Monitoring of Biopolymer Production Process Using Soft Sensors Based on Off-Gas Composition Analysis and Capacitance Measurement^†

Round 1

Reviewer 1 Report

In the abstract, please highlight the contribution.

Improve figure 4.

Please indicate your future direction.

What are the limitations ?

Author Response

1) In the abstract, please highlight the contribution.

Response: The text of the abstract was extended by a more detailed specification of the contribution of the submitted article.

2) Improve figure 4.

Response: Figure 4 has been modified, specifically the scheme of the type 2 soft-sensor has been improved to better describe the structure of its data inputs and outputs. 

3) Please indicate your future direction.

Response: The directions of future research were described in more detail in the penultimate paragraph of the Conclusions section. 

4) What are the limitations?

Response: The limitations of the proposed approach were specified in the last paragraph of the Conclusions section.

Reviewer 2 Report

This article studied the design of soft-sensor for the biopolymer production process based on off-gas composition analysis and capacitance measurement. The general structure of the article is good, and the author discussed the obtained results in detail. However, the article needs to be proofread by a native English speaker. I find the topic interesting for the readers; therefore, it can be published after addressing these below remarks:

Line 14, "The proposed software" the sentence is too long. Also, lines 17 to 23 are too long, and many "which" have been used. Please bear in mind using long sentences make it difficult for the reader to understand.

Again line 34 to 39 is too long and too hard to understand. Split it to the smaller sentences.

Line 69, the numbering is incorrect.

Line 145: How is the window length chosen for the moving median and Savitzky-Golay filters? Why did you choose 15 min? Why not 20 min?

Line 161: Are you sure that by using interpolation, some information wouldn't lose (as the sampling time was 3 hours and reduced to 1 min)?

Line 185: change the “The reason is, among other things” to “the reason among others is...”

Line 186 to 189: needs to be modified; it is not clear.

Line 223 to 227: This needs to be modified. Too long sentence.

Line 227: this relationship have -> this relationship has

Line 365: at their input are... at or as??

Line 401 to 403: needs to be modified.  

Please replace the software sensor with a soft-sensor in the whole text.

Author Response

1) Line 14, "The proposed software" the sentence is too long. Also, lines 17 to 23 are too long, and many "which" have been used. Please bear in mind using long sentences make it difficult for the reader to understand.

Response: The suggested corrections were made and long sentences were shortened or divided into shorter sentences. The whole text was also proofread by a native English speaker and a number of other long sentences in the text of the manuscript were divided into shorter sentences (see tracked changes). 

2) Again line 34 to 39 is too long and too hard to understand. Split it to the smaller sentences.

Response: The suggested corrections were made and long sentences were shortened or divided into shorter sentences, see lines 36-41 of the revised version.

3) Line 69, the numbering is incorrect.

Response: The numbering has been corrected.

4) Line 145: How is the window length chosen for the moving median and Savitzky-Golay filters? Why did you choose 15 min? Why not 20 min?

Response: The following text was added in the revised version of the manuscript on lines 151-154: "These specific time window length settings were chosen according to the recommendations published in the study by Maskow et al [16]. Alternative settings were tested, but they did not lead to better results."

5) Line 161: Are you sure that by using interpolation, some information wouldn't lose (as the sampling time was 3 hours and reduced to 1 min)?

Response: The following text was added in the revised version of the manuscript on lines 164-172: "The sampling times were chosen so that the samples captured key moments of the cultivation process, including transitions between the various process stages. To detect these transitions, the process operator used, among other indicators, on-line capacitance measurement provided by the Biomass Monitor 210 analyzer. In order to obtain a one-to-one correspondence between the on-line and the off-line measured data, the cell dry weight and biopolymer concentration data were interpolated using a piecewise cubic polynomial interpolation onto regular 1-min intervals. The combination of this interpolation method with off-line data measured at key moments of the cultivation process ensured that possible information losses due to interpolation were minimized."

6) Line 185: change the “The reason is, among other things” to “the reason among others is...”

Response: The text has been corrected.

7) Line 186 to 189: needs to be modified; it is not clear.

Response: The text has been modified, see lines 196-202 of the revised version.

8) Line 223 to 227: This needs to be modified. Too long sentence.
9) Line 227: this relationship have -> this relationship has

Response: The text has been modified, see lines 233-238 of the revised version.

10) Line 365: at their input are... at or as??

Response: The text has been corrected, see line 375 of the revised version.

11) Line 401 to 403: needs to be modified.

Response: The text has been modified, see lines 411-415 of the revised version.  

12) Please replace the software sensor with a soft-sensor in the whole text.

Response: As suggested, the term "software sensor" has been replaced by the term "soft-sensor" in the whole text.