Mini-Hydrocyclone Separation of Cyanobacterial and Green Algae: Impact on Cell Viability and Chlorine Consumption

Round 1

Reviewer 1 Report

The manuscript entitled "Mini-hydrocyclone Separation of Cyanobacterial and Green Algae: Impact on Cell Viability and Chlorine Consumption" refers to important aspect concerning the separation of non-toxic chlorophyte species from toxic cyanobacteria species. There is lacking of a scientific clear aim of this study. The section of Results contains some sentences that should be in Discussion part. A clear part of Discussion is lacking in this manuscript. The partly discussed parts in Results are very poor. Thus, this manuscript requires a major revision.

 

 Detailed comments

1. Please pay attention that Cyanobacteria is not the name of the class, it is division/phylum.

2. The codes used should be explained when you mention for the first time.

3. English language required to be improved

4. For examples: lines: 207-209; 217-219 – these sentences should be placed in Discussion part etc. Results are mixed with discussion.

5. The reference list should be extended.

Author Response

Please our response attached.

Warm regards,

Arash

Author Response File: Author Response.docx

Reviewer 2 Report

Dr. Zamyadi and his colleagues utilized a mini-hydrocyclone to separate the cyanobacteria and green algae. And they further studied the utilization of mini-hydrocyclone on the cellular viability and chlorine consumption. The separation of toxic algae and non-toxic algae is a desirable technology when used in the water treatment. The reviewer only has a concern about the sample type that was used in this work.

The authors used two representative species (toxic cyanobacterial Microcystis and nontoxic green algae Scenedesmus). Their difference in morphology is dramatic, therefore, the authors achieved a good separation results for them. However, in natural environment, the composition of phytoplankton is very complicated, however, the present work has not intensively tested such samples. Additionally, during the bloom period, cyanobacteria are the major algae, therefore, the utilization of hydrocylone might be not a good option unless there are new data to support.

 

Additionally, the reviewer is still confused about studying the effect of hydrocyclone-based separation on the chlorine consumption. Does the observed reduction in chorine consumption have a specific practical implication?

 

Additionally, the following minor comment/suggestion can be considered when revising the manuscript.

 

1.      Please specify the strains names and isolation sources for Microcystis and Scenedesmus used in this work.

2.      In natural environment, Microcystis is colonial. In this work, the strain name of Microcystis used here is unknown. If the used Microcystis is the non-colonial form, the authors should state the limitation of the work and make a brief discussion based on the fact that the natural Microcystis is colonial.

3.       The dot and column plots lacked the SD bars, were the experiments carried out in duplicate or replicates? If not, please specify the reason.

Author Response

Please our response attached.

Warm regards,

Arash

Author Response File: Author Response.docx

Reviewer 3 Report

Authors presented an interesting study where a 3D printed mini-hydrocylone was able to efficiently and quickly separate cells (Microcystis and Scenedesmus) with a minimum losing consistency over a 30-min experiment period, and high separation efficiency (but not 100%). The manuscript is very well written and the content would be of interest to readers of Water. However, the depth of the study seems short, especially when the time of development of the experiments is quite short and the manufacture of the mini-hydrocylones did not seem to be a major obstacle either. I would recommend this MS to be accepted if the following observations are addressed, clarified and /or considered.

1-The section of R&D may improve noticeably it the authors included in the interpretation results the effect of the size distribution of cells instead of using an average cell size (these data can be rescued from the flow cytometry measurements carried out in samples). Additionally, if possible, it would be ideal that the authors assess the distribution of cell densities by using, for example, percoll gradient centrifugation; and evaluate if it is needed to include it in the calculations.The existence of size and/or density distributions of the cell population used in the study may justify separation efficiencies below 100%. The cell death and the decrease of viability observed may be also justified by determining the shear stress field developed into the mini-hydrocyclone. Shear stress tolerance of different microalgal species (including Scenedesmus and Microcystis) is well-documented. Shear forces distribution in the mini-hydrocyclone may be estimated using CDF.

2-Since the experiments carried out are very few and of very short duration, the authors may have extended their study to assess the effect of design variables such as vortex finder diameter, spigot diameter, vortex finder height, etc., on the separation efficiency. Thus, several 3D-printed hydrocyclone designs based on CFD analysis (particularly to avoid shear-related cell damage and to forecast 100% separation efficiency) may have been manufactured and used to understand the interactions between the aforementioned design variables.

Author Response

Please our response attached.

Warm regards,

Arash

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The manuscript entitled "Mini-hydrocyclone Separation of Cyanobacterial and Green Algae: Impact on Cell Viability and Chlorine Consumption" was improved according to my suggestions. The small corrections should be done only in case of the list of references. Please carrefully check the writting style of references , eg. no 17.

