research article defluoridation of fluoride-rich ...orca.cf.ac.uk/125025/1/published cas.pdf ·...

11

JOURNAL OF THE CAMEROON ACADEMY OF SCIENCES Vol 15 No 1 (2019)

Defluoridation of Fluoride-rich Groundwater in Mayo Tsanaga River Basin-Cameroon using locally produced bone char

Wilson Y Fantong1 Clifford Ngappe2 Hycinth S Banseka3 Mathias F Fonteh4 Hubert Onibon5Ernest Chi Fru6 Etienne Yanne7 Bertold D Dontsa Tsafack8 Samuel N Ayonghe9

1 Institute of Geological and Mining Research (IRGM) Box 4110 Yaoundeacute-Cameroon2Department of Environmental Engineering National Advanced School of Public Works Yaoundeacute Box 510 Yaoundeacute-Cameroon3Global Water Partnership-Cameroon Yaoundeacute4College of Technology The University of Bamenda PO Box 39 Bambili - Cameroon5United Nations International Children Emergency Fund (UNICEF) Rue 1801 Boulevard de lrsquoURSS Quartier Bastos POBox 1181 Yaounde Cameroun6School of Earth and Ocean Sciences Cardiff University Cardiff Park Place Wales- United Kingdom7Department of Civil Engineering and Architecture National Advanced School of Engineering University of Maroua PO Box46 Maroua-Cameroon8Faculty of Agronomy and Agricultural Sciences University of Dschang-Cameroon Box 222 Dschang9University of Buea Interdisciplinary Climate Change Laboratory Department of Environmental Science Faculty of ScienceUniversity of Buea Box 63 Buea Cameroon

Corresponding author E-mail fyetohyahoocom fantongygmailcom

AbstractWith fluoride-rich groundwater causing a climatic-dependent fluorosis in Mayo-Tsanaga River Basinthe overall objective of this study was to reduce fluoride concentrations in drinking water to acceptablelevels thereby improving the resilience of the population to this climate change induced pathology Thespecific objectives were to (1) assess water chemistry in the study area to re-affirm the undesirablefluoride levels (2) assess the impact of seasons on the concentrations of fluoride (3) construct andevaluate the performance of a household bone char-based adsorption defluoridation filter A combinationof hydrogeochemical and engineering analyses demonstrated that the groundwater is predominantlyCa+Mg-HCO3 type which contains as much as 673 mgl of undesirable concentrations of geogenicfluoride These concentrations increased with elevated pH electrical conductivity and in the dry seasonand were reduced to less than 02 mgl when the groundwater was subjected to filtration through 300 gof 02-08 mm faction of charred cow bones in a home-based defluoridation filter The bone char in thefilter can effectively reduce fluoride concentration to less than 07 mgl which is the local thresholdlimit without negative impact on the organoleptic (taste color and odor) characteristics of drinkingwater Compared with the commercially activated carbon the bone char has an additional capacity ofadsorbing fluoride at a rate of 4 mgliter in 30 minutes which indicates that with a defined saturationtime the bone char filter can protect the population against climate change-induced fluoride enrichmentin drinking waterMots cleacutes Groundwater geogenic fluoride climate dependent fluorosis bone char defluoridationwater chemistry

Research Article

Received _12__04_2019_ Accepted _08__05_2019 DOI httpsdxdoiorg104314jcasv15i12 copy The Authors This work is licensed under the Creative Commons Attribution 40 International Licence

12

REVUE DE LrsquoACADEMIE DES SCIENCES DU CAMEROUN Vol 15 No 1 (2019)

