Long-Term Occurrence and Fate of Microplastics in WWTPs: A Case Study in Southwest Europe

Round 1

Reviewer 1 Report

see report

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 1 Comments

 

The article concerns the fate of polymeric micro-particles (MP) in wastewater treatment plants (WWTP). Reported are the results obtained from a typical WWTP situated in Spain. The study is of general interest. Compared to most publications on the mentioned topic, data were collected over a whole year. This allowed to observe eventual influences of temperatures and composition of the inlet flow of waste water. A lot of different particle properties were determined like size, shape, chemical composition, which may influence the efficiency of MP elimination during the waste water treatment. The article is well written and merits to be published.

Point 1: In Fig. 1 the line indicating the sludge recycle has a flash in forward and backward direction. Please explain or correct the design. In addition, indicate the percentage of the recycled sludge.

Response 1: Two arrows in opposite directions were included because part of the secondary sludge is recycled to the reactor and other part is removed as excess of sludge to be treated in the sludge line. Anyway, to clarify this, another arrow has been included to improve the understanding of the treatment process in Figure 1. The percentage of recycled sludge in a typical activated sludge treatment process is between 25 and 100% (Metcalf & Eddy, 2002). In this plant, during the year considered, the percentage varied between 40% and 100%, depending on the specific characteristics of the wastewater treated and biological process performance (it is an operational parameter that are used to optimize the plant performance).

 

• Metcalf, L., Eddy, H. P., Tchobanoglous, G. (2002). Wastewater engineering–Treatment 385 and reuse.

 

Point 2: Fig. 2a summarizes the MP-concentration (in [particles/L]?) measured in the incoming flow and the secondary and final effluent flow. As the values are quite different, quantitative information are difficult to estimate.

 

Response 2: The units in Figure 2a are MPs/L, as indicated on the ordinate axis. In addition, according to the Reviewer's suggestion, a table detailing the quantity of microplastics in influent, secondary and final effluents have been included in the Supplementary Material to make easier the understanding of quantitative information (please see Table S2).

 

Point 3: I propose to replace Fig. 2a by a table indicating the particle size concentrations in the different flows and the flow rate in m3 /time. It would be also desirable to add the MP particle concentration in the final dry sludge mass and the mass flow of the dry sludge. This would allow to obtain easily a mass balance and to estimate the removal efficiency.

 

Response 3: To supply the additional information requested by the Reviewer, two tables, which are shown below, have been included in the Supplementary Material (please see Tables S2, S3 and also S4).

 

 

 

	Months	Wastewater Line
			MP concentration (MPs/L)			Influent (average flow) (m3/day)	Effluent (average flow) (m3/day)
			Influent	Secondary treatment	Final Effluent
2020	May		23.85	2.36	1.16	5335	4931
	June		18.17	2.44	1.58	4741	4377
	July		18.45	1.76	0.99	4981	4328
	August		16.04	2.26	0.77	4089	3684
	September		17.49	2.39	1.52	4803	4235
	October		14.82	1.89	1.26	4707	4071
	November		14.91	1.67	1.34	4936	4412
	December		15.62	1.48	1.09	4672	4448
2021	January		11.90	1.36	1.31	4374	3934
	February		13.62	1.54	0.71	4584	3913
	March		11.44	1.97	0.59	4510	3865
	April		17.12	1.65	1.26	5770	5159

 

	Months			Sludge Line
			MP concentration in dehydrated sludge (MPs/g dry weight)		Average mass flow of sludge (kg dry weight)
2020	May		39.35		3095
	June		29.81		2421
	July		29.57		2452
	August		36.05		2667
	September		28.49		2097
	October		22.26		1764
	November		19.44		3262
	December		22.25		3973
2021	January		11.99		3976
	February		16.54		1994
	March		18.88		3544
	April		13.86		2701

 

 

Point 4: In Fig. 2c the MP-particle concentration in [particles/g] is given as well as the percentage of particles retained in the sludge with respect to the totally removed MPs removed during the treatment. For April 2021 only 45% of the removed particles are found in the sludge. Please explain, in which way the other 55% of the particles are removed.

