Separation Zone Required to Buffer Hazardous Waste Landfills Impact on Scattered Water Supply Sources: From a Whole Lifespan Perspective

Round 1

Reviewer 1 Report

Dear Authors

In my opinion the theme of the article is very actual and interesting for the readers of the journal.

 

The manuscript under revision study threatens from landfill leachate leakage to groundwater quality in remote areas is a major concern globally. The authors showed that Buffering distance preserved between landfill site and groundwater supply wells is important to prevent drinking water from contamination of dangerous pollutant and posing potential threaten to drinking safetyhe a very fascinating model to assess information of ecological sustainability.

This manuscript joined with the aging and defect evolution model of landfill engineering materials, construct a framework for buffering distance. This paper coupled with the aging and defect evolution model of landfill engineering materials, construct a framework for BFD This paper coupled with the aging and defect evolution model of landfill engineering materials, construct a framework for BFD prediction with the consideration of landfill performance degradation, and carried out model application and verification in a coastal hazardous waste landfill. The results show that during the life cycle of landfill, its BFD experienced 1.5 times increase from the start of its operation to its life end and reached to 3000 m. Under the condition of landfill performance degradation, the BFD required to attenuate heavy metals experience more increase than that of organic pollutants, BFD required for zinc(Zn), for example, increases 720 m over the none degradation condition, while 2,4-dichlorophenol(2,4-D) increase only 288 m. Considering the uncertainty sourced from model parameter and structure, the BFD should be more than 4050 m to ensure long-term safe drinking under unfavorite conditions such as large amount of leachate, weak degradation and fast diffusion of pollutant in vadose and aquifer. If the BFD cannot meet the demand at the end of the landfill life, the leaching behavior of solid waste can be controlled to reduce the depending on BFD. For example, when the leaching concentration of Cd in the waste is reduced from 0.6 mg/L to 0.17 mg/L, the buffering distance will be reduced from 3000 m to 500 m.

prediction with the consideration of landfill performance deprivation, and carried out model application and verification in a coastal hazardous waste landfill.

The authors showed that during the life cycle of landfill, its buffering distance experienced 1.5 times increase from the start of its operation to its life end and reached to 3000 m. Under the condition of landfill performance degradation, the This paper coupled with the aging and defect evolution model of landfill engineering materials, construct a framework for BFD prediction with the consideration of landfill performance degradation, and carried out model application and verification in a coastal hazardous waste landfill. The results show that during the life cycle of landfill, its BFD experienced 1.5 times increase from the start of its operation to its life end and reached to 3000 m. Under the condition of landfill performance degradation, the BFD required to attenuate heavy metals experience more increase than that of organic pollutants, BFD required for zinc(Zn), for example, increases 720 m over the none degradation condition, while 2,4-dichlorophenol(2,4-D) increase only 288 m. Considering the uncertainty sourced from model parameter and structure, the BFD should be more than 4050 m to ensure long-term safe drinking under unfavorite conditions such as large amount of leachate, weak degradation and fast diffusion of pollutant in vadose and aquifer. If the BFD cannot meet the demand at the end of the landfill life, the leaching behavior of solid waste can be controlled to reduce the depending on This paper coupled with the aging and defect evolution model of landfill engineering materials, construct a framework for BFD prediction with the consideration of landfill performance degradation, and carried out model application and verification in a coastal hazardous waste landfill. The results show that during the life cycle of landfill, its BFD experienced 1.5 times increase from the start of its operation to its life end and reached to 3000 m. Under the condition of landfill performance degradation, the BFD required to attenuate heavy metals experience more increase than that of organic pollutants, BFD required for zinc(Zn), for example, increases 720 m over the none degradation condition, while 2,4-dichlorophenol(2,4-D) increase only 288 m. Considering the uncertainty sourced from model parameter and structure, the BFD should be more than 4050 m to ensure long-term safe drinking under unfavorite conditions such as large amount of leachate, weak degradation and fast diffusion of pollutant in vadose and aquifer. If the BFD cannot meet the demand at the end of the landfill life, the leaching behavior of solid waste can be controlled to reduce the depending on BFD. For example, when the leaching concentration of Cd in the waste is reduced from 0.6 mg/L to 0.17 mg/L, the buffering distance will be reduced from 3000 m to 500 m.

Authors showed anexemple that when the leaching concentration of Cd in the waste is reduced from 0.6 mg/L to 0.17 mg/L, the buffering distance will be reduced from 3000 m to 500 m. Also, required to attenuate heavy metals experience more increase than that of organic pollutants, buffering distance required for zinc(Zn), for example, increases 720 m over the none degradation condition, while 2,4-dichlorophenol(2,4-D) increase only 288 m. Considering the uncertainty sourced from model parameter and structure, the buffering distance should be more than 4050 m to ensure long-term safe drinking under unfavorite conditions such as large amount of leachate, weak degradation and fast diffusion of pollutant in vadose and aquifer. If the buffering distance cannot meet the demand at the end of the landfill life, the leaching behavior of solid waste can be controlled to reduce the depending on buffering distance. For instance, when the leaching concentration of Cd in the waste is reduced from 0.6 mg/L to 0.17 mg/L, the buffering distance will be reduced from 3000 m to 500 m.

Estimate with the consideration of landfill performance degradation, and carried out model application and verification in a coastal hazardous waste landfill.

