White Teeth and Healthy Skeletons for All: The Path to Universal Fluoride-Free Drinking Water in Tanzania
, Zuleikha Pembe-Ali 3, Innocent Lugodisha 3, Risala Iddi Mureth 3, Mihayo Nkinda 3, Janeth Marwa 4, Willis Gwenzi 5,*, Tulinave Burton Mwamila 6, Mohammad Azizur Rahman 7, Chicgoua Noubactep 2 and Karoli N. Njau 3Round 1
Reviewer 1 Report
Interesting filtration systems containing activated carbon, biochar, metallic iron and other efficient materials were discussed.
Main findings should be highlighted in abstract.
47 delete 'the'
479 the electrical conductivity respectively are measured not 'measure'
Author Response
Reviewer # 1:
Interesting filtration systems containing activated carbon, biochar, metallic iron and other efficient materials were discussed.
We thank the reviewer for the positive comment.
Main findings should be highlighted in abstract.
We agree and revised as follows:
In summary, it is demonstrated that, by combining rainwater harvesting and low-cots water treatment methods, the Kilimanjaro Concept has the potential to provide clean drinking water, and overcome fluorosis on a long-term basis. However, a detailed design process is required to determine: (i) institutional roles, and community contributions and participation, (ii) optimal location and sizing of conveyance and storage facilities to avoid excessive pumping costs, and (iii) project funding mechanisms, including prospects for government subsidy.
47 delete 'the'
We agree and revised as suggested.
479 the electrical conductivity respectively are measured not 'measure'
We agree and revised as suggested.
Reviewer 2 Report
My comments as below,
Figure 1
I could not make sure the location of Kilimanjaro by figure 1.
Is Kilimanjaro not located in the area of high fluoride concentration?
2. p.3 to p.5, 3 the Kilimanjaro concept
Is Water using “the Kilimanjaro concept” do not include “fluoride”?
There is no data for water quality about “the Kilimanjaro concept water”
May I take it that the water is not contaminated by “fluoride”?
3. the title and contents of this paper
Is my understanding correct?
“healthy skeletons” has relations to the minerals of the treated water (p.13, 7) in this paper.
Author Response
Reviewer 2:
Comments and Suggestions for Authors
My comments as below,
Comments 1:
Figure 1
I could not make sure the location of Kilimanjaro by figure 1.
The location of Kilimanjaro Mountains is already indicated by the name, ‘Kilimanjaro‘ in Figure 1. However, to address the reviewer’s comments we inserted a blue triangle in Figure 1 to mark the location, and revised the figure caption accordingly.
Is Kilimanjaro not located in the area of high fluoride concentration?
The location of Kilimanjaro relative to the various fluoride zones is now clearly indicated in the revised map. The fluoride is of geogenic origin, hence is not expected to occur in rainwater, which will be harvested as part of the Kilimanjaro Concept. The fact that fluoride is of geogenic origin is indicated in Lines 100-102 and 349-350. Therefore, to avoid unnecessary repetition, we made no correction
Comments 2. p.3 to p.5, 3 the Kilimanjaro concept
Is Water using “the Kilimanjaro concept” do not include “fluoride”?
We considered the reviewer’s comment and have addressed it in previous response above i.e. Rainwater is fluoride-free since the fluoride is of geogenic origin (Lines 100-102 and 349-350).
There is no data for water quality about “the Kilimanjaro concept water”
We agree there is no data on rainwater quality in Kilimanjaro, but is expected to have no fluoride since the fluoride is of geogenic origin (See Lines 350-352). We reviewed literature on rainwater quality (Section 4.1.12), and we have indicated that where treatment may be needed on a case-by-case basis the treatment methods discussed in the paper may be used. Therefore, we made no correction.
May I take it that the water is not contaminated by “fluoride”?
Yes. This comment has been addressed in the earlier responses above.
Comments 3. the title and contents of this paper
Is my understanding correct?
“healthy skeletons” has relations to the minerals of the treated water (p.13, 7) in this paper.
High fluoride in drinking water causes skeletal fluorosis, thus provision of fluoride-free drinking water through rainwater harvesting (and eventual blending) will overcome this health problem resulting in healthy skeletons.