 

Response 4: In our work, the range of MP retained in sludge was between 47% and 100%. This wide variation is in accordance with values shown in literature (8-92%). In addition, those MP that are removed from the wastewater and are not entrapped in the sludge, are eliminated during the pre-treatments, i.e., screening systems, grit and grease system, etc. Some additional information regarding this issue has been included in the manuscript (please see page 13, lines 338-342).

 

• Gies, E. A., LeNoble, J. L., Noël, M., Etemadifar, A., Bishay, F., Hall, E. R., Ross, P. S. (2018). Retention of microplastics in a major secondary wastewater treatment plant in Vancouver, Canada. Marine pollution bulletin, 133, 553-561. https://doi.org/10.1016/j.marpolbul.2018.06.006.

 

• Lv, X., Dong, Q., Zuo, Z., Liu, Y., Huang, X., Wu, W. M. (2019). Microplastics in a municipal wastewater treatment plant: Fate, dynamic distribution, removal efficiencies, and control strategies. Journal of Cleaner Production, 225, 579-586. https://doi.org/10.1016/j.jclepro.2019.03.321.

 

• Jiang, J., Wang, X., Ren, H., Cao, G., Xie, G., Xing, D., Liu, B. (2020). Investigation and fate of microplastics in wastewater and sludge filter cake from a wastewater treatment plant in China. Science of the Total Environment, 746, 141378. https://doi.org/10.1016/j.scitotenv.2020.141378.

 

• Murphy, F., Ewins, C., Carbonnier, F., Quinn, B. (2016). Wastewater treatment works (WwTW) as a source of microplastics in the aquatic environment. Environmental science & technology, 50(11), 5800-5808. https://doi.org/10.1021/acs.est.5b05416.

 

• Ziajahromi, S., Neale, P. A., Silveira, I. T., Chua, A., Leusch, F. D. (2021). An audit of microplastic abundance throughout three Australian wastewater treatment plants. Chemosphere, 263, 128294. https://doi.org/10.1016/j.chemosphere.2020.128294.

 

Point 5: In Fig.3 the MP size distribution in the different flows is summarized. It seems to me indispensable to know how the size of the particle with different form is defined. Did you use an equivalent diameter? If yes, which equivalence did you use? (Volume-equivalent sphere diameter, surface-equivalent sphere diameter, projected area diameter corresponding to an equivalent sphere diameter).

 

Response 5: The MP size distribution is obtained by means of the sampling procedure. The water sampled is pumped through a sieve module assembled in a specific sampling device (Figure S1). This device is made up of four mesh stainless steel filters (CISA Sieving Technologies) of 150 mm of diameter and the following slot sizes: 500, 250, 100 and 20 µm. The filters are sequentially placed in the device from the largest to the smallest slot size, so that the MPs contained in the sampled water are retained in the corresponding sieve depending on their size. This information is detailed in subsection 2.2.Sampling points of Material and Methods section (please see page 3, lines 106-118).

 

Point 6: Indicate clearly the units of the presented values in tables and figures, including the supplementary materials. Example: MP is the abbreviation for microplastic. In Figure 2 the concentration is probably given in particles per volume.

 

Response 6: All abbreviations are summarized in page 16, in addition, according to the Reviewer's suggestion, all abbreviations and units in tables and figures have been revised and clarified (please, see Figures 2, 3, 5, 6, 7 and Supplementary Material).

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments for Applied Science-1551141

Manuscript Number: Applied Science-1551141

Title: Annual occurrence and fate of microplastics in WWTPs: a case study in Southwest Europe

Article Type: Original Research Paper

This paper analyses the occurrence and fate of MPs of a WWTP sited in Southwest Europe monthly in a year. As far as I am concerned,this research has little innovation, in this regard, the paper is not acceptable for publication in its present form.

In the revision process, the following revisions should be pay attention.

1. The title is “Annual occurrence…”, but the authors studied occurrence and fate of microplastics in a WWTP every month in a year. The content does not match the title.
2. The innovative aspects of the paper are weak. Many studies with the occurrence of MPs in WWTPs havebeen focused on wastewater and sludge samples collected over short periods, i.e., days or weeks, so what’s the meaning for the occurrence of MPs in WWTPs in wastewater and sludge samples collected monthly? I did not see the importance of that point.
3. What is the significance of using a camera to observe the color and shape of MPs?
4. The author only used FTIR to determine the chemical composition and percentage of different microplastics. I think it is not enough to support the results (Figure 6 and Figure 7). The peaks of the chemical components of these proposed microplastics are very close, in the case of microplastics mixture, it is difficult to distinguish these components and determine their content by FTIR.
5. The authors said the MPs more easily removed during the wastewater treatment processes were those with sizes greater than 500 μm, this is obvious, because the larger the particle, the easier it is to precipitate. But I can’t see such a result in Figure 3 or other figures.

