Environmental Impact Assessment of a Solar Drying Unit for the Transformation of Food Waste into Animal Feed

Round 1

Reviewer 1 Report (New Reviewer)

This study needs to include outputs from the system to be a full LCA. Do a systems description with proper boundaries and decide what you compare this to (landfilling waste?). The value of the feed needs to be included. The paper needs more structure (why not include operations in the first result table?), look up more up to date references and make sure to have right number of significant figures. Overall, the paper gives an impression to be a draft rather than a full paper.

Author Response

see attached file

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 2)

The resubmitted manuscript is much improved

please still correct the following

1) as stated before please explain the abbreviations in the tables and figures eg what is Sb? what is 1,4-DB and so on

2) as stated before-all chemical formulas should be corrected in the Tables and Figures with subscripts

3)as stated before  enrichment of references

eg

Musmarra et al  Efficient and sustainable environmental management as a means of addressing current pollution issues. Environ Sci Pollut Res 26, 14703–14705

A. Bernstad, J. la Cour Jansen,mReview of comparative LCAs of food waste management systems – Current status and potential improvements,Waste Management, 2012

the references for such a long manuscript should be at least 25-30

Author Response

see attached file

Author Response File: Author Response.pdf

Reviewer 3 Report (Previous Reviewer 1)

I think tha comments that I had made regarding the implementation of LCA were considered. I think that in ajother  job you should  consider the nutritional characteristic s of the generated product and  compar it ehit commercial balanced feed. A cost analysis would also be interesting.

Author Response

see attached file

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (New Reviewer)

Please find attached the zip.

Comments for author File: Comments.zip

Author Response

First of all, we thank Reviewer 1 for the detailed comments. Here is our reply:

 

Regarding the main question, i.e. the scope of the LCA study. We compare the burdens of the drying unit to the avoided impacts of the energy (derived from fossil diesel) required for the drying of the food waste. We have removed completely from the manuscript all references to the avoidance of landfilling.

The scientic importance is clearly stated in the Introduction: " The scientific importance of the F4F process in the transformation of food waste into animal feed, a process that facilitates the concept of Circular Economy. "

The system boundaries were better described

Regarding the references: new EU documents have been included within the text and in the reference list. The reference list has been updated and the order of appearance of the references has been corrected.

The significant numbers in the tables have been corrected

Finally, we remain at the disposal of the Reviewer for a further round of corrections

 

 

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments for author File: Comments.docx

Author Response

All the comments have been answered, please see the attached file

Author Response File: Author Response.docx

Reviewer 2 Report

This is an interesting piece of research. Please see the following comments

1) moderate English language corrections are needed. Please proofread by a fluent English speaker also try to have small consice sentences for better comprehension

2) you state food and moth disease-what is this, is it one disease or two? please elaborate

3) you state

The rigour of this process, though it may not lead to the destruction of 31 the protein that is implicated in encephalopathy (the great fear that overshadows any 32 discussion of utilising animal by-products of any form), dramatically increases the cost 33 and environmental footprint of the process, thereby reducing any benefit

 

I am confused-so there are two negatives and no positive outcomes? then you should rephrase the sentence. also so there is no way to eliminate the risk of encephalopathy? please elaborate

4) you state And finally, food waste exploitation as animal feed also affects the environmental footprint of the feed production process

unclear what is meant here

5) lines 50-55 this can be the conclusion of your introduction-you will have to show the connection of F4F with the information you showed before, how it anwers to (what?) problem, how the results may be used and why this is important for an international audience

6) I dont think that the explanation of the F4F proccess should be in the introduction but it should rather be in materials and methods with the subchapter: presentation of the F4F process method

7) In Fig 1 some of the numbers you state cannot be seen

8) in the description of the unit, wherever possible give manufacturer, city, country of origin for eg the shredder, the air condition units, plastic nets, insect nets etc...

