Universal Access to Safe Drinking Water: Escaping the Traps of Non-Frugal Technologies

Round 1

Reviewer 1 Report

The document addresses a topic of interest, but I think that it is fundamentally an informative and very unscientific work. I expected it more technical. There is only one table, it is a comparison of investments and costs, but its validity, outside the geographical scope of the authors, may be questionable.

The authors do not present an original work, rather they defend an idea in which they believe. In this sense, at the beginning of the last paragraph of the Introduction it is stated verbatim: “This communication seeks to demonstrate that universal self-reliance in safe drinking water provision is possible using locally available materials and the concept of the modular treatment train presented at YouTube by Aqueous Solutions (www.aqsolutions.org) .. ”. Likewise, in the first paragraph of the conclusions it says verbatim: “… Results indicate that the multiple barrier approach presented by Dr. Kearns is affordable and adaptable to any situation…”. In any case, I do not consider that the aforementioned conclusion can be drawn from the work carried out, since I consider that the work does not have results.

I consider that fundamental aspects that should be in a scientific work are almost absent. Aspects such as the methodology and the results themselves, along with their analysis and discussion. Nor can it be considered a bibliographic review in which the state of the art is analyzed.

Author Response

Comments 1: The document addresses a topic of interest, (Many thanks for this evaluation) but I think that it is fundamentally an informative and very unscientific work. I expected it more technical. There is only one table, it is a comparison of investments and costs, but its validity, outside the geographical scope of the authors, may be questionable.

 

Responses 1: We fully agree with the Reviewer that it is an informative peace. The information (that research for affordable water treatment systems are mostly starting at the wrong end) is necessarily scientific. Another reviewer used the wording “aggressive”  (for “unscientific”). We understand that this is because the original introduction didn’t contain information about the ancient status of sand filters. We avoided a detailed discussion of the science of the various technologies because these aspects are discussed in several reviews including those done by our research group. Moreover, the focus of the present paper is frugality not the fundamental mechanisms or performance of the various technologies. To address the reviewer’s comments we have now added the following sentences (with 10 references) to the introduction.

“It should be recalled that sound principles for designing affordable systems for safe drinking water supply are documented in many old textbooks [8-10], review articles [11,12] and books on the history of water treatment [7,13]. In particular, the century-old textbook “An Elementary Handbook on Potable Water” [10] by Floyd Davis (1891) is very illustrative. Floyd Davis had already identified filtration on sand and animal charcoal (bone char) as powerful tools to obtain high quality water for many purposes. However, while sand has been continuously used in water treatment plants [7],  bone char has been outscored by other active materials, including granular activated carbon (GAC) and was almost independently re-discovered twice for water defluoridation: (i) during the 1930s as fluoride was established as a severe water pollutant [14,15] and (ii) during the late 1970s to solve the fluoride crisis in the developing world [16.17].”

We also agree with the reviewer that there was a paucity of illustrative arguments. However, data in Table 1 compare investments and costs from Egypt, Nepal, and Tanzania and thus covers broad geographical regions. PAUL is sold in Germany at a fix prices and transferred to the point of used with the corresponding shipping fees. Such fees are necessarily dependent several factors, including national policy. However, we have not addressed these country-specific issues, we have limited the comparison to the flying cost for a scientist or an expert and we do believe, that it is enough to state that assembling and operation water treatment system for just the transport cost of an expert is very plausible. We doubt there are other additional costs that are peculiar to a particular country.

 

Comments 2: The authors do not present an original work, rather they defend an idea in which they believe. In this sense, at the beginning of the last paragraph of the Introduction it is stated verbatim: “This communication seeks to demonstrate that universal self-reliance in safe drinking water provision is possible using locally available materials and the concept of the modular treatment train presented at YouTube by Aqueous Solutions (www.aqsolutions.org) .. ”. Likewise, in the first paragraph of the conclusions it says verbatim: “… Results indicate that the multiple barrier approach presented by Dr. Kearns is affordable and adaptable to any situation…”. In any case, I do not consider that the aforementioned conclusion can be drawn from the work carried out, since I consider that the work does not have results.

 

Responses 2: We think that the reviewer is not fair with these comments we are not “defending an idea in which we believe” but we are presenting the facts as they are. The scientific community has been “misusing” the money of the tax payer or the sensible donor (NGO) to try to develop systems, that are not operational, in a context that simple amended SSFs are efficient. We have now given the example of As in Bangladesh and Nepal to illustrate that all the efforts were not really successful until Hussam and Munir (2007) developed their SONO filters. These efficient filters have not been broadly disseminated, perhaps because they are patented. At least two simple alternatives exist and are a rediscovery of technologies that were used at large scale (in Europe) during the 1880s.