Author Response

Response to Reviewer 2 Comments

This paper analyses the occurrence and fate of MPs of a WWTP sited in Southwest Europe monthly in a year. As far as I am concerned, this research has little innovation, in this regard, the paper is not acceptable for publication in its present form.

Point 1: The title is “Annual occurrence…”, but the authors studied occurrence and fate of microplastics in a WWTP every month in a year. The content does not match the title.

Response 1: The title has been modified according to the Reviewer's suggestion.

 

Point 2: The innovative aspects of the paper are weak. Many studies with the occurrence of MPs in WWTPs have been focused on wastewater and sludge samples collected over short periods, i.e., days or weeks, so what’s the meaning for the occurrence of MPs in WWTPs in wastewater and sludge samples collected monthly? I did not see the importance of that point.

 

Response 2: In the previous works, the majority studies analysed wastewater and/or sludge samples in a punctual period, i.e., 3-7 days or 3 days in 2 different months, etc., but no study carried out the analysis of this type of samples every month for one year. Our work allows the possibility of detecting the eventual seasonality in the occurrence and removal of MPs in WWTP.

 

Point 3: What is the significance of using a camera to observe the colour and shape of MPs?

 

Response 3: Although colour is not a crucial aspect to define microplastics, recording MP colour is considered important concerning aquatic organisms, since some species are thought to potentially ingest microplastics based on a colour preference behaviour (Frias & Nash, 2019). In addition, shape affects microplastic bioavailability to different species of zooplankton, with each species ingesting significantly more of a certain shape (Botterell, 2020). Hence, colour and shape of MPs is important regarding aquatic ecological risk assessment (Jung et al., 2021).

 

• Frias, J.P.G.L., Nash, R. (2019). Microplastics: finding a consensus on the definition. Marine pollution bulletin, 138, 145-147. https://doi.org/10.1016/j.marpolbul.2018.11.022
• Botterell, Z. L., Beaumont, N., Cole, M., Hopkins, F. E., Steinke, M., Thompson, R. C., Lindeque, P. K. (2020). Bioavailability of microplastics to marine zooplankton: Effect of shape and infochemicals. Environmental Science & Technology, 54(19), 12024-12033. https://doi.org/10.1021/acs.est.0c02715
• Jung, J. W., Park, J. W., Eo, S., Choi, J., Song, Y. K., Cho, Y., Shim, W. J. (2021). Ecological risk assessment of microplastics in coastal, shelf, and deep sea waters with a consideration of environmentally relevant size and shape. Environmental Pollution, 270, 116217. https://doi.org/10.1016/j.envpol.2020.116217

 

The equipment more commonly employed to analyse colour and shape of MPs is the stereomicroscope as it is reported in different works, see for example:

• Lv, X., Dong, Q., Zuo, Z., Liu, Y., Huang, X., Wu, W. M. (2019). Microplastics in a municipal wastewater treatment plant: Fate, dynamic distribution, removal efficiencies, and control strategies. Journal of Cleaner Production, 225, 579-586. https://doi.org/10.1016/j.jclepro.2019.03.321

 

• Jiang, J., Wang, X., Ren, H., Cao, G., Xie, G., Xing, D., Liu, B. (2020). Investigation and fate of microplastics in wastewater and sludge filter cake from a wastewater treatment plant in China. Science of the Total Environment, 746, 141378. https://doi.org/10.1016/j.scitotenv.2020.141378

 

• Naji, A., Azadkhah, S., Farahani, H., Uddin, S., Khan, F. R. (2021). Microplastics in wastewater outlets of Bandar Abbas city (Iran): A potential point source of microplastics into the Persian Gulf. Chemosphere, 262, 128039. https://doi.org/10.1016/j.chemosphere.2020.128039

 

