Round  1

Reviewer 1 Report

General: Rainwater harvesting a good method to get drinking water. This concept paper could, anyhow, be more realistic. How much rain there is annually and in which months it is coming? Are there unusual dry periods? Is it really necessary to store the water for 12 months? How many persons the rain water is assumed to serve? Typically, the volume of commercial plastic water storage tanks can be from 0.5 to  10 m3.  The price and transportation are still moderate.

Is it realistic to build only one main storage tank?  Remember that a big water tower would be rather expensive. Can you think any risks if there is only one main storage tank? How long distances you could pump water?

Abstract Think still once the last sentence. since there are many countries where rain water harvesting is very common, and it is possible to buy tanks and collection systems and there are local companies making tanks from concrete. In addition, even in my country there is one area with groundwater containing too much fluoride. The local water supply plant is mixing this groundwater and treated water originated from surface water to be able to supply drinking water with lower F-concentration and they have done this maybe for 50 year. Thus, your concept is not very new but can be transferred to many areas.

Keywords: one of them is solar pasteurization. In text you have pasteurization only at the end of the chain? If the roof material is dark, can you estimate what is the temperature on roof?  Have you ever read works about his for instance: Sourav Das, Neha Ranjana,  Ananyo Jyoti Misra, Mrutyunjay Suar, Amrita Mishra, Ashok J. Tamhankar, Cecilia Stålsby Lundborg and Suraj K. Tripathy  Disinfection of the Water Borne Pathogens Escherichia coli and Staphylococcus aureus by Solar Photocatalysis Using Sonochemically Synthesized Reusable Ag@ZnO Core-Shell Nanoparticles. Int. J. Environ. Res. Public Health 2017, 14(7), 747; https://doi.org/10.3390/ijerph14070747

Notice that also light control (only light – no silver) gave good results!  

 Introduction:

What is biosand? Add a reference!

 Part 2

Omit at least the text about some metal cations in line 83-88.

Omit text of lines 99-110. It is not important to use space for these. 

 Part 3.

line 121 use rainwater instead of runoff water!

Omit text in lines 141-144.

 Part 4. Concept for blending

This is a scientific journal. Most readers have done during their carrier several dilutions from stock solutions to determine different concentrations for different compound using linear regression or something other model of these dilutions.    Therefore, the table 1 do not seem intellectual  - especially as there are presented the same for 10 L and for 1000 L.  I would omit this table and all the texts between 169-177. Trust on the readers!  

 Part 5.

Present here what is asked in General comments”! If you think that something should be available commercially,  inform if those materials are available in Nairobi, Das es Salaam. Arusha or in other places. Could you comment the idea that some private families would like to install a roof, gutters and water tank?  Should the tank (common or private) be cleaned sometimes? How to avoid that malaria mosquitos do not breed in tank?

 line 195: what you mean with “free from additional chemicals”?

 In table 2 (coming 1).

Do you have  a reference about the effect of Fe0 amended SSF?

Is there any risks for corrosion?  Mineralisation is mystic? Which minerals you would think to be useful? Is this needed?

Pasteurization temperature? Time? If water has been in a tank for many days in tropical climate what happens to microorganisms?

 Part 6. Ion sensitive electrons are here useful. If the measurement will be very expensive, would it be more economical to use only harvested rainwater – especially if the fluoride concentration of groundwater varies highly so that the analysis should be done often?  

Author Response

Reviewer 1

Open Review: I would not like to sign my review report.

English language and style: English language and style are fine/minor spell check required.

Does the introduction provide sufficient background and include all relevant references?

Can be improved.

Is the research design appropriate? Not applicable

Are the methods adequately described? Not applicable

Are the results clearly presented? Not applicable

Are the conclusions supported by the results? Can be improved.

Comments and Suggestions for Authors:

General: Rainwater harvesting is a good method to get drinking water.

Many thanks for this evaluation.

This concept paper could, anyhow, be more realistic. How much rain there is annually and in which months it is coming? Are there unusual dry periods?

