Quantification of Floc Growth for Sediment with Mixing Intensity

Round 1

Reviewer 1 Report

The text that is the subject of this review is devoted to the problem of one of the dispersion systems types: the behaviour of suspension particles during mixing.

The paper's content is to discuss the results of an experiment consisting of observing a kaolin suspension of variable concentration, subjected to a mixing process with variable rotational speed, and thus with a variable speed gradient. In this way, the authors of the article wanted to reproduce the behaviour of suspensions in natural water reservoirs, particularly the processes of flock formation and disintegration.

 

The topic is significant. It carries significant cognitive values ​​of the processes in water dispersion systems but also shows great potential for practical use in slurry processing technologies.

 

While reading this article, the following observations come to mind.

 

First of all:

• What was the purpose of the research?
• What is the practical application of the results?

 

And later in detail:

• In L35, the authors write about "continuously accumulated contaminants" in general - it should be clarified that this concerns water pollution (and not, for example, soil).
• The list of references (References section) does not contain some cited references:
  • In L41, "Hollert et al. 2003" is not listed in the references.
  • L43 is "Chapman 1989" - only "Chapman and Hollert 2006" is listed.
  • L164 is "Gippel 1989" - not listed.
  • L202 is "van Lessen" should be "van Leussen".
• In L104, the unit "1/m3 • s" should be written unambiguously: "1/(m3•s)", preferably in exponential notation: "m-3•s-1".
• Equation 2 (L117) uses the symbol ρ, the meaning of which is not described.
• The L123 uses the "T-1" unit - is it time? If so, it should be "s-1".
• In equation 2? (L128) should be equation 3 (equation 2 is in L117).
• In L130, instead of "G`" it should be "G", as in L117.
• What was the research methodology? The graphic shown in Figure 2 is insufficient, and the experiment's methodology should be described in detail in chapter 2.2.
• There is no more detailed information about the kaolin used in the research. Have properties such as particle size distribution and mineral composition been determined? Is the literature data of an example of kaolin in L160 only quoted?
• In Figure 3 is marked the distance of the suspension collection point from the cylinder. However, from what depth was the sample taken? What was the sample taken with (pipette?)
• What stirrer was used in the experiment? The shape and dimensions of the mixer determine the hydrodynamic conditions in the mixing process.
• In L170, it was stated that the cylinder had a diameter of 10 cm; what was its volume? This information is necessary to determine the concentration, especially since Fig. 2 shows that a sample was taken, dried and weighed to determine the concentration ("Step 1-2-2. Concentration) - no concentration results are given anywhere. So why was the concentration determined?
• In L173, there is "which weighs up to 10-4 g", and it should be "which weighs with accuracy up to10-4g" - The text now suggests a maximum weighted weight of 10-4g.
• In L179-181, it is stated that the turbidity measurement was repeated three times. Was the measurement repeated for one sample, or were samples taken three times and the measurement repeated?
• Images from Figure 4 do not add any new content to the text and should be removed.
• Figure 5, according to the authors, presents "Turbidity with time" in 2 cases. However, these 2 cases show different dependencies! Fig 5(a) is "turbidity vs time", and Fig 5(b) is "turbidity vs RPM"! The signature needs to be changed in Figure 5.
• Chapter 3.2 presents "Particle measurement". What camera was used to capture the images of the particles? What was the algorithm, and what software was used for "image processing" (L227)?
• The table described as "figure5" shows the cases "A.500" and "C.500". There are no such cases in the list of cases in Table 1. Instead, there are "A.300~" (RPM: 300-500) and "C.###" (RPM: 30-250). These cases were for alternating stirrer revolutions! It is not authorized to describe them as A.500 and C.500
• Figure 7 shows the number and size of particles - how were these particles counted and measured? Was it the diameter? Equivalent Diameter? Equivalent Surface Diameter?
• Figure 8 is according to the description of the drawing "Turbidity change rate" and according to the description of the OY axis on 8(a) "Turbidity rate of change" and on 8(b) there is a symbolic formula - these descriptions should be standardized. The numbers on the x-axis in 8(a) should be in exponential form (e.g. 1x10^5)
• What do the numbers in successive series in Fig. 8(b) mean?
• Figure 8(c) is entirely illegible - please enlarge it.
• What is shown on the x-axis in Fig. 8(c)? In the description of the x-axis, there is "area" but in the description of the drawing "diameter". Maybe it could be guessed from the unit, but the units of the number on the x-axis from figure 8(c) are not shown!

 

To sum up:

The text contains the results of an interesting experiment, which was presented in the text only briefly and selectively. For example, concentration measurement results, turbidity-concentration relationships, or particle and flock sizes are not shown. The description provided is too general and leaves too many ambiguities. The text requires a thorough reconstruction. It is required to indicate the purpose of the research, supplement the description of the material and the exact methodology of both the experiment and the way of interpreting the results. The application of the results obtained should also be indicated.