• Pittura, L., Foglia, A., Akyol, Ç., Cipolletta, G., Benedetti, M., Regoli, F., Fatone, F. (2021). Microplastics in real wastewater treatment schemes: Comparative assessment and relevant inhibition effects on anaerobic processes. Chemosphere, 262, 128415. https://doi.org/10.1016/j.chemosphere.2020.128415

 

• Park, H. J., Oh, M. J., Kim, P. G., Kim, G., Jeong, D. H., Ju, B. K., Kwon, J. H. (2020). National reconnaissance survey of microplastics in municipal wastewater treatment plants in Korea. Environmental science & technology, 54(3), 1503-1512. https://doi.org/10.1021/acs.est.9b04929

 

• Alvim, C. B., Bes-Piá, M. A., Mendoza-Roca, J. A. (2020). Separation and identification of microplastics from primary and secondary effluents and activated sludge from wastewater treatment plants. Chemical Engineering Journal, 402, 126293. https://doi.org/10.1016/j.cej.2020.126293

 

Point 4: The author only used FTIR to determine the chemical composition and percentage of different microplastics. I think it is not enough to support the results (Figure 6 and Figure 7). The peaks of the chemical components of these proposed microplastics are very close, in the case of microplastics mixture, it is difficult to distinguish these components and determine their content by FTIR.

 

Response 4: Although FTIR may present some limitations, the vast majority of studies on MPs performs a visual inspection by stereomicroscope/microscope, which is normally combined with FTIR analysis. Below some reviews on MP analysis are included to show that FTIR is the most common technique to determine the chemical composition of microplastics:

 

• Alvim, C. B., Mendoza-Roca, J. A., Bes-Piá, A. (2020). Wastewater treatment plant as microplastics release source–Quantification and identification techniques. Journal of environmental management, 255, 109739. https://doi.org/10.1016/j.jenvman.2019.109739

 

• Iyare, P. U., Ouki, S. K., Bond, T. (2020). Microplastics removal in wastewater treatment plants: a critical review. Environmental Science: Water Research & Technology, 6(10), 2664-2675. https://doi.org/10.1039/D0EW00397B

 

• Elkhatib, D., Oyanedel-Craver, V. (2020). A critical review of extraction and identification methods of microplastics in wastewater and drinking water. Environmental Science & Technology, 54(12), 7037-7049. https://doi.org/10.1021/acs.est.9b06672

 

Point 5: The authors said the MPs more easily removed during the wastewater treatment processes were those with sizes greater than 500 μm, this is obvious, because the larger the particle, the easier it is to precipitate. But I can’t see such a result in Figure 3 or other figures.

 

Response 5: It important to consider that size is not the only parameter involved in MP removal. In fact, density is a parameter as important as size in relation with MPs removal by settling. Anyway, it can be observed a certain decrease in the percentage of MPs higher than 500 mm and a certain increase in the percentage of MPs smaller than 100 mm. In order to make easier to notice this aspect, the Table shown below has been included as Table S3 in the Supplementary Material.

 

Size	Influent	%	Secondary treatment	%	Final Effluent	%
20-100 µm	656	19.57	403	23.44	289	23.05
100-250 µm	832	24.82	468	27.23	325	25.92
250-500 µm	858	25.60	412	23.97	338	26.95
> 500 µm	1006	30.01	436	25.36	302	24.08

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Dear authors,

your paper "Annual occurrence and fate of microplastics in WWTPs: a case study in Southwest Europe" is interesting and worth publishing in Applied Sciences.

I have only a few comments, listed below:

When discussing the seasonal variation in the effluent, you can include the following reference: Jiang, F.;Wang, M.; Ding, J.; Cao,W.; Sun, C. Occurrence and Seasonal Variation of Microplastics in the Effluent fromWastewater
Treatment Plants in Qingdao, China. J. Mar. Sci. Eng. 2022, 10, 58. https://doi.org/10.3390/jmse10010058.

It appears that something went wrong with the template line numbering in your MS. According to the template, the figures and tables should not be bold when referenced in the text.

Line 81: please use "population equivalent (p.e.)" instead of "equivalent habitants".

Please improve the quality of Figure 1 if possible.

Lines 114 and 118: Please change the "degree Celsius" expression in the text.

Lines 148, 190 and 203: Please use "overall" or similar instead of "global".

Lines 168, 178, 180, 181, 185, 186, 195, 201, 236 and 345: Please cite properly according to the template - do not insert publication years.