These issues are addressed in the concept.

Is it really necessary to store the water for 12 months?

Yes, because the storage capacity is unlimited and the goal is to supply the population with fluoride free water.

How many persons the rain water is assumed to serve?

The whole population.

Typically, the volume of commercial plastic water storage tanks can be from 0.5 to 10 m3. The price and transportation are still moderate.

For a single household, storage in plastic tanks is possible. It is expected that excess is locally locally collected and stored.

Is it realistic to build only one main storage tank?

The title is suggesting the mountains as a RWH park.

Remember that a big water tower would be rather expensive. Can you think any risks if there is only one main storage tank? How long distances you could pump water?

This issue is not from our concept.

Abstract:

Think still once the last sentence. since there are many countries where rain water harvesting is very common, and it is possible to buy tanks and collection systems and there are local companies making tanks from concrete.

The concept thinks bigger that a small community. It is even excellent that so much skill is already locally available.

In addition, even in my country there is one area with groundwater containing too much fluoride.

This is exactely why the concept is proposed AND why harvested water should not contact the soill.

The local water supply plant is mixing this groundwater and treated water originated from surface water to be able to supply drinking water with lower F-concentration and they have done this maybe for 50 year. Thus, your concept is not very new but can be transferred to many areas.

Blending water is textbook knowledge but in the EARV, RWH is currently used as interim solution or low-tech alternative. The concept is about using RWH on a regional scale.

Keywords: one of them is solar pasteurization. In text you have pasteurization only at the end of the chain? If the roof material is dark, can you estimate what is the temperature on roof? Have you ever read works about his for instance:

Sourav Das, Neha Ranjana,  Ananyo Jyoti Misra, Mrutyunjay Suar, Amrita Mishra,Ashok J. Tamhankar, Cecilia Stålsby Lundborg and Suraj K. Tripathy  Disinfection of the Water Borne Pathogens Escherichia coli and Staphylococcus aureus by Solar Photocatalysis Using Sonochemically Synthesized Reusable Ag@ZnO Core-Shell Nanoparticles. Int. J. Environ. Res. Public Health 2017, 14(7), 747;https://doi.org/10.3390/ijerph14070747

Notice that also light control (only light – no silver) gave good results!

Many thanks for the hints. This could be an option in treating harvested water. We have suggested pasteurization as a tool. At some locations, the tanks can even be such designed that no PV is needed for disinfection.

Introduction:

What is biosand? Add a reference!

Thanks, a total of 10 well-selected references are added, also for SSF and iron amended BSFs.

Refs. [17-20]

Weber-Shirk, M.L.; Dick, R.I. Bacterivory by a chrysophyte in slow sand filters. Water Res. 1999, 33, 631–638.

Campos, L. Modelling and simulation of the biological and physical processes of slow sand filtration. PhD Dissertation, Imperial College, 2002.

Gottinger, A.M.; McMartin, D.W.; Price, D.; Hanson, B. The effectiveness of slow sand filters to treat Canadian rural prairie water. Can. J. Civil Eng. 2011, 38, 455–463.

Haig, S.J.; Collins, G.; Davies, R.L.; Dorea, C.C.; Quince, C. Biological aspects of slow sand filtration: past, present and future. Water Sci. Technol., Water Supply 2011, 11, 468–472.

Refs. [20,21]

Elliott, M.A.; Stauber, C.E.; Koksal, F.; DiGiano, F.A.; Sobsey, M.D. Reductions of E. coli, echovirus type 12 and bacteriophages in an intermittently operated household-scale slow sand filter. Water Res. 2008, 42, 2662–2670.

Kubare, M.; Haarhoff, J. Rational design of domestic biosand filters. J. Water Supply: Res. Technol. – AQUA 2010, 59, 1–15.

Refs. [22-25]

Rooklidge, S.J.; Ketchum Jr., L.H. Corrosion control enhancement from a dolomite-amended slow sand filter. Water Res. 2002, 36, 2689–2694.

