and significance of the paper in the introduction, and highlight the innovation of this study.

Point 2: It is suggested that the content of the third part "Materials and methods" and the fourth part "Results and discussion" be subdivided into several sub-headings to make the content of the article clear.

Point 3: Please check the horizontal axis in Figure 2. The axis title in the figure is "Measurement canpaing 1 [number of mesaurements". There are spelling errors and the symbol "] "is missing after the unit.

Point 4: Figure 5 and Figure 6 are missing axis titles, please add them.

Point 5: Figure 7, which is introduced in the paper, is the chart of the third Measurement, and the axis title is " 1 [number of measurements]", please check and correct. And determine if there are any spelling errors.

Point 6: The pictures in the manuscript are a little fuzzy, it is suggested to improve the clarity of the pictures.

Point 7: The document format cited in line 207 "(Kajolina et al. 2015)" and line 213 "(Cabera-Codony et al., 2014)" is wrong, please modify it.

Point 8: In line 343, the format of "H2S" is incorrect. Please modify it.

Point 9: In line 350, "[process" has an additional "[" symbol.

Point 10: In Table 2, "LFG parameters after the carbon filter," delete commas.

Point 11: It is suggested to add conclusions about the experiment in the "Conclusions" section.

Comments on the Quality of English Language

Please check for spelling and grammar errors that need fixing.

Author Response

Dear Reviewer
Thank you for your valuable comments that have helped us improve our work. Please find attached the responses to the Reviewer and the corrected work.

Agnieszka Generowicz

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

1. It is recommended to increase comparative analysis with previous studies.

2. It is recommended to write the conclusions point by point.

3. Minor editing of English language required.

 

The paper analyzes the adsorption of hydrogen sulfide in landfill gas by activated carbon, which is of certain value. However, there are many points that need to be improved in the paper, and it is recommended to major revision.

1. Line 158-159, “Methodology for performing landfill gas composition measurements for control and monitoring of landfill degassing installations”, it is recommended to add a reference about the method.

2. Table 1, It is recommended to add the percentage of hydrogen sulfide in Table 1.

3. The name of the abscissa axis in Figure 1 is wrong. “Measurement canpaing 1 [number of measurement” should be changed to “Measurement campaign 1 [number of measurement]”

4. There is an error in the name of Figure 3, the magnification of the third sub-figure is 1000 times.

5. Line 226-228, The related description for Figure 3 is too simple, and there are grammatical errors in the text.

6. Line 233, “washed activated carbon sample”, why not use the sample in Figure 3 for energy spectrum observations?

7. Line 239-243, the description in the text for Figure 4 is too simplistic.

8. There are four legends in Figure 5, but there are only three proportions in the figure.

9. Table 2, The data of LFG parameters before the carbon filter is inconsistent with the data in Table 1, why? Furthermore, as the mixed gas, after the carbon filter, the content of hydrogen sulfide is greatly reduced, which will lead to a significant decrease in the percentage of hydrogen sulfide and a significant increase in the percentage of the other gas. Why is there no significant change in the percentage of other gas data after carbon filter.

10. Figure 8, Why does the efficiency of hydrogen sulfide removal exceed 100%?

11. Line 342, “with an average reduction efficiency of 97.07%”, according to the Table 3, average reduction efficiency should be 97.05%.

12. Line 343, “ H2S”, Please note the subscript.

13. Line 349, “activated carbon plays a dual role in this [process”, what does this symbol “[” mean?

 

14. It is recommended to write the conclusion point by point.

Comments on the Quality of English Language

Minor editing of English language required

Author Response

Dear Reviewer
Thank you for your valuable comments that have helped us improve our work. Please find attached the responses to the Reviewer and the corrected work.

Agnieszka Generowicz

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

1.      How does the European Green Deal aim to transform the EU into a modern, resourceful, economical, and competitive economy, and what role does it play in addressing climate change and environmental degradation?

2.      What are the potential environmental and health risks associated with landfill gas generated in waste deposits, and how does its capture, treatment, and safe neutralization contribute to sustainability goals?

3.      In the context of cogeneration units, how does the treatment of landfill gas impact the proper operation, as well as the quantity and quality of electricity and heat generated?

4.      What specific challenges and threats does hydrogen sulfide in landfill gas pose to the environment and people, and why is its removal crucial for sustainable waste management?

5.      How does the activated carbon filter contribute to the removal of hydrogen sulfide from landfill gas, and what is the significance of the 97.05% efficiency in this process?

6.      Can you elaborate on the surface analysis performed on the activated carbon filter material and how it contributes to understanding its effectiveness in removing hydrogen sulfide?

7.      How does the use of impregnated activated carbon align with the broader sustainability objectives of the European Green Deal, and in what ways can it contribute to reliable operation of gas engines in cogeneration units?

8.      Considering the study's results, what implications does the high adsorption efficiency of impregnated activated carbon have for the broader adoption of similar technologies in landfill gas treatment?

9.      How might the findings of this research impact future policies and practices related to landfill gas management, especially in the context of achieving sustainability goals outlined in initiatives like the European Green Deal?

10.   In what ways can the results of this study be extrapolated or applied to other regions facing similar challenges related to landfill gas and environmental sustainability?

 

 

 

 

Comments on the Quality of English Language

Please avoid overselling statements.

Author Response

Dear Reviewer
Thank you for your valuable comments that have helped us improve our work. Please find attached the responses to the Reviewer and the corrected work.

Agnieszka Generowicz 

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

This manuscript concerns a case study of landfill gas treatment using impregnated activated carbon to remove hydrogen sulfide. The results showed that under the given experimental condition, the removal efficiency of hydrogen sulfide was measured to be ~97.05%, with the concentration of hydrogen sulfide in the post-treated LFG at ~16.8 ppm, passing the requirements specified by the equipment supplier. However, the measurements and analysis the author did only validated the hydrogen sulfide absorption performance of the impregnated activated carbon they used at a certain test plant under the certain experimental condition. The scientific significance is very limited, with the lack of relevant supporting details in the discussion, which prevent this manuscript to be suitable for publication. Additionally, the data presentation and writing need to be thoroughly improved, since it causes confusions in understanding the results. Here’re some specific comments--

1.  SEM and EDS measurements were used to characterize the morphology and elemental composition of the activated carbon, yet no discussion regarding the morphology/composition- adsorption performance relation was provided. Authors mentioned in line 240-241 that ‘The activated carbon used is characterized by optimal physicochemical properties, having a very large specific surface area and a large pore volume.’, but the specific surface area and pore volume of the activated carbon used in this work were not characterized.

 

 

2.  Whether and how parameters such as the flowrate and pressure of the landfill gas can impact the hydrogen sulfide removal efficiency? 

3. In Figure 8, why does the hydrogen sulfide removal efficiency at some data points can be above 100%?

Comments on the Quality of English Language

Inappropriate punctuation: (Line 101-102) ‘European Green Deal, includes initiatives in a number of closely related areas, such as climate, environment, energy, transportation, industry, agriculture and sustainable financing.’

Typo:( Line 348) ‘flue gas’; figure 1 ‘elektricity’

Long sentences that are hard to read: (line 240-241) ‘The activated carbon used is characterized by optimal physicochemical properties, having a very large specific surface area and a large pore volume.’

Author Response

Dear Reviewer
Thank you for your valuable comments that have helped us improve our work. Please find attached the responses to the Reviewer and the corrected work.

Author Response File: Author Response.pdf

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

The revised manuscript adquately addressed the comments from reviewers. Would recommend to accept in present form.