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

The manuscript presents  limiting factors that affect the distribution of macroinvertebrate communities with land use gradients and estimates thresholds for the conservation of macroinvertebrate communities derived from generalized additive models (GAMs) and Threshold Indicator Taxa ANalysis (TITAN). The problem has been presented properly, based on a 256 benthic fauna samples  from a river network in NE China. In general, I like the idea of statistical procedure performed in the manuscript.  Although the analysis of the data is comprehensive, and logically and consequently performed,  the authors attempted to generalize the  whole community of macroinvertebrates’ response to  land use gradients. I have the impression that performed analyses, including GAM models may refer only to local or regional scale (catchment).

Too little information is given about environmental conditions of the river hydrodynamics, its flow variability and ways of water runoff in the catchment (I mean geological structure, geomorphology: if it is a lowland or mountainous area) but mot of all: the source of river water: rainfall or groundwater, residence time of water, point and areal sources of pollution,  etc..

High variability of physicochemical parameters of water quality in the Hun-Tai  River Basin  indicates both  oligotrophic (rain-fed) waters as well as  local sources of pollution (oxygen deficits and high salinity), what determines different taxa inhabiting those environments. Site specific conditions are crucial to define habitat conditions of the benthic fauna and preferences of individual assemblages or even species.

The authors should refer their results to other (at least not mountainous) regions in the world. The reference cited [47], to support r results, is based on the Appalachian region. 

For those who are familiar with lowland areas covered with  sedimentary permeable rocks with  loamy, or  sandy soils on top,  it is hardly to accept (with no additional assumptions delivered) that the optimal threshold for conductivity for macrozoobenthos is as low as 283 µS/cm (below a natural background). As the EC is related to mineralization of water, and thus concentrations of ions Ca2+, Mg2+, etc. , thus:  is the value referred to malacofauna, as well?

Moreover, I would expect the thresholds identified  (COD, EC and NH3-N) will be provided for the most abundant or characteristic individual benthic species/taxa.

Some detailed remarks:

Figure 1 : what is the difference between conventional and dense sites? Could not find in the text

l.133 – please explain abbreviation KMO

Table 1 – please add no of samples

Figure 3 –although very promising, is difficult to follow as it is illegible.

Reviewer 2 Report

Review of “Assessing limitation factors and thresholds for macroinvertebrate communities in response to land use gradients”

 

LINE

9              Awkward English language in both diction (“anthropic”) and sentence construction. Not an ideal way to begin the manuscript.

10-12     I don’t understand this sentence.

13           I can imagine what this means (“conservation threshold values for land use”) but shouldn’t have to. Better explanation needed.

15           Better geographical reference for non-Chinese readers needed.

16           Why do you need to invoke “limiting factors”? What is actually meant? This is a term usually reserved for population-scale studies. And “distribution…with” doesn’t really make sense.

18           GAMs and TITAN need better explanations than just their titles.

20           Avoid using variable names in an abstract—just their natural language equivalent. These are, fortunately, rather intuitive—but still distracting. And “nutrient” isn’t grammatical. “nutrients”?

21-22     I don’t know what “change point” is, but I assume you mean “threshold.” The literature has much to say about the value (or lack) of such a conceptual framework. And to specify one (setting aside for the moment whether it even makes sense) at 0.01% precision is dubious, to say the least. But at least you’ve dropped the variable-name convention.

23-26     This should be the grand wrap-up of the abstract, but it’s almost impossible to figure out what it’s actually trying to say. “Some useful strategies” is not useful for the reader of an abstract—but for most, this is all they’ll ever look at. Thus, some specificity is needed.

28           From the abstract, it’s hard to see how “river restoration management” figures into this research.

31           “were”? No more?

32            “affection” not a word in this context; no comma.

35-36     Not grammatical. The quality of the English language is very problematic and is going to influence the evaluation of the underlying science. Not a good strategy for an author seeking publication.

38-39     A somewhat bizarre generalization. Presumably defensible in the specific study cited but hardly a generalized finding.

40-43     Grammar.

 

Given the state of the language, I have stopped any sort of detailed review at this point. Reading of the remainder of the manuscript indicates that these problems persist, and independent of the content they render the present version unacceptable for publication.

 

As for the content, a few points:

 

1. The discussion of the range of land cover percentages over which significant degradation occurs is quite reasonably presented; its translation into the hyper-precise thresholds articulated in the abstract is curious and unwarranted.

 

2. The trend lines of Figure 2 make no physical sense. That they are generated by a statistical program is not relevant; they should have some relationship to reality or should not be included. The S-shaped curves are particularly bizarre.

 

3. The references are not particularly current; most are a decade or more old.