Environmental Impact of Lead-Acid Batteries: A Review of Sustainable Alternatives for Production and Recycling Based on Life Cycle Analysis

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

1. The abstract effectively summarizes the scope and key findings but could more explicitly state the review's methodological approach (e.g., systematic review criteria, database sources). The introduction sets a strong context but could better articulate the specific research gaps this review aims to fill, especially in relation to prior reviews.
2. While Section 3.2 and Table 1 present valuable data on health impacts, the presentation could be enhanced by clearly distinguishing between occupational and community exposure. It should include more recent and regionally specific health studies from Latin America and Africa to strengthen its global relevance. You can also add a brief discussion on the socioeconomic determinants of exposure (e.g., poverty, informal labor).
3. Section 4 provides a good overview of sustainable technologies, but would benefit from a more critical and comparative analysis. For instance, firstly, you should discuss the economic and scalability barriers of hydrometallurgy in developing regions. Secondly, you can compare the lifecycle carbon footprint of pyrometallurgical vs. hydrometallurgical processes more quantitatively. Finally, you need to address the limitations of LCA in capturing the impacts of the informal sector.
4. Table 1 is informative but cluttered and incomplete in the excerpt provided. It should be reformatted for clarity, with consistent units and complete reference citations. Figures 1, 2, and 3 are referenced but not included in the text. Ensure all figures are present and have descriptive captions that allow them to stand alone. Consider adding a summary table comparing the environmental performance of different recycling technologies (e.g., emissions, recovery rates, costs).
5. Please refer to the related literature to enhance the deep and comprehensive analysis of your paper as follows:

A review on dynamic recycling of electric vehicle battery: disassembly and echelon utilization

A comprehensive review on human–robot collaboration remanufacturing towards uncertain and dynamic disassembly

Author Response

Comments 1: The abstract effectively summarizes the scope and key findings but could more explicitly state the review's methodological approach (e.g., systematic review criteria, database sources). The introduction sets a strong context but could better articulate the specific research gaps this review aims to fill, especially in relation to prior reviews.

Response 1: The authors appreciate the reviewer's comments. In this regard, the methodological approach of the review was added to the abstract (lines 15-20), indicating the databases reviewed, the keywords used, the number of manuscripts obtained and reviewed, as well as the inclusion/exclusion criteria. In addition, a paragraph was added to the introduction mentioning the specific research gaps addressed by the literature review (lines 68-85), highlighting the novelty of the manuscript with respect to previous work.

Comments 2: While Section 3.2 and Table 1 present valuable data on health impacts, the presentation could be enhanced by clearly distinguishing between occupational and community exposure. It should include more recent and regionally specific health studies from Latin America and Africa to strengthen its global relevance. You can also add a brief discussion on the socioeconomic determinants of exposure (e.g., poverty, informal labor).

Response 2: The authors agree with the reviewer's comment. Accordingly, the suggested changes were made. The entire section 3.2 was modified to clearly define the type of exposure (community and occupational) in the discussions and comparisons, while Table 1 also specifies the type of contamination. More recent studies in regions that group developing countries were included, and a subsection on socioeconomic determinants was added, addressing the effect of these determinants on exposure and, consequently, on the deterioration of public health (lines 360-446).

Comments 3: Section 4 provides a good overview of sustainable technologies, but would benefit from a more critical and comparative analysis. For instance, firstly, you should discuss the economic and scalability barriers of hydrometallurgy in developing regions. Secondly, you can compare the lifecycle carbon footprint of pyrometallurgical vs. hydrometallurgical processes more quantitatively. Finally, you need to address the limitations of LCA in capturing the impacts of the informal sector.

Response 3: The authors appreciate the reviewer's comment. In this regard, substantial modifications were made in section 4. The issue of economic barriers and scalability of hydrometallurgy in developing regions was discussed (lines 486-508). A quantitative comparison was also made of the life cycle carbon footprint of pyrometallurgical processes versus hydrometallurgical processes (lines 466-485). Finally, the limitations of life cycle assessment in capturing the impacts of the informal sector were addressed (lines 641-669).

Comments 4: Table 1 is informative but cluttered and incomplete in the excerpt provided. It should be reformatted for clarity, with consistent units and complete reference citations. Figures 1, 2, and 3 are referenced but not included in the text. Ensure all figures are present and have descriptive captions that allow them to stand alone. Consider adding a summary table comparing the environmental performance of different recycling technologies (e.g., emissions, recovery rates, costs).