ReacutesumeacuteAvec lrsquoenrichissement en fluor causant la fluorose dans le bassin versant du Mayo-Tsanaga lrsquoobjectifprincipal de cette eacutetude est drsquoameacuteliorer la capaciteacute de reacutesilience des habitants de la zone drsquoeacutetude parrapport agrave lrsquoimpact du changement climatique en reacuteduisant agrave des niveaux acceptables la concentrationdu fluor dans lrsquoeau de boisson Les objectifs speacutecifiques eacutetant (i) acceacuteder agrave la chimie des eaux de la zonedrsquoeacutetude afin de reacuteaffirmer que la nappe souterraine est toujours caracteacuteriseacutee par des taux de fluorindeacutesirable (ii) estimer lrsquoimpact des changements de saison sur la concentration du fluor dans la nappe (iii) construire et eacutevaluer la performance drsquoun filtre domestique agrave deacutefluoration par adsorption baseacute surla carbonisation des ossements des bœufs Une combinaison des approches hydrogeacuteochimique ettechnologique a eacuteteacute utiliseacutee pour deacutemontrer que le facies des eaux souterraines est principalement detype Ca+Mg-HCO3 contenant des concentrations pouvant attendre jusqursquoagrave 67 mgl de fluor geacuteogeacuteniqueindeacutesirable Ces concentrations augmentent avec lrsquoeacuteleacutevation du pH la conductiviteacute eacutelectrique et pendentla saison segraveche et sont reacuteduite agrave moins de 02 mgl lorsque lrsquoeau de la nappe est soumise agrave une filtrationagrave travers 300g de couche drsquoossements de bœufs carboniseacutes de 02 agrave 08 mm taille de grain disposeacuteecomme filtre de deacutefluoration Les ossements de boeuf carboniseacutes dans le filtre peuvent reacuteduire laconcentration de fluorure agrave moins de 07 mgl qui est le seuil limite local avec aucun impact neacutegatifsur les caracteacuteristiques organoleptique de lrsquoeau potable Reacutelativement au charbon activeacute vendu lesossements de boeuf ont la capaciteacutee drsquoadsorption de 4 mgl en 30 minutes Ceci implique qursquoavec untemps de saturation connu les ossements de bœufs carboniseacutes peuvent proteacuteger la population des meacutefaitsdu changement climatique induisant lrsquoenrichissement en fluor des eaux de boisson de la nappe souterraine

Keywords Chimie des eaux souterraine Fluor geacuteogeacutenique Fluorose Deacutefluoration Ossements debœufs carboniseacutes Reacutesilience

13


1 Introduction

A study by Fantong et al (2010) revealed thatgeogenic fluoride in groundwater resources inMayo Tsanaga River Basin (MTRB) was affectingthe oraldental health of mostly children of about500000 residents in the basin (Fig 1) Followingthis menace a cross section of water sectorstakeholders in Cameroon strongly recommendedthat ground water in the zone should bedefluoridated before it can be used for drinkingMoreover Fantong et al (2010 2013) suggestedthat the WHO upper limit of 15 mgl fluoridein drinking water (WHO 1994) should beadjusted to 07 mgl for the Mayo Tsanaga RiverBasin where consumption rate of groundwateris on the rise due to climate change-inducedincrease in atmospheric temperature Moreoverphysical scarcity of surface water in the zone asa result of climate change leaves the inhabitantsto depend entirely on the deterioratinggroundwater resources for all developmentalactivities and especially for drinking (Fantong etal 2009 2010)

Figure 1 Manifestations of dental fluorosis invarious localities in the Mayo Tsanaga River Basin

Considering that fluoride is often described as alsquodouble-edged swordrsquo as inadequate ingestion isassociated with dental caries whereas excessiveintake leads to fluorosis an irreversible conditionthat has no cure making prevention the onlysolution for this menace Accordingly provisionof water with optimal fluoride concentration is

the only way by which the generation yet to beborn can be totally protected against fluorosis(Kaseva 2006) Defluoridation has been theconventional and widely tested method forsupplying safe water to the fluorosis affectedcommunities (Dahi 1997) The defluoridationtechniques can be broadly classified into thefollowing four categories adsorption ion-exchange precipitation and other techniqueswhich include electro chemical defluoridation andreverse osmosis (Piddennavar and Krishnappa2013) Among these categories the adsorptiontechnique which uses charred bones has beensuccessfully employed to remove fluoride fromfluoride-rich groundwater in Tanzania KenyaUganda Ethiopia and South Africa (Dahi 2016Pindjou 2015)