Ali Baig, S.; Mahmood, Q.; Nawab, B.; Shafqat, M.N.; Pervez, A. Improvement of drinking water quality by using plant biomass through household biosand filter – A decentralized approach. Ecol. Eng. 2011, 37, 1842–1848.

Bradley, I.; Straub, A.; Maraccini, P.; Markazi, S.; Nguyen, T.H. Iron oxide amended biosand filters for virus removal. Water Res. 2011, 45, 4501–4510.

Noubactep, C.; Temgoua, E.; Rahman, M.A. Designing iron-amended biosand filters for decentralized safe drinking water provision. CLEAN – Soil, Air, Water 2012, 40, 798–807.

Part 2

Omit at least the text about some metal cations in line 83-88. Why, no action!

Omit text of lines 99-110. It is not important to use space for these. Why, no action!

Part 3.

line 121 use rainwater instead of runoff water!  Why, no action!

Omit text in lines 141-144. Why, no action!

Part 4. Concept for blending

This is a scientific journal. Most readers have done during their carrier several dilutions from stock solutions to determine different concentrations for different compound using linear regression or something other model of these dilutions. Therefore, the table 1 do not seem intellectual - especially as there are presented the same for 10 L and for 1000 L. I would omit this table and all the texts between 169-177. Trust on the readers! Why, no action!

Part 5.

Present here what is asked in General comments”! If you think that something should be available commercially. inform if those materials are available in Nairobi, Das es Salaam. Arusha or in other places. Could you comment the idea that some private families would like to install a roof, gutters and water tank? Should the tank (common or private) be cleaned sometimes? How to avoid that malaria mosquitos do not breed in tank? The last point is certainly a good one but is not addressed herein. Protecting harvested water from mosquitos has been successfully performed in Rwanda and elsewhere.

line 195: what you mean with “free from additional chemicals”? No chlorine for example!

In table 2 (coming 1).

Do you have a reference about the effect of Fe0 amended SSF?

Thanks, a total of 10 references are added for SSF, BSF and  Fe0-amended BSF/SSF.

Is there any risks for corrosion? Mineralisation is mystic? Which minerals you would think to be useful? Is this needed?

Corrosion is not a risk here, but rather a blessing. It is not addressed herein!

Pasteurization temperature? Time? If water has been in a tank for many days in tropical climate what happens to microorganisms?

These are site-specific design aspects!

Part 6. Ion sensitive electrons are here useful. If the measurement will be very expensive (Not acceptable, the quality of water should be controlled before and after treatment!), would it be more economical to use only harvested rainwater (analytical labs are needed and can be made affordable) – especially if the fluoride concentration of groundwater varies highly so that the analysis should be done often?Only chemical analysis should decide about the water quality. There is NO single acceptable argument against water analysis!

Reviewer 2 Report

This version of the paper "Defeating Fluorisis in the East African Rift Valley: Transforming the Kilimanjaro into a Rainwater Harvesting Park", presented as a concept is greatly improved compared to the version submitted as research article. 

Very good organization, documentation and presentation - easy to follow and understand. The purpose of the paper is clear, the context is well outlined, a concept supported by previous research.

Table 1., page 4, requires correcting page fitting.

Author Response

Many thanks for this evaluation. 

Table 1.  has been fixed.

Reviewer 3 Report

Good paper, and much improved from the last edit. Some minor spelling errors in a couple of areas of new text, but otherwise looks fine. There are no further comments than those I made from last time, which seem to have been incorporated. 

Author Response

Many thanks for this evaluation. 

Round  2

Reviewer 1 Report

The authors have not considered the comments even not to present multiplication table in a scientific article.

They have not understood or read from microbiological literature what kind of microorganisms and which numbers can be present in outdoor air and which of them can be human pathogens. Further they should estimate which of them originated from air or from roof contaminants will transport to rain water. Would it be possible to allow the first rain water to flush the roof and then allow this water to run away into soil? Further they should understand what happens to the  microorganisms in storage tank situation at tropical climate. 

