the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
26 Feb 2021
26 Feb 2021
Defluoridation of drinking water by modified natural zeolite with Cationic surfactant, in case of Ziway town, Ethiopia
- 1Lecture in Department of Water Supply and Environmental Engineering, School of Civil and Environmental Engineering Jimma University Institute of Technology, Jimma University
- 2Lecture and Department Co-ordinate for Water Supply and Environmental Engineering, School of Civil and Environmental Engineering Jimma University Institute of Technology, Jimma University
- 1Lecture in Department of Water Supply and Environmental Engineering, School of Civil and Environmental Engineering Jimma University Institute of Technology, Jimma University
- 2Lecture and Department Co-ordinate for Water Supply and Environmental Engineering, School of Civil and Environmental Engineering Jimma University Institute of Technology, Jimma University
Abstract. In Ethiopia (Ziway town) an excess fluoride (≥ 1.5 mg/L) consumption in drinking water (ground water and Lake Ziway) sources causes a health problem on the communities. The surrounding of inhabitant's peasant farmers of drinking water sources was extremely relying on this polluted fluoride concentration of water. This investigation was focused on defluoridation of drinking water by natural zeolite modified with a cationic surfactant in a batch system and Hexadecy Trimethyl Ammonium Bromide were used for zeolite modification. The Batch experiments also conducted to test for preferential removal of fluoride from water by surfactant-modified zeolite. The zeolite treatments had an aggregate size of 1.4 to 2.4 mm. The cationic surfactant-modified zeolite, and raw zeolite were used in all experiments. The removal efficiency of the treatment was influence by pH of solution (5.5 ± 0.2–8.5 ± 0.2), initial concentration of fluoride (1–10 mg/L), dose of surfactant-modified zeolite (2.5–18 g/L), contact time (30–180 Minute), and effect of temperature was investigated. The study investigated that, at the constant Blank of 10 mg/L, 5 g/L of Hexadecy Trimethyl Ammonium Bromide dosage noted the highest fluoride removal potential at the end of the 3hours runtime: Na-LSX (88.4 %), Na-LTA (64.6 %) and ZR (79.8 %). Incompatible to this reflection, the model waters with pH maintained at 5.5 ± 0.2 and 6.5 ± 0.2 verified rapid fluoride removal (89.7 % and 72.3 % respectively) within the first 60 minutes of runtime.
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Dessalegn Geleta Ebsa and Adisu Befekadu Kebede
Status: final response (author comments only)
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RC1: 'Comment on dwes-2020-35', Anonymous Referee #1, 24 Mar 2021
Defluoridation of drinking water by modified natural zeolite with Cationic surfactant, in case of Ziway town, Ethiopia
I believe that the present paper contains interesting results, the structure of experimental and that of results and discussion should be substantially modified. Therefore, I think the manuscript could be accepted for publication after the following major issues are addressed. The whole manuscript revised once again - it has many grammatical, stylistic and typographical mistakes. English should be checked by native speaker. Concrete comments are shown as follows.
- Abstract
Line 17 and 18 – “by natural zeolite modified with a cationic surfactant in a batch system and Hexadecy Trimethyl Ammonium Bromide were used for zeolite modification. The Batch experiments also conducted”. The chemicals and batch experiment should not be written in capital. Abbreviation HDTMA should be here introduced for the first time.
Line 18 - ” The Batch experiments also conducted to test for preferential removal of fluoride from water by surfactant-modified zeolite.”
This is repetition and should be removed.
Overall English should be checked and corrected (just some of the examples):
Line 21 - “was influence”
Line 32 – “the most electronegative elements which have a negative charge”
Line 71 – “Drinking water samples will collects”
Line 74 – “A cross-sectional study was conducted to removes”
Line 78 – “cationic surfactants will analyzed by”
Line 124 – “were under took for adsorption”
Line 152 – “followed with lesser fluoride”
Line 24 - “The removal efficiency of the treatment was influence by pH of solution (5.5 ± 0.2 – 8.5 ± 0.2), initial concentration of fluoride(1-10mg/L), dose of surfactant-modified zeolite (2.5-18 g/L), contact time (30-180 Minute), and effect of temperature
was investigated.” – What is the temperature range that is being investigated?