 

Author Response

Response to Reviewer 3 Comments

Dear authors, your paper "Annual occurrence and fate of microplastics in WWTPs: a case study in Southwest Europe" is interesting and worth publishing in Applied Sciences.

Point 1: When discussing the seasonal variation in the effluent, you can include the following reference: Jiang, F.; Wang, M.; Ding, J.; Cao, W.; Sun, C. Occurrence and Seasonal Variation of Microplastics in the Effluent from Wastewater Treatment Plants in Qingdao, China. J. Mar. Sci. Eng. 2022, 10, 58. https://doi.org/10.3390/jmse10010058.

Response 1: This reference has been included in the results and discussion section (please see page 6, line 202-205).

 

Point 2: It appears that something went wrong with the template line numbering in your MS. According to the template, the figures and tables should not be bold when referenced in the text.

 

Response 2: This mistake has been corrected according to the Reviewer’s suggestion.

 

Point 3: Line 81: please use "population equivalent (p.e.)" instead of "equivalent habitants".

 

Response 3: This has been modified according to the Reviewer’s indication (please see page 2, lines 81-82).

 

Point 4: Please improve the quality of Figure 1 if possible.

 

Response 4: The quality of Figure 1 has been improved.

 

Point 5: Lines 114 and 118: Please change the "degree Celsius" expression in the text.

 

Response 5: This has been modified according to the Reviewer’s indication (please see page 3 and 4, lines 123 and 127).

Point 6: Lines 148, 190 and 203: Please use "overall" or similar instead of "global".

Response 6: The word “global” has been changed according to the Reviewer’s suggestion (please see pages 5-7 and lines 159, 201 and 217).

Point 7: Lines 168, 178, 180, 181, 185, 186, 195, 201, 236 and 345: Please cite properly according to the template - do not insert publication years.

Response 7: The citation mistakes has been corrected according to the template and the Reviewer’s indications.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The seriously corrected version of the paper can be published as it is. 

Author Response

Dear Reviewer 1,

We are glad that our revised version satisfied your scientific standards. Thank you for all.

 

Reviewer 2 Report

Comments for applsci-1551141.R1

Manuscript Number: applsci-1551141.R1

Title: Long-term occurrence and fate of microplastics in WWTPs: a case study in Southwest Europe

Article Type: Original Research Paper

 

 This paper analyses the occurrence and fate of MPs of a WWTP sited in Southwest Europe monthly in a year. I revised this manuscript for the second time. I had read the response to my comments by the authors, and some of my questions were answered reasonably. There are still some questions should be solved.

1. About the question 4 of last comments: The author only used FTIR to determine the chemical composition and percentage of different microplastics. I think it is not enough to support the results (Figure 6 and Figure 7). The peaks of the chemical components of these proposed microplastics are very close, in the case of microplastics mixture, it is difficult to distinguish these components and determine their content by FTIR.

The authors said the vast majority of studies on MPs perform a visual inspection by stereomicroscope/microscope, which is normally combined with FTIR analysis, while this explanation cannot answer my question.

How did the authors use FTIR to determine various components in mixed micro plastics and calculate their proportion? I don’t think stereomicroscope/microscope have these functions. Were Figure S2 the results measured after separating various plastic components? And how did the authors separated all kinds of plastics?

 

2. I think the authors should give us the removal ratios of different sizes, different kinds of MPs after different treatments. As I said in question 5 of last comments, the authors didn’t give us data to show the results that MPs more easily removed during the wastewater treatment processes were those with sizes greater than 500 μm. 

Author Response

Response to Reviewer 2 Comments

This paper analyses the occurrence and fate of MPs of a WWTP sited in Southwest Europe monthly in a year. I revised this manuscript for the second time. I had read the response to my comments by the authors, and some of my questions were answered reasonably. There are still some questions should be solved.

Point 1: About the question 4 of last comments: The author only used FTIR to determine the chemical composition and percentage of different microplastics. I think it is not enough to support the results (Figure 6 and Figure 7). The peaks of the chemical components of these proposed microplastics are very close, in the case of microplastics mixture, it is difficult to distinguish these components and determine their content by FTIR.

The authors said the vast majority of studies on MPs perform a visual inspection by stereomicroscope/microscope, which is normally combined with FTIR analysis, while this explanation cannot answer my question.