We revised text as follows (Lines 65-67):
High fluoride concentration (>1.5 mg/L) in drinking water causes dental and skeletal fluorosis. Therefore, the provision of fluoride-free drinking water provides a long-term solution to overcoming fluorosis.
Author Response File: 
Author Response.doc
Reviewer 3 Report
This study is very important and very interesting. It deals with an important topic that combines provision of clean safe water to an increasing number of population which can adversely be affected by climate change. However, there are few points need to be addressed before it can be accepted for published in Water.
Comments:
1-The authors talked about fluoride contamination in Tanzania without showing the source of the fluoride and where it is mixed with water.
2-Since provision of fluoride-free water through RWH is the central theme of the study, the reader would like to know more about the past experience of RWH in Tanzania.
3-The objective of the study is not clearly stated: There are two objectives, 1- lines 79-81 and 2- on lines 89-91. It will be better to combine both of them in one solid statement.
4-The paper needs to be consolidated because there is a lot of repetition.
5-Before asking what is the effect of RWH on the recharge of groundwater (line 180), the reader would like to know what are the methods of rainwater harvesting in Kilimanjaro Mountain because in other studies RWH increases the recharge of ground water.
6-Research methodology and all methods of data collection used, need to be clearly explained before analyzing the data.
Author Response
Reviewer #2:
This study is very important and very interesting. It deals with an important topic that combines provision of clean safe water to an increasing number of population which can adversely be affected by climate change. However, there are few points need to be addressed before it can be accepted for published in Water.
We thank the reviewer for the overall positive comment. We have considered and addressed all the comments raised.
Comments:
1-The authors talked about fluoride contamination in Tanzania without showing the source of the fluoride and where it is mixed with water.
We agree and revised by indicating that fluoride originates from geoegenic sources:
‘In the East African Rift valley, including Tanzania, high fluoride in drinking water originates from geogenic sources (Pittalis, 2010; Bhattacharya et al., 2016).’
Pittalis, D., 2010. Interdisciplinary studies for the knowledge of the groundwater fluoride contamination in the eastern African rift: Meru district-North Tanzania. PhD thesis. University of Sassari, Sassari.
Bhattacharya, P., Lesafi, F., Filemon, R., Ligate, F., Ijumulana, J. and Mtalo, F., 2016, April. Geogenic fluoride and arsenic contamination in the groundwater environments in Tanzania. In EGU General Assembly Conference Abstracts (Vol. 18, p. 16677).
2-Since provision of fluoride-free water through RWH is the central theme of the study, the reader would like to know more about the past experience of RWH in Tanzania.
We agree and provided an overview of RWH in Tanzania as follows:
‘RWH has a long history in Tanzania, and indigenous knowledge exists on the utilizing rainwater especially for agricultural purposes. Traditional rainwater harvesting structures, include storage structures (known locally as ndiva) in Kilimanjaro Region, excavated bunded basins (majaluba) in the lake zone, and raised broad basins (vinyungu) in Iringa Region. These systems have been sustainable for centuries due to their compatibility with local lifestyles, and institutional and social systems (Mbilinyi et al. 2005). For domestic purposes, it is common to find people aligning their water collecting devices such as buckets, pots, jars, basins, and drums under roof eaves during the rainy season. However, due to limited storage capacity, water from such RWH systems hardly lasts to the dry season. A number of studies have been conducted to promote the sustainability of RWH systems in Tanzania [54, 56, 57, 58]. Therefore, the Kilimanjaro Concept builds on this existing local knowledge, and extends it to an even larger scale by incorporating conveyance and storage facilities, and low-cost water treatment systems.’
Mbilinyi, B.P., Tumbo, S.D., Mahoo, H.F., Senkondo, E.M., Hatibu, N. (2005). Indigenous knowledge as decision support tool in rainwater harvesting. Physics and chemistry of the earth 30: 792 – 798.
3-The objective of the study is not clearly stated: There are two objectives, 1- lines 79-81 and 2- on lines 89-91. It will be better to combine both of them in one solid statement.