Line 26 – Abbreviations that are mentioned for the first time in the abstract are not clear and confusing. What does Na-LSX, Na- LTA and ZR mean?
Line 27 – At what initial fluoride concentration was rapid fluoride removal?
General remark
Numbering is incorrect. Introduction should be 1. It is confusing that Materials and methods suddenly start with 3. What happened with 2.?
Introduction
- Line 33 - ions of group IA should be stated
- Line 36 – Introduction on fluoride and concentrations/ the values found in water should be added. Regulations by WHO should be added.
- Line 42 - “Thus, defluoridation of drinking water is the best alternative technology in order to reduce health menace.” –It is not clear why defluoridation is the best technology and alternative to which technologies?
- Explanation on why zeolite should be modified is missing and why HDTMA-Br?
Materials and Methods
- Line 72 – “Drinking water samples will collects from sampling sites in the Batu town, mainly in the drinking water distribution system” – Where are exactly sampling points? What is the population?
- Line 74 –“A cross-sectional study was conducted to removes the concentration fluoride in the drinking water and defluoridation by using natural zeolite with cationic surfactant from community water supply and private tap of the town.”- In the manuscript the defluoridation was described by natural zeolite and modified. What is meant by cross-sectional study to remove fluoride? That should be better described.
- Line 79 – what are the standard procedures?
- Line 99 – How was composition and surface area determined? The procedure and measurements should be in detail explained in the materials and methods.
- Line 103 – Column experiments? There is no description on column experiments or details regarding the column and flow. This is completely out of nowhere.
Results and discussion
- Line 113 – Once again what does LST, LTA and ZR means? The difference in the preparation of the samples should be described and mentioned in the materials and methods.
- Table 1 – What is the difference between unmodified zeolite? Why are the values changing? I assume those are different types of zeolites but it is not mentioned in the manuscript. Additionally list of elements should be the same in the all columns, following the same order.
- Big issue is that in line 97 only ONE zeolite type is mentioned. Where are all the other ones coming from? “The zeolite used in this study was a natural clinoptilolite-rich tuff obtained from the St. Cloud mine near Winston,”
- Line 126 – “variation of HDTMA dosages, at variation of pH, at variation of mixing time and the duration of adsorption in order to follow up best fluoride removal efficiency were considered.” Why is temperature here not mentioned and in abstract well?
- Figure 1 – typo it should be Blank and not Bank in legend
- Line 143 – Why was desorption present?
- Line 149 – “From Figure 4.1, a remarkable fluoride uptake was observed within the initial 30 minutes of runtime for all the zeolites” – Removal from 10 to 9.6, 9.4 mg/L wouldn’t call remarkable. I think that here should be written Figure 4.2 instead 4.1!
- Line 151 – “The synthesized zeolite from only laboratory reagents gave the highest fluoride removal (88.4 %) at the end of the 3 hours runtime. Zeolite Na-LSX and Na-LTA followed with lesser fluoride removals of 64.6 and 25% respectively” – Where are these results coming from? All the graphs go up to 120 min or 135 min!
- Line 155 – It should be figure 4.2 instead of 4.3. It is really confusing to read the manuscript where Figures don’t match with the text.
- Line 157 – “Probably, the interference from the OH− anions was reduced, providing additional free adsorption sites for the fluoride ions” – this should be supported with the literature.
- Figure 3 – Dosages of HDTMA should be reported in the materials and methods and not found in the label.
- Line 212 – “It is also observed that the 24 hours modification reaction time exhibited the highest fluoride removal potential (73%) whilst the 36 hours resulted in a slightly lower performance (73 %).” – 24h and 36h have both same removal! How can it be higher or lower?