Current assessments of the impacts of climatevariability and change on water resourcescommonly exclude groundwater This omission isof particular concern in the semi-arid zone ofAfrica where the current usage of water and futureadaptations in response to climate variability andchange together with rapid population growthplace considerable reliance upon groundwater tomeet domestic agricultural and industrial waterdemands In a bid to fill up this gap the firstconference that focused on groundwater andclimate in Africa was held from 24-28 June 2008in Kampala Uganda (IAHS 2008) The keypolicy-relevant outcomes were summarized in TheKampala Statement and selected articles werepublished by IAHS (2009) which among othersdeclared that episodic deterioration in groundwaterquality and the risk of waterborne diseases areexpected to increase as a result of climate changeIt was accordingly recommended that waterbornediseases from contaminated groundwater beidentified to ensure preventive measures whichare less costly than remediation In response tothis recommendation several research works havebeen conducted on groundwater and health in Sub-Saharan Africa and reviewed by Adelana et al

14


(2011) However none of those findingsattempted to show how climate change mayimpact groundwater-borne diseases such asfluorosis which is manifested initially as pittedteeth with white horizontal striations pittedbrown teeth and un-pitted teeth with blackbrown and chalky coats and skeletaldeformation in long term Against this backdropthe main objective of this paper is to improveresilience to the impacts of climate change in thearea of study by designing and testing in situtechnologies aimed at reducing fluoride levels indrinking water to acceptable levels The specificobjectives include (1) assess water chemistry inthe study area to re-affirm that in real time thegroundwater resource is still characterized byundesirable concentration of fluoride (2) assessthe impact of change of season on theconcentrations of fluoride in groundwater inMayo Tsanaga River Basin (MTRB) of Cameroon(3) construct and evaluate the performance ofan experimental household bone char-basedadsorption defluoridation filter consisting oflocally available and affordable materials

2 Study Area21 Location and description

The MTRB covers an estimated area of 1602km2 extending from 10deg30rsquo00rdquo to 10deg45rsquo00rdquoNorth latitude and 13deg45rsquo00rdquo to 14deg45rsquo00rdquo Eastlongitude as shown in Fig2a The rivers in thebasin ucircow over a distance of about 105 kmfollowing a west to east direction (Nouvelot1972) Twenty-ucircve kilometers eastward from thewestern end is considered as the western upstreamregion with tributaries that rise entirely fromgranite terrain of the Mandara Mountains thatpeak at ~700-1400 m asl The midstream regionrises ~ 425 - 700 m asl between 25-65 km fromthe source and consists of the granitic mountainsand inter-mountain valleys ucirclled with piedmontalluvium The tributaries increase in number

broadening the basin in this region whichterminates at a conucircuence spread over a distanceof 65-70 km From 70 to 105 km is consideredthe downstream region where the basin narrowseastward in this region with a monotonous reliefthat ranges from 426-328 m asl (Nouvelot1972)The present climatic regime in the basin consistsof a long dry season from October to May and ashorter rainy season from June to SeptemberDuring the dry season the Harmattan winds blowfrom the Sahara in the north lowering the relativehumidity During the rainy season moisture-ladenwinds that blow from the Gulf of Guinea in thesouth bring higher humidity and rain generatingrunoff into rivers and draining the basindendritically (Nouvelot 1972) During drymonths the surface of the draining channels rundry but with underucircow at depths of about 075m Sixteen-year (1980ndash2006) meteorological datafrom the national archive in Douala-Cameroonshow that average annual rainfall in the basin is850 mm average annual evapotranspiration is2127 mm and annual average humidity is 48

Figure 2a Location of Mayo Tsanaga River basin

22 Geologic and hydrogeologic settingThe Mandara mountains are within thenortheastern extension of the Benue trough(Wilson 1988) which constitutes a failed rift thatstretches from the Gulf of Guinea inland towardLake Chad Their origin has been related to thefolding and volcanism associated with tectonic