We agree and revised as follows:
‘The purpose of this communication is to pave the way for the integration of the three first named individually mature technologies necessary for the implementation of the Kilimanjaro Concept using Tanzania as a case study. The specific objectives are to: (i) highlight the severity and distribution of fluoride contaminated water in Tanzania, (ii) discuss the quality and quantity of rainwater, and current rainwater harvesting practices in Tanzania, (iii) discuss how the integration of rainwater harvesting systems within the Kilimanjaro catchment and low-cost water treatment methods can provide clean drinking water and overcome fluorosis (the Kilimanjaro Concept), and (iv) discuss the institutional and regulatory framework necessary for the implementation of the concept.’
4-The paper needs to be consolidated because there is a lot of repetition.
We agree, and proof-read and revised the manuscript to remove any repetitions.
5-Before asking what is the effect of RWH on the recharge of groundwater (line 180), the reader would like to know what are the methods of rainwater harvesting in Kilimanjaro Mountain because in other studies RWH increases the recharge of ground water.
We considered the reviewer’s comments and have indicated in the overview section on RWH in Tanzania that traditional rainwater harvesting systems are limited mainly to agriculture and household level using simple devices such as buckets, but with limited storage (See Section 3.1)
6-Research methodology and all methods of data collection used, need to be clearly explained before analyzing the data.
We considered the reviewer’s comment and would like to respond as follows:
The current paper presents a concept that is yet to be implemented, and is largely based on a discussion and critical analysis of issues, hence lacks a systematic methodological approach. We are of the opinion that a dedicated section on methodology may add little to the discussion. Therefore we made no correction.
Reviewer 4 Report
Suggested writing and punctuation corrections:
Line 28: add the underlined word in red: “…(EARV) since before…”
Line 34: add the underlined word on red: “…Kilimanjaro as a rainwater…”
Line 38: replace the semi-colon (;) with a colon (:) after the word “following:” Also lines 114, 334, 377, 379, 453, 505, 516, 518, 523 - replace the semi-colon with a colon.
Line 39: remove the words “is presented”
Line 47: remove the word “the” after the word “increasing”
Line 49: is “Bone Char” supposed to be “Biochar”?
Line 88: add the underlined red word “be”: “…source should be analytically…”
Line 89: remove the word “is” after the word “study”
Line 102-103: suggested change from “fluoride-poor” to “low-fluoride”, and “fluoride-rich” to “high-fluoride”
Line 34: and throughout manuscript (37, 72, 80, 102, 114, 166, 182, 219, 235, 298, 529, 534, 539): be consistent with “Kilimanjaro Concept” – is this considered a proper name? If so, make sure the word “concept” is always capitalized in the manuscript. If not, keep it lower case.
Line 168: replace the word “This” with “These”.
Line 177: correct the citation “[45,$(;$)]”
Line 181: the word ”represent” should be plural - “represents”
Line 198: the word “system” should be plural – “systems”
Line 202: the word “complement” should be plural – “complements”
Line 204: the word “reduce” should be plural – “reduces”
Line 244: remove the space after “44” to - “(44%)”
Line 301: change the word “achieving” to “achieve”
Lines 306-307: suggested change to sentence from “…is it considered relatively cleaner…” to “…it is generally considered cleaner…”
Line 314: the word ”present” should be plural - “presents”
Line 319: add a comma after “sheets” – “metal sheets, and…”
Line 320: remove the word “are” from “…are drawn from Australia…” to “…drawn from Australia…”
Line 328: change the word “virulence” to “virulent”
Line 338: remove the word “effects” from “…no known effects adverse effects…” to “…no know adverse effects…”
Line 340: add the underlined word in red: “…imported chlorine, and generates…”
Line 341: change “…contaminants increase…” to “…contaminants, increases...”
Line 343: change “…systems is often…” to “…systems—both of which are often…”
Line 350: make the word “counterpart” plural (“counterparts”)
Line 462: remove the word “however”
Other comments:
Line 59: describing fluoride as having “extreme stability” in water may be a little inaccurate. Possibly say “is often stable”? Fluoride is stable in certain types of water – it depends on the chemistry and surrounding materials.
Lines 268-26: why is there a difference of 70L/person/day for consumers with household connections and 25L/person/day for consumers with yard connections, and through water points? Maybe explain the different needs?
Figure 4: on the vertical axis, are the Quantity units in L/p/d with quantities 10, 20, 30, 40, 50, 60, 70 (e.g not 70000)?