Our research group has demonstrated already in 2012, that the Kanchan arsenic filter was designed with a thinking mistake. We have continued our investigations and have recently present a filter (using steel wool and) able to work for one year. We have made no efforts to focus the presentation on our achievements to avoid repeating information already published elsewhere (and properly referenced herein) but rather, we have outline the fact that it is the bright idea of Dr. Kearns and Aqueous Solutions that makes our solution universal. No, we are not interested in being popular, we want people to adopt simple solutions and use the science of self-reliance we and the research group of Dr. Kearns have been advocating for the past 15 years.

Again, we present the results of a critical analysis of presented solutions and we recognized that Dr. Kearns and his team presented a modular systems, that rendered other locally available ideas or treatment units more efficient. That was the objective of of presentation. Although we have not directly answered to this concern, these comments were very useful in focusing the presentation in the revised manuscript.

Comments 3: I consider that fundamental aspects that should be in a scientific work are almost absent. Aspects such as the methodology and the results themselves, along with their analysis and discussion. Nor can it be considered a bibliographic review in which the state of the art is analyzed.

 

Responses 3:

The reviewer’s concern on the absence of scientific work is addressed in earlier comments where we indicated that the science of the various technologies are discussed elsewhere in literature already in the public domain. The focus here is the frugality of the technology, an aspect which has received a cursory attention in earlier reviews. The paper is based on collation of data on the costs of the various technologies and estimated flight costs for experts to install and maintain such systems in order to provide indicate costs for the various technologies. There is no comprehensive database of studies with costs for the various technologies to enable a quantitative review based on meta-analysis of bibliometric analysis. The comparative table clearly indicates what data was considered in estimating the costs for the various technologies.

To address the reviewer’s comments we revised and included the following text:

In the present paper the initial cost of each technology, and the corresponding costs for shipping and flights costs for external experts for each system were estimated based on current prices. This is meant to provide an indicative cost of each technology, and its frugality in the context of clean drinking water provision. Note that because comparative costs for the various technologies have received a cursory research attention, a quantitative review based on meta-analysis or bibliometric analysis was not feasible.

Reviewer 2 Report

Congratulation for the work done.

Firstly, although I think the overall introduction section was fine, paragraphs 3 and 4 seems to be writen in a aggressive way.

There are a lack of discussion about the benefits and the mechanisms of action of GAC, as well as for Fe0 and the overall SSF.

Rearange and uniformize the format of table 1, and add the necessary references. If it is from your work, what is the basis of your calculations. A section with an explanation of these values should be added, with proper comparisons and data support.

In my opinion, there are a lack of data in the paper to suport the discussion and the values presented in table 1.

Line 347: the granular word in (GAC) definition is missing, and this abbreviation was already introduced in Figure 1. Not needed here

 

Author Response

Comments 1: Congratulation for the work done.

 

Responses 1: We thanks the reviewer for the positive comment.

 

Comments 2: Firstly, although I think the overall introduction section was fine, paragraphs 3 and 4 seems to be written in an aggressive way.

 

Responses 2: Paragraph 3: We revised the phrase ‘are declared incompetent and condemned to wait for’ to ‘highly dependent on’

 

Comments 3: There are a lack of discussion about the benefits and the mechanisms of action of GAC, as well as for Fe⁰ and the overall SSF.

 

Responses 3:

We considered the reviewer’s comment and would like to respond that several review papers exists on the mechanisms of contaminant removal by the systems discussed. These reviews include those by our research group, and this information is already in the public domain. Therefore, in line with the focus of the present paper on frugality, we focused on the cost aspects which are currently poorly addressed in literature.

 

Comments 4: Rearange and uniformize the format of table 1, and add the necessary references. If it is from your work, what is the basis of your calculations. A section with an explanation of these values should be added, with proper comparisons and data support.

 

Responses 4: Done thanks, The prices for PAUL and Autarcon are as given by the authors, the one of the biochar filters as well. A reference (Naseri et al. 2017)  is added for the economics of Fe⁰ filters.

 

Comments 5: In my opinion, there are a lack of data in the paper to support the discussion and the values presented in table 1.

 

Responses 5: We have considered this concern and added information with references.

 

Comments 6: Line 347: the granular word in (GAC) definition is missing, and this abbreviation was already introduced in Figure 1. Not needed here.