Response 4: The authors are grateful for the reviewer's comments. Therefore, Table 1 was reformatted, reorganizing the available information and adding data such as the type of exposure. The columns were organized more clearly, and the data presented were arranged according to the reported concentration, from the lowest to the highest concentration for the three environmental matrices (soil, air, and water). In addition, some texts were paraphrased, and it was verified that each piece of data presented had its bibliographic reference. With regard to the units, each one was verified, noting that all data presented for the soil matrix are expressed in mg/kg, while data for the air and water matrices are expressed in mg/L (lines 367-369).
Figures 1, 2, and 3 were mentioned in the text before and after their appearance (lines 110-114, 200-206, 455-460). We also verified that all figures have descriptive captions that allow them to be independent.
A table was added (Table 2: lines 477-479), comparing the environmental performance of different battery recycling technologies with data on lead recovery rates, carbon footprint, emissions, energy demands, costs, and environmental benefits.

Comments 5: Please refer to the related literature to enhance the deep and comprehensive analysis of your paper as follows:

A review on dynamic recycling of electric vehicle battery: disassembly and echelon utilization

A comprehensive review on human–robot collaboration remanufacturing towards uncertain and dynamic disassembly.

Response 5: The authors appreciate the reviewer's comments. Consequently, other scientific manuscripts were consulted and referenced to discuss the arguments and data added in the revision of the paper, including those suggested by the reviewer (lines 412, 420, 435, 482, 493, 505, 507,  656, 668). 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

2.1. Advances in the LAB production industry

In sentence:

“Other innovations are geared toward energy efficiency in production, such as waste heat recovery in plate curing, the use of renewable energy in thermal stages, and the automation of active paste applications to ensure structural homogeneity.”

Explain better the waste heat recovery and cite the renewable energy used in thermal stages.

 

4. Sustainable alternatives to mitigate the environmental impact of LAB

 

In sentence: “For example, one option that would help minimize the impact of lead on the ecosystem is the recycling of used LAB electrodes using innovative, low-cost, energy-efficient, and environmentally friendly technologies capable of effectively desulfurizing the plates”

Explain better the process of recycling of used LAB, cite examples.

 

In sentence: “Currently, the most widely used methods in this field are pyrometallurgy and hydrometallurgy. The pyrometallurgical technique requires temperatures above 1000 °C, which generates significant environmental impacts, including sulfur oxide emissions (approximately 70 kg/t) and lead fumes (between 30 and 50 kg/t) [34]. This technique also uses alkaline or organic reagents for the desulfurization of the LAB paste used [33].”

Explain the process hydrometallurgy

Author Response

Comments 1: 

2.1. Advances in the LAB production industry

In sentence:

“Other innovations are geared toward energy efficiency in production, such as waste heat recovery in plate curing, the use of renewable energy in thermal stages, and the automation of active paste applications to ensure structural homogeneity.”

Explain better the waste heat recovery and cite the renewable energy used in thermal stages.

Response 1: The authors appreciate the reviewer's comments. Consequently, the sentence in question was explained in detail, adding information about the thermal energy recovery systems involved in the lead-acid battery production process, as well as the types of renewable energy that can be implemented to optimize the production of these batteries (lines 171-184).

Comments 2:  

4. Sustainable alternatives to mitigate the environmental impact of LAB

In sentence: “For example, one option that would help minimize the impact of lead on the ecosystem is the recycling of used LAB electrodes using innovative, low-cost, energy-efficient, and environmentally friendly technologies capable of effectively desulfurizing the plates”

Explain better the process of recycling of used LAB, cite examples.

Response 2: The authors appreciate this comment from the reviewer. Therefore, the different LAB recycling processes were explained, highlighting pyrometallurgical and hydrometallurgical processes. In addition, Table 2 was added to summarize this information and discuss it after the table (lines 459-508).

Comments 3: 

In sentence: “Currently, the most widely used methods in this field are pyrometallurgy and hydrometallurgy. The pyrometallurgical technique requires temperatures above 1000 °C, which generates significant environmental impacts, including sulfur oxide emissions (approximately 70 kg/t) and lead fumes (between 30 and 50 kg/t) [34]. This technique also uses alkaline or organic reagents for the desulfurization of the LAB paste used [33].”

Explain the process hydrometallurgy.

Response 3: The authors agree with the reviewer's comment. In this regard, a paragraph was added with explanatory information on the hydrometallurgical process, so that it can be compared with the pyrometallurgical process (lines 466-473).

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

It can be accepted now.

Author Response

Comments 1: It can be accepted now.

Response 1: The authors appreciate the reviewer's comments.