Figure 5: similarly, on the vertical axis, are the units in L/p/d with the maximum quantity 25 (not 25000)?
Line 298 and going…: how will excess water from individual households be captured and transported to a central storage tank? Will pumps be needed to 356-408 uphill? How will this be supported financially?
Line 309: rainwater would likely be free of F, U, and As.
Lines 346-349: citation(s) for the effectiveness of biochar and Fe0 to remove all of these contaminants.
Line352- 408: how do these filters remove microbial contaminants? - Also referred to in line 424. What types of contaminants will be targeted with these filters? Pb and Al from rainwater? Do they remove metals from water? They are generally used to remove anionic contaminants, such as As (which shouldn’t be needed for rainwater). There is a question as to whether biochar/ Fe0 filters are needed or appropriate for rainwater filtration.
This is an ambitious idea for providing low-fluoride water to all people of Tanzania. It is entirely designed by researchers in several African countries, which is a necessary step for solving problems that affect Africans. There remain questions on how the engineering will be coordinated: how far will water be transported for storage, will it need to be pumped up to high elevations, how many/how large will storage tanks need to be, who will be tasked with maintenance of the units (including filters)……And an ongoing question with all large projects is who will cover the costs? Will communities need to contribute financially? Will the government be able to subsidize it, at least in part?
Author Response
Reviewer #3:
Suggested writing and punctuation corrections:
Line 28: add the underlined word in red: “…(EARV) since before…”
We agree and revised as suggested.
Line 34: add the underlined word on red: “…Kilimanjaro as a rainwater…”
We agree and revised as suggested.
Line 38: replace the semi-colon (;) with a colon (:) after the word “following:” Also lines
114, 334, 377, 379, 453, 505, 516, 518, 523 - replace the semi-colon with a colon.
We agree and revised as suggested.
Line 39: remove the words “is presented”
We agree and revised as suggested.
Line 47: remove the word “the” after the word “increasing”
We agree and revised as suggested.
Line 49: is “Bone Char” supposed to be “Biochar”?
We have considered the comment and would like to respond as follows:
bone char is char made using animal bones as a feedstock. Therefore, to avoid confusion with biochars made from plant materials, we retained ‘bone char’.
Line 88: add the underlined red word “be”: “…source should be analytically…”
We agree and revised as suggested.
Line 89: remove the word “is” after the word “study”
We agree and revised as suggested.
Line 102-103: suggested change from “fluoride-poor” to “low-fluoride”, and “fluoride-rich” to “high-fluoride”
We agree and revised as suggested.
Line 34: and throughout manuscript (37, 72, 80, 102, 114, 166, 182, 219, 235, 298, 529, 534, 539): be consistent with “Kilimanjaro Concept” – is this considered a proper name? If so, make sure the word “concept” is always capitalized in the manuscript. If not, keep it lower case.
We agree and revised to Kilimanjaro Concept throughout.
Line 168: replace the word “This” with “These”.
We agree and revised as suggested.
Line 177: correct the citation “[45,$(;$)]”
We agree and corrected.
Line 181: the word ”represent” should be plural - “represents”
We agree and revised as suggested.
Line 198: the word “system” should be plural – “systems”
We agree and revised as suggested.
Line 202: the word “complement” should be plural – “complements”
We agree and revised as suggested.
Line 204: the word “reduce” should be plural – “reduces”
We agree and revised as suggested.
Line 244: remove the space after “44” to - “(44%)”
We agree and revised as suggested.
Line 301: change the word “achieving” to “achieve”
We agree and revised as suggested.
Lines 306-307: suggested change to sentence from “…is it considered relatively cleaner…” to “…it is generally considered cleaner…”
We agree and revised as suggested.
Line 314: the word ”present” should be plural - “presents”
We agree and revised as suggested.
Line 319: add a comma after “sheets” – “metal sheets, and…”
We agree and revised as suggested.
Line 320: remove the word “are” from “…are drawn from Australia…” to “…drawn from Australia…”
We agree and revised as suggested.
Line 328: change the word “virulence” to “virulent”
We agree and revised as suggested.
Line 338: remove the word “effects” from “…no known effects adverse effects…” to “…no know adverse effects…”
We agree and revised as suggested.