9) In materials and methods some things should be rearranged, as stated before incorporate the description of the unit, so some things described again as duplicates should be erased. The scope of the paper should definetely be trasnfered in the introduction

10) you state electricity production were sourced from Ecoinvent databases using Greek data., this should be in the references

11) the data in Table 2- I do not understand with what method they were derived, for example why the concerete should be X kg and not Y? So for each input a justification should be added, whenever possible. also if possible, a reference justifying this value should be given

12) please correct the chemical formulas eg Al2O3 CO2 with subscripts throughout the document and the tables 

13) I dont undertstand the title of Figure 3. Schematic representation of the scope of the assessment. The scope of the assesment is the calculation of CO2-this is the processes that will be added in the calculation (?) so the title is not correct

14) I am not sure which ones of the Tables 2 to 4 belong to the inputs (materials and methods) and which to results-please elaborate, also I am not sure if all the tables are needed. Please in the results and discussion quote each and everyone of the tables and figures and give a qualitatitve evaluation in the text of these results

15) I am not sure why some units are eg in kg Sb eq and some in CO2 please elaborate

16) I am not sure if you stated what method exactly you used for LCA please quote the method

17) for so many results the actual discussion is extremely short, please elaborate and enrich with relevant references such as 

Musmarra et al  Efficient and sustainable environmental management as a means of addressing current pollution issues. Environ Sci Pollut Res 26, 14703–14705

A. Bernstad, J. la Cour Jansen,mReview of comparative LCAs of food waste management systems – Current status and potential improvements,Waste Management, 2012

the discussion should compare your results with other similar results because right now this comparison is very limited

 

Author Response

All the comments have been answered, please see the attached file

Author Response File: Author Response.docx

Reviewer 3 Report

The Ms. describes a pilot-scale facility that converts consumer food waste into animal feed, featuring a solar drying unit for producing dry feed. This would spare the use of fossil-fuel based energy for the drying process.  LCA-based impacts are assessed, including GWP100 and 9 other environmental parameters.  The research topic is interesting and timely. However, the Ms. needs considerable revision to address a number of issues.

 

My main concern is that the Ms. is short of appropriate interpretation of project findings in a meaningful and comparative context. Many questions remain. For example, with the environmental impacts projected, particularly those showing large numerical numbers as presented in Table 4, what implication may be drawn? Would it be a better option to simply landfill the wasted food stuff instead? What is the default destination in the region for food waste (landfill? Incineration? or something else)? Furthermore, how do your assessment outcomes compare with other ‘food waste to feed’ findings?  Regarding the C-footprint (217 kg CO2-e/t food wasted treated), your result is similar to Kim and Kim’s (200 kg). But, isn’t the drying process most energy intensive?  If Kim and Kim used fossil-fuel based energy to dry their feed, how do you explain the apparent lack of C-footprint reduction between yours using the solar drying unit and Kim’s?  The Ms. would be much stronger and more informational when the findings are put into relevant perspectives.

 

I kept wondering if carbon footprint was the sole parameter being assessed, because the phrase “environmental impact” assessment remains vague.  It was not until Table 2 when the ‘AHA’ moment occurred. Suggest to indicate sooner in text that there are 9 other environmental indices being assessed, relevant to human health, aquatic system indices, etc. 

 

The Ms. builds on a strong footing pertaining to the significance of recovery and conversion of food waste into feed for animals (e.g. L23-28, L223). However, no information is presented regarding feed sample analysis and feed quality parameters – such is key, regardless of its potential suitability for feeding pets or farm animals (even though current EU laws prohibit the latter). I strongly suggest the addition of such information. Otherwise, it leaves a big hole.

 

The Discussion section is too thin. See comments above.

           

L174-176. “The CML2 … assessment method was utilised.”  This needs adequate description with proper references in Methods section.  “The impact categories and their respective units of measurement…”  incomplete sentence?

 

A total of 144 t food waste was treated via the facility over 126 days, averaging 1.14 t/day. Is this the full capacity of the pilot facility, or was the facility operated at partial capacity? If latter, was it due to substrate limitation (e.g. not enough supply of food waste) or other operational/management considerations?  

 

Fig. 1. “1”,”2”, “3”  are hardly eligible in the graphs, although one can guess their approximate locations.

 

Table 4. numerical numbers: comma or decimal point?

 

Table 5. last two rows- does it mean 254,913.48 MJ would be required to evaporate the 104.4 t water? which would be equivalent to 5984 t of low sulfur diesel? for the latter, what would be the equivalent GHG emissions (mitigation)? This sort of issues is worth exploring and distilling out.

 

Author Response

All the comments have been answered, please see the attached file

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The author again not thoroughly reviw the of LCA. The environmental charges associated with mobile and inmobile infrastructure are not addressed; as is the casein your work.  The methodology is not clear. As you can se,  nmost of the environmental loads are associated with the construction of the concrete slab. But all that load must be distributed among the total number of FUs processed throughout the lifetime of the project.

Reviewer 3 Report

 

..