 

Responses 6: Corrected, thanks!

Reviewer 3 Report

This communication reviewed drinking water purification methods for developing countries and remoted communities. The authors concluded that the biochar and metallic iron (Fe⁰) based systems are included in the affordable and self-reliance methods, but still need to be further improved through internal processes before to be popularized. The paper is interesting but its framework, hypothesis, premises and criteria need to be significantly re-organized before the consideration for publishing in the Journal.  

 

The quality of raw water is variant among various countries even different areas in the same country, particularly for the region-specific pollutants and the health-concerned issues, which may not be effectively treated with same methods. I strongly suggested that the framework of the manuscript could be pollutant based or water quality oriented in the premises of chemical-free, affordable, and self-reliance features. Besides, the SSF, biochar, GAC, Fe0/sand, SSF technologies have advantage on various pollutants, selection and integration criteria are also water quality based and need to be addressed in the manuscript.

 

Why did the study choose the two technologies “biochar” and metallic iron (Fe0) as the basic unit? Is there fundamental basis or just the research group continuously working on them? If the authors aimed to promote their innovated technologies, the experimental results should be presented. Have the authors surveyed most allowable literatures and information to select the most appropriate methods for the developing countries, rural communities to build their own drinking water purification systems? The aim of the study should be strengthened in the manuscript for the broad readers of the Journal.

 

Table 1 shows the costs of four small-scale water supply systems, the basis (raw water quality, discharge water quality and quantity etc.), assumption, conditions of the assessment should be provided, as well as the references should be cited. For instance, why the material cost of PAUL is zero? The zero cost for the operation and maintenance per year of biochar, metal iron, PAUL is doubtful; backwash, trouble shooting, fixation of system, regeneration (or disposal) of adsorbents during operation could be inevitable.   

 

As the authors presented in the conclusions “…water treatment options to provide small communities with safe drinking water is given”, but how safe is safe? The hypothesis, premises and criteria should be given.

   

A new idea occurred in conclusion about “the site-specific adaptation depends not only on the nature of polluted water but also from the available expertise” would not be appropriate.  

Author Response

Comments 1: This communication reviewed drinking water purification methods for developing countries and remote communities. The authors concluded that the biochar and metallic iron (Fe0) based systems are included in the affordable and self-reliance methods, but still need to be further improved through internal processes before to be popularized. The paper is interesting but its framework, hypothesis, premises and criteria need to be significantly re-organized before the consideration for publishing in the Journal.

 

Responses 1: Thanks for this evaluation. We have added a methodology section to improve the understanding and profoundly revised individual sections.  Three tables are added.

 

Comments 2: The quality of raw water is variant among various countries even different areas in the same country, particularly for the region-specific pollutants and the health-concerned issues, which may not be effectively treated with same methods. I strongly suggested that the framework of the manuscript could be pollutant based or water quality oriented in the premises of chemical-free, affordable, and self-reliance features. Besides, the SSF, biochar, GAC, Fe⁰/sand, SSF technologies have advantage on various pollutants, selection and integration criteria are also water quality based and need to be addressed in the manuscript.

 

Responses 2: The original manuscript had already specify that the design is site-specific but pathogens must be addressed by all designs. The next widely addressed contaminant are As; F and U as reflected in the presentation.

 

Comments 3: Why did the study choose the two technologies “biochar” and metallic iron (Fe⁰) as the basic unit? Is there fundamental basis or just the research group continuously working on them? If the authors aimed to promote their innovated technologies, the experimental results should be presented. Have the authors surveyed most allowable literature and information to select the most appropriate methods for the developing countries, rural communities to build their own drinking water purification systems? The aim of the study should be strengthened in the manuscript for the broad readers of the Journal.

 

Responses 3: The methodology -new- answers this question.

 

Comments 4: Table 1 shows the costs of four small-scale water supply systems, the basis (raw water quality, discharge water quality and quantity etc.), assumption, conditions of the assessment should be provided, as well as the references should be cited. For instance, why the material cost of PAUL is zero? The zero cost for the operation and maintenance per year of biochar, metal iron, PAUL is doubtful; backwash, trouble shooting, fixation of system, regeneration (or disposal) of adsorbents during operation could be inevitable.

 

Responses 4: All costs that are equal everywhere is take for zero. Zero is also no money expense. All other cost are given by the authors of referenced works and are either fix like for PAUL or recent.

