Turning Agricultural Wastes into Biomaterials: Assessing the Sustainability of Scenarios of Circular Valorization of Corn Cob in a Life-Cycle Perspective
, Marco Bovo †, Alberto Barbaresi †, Daniele Torreggiani and Patrizia Tassinari *Round 1
Reviewer 1 Report
The paper presents an attempt to an LCA of corncobs products and compare with products with similar application- among others wood pellets. A main concern is that whereas the LCA of corncobs is based on a direct data sampling (while too superfluous described) the ‘competing’ products are table values from a database. This makes it much less interesting since a number of assumptions that are important for the interpretation of the results are not critically assessed and documented. Next, the function of the ‘competing’ products are not described, and in particular, the fate of the products after use is not given. is not given. Since in the study negative values for climate impact are found, it must be an assumption that the products are not decomposed over a 100 Y period.
All I all I find that the work is not adding sufficiently to be acceptable for publication
Details:
Line 22: has been defined
Lines 24-25. Something is wrong with the sentence
Line 62: why cobs the most valuable part of the stover ?? in what sense?
Line 65: do not think that ‘disposal’ is the right word here
Introduction: I think that the introduction should provide a better justification for the potential use of cobs to produce the material in question here
Line 208-209: estimations of amounts of corn cobs per ha seems not logically – based on the information given
Section 2.4: it is questionable to apply physical allocation in this case – in particularly since grain has a higher dry matter content than cobs, I suppose
Author Response
Dear Reviewer,
Thank you for the considerations and the highlighted criticalities of our work. We try to improve the quality of the paper and to add the proper information to clarify the LCA procedure performed. Moreover, if we understand well, the Reviewer refers to from-cradle-to-grave analysis that is out of the scope of the research in the present form. Indeed, in order to identify the most promising material a first selection can be carried out with from-cradle-to-gate analysis. Namely, this paper would represent a preliminary study of the possible valorization, in the Italian panorama, of a specific agro-waste considering its current rare valorization in the territory. Due to these aspects, the primary data have been collected from the corn cob production phase in order to properly model the processes and to evaluate possible applications of corn cobs in a new guise, i.e. from waste to secondary raw material. The processing phases of the novel cob-based materials have been modelled through database data, in order to consistently reduce the possible differences between the cob based materials and those already on the market. Moreover, the use of data/processes available in the database ensures high homogeneity and reliability of the results, while it gives solidity to the conducted analysis and allows for direct comparison with the analyses of other products which follow the same methodology.
In this context, the study has been dimensioned to be a cradle to gate study (a standard approach in several studies), avoiding to consider the usage phase of the product, which is analogous for the cob product and the related product on the market. Analogously, the end-of-life phase for these materials has been considered out of the scope of this study. The pellets comparison needs detailed information about the burning phase and related emissions in order to be able to appreciate the differences between the two products, considering their strong similarities under almost all points of view. Similarly, the corn cob and the inert grits have the same usage phase, which do not add information to the comparison and, in order to maintain an homogenous boundary for the system, the end-of-life phase has not been considered. Because of these assumptions, the decay of the materials has not been taken into account.
Details:
Line 22: has been defined
The authors have corrected the sentence as suggested.
Lines 24-25. Something is wrong with the sentence
The sentence presented some errors, which have been corrected.
Line 62: why cobs is the most valuable part of the stover ?? in what sense?
The original version of the sentence has been considered not clear, which could mislead the potential reader. Then, the authors have removed this part, thanks to the Reviewer’s suggestion.
Line 65: do not think that ‘disposal’ is the right word here
The term “disposal” has been substituted with a more proper term in this sentence.
Introduction: I think that the introduction should provide a better justification for the potential use of cobs to produce the material in question here
Additional information about the structure and the composition of corn cobs have been added. The additional information provide robust reasons for the selection of corn cob as potential secondary raw material.
Line 208-209: estimations of amounts of corn cobs per ha seems not logically – based on the information given
In this section, the data of average productions of maize grain and corn cobs have been reported not only in the Table 3 but also in the text; on the contrary the ratio between the two products based on dry matter data (both elements at 14% of humidity) has been reported only in the Table 3. This last parameter has been taken into account for the determination of the harvested corn cobs production, which would be considered an available quantity for the valorization processes. These aspects have been clarified in the text and further useful data have been added in Table 3.