15


activities along the trough and the volcanic line(Ngako et al 2006) The rocks here are made upof lower Precambrian mesozonal granitesCretaceous basalts and Tertiary-Quaternarysediments (Peronne and Dumort 1968) Theinterplay of relief tectonics and weathering leavethis rugged granite upstream region with acombination of boulders and weatheredcrystalline aquifers Eastward from the graniticMandara Mountains is a piedmont belt (25ndash60km) of diverse sediments (McEachern 2003)These sediments form the piedmont alluviumaquifers in valleys between the granitic mountains(Tillement 1972) The basin extends further eastinto a north to south trending outcrops of basalticdomes (65ndash70 km) which seemingly isolate thepiedmont alluvium to the west from the plainalluvium to the east The plain alluviumconstitutes a combination of continental andlacustrine sediments which are separated by asandy ridge called Limani Yagoua ridge (95ndash105km) in Cameroon This ridge which portrays atectonic structure is also considered as apalaeoshore of the mega Lake Chad (Ngounou-Ngatcha et al 2001) Based on selectedlithological logs from boreholes and wells thatwere constructed in the basin (UNDP 1975) thecrystalline aquifer in the west is made up fromtop to bottom of lateritic clay kaolinitic clay withquartz grains very altered granite slightly alteredgranite unaltered granite with fractures cloggedwith clay and unaltered granite with open

fractures Transmissivity of 7 times10 -6 ms speciucirccyield of 750 lh and drainage slope of 10ndash40have also been reported (Betah 1976 UNDP1975) From the piedmont belt to the Limani-Yagoua ridge Quaternary sediments constitute twoaquifers (Tillement 1972 Njitchoua andNgounou-Ngatcha 1997)

1) an approximately 40-m thick sub-regionalaquifer consisting predominantly of clays andsands and

2) local perched aquifers made up of sands andgravels A transmissivity of 1ndash6 times 10-3 m2sspeciucircc yield of less than 45 m3h inucircltrationrate of 25ndash225 mmyear drainage slope of 15ndash3 and depth to basement of 2ndash60 m have beenreported for these Quaternary sedimentary aquifers(Betah 1976 UNDP 1975)

3 Materials and methods

31 Field work groundwater samplingchemistry and effect of seasons on fluoride

concentrationsSampling campaigns were conducted during therainy and dry season months of September andApril respectively for a total of 40 water samplesthirty-six (36) (Fig 2b) from 18 villages and fourdry season samples from four boreholes in the MeriSub Division based on their use location andresults obtained in the rainy season

Figure 2b Location of the pilot study area of Meri Sub Division

16


Priority for water sampling sites was given toboreholes located in public institutions (hospitalsand schools) In villages with no publicinstitutions water samples were collected fromboreholeswells from where the population preferto fetch drinking water Geographic location andaltitude of selected sample sites were obtainedon the field with a Garmin Vista CX GPS Waterwas drawn from shallow wells using buckets tiedwith ropes while hand pump wells and boreholeswere pumped for 5-15 minutes before samplingFrom all the water sources the water to besampled was initially collected into a bucket thatwas thoroughly rinsed and filled into three setsof new 100 ml capacity plastic bottles after threerinses with the samples One set of bottlescontaining samples to be analyzed for cations (NaK Mg and Ca) were acidified with nitric acidafter filtration with 045 micrometer cellulosefilter The second set for anion (Cl- SO4

2- NO3-

and F-) analysis was left unacidified but filteredThe third set of bottles were filled with watersamples that were neither filtered nor acidifiedfor determination of alkalinity (HCO 3