- Line 219 –“ The effect of pH on fluoride uptake using modified zeolite Na-LSX was conducted considering” – Which modified zeolite was that? Which concentration was used?
- Figure 7 – it should be Na – LSX and not Na-LST
- Why were pH 8 and 9 not included? Maybe there would be still increase.
- Figures 7 and 8 are showing same data. However it is not clear where 88% removal is coming from! Additionally figure 7 shows the best removal at pH 7.5 while at Figure 8 at pH 5.5????? typo Ph should be corrected in the Figure 8 into pH!
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AC1: 'Reply on RC1', Dessalegn Geleta, 07 Apr 2021
The comment was uploaded in the form of a supplement: https://dwes.copernicus.org/preprints/dwes-2020-35/dwes-2020-35-AC1-supplement.pdf
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RC2: 'Comment on dwes-2020-35', Anonymous Referee #2, 25 Mar 2021
The paper is about the removal of fluoride with modified zeolites. This is an important topic, since fluoride contamination of drinking water is a serious problem in the region where the study was conducted. However, the quality of the paper is low. The set-up of the experiments have drawbacks, the analysis of the results are weak, the use of references for the discussion of the results is poor, and the manuscript has severe language issues.
General comments:
- Let the language be checked by a native speaking person
- Explain at the end of the introduction, what is the “knowledge” gap, what is the “objective” of the study and how does it “contribute” to science/engineering.
- Explain why the use method of modification is chosen (based on literature), what other modifications are possible?
- Batch experiments should have been performed in the form of Isotherms (varying concentration of dosages) to determine adsorption capacity.
- Now only “kinetic” tests are performed with a fixed dosage
- The data in the figures do always not reflect the values given in the text.
- Avoid representation of same data different Figures (e.g. 7 and 8)
- Although it was mentioned that column test were performed too, the results only reflect the batch tests.
- Check numbering of (and reference to) figures.
- Use literature to discuss the results (how do they compare to other studies)
- Do not use “runtime” for batch tests
- Do not use “significant” when no statistical analysis is performed.
Specific comments:
- Line 48, what are these “natural characteristics”? explain
- Line 67, not needed to give the coordinates
- Line 82, ORII and MB?
- Line 85-89, not needed to explain
- Line 90-94, not further used in the analysis of the results
- Line 127, check numbering of the sections (4.2 should not be a separate section)
- Line 151, the value does not correspond to Figure 2.. (from 10 mg/L to 8 mg/L is not 88% removal), see general comment and check entire document
- Line 160, how is it concluded that the surface is hydrophilic?
- Line 163-164, too obvious statement => delete
- Line 194, difference is very small and conclusions cannot be drawn
- Line 212-217, see comment above..
- Line 230-234, values shown in Figure 7 do not compare to data presented in the other Figures..
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AC2: 'Reply on RC2', Dessalegn Geleta, 07 Apr 2021
The comment was uploaded in the form of a supplement: https://dwes.copernicus.org/preprints/dwes-2020-35/dwes-2020-35-AC2-supplement.pdf
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RC3: 'Comment on dwes-2020-35', Anonymous Referee #3, 28 Mar 2021
The comment was uploaded in the form of a supplement: https://dwes.copernicus.org/preprints/dwes-2020-35/dwes-2020-35-RC3-supplement.pdf
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AC3: 'Reply on RC3', Dessalegn Geleta, 07 Apr 2021
The comment was uploaded in the form of a supplement: https://dwes.copernicus.org/preprints/dwes-2020-35/dwes-2020-35-AC3-supplement.pdf
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AC3: 'Reply on RC3', Dessalegn Geleta, 07 Apr 2021
Dessalegn Geleta Ebsa and Adisu Befekadu Kebede
Dessalegn Geleta Ebsa and Adisu Befekadu Kebede
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