Exploration and Optimisation of High-Salt Wastewater Defluorination Process

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

Exploration and optimization of high-salt wastewater defluorination process (Manuscript ID: water-1904351).

The manuscript focused on the removal of fluoride ions in waste water by chemical precipitation method. The reported work is attractive and a good contribution in scientific field. 

Prior to accept the manuscript for publication in Water, the following comments are to be considered.

1. In general, the authors should write the investigated work in past tense. This condition is applicable to whole manuscript.

Reply：The research content in this paper has been changed to the past tense

2. Abstract-line 12-16: write the experimental procedures in a clear way in past tense; line 21: report the % removal of fluoride ions in %; line 23 & 24: enter the experimental values of COD, total phosphorus, ammonia nitrogen and chloride ions; line 27-29: delete; include the proposed method for removal of fluoride ions in real samples (at least consider 3 water samples for application and compare the values). Delete include the proposed

Reply：The experimental procedure has been changed to the past formula. line 12-16: Content changed to“In this study, calcium hydroxide was used to adjust the pH and achieve a significant fluoride removal effect at the same time.”

Fluorine ion removal rate has been added. line 21: Content changed to “The fluoride ion concentration in high-salt wastewater can be reduced from 446.6 mg/L to 35.4 mg/L by defluorination after pretreatment whose removal rate was 92.1%.”

Line 27-29: “The goal of this research is to improve and optimise the process on the basis of the original facilities for enhancing the defluorination effect of high-salt wastewater for reference.” has been deleted.

 

3. Introduction- include the references of fluoride ions and its management in waste water. Discuss: How to clean the waste water, how to make this water suitable for drinking or irrigation purposes or some other valuable work? What is the permissible range of fluoride ions in drinking water fixed by WHO, EPA and Chinese regulatory body? Discuss and include references (reported/published work) based on the chemical precipitation method. Write a concise and specified introduction. Delete irrelevant text other than your proposed technology.

Reply: The source of water is a solid waste disposal company. Fluorine in waste water after treatment should meet the standard of connecting pipe, not for irrigation or reference. Fluoride is 10mg/L in the first level discharge standard of comprehensive sewage discharge standard.

4. Materials and methods: What are the sources of fluoride and chloride ions in China for the results reported in Table 1? Discuss and include references.

Reply: The wastewater is from a solid waste disposal company, so the fluoride ion mainly comes from the tail water after solid waste disposal

5. 2. Experimental method: line 170, Is it fluoride ions or fluorine, please specify; line 170-179:

write the procedures in a clear manner and in past tense.

Reply: It is fluoride ions and the past tense has been modified. Line 170-179: Content changed to：“In this experiment, chemical precipitation method was used to remove fluoride ions, calcium precipitation + coagulation precipitation combination was utilised such that fluoride ions form CaF2 and the pH value of the solution was adjusted to achieve the best effect. The other group adds CaCl2 for comparison and provides remaining Ca2+. In this study, PAC was used as a coagulant, and the general formula of polyaluminium chloride could be expressed as AlnCl3n. Polyaluminium chloride could be regarded as an intermediate product of AlCl3, which is gradually converted into AI(OH)3 by hydrolysis. It is a compound composed of many different forms of hydrolysis products. As soon as polyaluminium chloride was added to the water, it could directly neutralise electricity, adsorb and bridge and was less affected by the original water quality.”

Author Response File: Author Response.docx

Reviewer 2 Report

 

• This article studied the proposed methods for defluorination in wastewater treatment. The writing needs to be more precise, though it is clear. It is recommended for major revision.
• The theoretical aspects of the proposed methods were analyzed. However, more elaboration/ discussion on the practical implications of this work would be important. Two references are recommended: 1. Engineering interface between bioenergy recovery and biogas desulfurization: Sustainability interplays of biochar application; 2. Methodological framework for wastewater treatment plants delivering expanded service: Economic tradeoffs and technological decisions. The discussion is important to support the practical application of this work.

Author Response

This article studied the proposed methods for defluorination in wastewater treatment. The writing needs to be more precise, though it is clear. It is recommended for major revision.

The theoretical aspects of the proposed methods were analyzed. However, more elaboration/ discussion on the practical implications of this work would be important. Two references are recommended:

1. Engineering interface between bioenergy recovery and biogas desulfurization: Sustainability interplays of biochar application;
2. Methodological framework for wastewater treatment plants delivering expanded service: Economic tradeoffs and technological decisions. The discussion is important to support the practical application of this work

 

Reply: The analysis content has been improved and the above two articles have been referenced.

Line 331-334: In the meantime, the case for TP is the opposite. In addition to removing fluorine, the pro-cess is also very effective in removing phosphate radicals in wastewater and converting soluble phosphates into insoluble phosphates. This solution can simultaneously remove phosphorus whilst removing fluorine [42,43].

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear Respected Sir, Greetings! Thank you very much for providing me the opportunity to review the manuscript entitled "Exploration and optimization of high-salt wastewater defluorination process" (1904351) for Water:  The manuscript has been re-reviewed thoroughly and found that the authors incorporated and answered raised comments in the revised manuscript. Hence, the revised manuscript is accepted for publication in Water. Thanking You Best regards Dr. Syed Najmul Hejaz Azmi  

Reviewer 2 Report

accept