-) Temperature electrical conductivity (EC) andpH were measured in the field using a portable

electrical conductivity meter (pHEC water proofHANNA Dist 5) and a portable pH meter(Shindengen ISFET pH meter KS723) The pHmeter was calibrated with pH 40 and 68 buffersolutions and ambient temperature was measuredusing a custom CT-450WR thermometer Eachsample was collected after EC pH andtemperature values stabilized All of the 40samples were sent to the ldquoLaboratoire drsquoAnalyseGeochemie des Eaux (LAGE)rdquo of the Instituteof Geology and Mining Research-NkolbissonYaounde where Ion Chromatography (IC) wasused to analyze for major ions (potassiumcalcium sodium magnesium fluoride chloridenitrate and sulfate) With the use of ion balanceequation (Appelo and Postma 2005) thereliability of the results ranged within anacceptable limit of plusmn10

32 Production of bone char andconstruction of experimental house-holddefluoridation units

The experimental defluoridation system wasdeveloped through a two phase process as follows

Figure 3 Internal components of the furnace (a) and external view of the constructed furnace (b)

17


321 Phase 1 Production of appropriate size bone charOne of the principal components of the envisaged defluoridation system is treated cow bones Thetreatment involve charring which is heating the bones at a temperature of 530 to 600 degC for 30 minutesin an oxygen-limited environment To provide such an environment a pyrolyzer (furnace) was constructedas shown in Fig 3a and 3b Cow bones were collected from slaughter houses and restaurants within thestudy area cleaned and dried in open air (Fig 4a) The bones were then charred at a temperature of600degC for 30 minutes to obtain a dark colored bone (Fig 4b) The bones were treated as such in orderto render them free of fats proteins and tendons and at the same time enrich them in CaPO4 whichhas a strong affinity for fluoride ion At the Laboratory of Material Science in the National Institute ofPolytechnic Maroua the charred bones were crushed in an agate mortar and sieved (Fig 4c) to collect02 to 08 mm grain size bone char (Fig 4d) which was washed with tap water and dried

Figure 4 Dried washed tendon and flesh- free cow bones (a) Dark coloured cow bones after charring in the furnace at 530degC for 30minutes (b) Sieved faction (02-08mm) of powdered charred bones (c)

322 Phase 11 Construction of experimental household defluoridation systemA commercial household water filter with its components (Fig 5a) was bought and adapted by replacingactivated carbon with the washed bone char (Fig 5b)

Figure 5 Components of the unadapted commercial household water filter (a) Adapted commercial household filter with activatedcarbon replaced with bone char (b))

18


33 Testing the effectiveness of thedefluoridation filtration system

To ensure that the adapted filter with the bonechar could defluoridize fluoride-rich water it wasfirstly tested for the organoleptic properties (colorand odour) of water dispensing from it andsecondly for its capacity to reduce fluorideconcentration in water

Given that drinking water should befundamentally colorless tasteless and odourlesstap water with no colour taste and odour wasallowed to go through the defluoridation systemand a colorless odourless and tasteless waterobtained from the filter

To test the functionality of the defluoridationsystem vis-a-vis it capacity to removereduceconcentration of fluoride in water it dispenseswater with known concentration of fluoride fromthe four selected boreholes (Meri Health CenterDouvangar Health Center Bamguel communityborehole and Godola community borehole) wasallowed to drain through the filtration systemcontaining 150 g and 300 g of washed bone charWater samples collected before filtration and afterfiltration were analysed at the LAGE-IRGM-Nkolbisson laboratory for major ions In additionto the water chemistry data that were reliable allthe other procedures that were employed forproduction of appropriate size bone charconstruction of experimental householddefluoridation system and to test the effectivenessof the defluoridation filtration system arereproducible

4 Results41 Groundwater chemistry

411 Groundwater in the rainy seasonThe physico-chemical and chemical data for allthe investigated groundwater during the rainyseason are presented in Table 1 Watertemperature ranged from 289 to 325degC with thelowest values (289degC) observed in TozomMenguir and the highest (325degC) in Bamguel 2