Line 340: add the underlined word in red: “…imported chlorine, and generates…”
We agree and revised as suggested.
Line 341: change “…contaminants increase…” to “…contaminants, increases...”
We agree and revised as suggested.
Line 343: change “…systems is often…” to “…systems—both of which are often…”
We agree and revised as suggested.
Line 350: make the word “counterpart” plural (“counterparts”)
We agree and revised as suggested.
Line 462: remove the word “however”
We agree and revised as suggested.
Other comments:
Line 59: describing fluoride as having “extreme stability” in water may be a little inaccurate. Possibly say “is often stable”? Fluoride is stable in certain types of water – it depends on the chemistry and surrounding materials.
We agree and revised as suggested to:
‘Given that fluoride is often stable in water, and has a very small ionic size, it is very difficult to remove from the aqueous phase [8,14-17].’
Lines 268-26: why is there a difference of 70L/person/day for consumers with household connections and 25L/person/day for consumers with yard connections, and through water points? Maybe explain the different needs?
We considered the comment and explained the reason for the different per capita daily water requirements, and revised as follows:
‘‘The difference in water requirements is attributed to the fact that water consumption is more difficult to control for consumers with household connections, while delays caused by queuing for water in public water points tends to reduce consumption. Moreover, consumers with household connections are likely to have higher incomes than those without.’
‘Comparison of Figures 4 and 5 shows that increasing the storage capacity, and reducing the per capita daily water requirement, increases the capacity of RWH to meet drinking water requirements without groundwater supplementation. Using a per capita water requirement of 10 L/person/day, scope exists to meet most cooking and drinking water requirement from RWH (Figure 6), while other domestic uses (e.g., toilet flushing) are met from groundwater supply (i.e., a dual system).’
Figure 4: on the vertical axis, are the Quantity units in L/p/d with quantities 10, 20, 30, 40, 50, 60, 70 (e.g not 70000)?
We considered the comment and would like to respond as follows:
The vertical axes represent consumption in L/day obtained by multiplying per capita daily water requirements in L/person/day (ie 70 L/person/day in this case) by population. For clarity, we revised by indicating the population used to estimate the consumption in both Figures 4 and 5.
Figure 5: similarly, on the vertical axis, are the units in L/p/d with the maximum quantity 25 (not 25000)?
We considered the comment and would like to respond as follows:
The vertical axes represent consumption in L/day obtained by multiplying per capita daily water requirements in L/person/day (i.e., 25 L/person/day in this case) by population. For clarity, we revised by indicating the population used to estimate the consumption in both Figures 4 and 5.
Line 298 and going…: how will excess water from individual households be captured and transported to a central storage tank? Will pumps be needed to 356-408 uphill? How will this be supported financially?
We considered the comment and would like to respond as follows: Detailed financial analysis and design layout of the whole system were no addressed in the concept paper.
We revised and highlighted this as follows:
‘The concept paper highlighted the potential of integrating RWH and low-cost water treatment systems to overcome fluorosis in Tanzania, but did not address detailed design and cost estimation of the proposed system. Therefore, the following aspects will need to be addressed in the detailed design process: (i) including institutional roles, and community contributions and participation, (ii) optimal location and sizing of conveyance and storage facilities to avoid excessive pumping costs, and (iii) project funding mechanisms, including any prospects for government subsidy.’ Moreover, some communities are likely to be self-reliant in drinking water and may export or ‘sell’ excess rainwater to communities in need. The details of the water transfer mechanism among self-reliant communities and those in need will need to be determined during the detailed design phase. The current paper provides the underpinning concept that will guide policy makers, researchers and other development partners on the long journey towards overcoming fluorosis through clean water provision.’
Line 309: rainwater would likely be free of F, U, and As.
We and revised as suggested.
Lines 346-349: citation(s) for the effectiveness of biochar and Fe0 to remove all of these contaminants.
We agree and revised by including text and references indicating that biochars and Fe0/H20 systems can remove contaminants in aqueous systems.
‘The capacity of biochars to remove microbiological and physico-chemical contaminants, and the removal mechanisms involved have been the subject of recent reviews (Mohan et al., 2014; Gwenzi et al., 2017).’