 

The results show that during the life cycle of landfill, its buffering distance experienced 1.5 times increase from the start of its operation to its life end and reached to 3000 m. Under the condition of landfill performance degradation, the buffering distance required to attenuate heavy metals experience more increase than that of organic pollutants, BFD required for zinc(Zn), for example, increases 720 m over the none degradation condition, while 2,4-dichlorophenol(2,4-D) increase only 288 m. Considering the uncertainty sourced from model parameter and structure, the BFD should be more than 4050 m to ensure long-term safe drinking under unfavorite conditions such as large amount of leachate, weak degradation and fast diffusion of pollutant in vadose and aquifer. If the BFD cannot meet the demand at the end of the landfill life, the leaching behavior of solid waste can be controlled to reduce the depending on BFD. For example, when the leaching concentration of Cd in the waste is reduced from 0.6 mg/L to 0.17 mg/L, the buffering distance will be reduced from 3000 m to 500 m.

 

The conclusion of this research show ed:

1) Different types of pollutants require different dilution attenuation factors (RDAF), with more dilution attenuation required for high initial concentrations and high toxicity in leachate. For example, 2,4-D in this case requires a dilution attenuation of 2,249.7 times, which is 66.6、16.7 and 11.1 times higher than that for the heavy metals Ni, Zn and Cd, 416 respectively.

 

2) The sensitivity of the dilution attenuation fraction (DAF) to buffer distance is not uniform for different pollutants, with the dilution and attenuation fractions for organic pollutants being more sensitive to buffer distance. For example, for 2,4-D, although the RDAF was the largest, the buffer distance was only 13.6% and 12.6% for the heavy metals and Cd.

 

3) A safety buffering distance of 3,000 m is required to take into account the impact of long-term ageing of the geomembranes on groundwater quality for each pollutant and hazardous waste landfill, and buffering distance of 4,050 m is required to take further account of parameter 0 0.002 0.004 0.006 0.008 0.01 0.012 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 concentration in wells,mg/l Initial concentration of Cd,mg/l 500m 1000m 1500m 2000m 2500m 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0 5 10 15 20 concentration in wells,mg/l Initial concentration of 2,4-D,mg/l 50m 100m 150m 200m 250m Acoustics 2022

 

4) In the case that the actual buffering distance cannot meet the demand with the degradation of the landfill performance, the demand for BFD can be reduced by reducing the concentrations of pollutants in the waste through pretreatment methods such as solidification and stabilization. Taking Cd as an example, when the concentration of Cd in waste is reduced from 0.6 mg/L to 0.53、0.39、0.3、0.23 and 0.17mg/L by pretreatment, the BFD will be adjusted from 3000 m to 2500, 2000, 1500, 1000, and 500 m

 

The paper is well structured, well written, the language is correct and clear, and the title and abstract clearly describe the content of the manuscript.

 

 In my opinion no revision is needed.

Best regards

Author Response

We thank the experts for their recognition and encouragement and will continue to work on this area of research in the future.

Reviewer 2 Report

It is interesting to assess the risks and hazards for drinking water sourced near a landfill. The presented results are valuable and should be published.  

 

Author Response

We thank the experts for their recognition and encouragement and will continue to work on this area of research in the future.

Reviewer 3 Report

I would like to congratulate the authors for their interest in researching in this field, however, the work presented presents some deficiencies.

a)       The title is not appropriate for the article. authors cite life cycle analysis but do not include such analysis, which implies that the content of the article is not accurate according to the title by not considering the life cycle perspective to which they commit.

The title should have the following characteristics:

-Describe the content of the article in a specific, clear, accurate, brief, and concise manner.

-Enable the reader to identify the topic easily.

-Allow a precise indexing of the article.

I propose that either the authors modify the title or include the life cycle analysis or, failing that, a well-founded explanation of the variation in the environmental impact derived from the proposed actions.

b) Abstract is, in my opinion, correct and meets the requirements of this section. In this way, a reader can, from reading the abstract, know the object and summarized content of the research carried out.

c) Keywords should be simple words or short combinations of words that allow, in a simple way, to index the article in such a way that it is easy to determine its area, content,...and to quickly associate it to other related research and documents. I think that the inclusion of words such as Dilution attenuation; Safe drinking wáter is not justified in this case. That is why I suggest the authors to modify these keywords.

d) The introduction should be expanded to include a review of the complete state of the art and other related research, sources and documents... at present, this section is overly simple and sparse in content.

e) I believe that the introduction should include references to life cycle analysis. This could be the first point of reference to such a life cycle analysis that justifies the relationship between the environmental impact and the analysis performed by the authors.

f) Figure 1 "Framework and process of BFD for hazardous waste landfills under long-term aging conditions" seems to me correct although it should, for each model, include all inputs and outputs (materials, energy, information,..).

g) From reading the article, I understand that the model presented is not limited to the case shown in Figure 2.

If this is the case, I encourage you to specify it in the initial sections to avoid this doubt to the readers.

Here are a couple of articles that I consider of interest. As you will see, there is no relationship on the part of the reviewer with any of the authors, neither directly nor indirectly.

I believe that, especially the first one, may help you to specify the relationship between your research and the LCA.

https://www.sciencedirect.com/science/article/abs/pii/S0048969722019969

https://pubs.acs.org/doi/10.1021/acs.est.1c02526

 

I hope that these changes will help to improve your article and make it a document of great scientific interest.

Author Response

Thank you very much for your comments and professional advice. These opinions help to improve academic rigor of our article, Based on your suggestion and request we have made corrected modifications on the revised manuscript. We hope that our work can be improved again Furthermore, we would like to show details as follows:

Author Response File: Author Response.docx