The pH values showed acidic (59) to circum-neutral (725) the lowest observed in LyceeTechnique Meri and the highest in Godola 1 TheEC values ranged from 208 microscm in Gabo to404 microscm in Mbozo Out of the 36 833 55111 were Ca+Mg-HCO3 type Ca+Mg-NO3

type and Na+K-HCO3 type respectively (Fig6a) Based on both the 15 mgl WHO (2004)upper limit of fluoride in drinking water and thatof 07mgl at the local level (Fantong et al 2010)only 4 out of the 36 samples contained water thatcould be consumed without fear of causingfluorosis (Fig 6b) From the laboratory resultsfluoride concentrations varied from below the IonChromatography detection limit in the Douvangercommunity borehole to 67 mgl (about 52 mgl above the WHO upper limit) in Bamguelborehole Considering that the survey was donein the rainy season when concentrations offluoride is expected to be lowest due to dilutioneffect and still 32 of the 36 sample sitescontained undesirable concentrations it is likelythat the fluoride concentrations would be on thehigher side in the dry season due to evaporationThis result therefore confirmed that the elevatedfluoride levels reported seven years ago (Fantonget al 2010) is a persistent problem in the studyarea

Figure 6a Piperrsquos diagram showing that the composition ofsampled water was dominantly Ca+Mg-HCO3 type

19


Figure 6b Bar chart showing the variation of fluoride concentrations in groundwater from 18 villages in MeriSub Division

412 Groundwater chemistry in the dryseason

During the dry season groundwater chemistrywas assessed fo the selected four communitypublic boreholes in Meri Douvangar Bemgueland Godola The physico-chemical andchemical data for the boreholes investigatedduring the rainy season are presented in Table2 Water temperature increased to 32-35degCThe pH values were circum - neutral (699-701)and EC ranged from 96 microscm in Meri hospitalto 198 microscm in Bemguel 2 For the fourboreholes the observed data indicate that waterincreased in EC pH and temperature and thatout of the 4 samples 60 and 40 wereCa+Mg-HCO

3 and Ca+Mg-NO

3 type

respectively (Fig 6c) Compared to the rainyseason samples the water chemistry type didnot show remarkable changes in the dry seasonalthough a slight increase in dissolved ions dueto evaporation caused a noticeable enrichmentin bicarbonates Ca Mg and Na

Figure 6c Piperrsquos diagram showing that the groundwaterchemistry remains dominantly Ca+Mg-HCO3 type with changeof seasons

20


42 Effect of seasons on fluoride

concentrationsBased on the fluoride concentrations of waterfrom boreholes that were observed in the rainyseason four communitypublic boreholes wereselected for continuous monitoring These fourboreholes located in Meri hospital Douvangarhospital Bemguel 1 and Godola were sampledand analyzed in the dry season (April 2018) andthe variation in the concentrations from rainyseason to dry season is shown in Tables 1 and 2These variation as shown in Fig 7 indicates thatrelative to the rainy season the fluorideconcentrations in mgl for all the four boreholesincreased in the dry season as follows from 292to 311 in the Meri hospital borehole 235 to 401in the Douvangar hospital borehole 437 to 541in the Bemguel1 community borehole and from292 to 320 in the Godola community borehole

Figure 7 Bar charts showing that concentration of fluoride

in the groundwater increases in dry season when compared

to the rainy season

Such an increase may be due to evaporationduring the dry season when atmospherictemperature in the study area increases from theaverage of 28degC to 40deg C at the peak of the dryseason This suggests that with the incidentimpact of climate change (increase ofatmospheric temperature) as reported bySighomnou (2004) the concentration of fluoridein the groundwater shall also be increasing

