Ceramic Aggregate Material Formulated with MSWI Fly Ash and Fuel Ash for Use as Filter Media
Round 1
Reviewer 1 Report
- A brief summary: The submitted publication matches the selected section of the journal: Clays and Engineered Mineral Materials, and the special issue: Alkali-Activated Binders. The article is in line with global trends. In this study, a FMC for high ammonium nitrogen adsorption and with high porosity was prepared. Authors used MSWI fly ash, pulvervized fly ash and small amount of silicone carbide and magnesia. The effects of MSWI fly ash content, roasting time, and roasting temperature on the properties, adsorption performance, microstructure, and crystal phases of the FMC were investigated.
- General concept comments
Article: The reviewer noticed minor deficiencies, which he will mention in Specific comments.
Review: - Specific comments
- line 24-124: The following work is worth quoting in the introduction https://doi.org/10.1016/j.scitotenv.2023.163267 as an article where silicon carbide as foaming agents was used.
- line 132 and 135: When describing the ash, give the mode and the median.
- line 142: Describe in detail the method of testing the leachability of heavy metals.
- line 152: Why the leachability of heavy metals from pulverized fly ash heavy metal content is not shown in Table 2? The title of Table 2 is wrong. It is no heavy metal content but leachability of heavy metals from fly ash. What do the numbers after the ">" sign mean? If they are requirements from the standards, they don't meet the requirements from Table 4 (Pb leachability).
- line 156: Plesase give the exact recipes of ceramsites or refer to the place in the text or table where they are. The reviewer is in favor of creating a table with tested compositions.
- line 162: Please refer to Figure 4 and Table 3.
- line 173: If you are discussing about previous research, provide it or a link to the repository
- line 195: not single-particle but single-granule
- line 196: Probably there is an error in the formula assuming that we are referring to the maximum surface area the strength should be equal: S=4P/(π?2)
- line 209: Please provide model of spectrometer and measurement conditions
- line 253-258 and 283-287: These paragraphs should be in chapter 2.
- line 343: How do you know about the pore distribution if it is not shown?
- line 353: Not Figure 6d but Figure 8d
- line 413: Figure 10 d - please sign zeolite and commercial ceramsite.
- line: 453 and 454: Not internal-structure but microstructure.
- line 480: please sign NH4+.
- line 490: Please show the initial leachability from the raw mix (even calculated based on ashes, and describe ND - not detected. Standard leachability for Pb doesn't meet the leachability in Table 2.
- line 531: the accuracy of the compressive strength is too high. Up to 1 decimal place is enough (apply throughout the article).
- Please correct the bibliography. There are no DOI numbers or access dates.
- The reviewer has no more comments.
Author Response
Dear Reviewer,
Thanks for your insightful comments and suggestions. Please kindly find attachment for the response.
Best regards,
Yifang Cao
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Generally, the paper describes a method to apply an important waste materials according to chinese standards (the reviewer is not aquainted with them).
One important question is not answered: What happen to the salt content of the municipal waste. There is no analysis of the starting materials telling its concentartion nor informations where it goes to. The authors should report aboaut that,
Some more detailed comments:
Line 12: … and the pulverized… (why the article? Is it a special fly ash?)
Line 53: What is “volcanic ash reactivity”? Does it mean pozzolanic properties?
Line 58: Is “ceramsite” a trademark or a defined product? Who invented it?
Line 65: 20.69 % is very specific, usually a broader range is applicable.
Line 67: diopside and wollastonite immobilize calcium: Is that OK for binder applications?
Line 80: 36.80 MPa: that accurate??
Line 82: Pore characterization? E. g. Hg – porosimetry?
Line 96: Is ceramsite only a filtering medium
Line 132: d50 values?
Table 1: It doesn’t add up to 100 %. What is the rest?
Fig. 3: Please indicate the expansion step
Generally: Please establish the chemical expansion reaction!
Line 202, not understandable. The reviewer guesses that the drying was applied until weight loss in a certain time period was less than 0.01 g
Line 209: Please specify type and manufacturer of ICP (specify also SEM and XRD; and UV/Vis spectrometer)
Chapter 2.4: Porosity measurements by Hg porosimetry or by N2 adsorption would be more appropriate.
Lines 255 to 258: partially reported already in chapter 2.2
Lines 258 to 259: porosity and BET methods should be reported in experimental section. Please specify equipment.
Lines 276 and 277: Is accuracy that good?