How did the authors use FTIR to determine various components in mixed micro plastics and calculate their proportion? I do not think stereomicroscope/microscope have these functions. Were Figure S2 the results measured after separating various plastic components? And how did the authors separated all kinds of plastics?

Response 1: In this work, the analysis of microplastics found in wastewater and sludge samples was carried out following the methodology described in the vast majority of published works on MPs (Alvim et al. (2020), Iyare et al. (2020)). Specifically, the chemical composition of MPs was conducted by means of FTIR analysis according to the list of absorption bands of sixteen polymers found in microplastics from marine samples described by Jung et al. (2018). The objective of our work with the FTIR analysis was to determinate the abundance of polymers that constituted the MPs found in samples analysed. These polymers were polyamide (PA), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC), according with other works (Sol et al. (2020), Wang et al. (2020), Ali et al. (2021)) and the absorption bands were identified without uncertainty. In our case, MPs suspicious of being copolymers were not found. In any case, different works have proved the FTIR as a suitable technique to analyse also copolymers in microplastic particles, see for example:

• Zhang et al. (2021). https://doi.org/10.1016/j.jclepro.2021.125968
• Xu et al. (2021). https://doi.org/10.1016/j.marpolbul.2021.112448
• Cao et al. (2020). https://doi.org/10.1016/j.marpolbul.2020.111535
• Magni et al. (2019). https://doi.org/10.1016/j.scitotenv.2018.10.269

Other references:

• Alvim et al. (2020). https://doi.org/10.1016/j.jenvman.2019.109739
• Iyare et al. (2020). https://doi.org/10.1039/D0EW00397B
• Jung et al. (2018). https://doi.org/10.1016/j.marpolbul.2017.12.061.
• Sol et al. (2020). https://doi.org/10.1016/j.scitotenv.2020.140016.
• Wang et al. (2020). https://doi.org/10.1016/j.watres.2020.115956.
• Ali et al. (2021). https://doi.org/10.1016/j.cej.2021.130205.

Point 2: I think the authors should give us the removal ratios of different sizes, different kinds of MPs after different treatments. As I said in question five of last comments, the authors did not give us data to show the results that MPs more easily removed during the wastewater treatment processes were those with sizes greater than 500 μm. 

Response 2: This can be deduced by comparing graphs shown in Figure 3. For a better understanding, Table S4 has been included as Suplementary Material showing the size and shape evolution of microplastics after each treatment (influent, secondary effluent and final effluent) and the overall removal efficiency of each type of microplastic. As it is shown, the removal efficiency of the MPs greater than 500 mm after secondary treatment corresponds to approximately 57%, whereas, at this point, a removal efficiency of 39% was found for the MPs with a size between 20 and 100 mm. In addition, the MPs with a size greater than 500 mm were eliminated with an overall efficiency of 70%, whereas for MPs in the range 20-100 mm the overall removal efficiency was 50% (please see page 7, lines 233-236, 244-246, 255-256).

Regarding the morphology of the MPs, it was observed that the fibres and fragments constitute approximately 98% of the MPs and, as can be seen in Table S4, the fragments were removed in a higher percentage than the fibres (overall removal efficiency of 67% vs. 56%). This information has been included in the main text (please see page 9, lines 288, 290-291).

 

Table S4. Size and shape evolution of microplastics after each treatment (influent, secondary effluent and final effluent) and the overall removal efficiency of each type of microplastic.

 

		Influent		Secondary treatment			Final effluent			Overall removal efficiency (%)
		Number of MPs	Abundance (%)	Number of MPs	Abundance (%)	Removal efficiency (%)	Number of MPs	Abundance (%)	Removal efficiency (%)
Size	20-100 mm	656	19.57	403	23.44	38.56	289	23.05	28.28	55.95
	100-250 mm	832	24.82	468	27.23	43.75	325	25.92	30.55	60.94
	250-500 mm	858	25.60	412	23.97	51.98	338	26.95	17.96	60.61
	>500 mm	1006	30.01	436	25.36	56.66	302	24.08	30.73	69.98
Shape	Fibres	1161	34.20	667	36.19	42.54	508	40.32	23.83	56.24
	Fragments	2163	64.88	1157	63.32	46.50	712	57.28	38.46	67.08

 

Author Response File: Author Response.pdf