Section 2.4: it is questionable to apply physical allocation in this case – in particularly since grain has a higher dry matter content than cobs, I suppose
The evaluation of the productions of corn cobs and maize grains have been performed based on data of production per hectare of dry matter, as reported in Table 3. Considering these results, the allocation between the two products has been carried out considering the production of dry matter for both, allowing for the application of a physical allocation method.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This paper considers the environmental impact of two valorization scenarios of corn cob through Life Cycle Assessment analysis. Thus, the material was compared with two materials used in different application, wood pellets and silicon carbide. The submitted article is interesting, original and within the scope of the journal. In addition, the manuscript presents in a scientific manner the subject, but some minor changes should be addressed:
- In the introduction section the authors highlighted the importance of obtaining the add value products generated from agricultural wastes. Considering, the large amounts of fly ash resulted from the combustion of some agricultural waste it will be interesting to discuss briefly about the potential use of fly ash for mesoporous silica synthesis (please see https://doi.org/10.3390/nano10030474 and https://doi.org/10.3390/membranes11020078).
- Please use the same font and font size for the figures legends and scales.
- Please use the same font and font size for the data presented in the tables.
- I recommend to make the figure 1 more readable.
- At line 213, please use “In a study [17]...” instead of “According to [17]..”.
- Please remove the comment from line 288 to line 290, “In this section…reported and compared.”.
Author Response
This paper considers the environmental impact of two valorization scenarios of corn cob through Life Cycle Assessment analysis. Thus, the material was compared with two materials used in different application, wood pellets and silicon carbide. The submitted article is interesting, original and within the scope of the journal. In addition, the manuscript presents in a scientific manner the subject, but some minor changes should be addressed:
In the introduction section the authors highlighted the importance of obtaining the add value products generated from agricultural wastes. Considering, the large amounts of fly ash resulted from the combustion of some agricultural waste it will be interesting to discuss briefly about the potential use of fly ash for mesoporous silica synthesis (please see https://doi.org/10.3390/nano10030474 and https://doi.org/10.3390/membranes11020078).
The authors briefly addressed, in the introduction, the valorization of fly ash form the agricultural waste combustion as suggested from the reviewer. Moreover, the two suggested references have been added.
Please use the same font and font size for the figures legends and scales.
Please use the same font and font size for the data presented in the tables.
The Authors correctly used the template proposed by the Journal “Applied Science”, possible mistakes can be corrected in the final edition if the paper will be accepted for publication.
I recommend to make the figure 1 more readable.
The Figure 1 has been modified to be more readable as suggested by the Reviewer; moreover, some additional corrections have been added.
At line 213, please use “In a study [17]...” instead of “According to [17]..”.
The sentence at line 213 has been modified as suggested by the Reviewer.
Please remove the comment from line 288 to line 290, “In this section…reported and compared.”.
The sentence has been removed from the section “Results”.
Author Response File: Author Response.docx
Reviewer 3 Report
Introduction
The introduction is systematically written and easy to follow to open up reader’s mind and awareness of the project’s about.
Materials and Method
Line 125-126
- To put a reader in a quick and clear context between these two standards, it would be good if titles of ISO 14040&14044 are provided.
Line 222
- Same comment as above
Results
Please be mindful of writing consistency; i.e.
Line 297-298 is only using abbreviation in mentioning cob-based materials
Line 300 it not using abbreviation.
Conclusion
The authors have suggested a technical improvement as well as further study in economic aspects for potential
Author Response
Introduction
The introduction is systematically written and easy to follow to open up reader’s mind and awareness of the project’s about.
We are glad that the Reviewer has found the introduction effective and appropriate for the paper.
Materials and Method
Line 125-126
To put a reader in a quick and clear context between these two standards, it would be good if titles of ISO 14040&14044 are provided.
The titles of the ISO 14040 e 14044 have been added in the text as suggested.
Line 222
Same comment as above
The title of the ISO 14041 has been added in the text as suggested.
Results
Please be mindful of writing consistency; i.e.
Line 297-298 is only using abbreviation in mentioning cob-based materials
Line 300 it not using abbreviation.
The presence of a two-time-written sentence has been the cause of the writing inconsistency. The sentence has been eliminated and the abbreviations have been respected.
Conclusion
The authors have suggested a technical improvement as well as further study in economic aspects for potential.
Thanks for your positive feedback.
Author Response File: Author Response.docx