 

Comments 5: As the authors presented in the conclusions “…water treatment options to provide small communities with safe drinking water is given”, but how safe is safe? The hypothesis, premises and criteria should be given.

 

Responses 5: The presentation had already insisted in the instrumental lab analysis as SOLE tool to assess water quality.

 

Comments 6: A new idea occurred in conclusion about “the site-specific adaptation depends not only on the nature of polluted water but also from the available expertise” would not be appropriate.

 

Responses 6: The idea has already been presented in the text, for example as the fluoride contamination was address, Fig: 1.

 

Although the answers to this reviewer are rather short, his constructive comment were very usefull in revising the whole manuscript, thanks again1

Round 2

Reviewer 1 Report

I think that the manuscript has not been improved enough to warrant publication in Sustainability

Author Response

Dear colleague,

We have tried to answer each aspect of your former concerns and would have contiinue tu discussion to optimize the communication.

It is unfortunate that we are left alone with the manuscript has not been improved enough

Sincerely,

Dr. Noubactep

Reviewer 2 Report

No more comments. It is ok for publication

Author Response

Many thanks for this evaluation.

Sincerely,

Dr. Noubactep

Reviewer 3 Report

The revised manuscript has been improved in accordance with my previous reviewing. I suggest it could be published in the Journal after several minor issues are amended.

 

A newly added table (Table 4) comparing the efficiency of various techniques benefits for the impurity-specific selection in rural areas, while the total cost of each one is also suggested to add on. In addition, specific categories will be more preferable than the general item of chemicals, i.e. suspended solid, dissolved components, organics, inorganics, cations, and anions, depending on the context.

 

At line 429, three amended SSFs were indicated in the table caption, but only two was listed in the table 4.

 

At line 252, the full name of BSFs should be indicated as it was showed at the first time in the manuscript rather at the later of line 379.

 

At line 248, is SFFs a typo? Or it should be SSFs?

 

A list of abbreviation versus full name would be better for reading.

Author Response

The revised manuscript has been improved in accordance with my previous reviewing. I
suggest it could be published in the Journal after several minor issues are amended.
Authors’ response:
 We thank the review for the overall positive comments. We have revised to address
the minor comments raised as explained below.
A newly added table (Table 4) comparing the efficiency of various techniques benefits for
the impurity-specific selection in rural areas, while the total cost of each one is also
suggested to add on. In addition, specific categories will be more preferable than the
general item of chemicals, i.e. suspended solid, dissolved components, organics,
inorganics, cations, and anions, depending on the context.
Authors’ response:
 We thank the reviewer for the suggestion. However details of the removal
efficiencies and mechanisms for specific contaminants are discussed in detail in
several earlier papers, and the key ones are presented in Table 2. To avoid
repetition, we avoided a discussion of the same aspects in the present paper. To
address the reviewer’s comments and to refer the reader to literature with such
details we revised by inserting the statement below (Pg 12 Ln 452-456):
‘Details of the removal efficiencies and mechanisms for specific types of dissolved organic
and inorganic contaminants, pathogenic organisms and suspended solids are given in
literature summarized in Table 2. Hence, for brevity, these aspects are not repeated in the
present paper.’
At line 429, three amended SSFs were indicated in the table caption, but only two was
listed in the table 4.
Authors’ response:
 Thanks for the observation – we corrected the table caption to ‘two’
amended SSFs to be consistent with the two in the table (See Pg 12 Ln 461).
At line 252, the full name of BSFs should be indicated as it was showed at the first time in
the manuscript rather at the later of line 379.
Authors’s response:
 We agree and defined BSFs the first time it was mentioned (Pg 6 Ln 276).
At line 248, is SFFs a typo? Or it should be SSFs?
Authors’s response:
 Thanks for noting the error. We corrected to SSFs (Pg 6 Ln 272).
A list of abbreviation versus full name would be better for reading.
Authors’ response:
 We considered the comment and included the list below in alphabetical order (Pg
1-2 Ln 38-53):
Abbreviations:

BC BSF(s) Fe0	Biochar Biological sand filter(s) Metallic or zero-valernt iron
GAC	Granular activated carbon
RWH	Rainwater harvesting
NGO O & M POU RSF(s) SDG	Non-governmental organization Operation and maintenance Point-of-use Rapid sand filter(s) Sustainable Development Goal
SOPAS SSF(s) WATER	Solar pasteurization Slow sand filter(s) Water Applied Testing and Environmental Research
WQQI	Water Quality and Quantity Index
WTS	Water treatment system

 

Author Response File: Author Response.pdf