‘Studies have showed that Fe0- and Fe0/biosand - filters effectively remove pathogenic and indicator organisms in aquesous systems (You et al., 2005; Tellen et al., 2010; Ingram et al., 2012; Shi et al., 2012; Lefevre et al., 2016). Key mechanisms accounting for the removal of microbiological organisms include, inactivation and irreversible adsorption on iron (You et al., 2005). Moreover, several recent studies show that Fe0/H2O can remove toxic metals (e.g., Zn, Pb), metalloids (As, Mo) and radionuclides (e.g., U) in aqueous systems (Cantrell et al., 1995; Ponder et al., 2000, Morrison et al., 2002, Wilkin and Mcneil, 2003, Rangsivek and Jekel, 2005, Bartzas et al., 2006, Zhang et al., 2010; Kishimoto et al., 2011, Kim et al., 2013).’
‘The capacity of biochars and Fe0/H20 filters to remove microbiological and toxic chemicals is particularly important given their potential to pose human health risks. Moreover, as discussed in Section 5.1, in some instances, rainwater may contain pathogenic organisms and toxic metals such as Pb and Zn from roof materials.’
Line352- 408: how do these filters remove microbial contaminants? - Also referred to in line 424. What types of contaminants will be targeted with these filters? Pb and Al from rainwater? Do they remove metals from water? They are generally used to remove anionic contaminants, such as As (which shouldn’t be needed for rainwater). There is a question as to whether biochar/ Fe0 filters are needed or appropriate for rainwater filtration.
We considered the comment and have revised by including the following statements:
‘The capacity of biochars to remove microbiological and physico-chemical contaminants, and the removal mechanisms involved have been the subject of recent reviews (Mohan et al., 2014; Gwenzi et al., 2017).’
‘Studies have showed that Fe0- and Fe0/biosand - filters effectively remove pathogenic and indicator organisms in aqueous systems (You et al., 2005; Tellen et al., 2010; Ingram et al., 2012; Shi et al., 2012; Lefevre et al., 2016). Key mechanisms accounting for the removal of microbiological organisms include, inactivation and irreversible adsorption on iron (You et al., 2005). Moreover, several recent studies show that Fe0/H2O can remove toxic metals (e.g., Zn, Pb), metalloids (As, Mo) and radionuclides (e.g., U) in aqueous systems (Cantrell et al., 1995; Ponder et al., 2000, Morrison et al., 2002, Wilkin and Mcneil, 2003, Rangsivek and Jekel, 2005, Bartzas et al., 2006, Zhang et al., 2010; Kishimoto et al., 2011, Kim et al., 2013).’
‘The capacity of biochars and Fe0/H20 filters to remove microbiological and toxic chemicals is particularly important given their potential to pose human health risks. Moreover, as discussed in Section 5.1, in some instances, rainwater may contain pathogenic organisms and toxic metals such as Pb and Zn from roof materials.’
The above statement also explains why water filters may be needed in some cases.
This is an ambitious idea for providing low-fluoride water to all people of Tanzania. It is entirely designed by researchers in several African countries, which is a necessary step for solving problems that affect Africans. There remain questions on how the engineering will be coordinated: how far will water be transported for storage, will it need to be pumped up to high elevations, how many/how large will storage tanks need to be, who will be tasked with maintenance of the units (including filters)……And an ongoing question with all large projects is who will cover the costs? Will communities need to contribute financially? Will the government be able to subsidize it, at least in part?
We agree and revised as follows:
‘The concept paper highlighted the potential of integrating RWH and low-cost water treatment systems to overcome fluorosis in Tanzania, but did not address detailed design and cost estimation of the proposed system. Therefore, the following aspects will need to be addressed in the detailed design process: (i) including institutional roles, and community contributions and participation, (ii) optimal location and sizing of conveyance and storage facilities to avoid excessive pumping costs, and (iii) project funding mechanisms, including any prospects for government subsidy.’ Moreover, some communities are likely to be self-reliant in drinking water and may export or ‘sell’ excess rainwater to communities in need. The details of the water transfer mechanism among self-reliant communities and those in need will need to be determined during the detailed design phase. The current paper provides the underpinning concept that will guide policy makers, researchers and other development partners on the long journey towards overcoming fluorosis through clean water provision.’