The scaling has not evaluated. They should really think for how many persons they present this water treatment system. The whole population in the whole East African Rift valley or in Moshi is not a correct answer. According to my knowledge already Moshi includes more than 200 000 inhabitants. The authors have not estimated the roof area to harvest rain water for all these people and what kind of storage tanks should be needed. Should they estimate evaporation? In addition, the should have estimated the size of sand filters.

This concept is so preliminary and so open that its merit is too low to be accepted in a scientific journal.     

Author Response

Responses are attached

Author Response File: Author Response.doc

Round  3

Reviewer 1 Report

In the journal Sustainability it is a “journal of environmental, cultural, economic and social sustainability of human beings, which provides an advanced forum for studies related to sustainability and sustainable development”. If we solve one problem we should not make new one. Thus, if you solve fluorosis, you should not increase malaria or if you solve microbiological quality of water you should not increase to shortage of fuel.  

A concept is made so that more detailed planning could be continued. Anyhow, it should base on those facts what we have. If the concept is very preliminary or bases on false facts the plant will not continue.  I have been one co-worker in research project to Tanzania and we must make always a detailed application to donor in order to get money. Therefore, we have to visit Tanzania and collect facts from Tanzania – including its climate and precipitation. According this data there is precipitation during some months in Moshi area. Thus, it is not necessary to store rain water for 12 months.

As reviewer in a scientific journal I try to see if a manuscript fits to the scope of journal and if it has some merits that it could (and should) be improved. As author we have considered these improving proposals and almost always they have been useful.  

I think also the journal. In Sustainability the impact factor is more than 2, which is good, and a mark of quality.  

Still I see that the corrections should be done. I have not discussed with the other reviewers and they do their own comments.  

Author Response

Comments and Suggestions for Authors:

In the journal Sustainability it is a “journal of environmental, cultural, economic and social sustainability of human beings, which provides an advanced forum for studies related to sustainability and sustainable development”.

Many thanks for this recall!

If we solve one problem we should not make new one. Thus, if you solve fluorosis, you should not increase malaria or if you solve microbiological quality of water you should not increase to shortage of fuel.

We have not understood this point. We have pointed out that Australia and Germany have the expertise on many aspects of RWH. In Australia, RWH was stopped in the 1960s because of outbreaks of mosquito-borne diseases (including malaria) and is re-introduced because we know how to cope with those vectors.

A concept is made so that more detailed planning could be continued (information is available, including in our manuscript). Anyhow, it should base on those facts what we have (we have all useful facts!). If the concept is very preliminary (strongly desagree!) or bases on false facts (there are not false facts in our manuscript) the plant will not continue.

I have been one co-worker in research project to Tanzania (we are currently working and partly living in Tanzania) and we must make always a detailed application to donor in order to get money (We are not asking for money. A scientific communication is not a grant application). Therefore, we have to visit Tanzania and collect facts from Tanzania – including its climate and precipitation (Eventhough we are working drom Tanzania, all relevant data for this concept are universally available). According this data there is precipitation during some months in Moshi area. Thus, it is not necessary to store rain water for 12 months (please give the passage recommending this in our manuscript. Depending from the local situations, some location will store water for eight months oder for 4 months. But we are considering the whole region and suggesting that rain-rich regions store water and store for poorer regions in tanks in the montains. Thanks can be burried or not, tools to avoid mosquitoes access are known!).

As reviewer in a scientific journal I try to see if a manuscript fits to the scope of journal (Thanks!) and if it has some merits that it could (and should) be improved (Thanks!). As author we have considered these improving proposals and almost always they have been useful (The problem here is the usefulness of your suggestions!).

I think also the journal. In Sustainability the impact factor is more than 2, which is good, and a mark of quality.

This was known to us while preparing the manuscript and selecting the journal!

Still I see that the corrections should be done. I have not discussed with the other reviewers and they do their own comments.

Yes but which corrections? We have added a section on protection against malaria but we cannot see any added value, eventhough there is no damage for our concept!