Line 294: Is there any proof of filling the internal pores?
Line 307: BET is quite low. How was it measured?
Lines 329 and 332: How was the liquid phase determined? XRD with Rietveld analysis could get it.
Line 335: Don’t understand the last sentence.
Line 343. Nomenclature of pore sizes according to IUPAC?
Line 372: .. fly ah content increases from …
Fig. 10 d: too many digits. What are sample 1 and sample 2?
Line 443: Why does volatilization produce a glass phase?
Line 452: Usually, the specific surface area is reduced by higher sintering temperatures.
Fig 13: Microstructure can only be discussed qualitatively with SEM pictures. If you want to discuss quantitativelyone has to use at least picture analysis.
Line 473: There is no proof for the offered mechanism.
Table 4: Last column: what does it mean? What do the numbers tell.
Line 502: Compare the heavy metal contents of the leachate with the initial content of the starting materials.
Line 503: the numbers in Table 4 suggests a decrease of Zn concentration with roasting temperatures, too.
Lines 529 to 533: too many digits.
The english is of good quality. Probably a professional translator worked here. But some words and phrases sound unfamiliar to science people.
Author Response
Dear Reviewer,
Thanks for your insightful comments and suggestions. Please kindly find attachment for the response.
Best regards,
Yifang Cao
Author Response File: 
Author Response.doc
Reviewer 3 Report
The paper refers to an interesting subject, that of transforming a dangerous waste into a useful product by coupling a ceramsite material with MSWI fly ashes to build up a filtering medium. The toxicity of fly ashes is high especially due to heavy metals and the attempt to block their leaching is interesting. Even if the use of wastes in building porous materials based on ceramsite is not a novelty ( the present paper is correctly citing main papers dealing with this subject) some particularities of the present paper makes it interesting.
The experimental section is well constructed:
-It starts with the analysis of raw materials and also clearly presents the content of heavy metals in MSWI fly ashes which are not likely to recommend them as builder for a water filtering medium. So, the target to find out adequate conditions to prepare the filtering medium using this waste is of interest and is a novelty.
-The preparation methods are according to general rules presented also in other papers , but are adapted to the present study and the operating parameters were further optimized. The optimization factor by factor is not the best approach ,a design experiment where all factors vary would have been more efficient in my opinion. Nevertheless, the values of operation parameters obtained seem to give good results.
-the characterization of final material is done by adequate methods.
- The investigation of leaching capacity of heavy metals is a good approach as the MSWI fly ashes incorporated could have been harmful for the environment when using the filter for water filtering. This is an original contribution. At this point the method of testing the leachability of heavy metals should be given in more details and compared to the leachability of heavy metals from fly ashes.
In table 4, are the accepted values for GB5085.3-2007 correct? They seem quite high. For Pb 1 mg/L is very high for waste water, and so is the limit of Cd. Is the unit mg/L used also for the standard accepted values?
The synthesizing of FMCs and adsorption mechanism is not original but well adapted for the present study justifies the experimental results
The conclusions are clear and well written to give a final general view of the research results.
The paper may be published in the present form.
Author Response
Dear Reviewer,
Thanks for your insightful comments and suggestions. Please kindly find attachment for the response.
Best regards,
Yifang Cao
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comment on revised version of:
Ning Lu et al.: Ceramsite Material Formulated with MSWI Fly Ash and Pul-2 verized Fly Ash for Use as Filter Media
Comments:
The authors answered a number of questions and remarks but not all. The following items are still open:
Line 11: … and the pulverized… (why the article? Is it a special fly ash?) just omit the article
Line 57 to 61: Is “ceramsite” a trademark or a defined product? Who invented it? Did Han [15] invent it?
Line 70: diopside and wollastonite immobilize calcium: Is that OK for binder applications?
Line 85: Pore characterization? E. g. Hg – porosimetry? How did they find, that most of the pores are filled?
Table 1: It doesn’t add up to 100 %. What is the rest?
Fig. 3: Please indicate the expansion step
Line 294: Is there any proof of filling the internal pores?
Lines 329 and 332: How was the liquid phase determined? XRD with Rietveld analysis could get it.
Line 384: Still don’t understand the last sentence.
Line 395. Nomenclature of pore sizes according to IUPAC?
Line 562: the numbers in Table 4 suggests a decrease of Zn concentration with roasting temperatures, too.
Author Response
The authors give thanks to Reviewer 2's comments. The comments are now addressed.
Author Response File: Author Response.doc
