Comment on Khairul Zaman et al. Eco-Friendly Coagulant versus Industrially Used Coagulants: Identification of Their Coagulation Performance, Mechanism and Optimization in Water Treatment Process. Int. J. Environ. Res. Public Health 2021, 18, 9164

Round 1

Reviewer 1 Report

The manuscript deals with justifying some important parts of the paper entitled "Eco-Friendly Coagulant versus Industrially Used Coagulants: Identification of Their Coagulation Performance, Mechanism and Optimization in Water Treatment Process”. In my opinion, the manuscript could clarify some lacks of the paper published by Zaman et al. (2021) in a logical way.  

Drinking water is usually treated via different techniques depending on the quality of the raw water, the degree of contamination, and regulations for public health safeguarding. Among all water treatment technologies, coagulation and flocculation have been an essential part of drinking water and wastewater treatment processes for decades. To date, research and development of coagulants have been carried out intensively to improve and establish coagulants with certain properties such as being less hazardous to the environment, having high stability, and being resilient to various process conditions so as to allow maximum coagulation performances (https://doi.org/10.3390/ijerph18179164).

In the study performed by Zaman et al. (2021), the process optimization was investigated by comparing an eco-friendly chitosan with the industrially used coagulants namely aluminum sulfate (alum), polyaluminum chloride (PAC), and aluminum chlorohydrate (ACH) in compliance with national drinking water standards. Zaman et al. (2021) claimed that a potential link between the neurotoxicity sourced from aluminum and its pathogenesis to Alzheimer’s disease was reported by Berube and Dorea (2008). The inorganic coagulants could also cause the generation of a large volume of toxic metal hydroxide sludge, which is also a health hazard due to its carcinogenic property. This has resulted in disposal problems, as well as an increase in an ionic metal concentration of aluminum, specifically in treated water. In comparison to inorganic coagulants, the organic/bio-coagulant of chitosan promises excellent properties and performances with additional values of being more economical, widely available, free of toxins, and biodegradable. Ivy et al. have tried to explain this part of the paper in details.

Author Response

First of all, many thanks for considering our Comment for publication in your journal. We really welcome this opportunity, as we feel it allows a deeper discussion of the topic and encourages a post-publication active engagement of the readership with the contents of IJERPH. We would like to enquire on the process being adopted for the publication of this Comment. We received a notification to revise our commentary. This has left us with a few procedural questions in mind. When we drafted it, we followed our experience from doing similar contributions to other journals that routinely publish this type of manuscript. Our intention was to provide arguments that are reasoned, and not presented in a confrontational fashion. Our understanding was that these would will be sent to the authors of the original paper for reply, the outcome of which may be publication in a future issue. Our experience is that this type of contribution is accepted or rejected without corrections. We believe our Comment presents a sufficiently reasoned critique that is not confrontational.  More importantly, we think our Comment and the response of the authors provide a healthy, high-level, and timely debate on an important thematic; which the readership will enjoy and can use to further their thoughts. We feel strongly that scientific debate is not a zero sum game with a binary result (i.e. only one perspective is right). I think the Comment and its reply provide different views that can form the springboard for future thinking on the topic.

Considering the above, we are uncertain as to the most appropriate reaction to the notification we received. The reviewer suggests we amend our Comment. We respond with the following:

• It is unclear what the amendment should be. That is, a few points are stated, but no explicit request is made. Implicitly, it seems there is a suggestion that we should change how our argumentation is presented, which we stand by.
• Any suggestion of change is in our opinion contrary to what our experience with other journals on how a Commentary is published (i.e. accepted/rejected with no corrections). In most cases, the Commentary is evaluated on whether it presents a well-argued contribution in a respectful way that will be of interest to the readership. We believe this is the case.
• To modify our Comment would alter (and effectively censor) the core essence of our reasoning. This is a Comment and the authors have had the chance to express their view on it through their rebuttal.
• If we modify our Comment, this will be incongruous with the authors’ reply to our original text and lead to reader confusion. This is the practice adopted by other high ranking journals that publish such discussions.

In view of this, we believe our Commentary should be subject to an editorial decision as is without modifications in a process similar to other journals. We have provided a detail rebuttal above to the comments received to justify our positioning. However, we feel it would be procedurally inappropriate to modify our text, as this is not a typical manuscript; rather a Comment on another paper.
Thanks in advance for your time and consideration.
Kind regards,
Prof. Caetano C. Dorea, PhD