Some help with the necessary reconstruction of the text should be the specific comments indicated above.

 

Author Response

Please check the attached file. 

Author Response File: Author Response.docx

Reviewer 2 Report

The work is good but needs minor revision.

 

1. The authors should update the introduction part using recent references.
2. The novelty of the work should be established.
3. Check the physical units.
4. Check the equation numbers.
5. Check the figure 2 caption in the figures list.
6. Rewrite the conclusion part.
7. More typo errors in the manuscript. 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

This is the second review of the text with the author’s correction after the reviewer’s comments.

Some of the authors’ corrections increase the text’s readability. Unfortunately, in a few cases, modifications not only do not improve the quality of the text but also introduce new ambiguities and even cardinal errors!

Here they are:

1. In L125, the authors gave a new version of the unit of the variable “P” (“power per unit volume”). In the previous version of the text, it was: “N•m/s•m3”, which the reviewer found ambiguous. So the authors corrected it to “N•m•s-1•m3” - and this is an error! The fact that the authors corrected the notation of this unit in this way means that the concerns about the ambiguity of the reading were justified. The correct unit should be: “N•m•s-1•m-3”.
2. In L152, the authors write that they measured “velocity in the tank (...) through PIV test”. This is a novelty that was not present in the previous text. Neither the results of these measurements nor the information on the apparatus used or the measurement methodology was provided.
3. In the identical L152, the authors added that “3D test”. What is this test, what was it about, what was its methodology and where were its results shown?
4. In the identical L152, the authors write about “and numerical simulation”. What kind of simulation is it, what was it about, what was its methodology and where were its results shown?
5. In L185, the authors, to the reviewer’s question, “Have properties such as particle size distribution and mineral composition been determined? Is the literature data of an example of kaolin in L160 only quoted?” The authors basically did not answer this question! They gave only brief information about kaolin - but is it about the properties of the kaolin used in the experiment? The information provided is incomprehensible! Because how should it be understood that the content of “chlorinated (Cl)”? Is it chlorine? - word “chlorinated” does not mean “chlorine” despite adding its chemical symbol in brackets!
6. In the identical L185, the authors reported that it was stated that “specific gravity was found to be 1.8 to 2.6”. Is it for sure “specific gravity”? Maybe it is about “density” the reader would find out by analysing the unit - the authors did not include it!? The authors gave a density range - what exactly value has the kaolin density used in the experiment?
7. In L204, it is stated that the camera used “has a frame rate of 30 fps”. Why this information? Were videos recorded during the experiments?
8. In L184, (and on Figure 8(b)) stated “initial concentration: 0.005%, 0.010% and 0.015%”. Is it volumetric concentrations? How are they designated? – the density of the kaolin used in the experiment was not given.
9. In L309 and 313, the authors commenting Figure 8(c) write about “particle size”. There is no “particle size” in this Figure, but “particle area”!
10. How will the authors explain the content of Figure 7(b) with the content of Figure 8(c) for time 120 minutes? Does it happen at this point? aggregation (according to Figure 7(b)), or disaggregation (according to Figure 8(c))?
11. In the table, the groups “1.B.##” and “1.C.###” have been expanded, leaving “1.A.300~”. Because “1.A.300~” is a collective description of the group, the measurements are indicated by the legend in diagram 8(a). There is no 1.A.300, 1.A.400 and 1.A.500 in table 1. Please correct table 1.
12. In Fig. 7(b), there is still no OY axis unit. The term “equivalent diameter” is ambiguous as to what kind of “equivalent diameter”? (mass, volume,...)
13. How to understand the entry from L326: “flocculation was performed by measuring major factors as particle properties of sample and flow velocity”? First, it must state what particle properties” were measured! Secondly, it was not measured flow rate”!, at most stirrer rpm.
14. The record of heavy metal flocculation in L342 is ambiguous and misleading - do the authors suggest that these “heavy metals” exist in sediments in the form of particles? This is a too far-reaching simplification because heavy metals can be part of sediments. However, they do not occur in the form of single sedimenting particles - unless we consider non-sedimentary particles with sizes, not micrometers but nanometers, and such was not the subject of the reviewed text.

 

The text of the author’s corrections made in reply seems to have been drafted very carelessly and hastily. This applies to both the substantive layer (detailed comments are shown above) and the language layer - the text is vague and very difficult to read - it is NECESSARY to cooperate with a person fluent in technical English - preferably a native speaker.

 

To sum up:

The corrections applied by the authors to the text have significantly worsened its quality (of the text)! Authors should carefully edit the text before it can be considered for publication. To proceed with the publication of this text requires real (and not apparent) redrafting.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 3

Reviewer 1 Report

The authors have improved this text, and all my objections have cleared.