Improving the Separation of PS and ABS Plastics Using Modified Induced Air Flotation with a Mixing Device

Round 1

Reviewer 1 Report

Dear authors,

thank you very much for your article.

My main concern about your article is, that it is not clear to me, how it is related to the state of the art.

Please include more state of the art, for example in the form of a table and describe wich aspect of your research goes beyond state of the art.

Your article is a good contribution to practical engineering but I do not see the scientific relevance.

I hope you will be able to sharpen these aspects!

 

Best regards,

Author Response

Thank you for the comments and suggestions. The response to reviewer 1 was attached below. Please see the attachment. Thank you very much.

Author Response File: Author Response.pdf

Reviewer 2 Report

This work is a very interesting and actual subject. This paper has presented the influences of design and operational factors on the bubble hydrodynamic and mixing parameters in an induced air flotation (IAF) with a mixing device for plastic waste separation. Two plastic types, polystyrene (PS from CD case) and acrylonitrile butadiene styrene (ABS from fan frame) were used in this study. PS could recover 89.32% with a purity of 94.45%, whereas ABS could recover 94.76% with a purity rate of 89.88%.

Author Response

Thank you for the comments and suggestions. The English style in the manuscript was already revised and the response to the reviewer 2 comments was attached below. Please see the attachment. Thank you very much.

Author Response File: Author Response.pdf

Reviewer 3 Report

This article focuses on the influences of design and operating factors on the bubble hydrodynamic and mixing parameters in induced air flotation with mixing devices and on the overall plastic separation efficiency. Optimal parameters have been experimentally determined to improve the plastic separation performance as well as the plastic recovery. In general, the manuscript is well structured and written well. The key experimental features are provided to make this work reproducible. The overall presentation of the manuscript and the claimed insights from their experiments are sufficiently supported by their experimental results. Overall, I think this work is significant and provides interesting results, hence I consider it suitable to be published in "Recycling" in its present form.

Author Response

Thank you for the comments and suggestions. The response to reviewer 3 comments was attached below. Please see the attachment. Thank you very much.

Author Response File: Author Response.pdf

Reviewer 4 Report

This paper describes a study of bubble hydrodynamic and mixing parameters in induced air flotation (IAF) process with mixing device for plastic separation process. Although the information presented in this paper is relevant and the methodology used, based on experimental design using Plackett – Burman design, is appropriate, the objectives of this paper do not correspond with the described results. Indeed, the objective is plastic separation but only two plastic were assayed, PS and ABS, and there are many more. The following modifications are suggested:

-       In the introduction, the different types of plastics must be described as well as typical mass percentages of each type of plastic must be given.

-       The title must describe the real objective of the paper – the separation of PS and ABS.

-       The optimization of the IAF was done without the application to the problem under analysis, the separation of the plastics! 

-       The application of the IAF to the PS and ABS separation should use a real residual with many mixed plastics. Indeed, using two samples of PS and ABS well prepared for the assay is not realistic. 

Author Response

Thank you for the comments and suggestions. The response to reviewer 4 was attached below. Please see the attachment. Thank you very much.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

For me it is still unclear what the scientific relevance is.

However as it is a nice applied article about a relevant engineering work...

therefore it could fit into the special issue.

Author Response

Thank you for the comments and suggestions. 

Author Response File: Author Response.pdf

Reviewer 4 Report

The authors have answered satisfactorily to the referee questions.

Author Response

Thank you for the comments and suggestions.

Author Response File: Author Response.pdf