43 Variation in fluoride concentrations withvarying quantity of bone char in the

filtration unitThe Variation in fluoride concentrations withvarying quantity of bone char in the filtration unitis presented in Table 3 Upon filtering watercollected in the dry season from the fourboreholes in Meri Douvangar Bemguel 2 andGodola through a filtration unit with 150 g ofwashed bone char (Fig 8) the fluorideconcentrations dropped by a factor of 4 34 45and 28 from 311 to 076 mgl for the Merihospital borehole 401 to 119 mgl for theDouvangar hospital borehole 541 to 121 mglfor the Bemguel community borehole and 320to 115 mgl for the Godola community boreholerespectively The decline in fluoride contentindicates that the observed groundwaters weredefluoridated to below the 15mgl upper limitof fluoride acceptable in drinking water (WHO1994) Considering that Fantong et al (2010)estimate that the upper limit of fluoride in drinkingwater in the study area should be adjusted to07mgl the quantity of washed bone char in thedefluoridation unit was doubled to 300g Figure8 shows that with 300 g of bone char theobserved dry season groundwater samples weredefluoridated from 311 to below detection limitfor the Meri hospital borehole 401 to 011 mglfor the Douvangar hospital borehole 541 to 010for the Bemguel 2 community borehole and 320to 005 for the Godola community borehole Theobserved drops with 300 g of washed bone charshowed that the tested groundwater weredefluoridated to below the 07 mgl local upperlimit as shown in Fig 8 This implies that if thedefluoridation unit and its component are properlymanaged it would reduce fluoride concentrationsto levels that render the populations more resilientto the impact of climate change-inducedenrichment of fluoride in drinking water with thepotential to dramatically reduce fluoride intakethrough drinking water in the study area

21


Figure 8 Reduction in fluoride concentration inthe pristine dry season samples (1 DSS) to valuesbetween 15mgl and 07mgl (2) when water isfiltered through the adapted defluoridation (DF)system that contains 150 g of bone char (BC)and drops to values below 07mgl (3) when wateris filtered through the adapted defluoridationsystem that contains 300 g of bone char

5 Discussion

51 Geochemical provenance and controlof fluoride in the groundwater

Given that the study area is the same as the areastudied by Fantong et al (2010) it can be inferredthat granites that host secondary minerals suchas fluorapatite (Ca10F2(PO4)6) fluorite (CaF2)and fluoropyromorphite (Pb5(PO4)3F are thelithogenic sources of fluoride followingincongruent dissolution of the aquifer rocks Thisview is supported in this study by the observationthat fluoride concentration increases in water withincrease in electrical conductivity (Fig 9a) andpH (Fig 9b) Rise in F- content with increasingEC and pH is also an indication of an extensiveinteraction between water and the mineral phases

as has been observed by other workers includingChae et al (2006a 2006b)

Figure 9a Bivariate plot showing increasing fluorideconcentration with increase in electrical conductivity

Figure 9b Except for the circled points fluoride concentrationincreased with increase in pH values

22


52 Performance of the household filtration unit to defluoridate groundwater

The effectiveness of the home-based filtration unit to defluoridate groundwater was tested by varyingthe quantity of washed bone char in the unit The bone char in the unit had the capacity of reducingfluoride by 311 mg 401 mg 32 mg and 541 mg in drinking water from Meri (Fig 10a) Douvangar(Fig 10b) Godola (Fig 10c) and Bamguel (Fig 10d) respectively representing an average of about 4mg of fluoride adsorbed per liter of water that was filtered in 12 minutes

Figure 10 Regression curves showing the bone char capacity of reducing fluoride by 311 mg 401 mg 32 mg and 541 mg in

drinking water from Meri (a) Douvangar (Fig b) Godola (Fig c) and Bamguel (Fig d) respectively

Assuming that each person consumes 3 liters ofwater daily the filter with 300 g of bone char hasthe capacity of adsorbing 12 mg of fluoride inwater consumed per person in a day Comparedwith commercially activated carbon whichadsorbs chlorine organic chemicalstrihalomethane and unpleasant odour and colorthe bone char gives the filter an additional abilityto adsorb fluoride The observation that the bonechar in the filter has the capacity to reduce fluorideto acceptable levels and maintains acceptableorganoleptic (color odor and taste) characteristicsof drinking water is in agreement with the findingsin Tanzania Kenya Uganda Ethiopia and SouthAfrica (Dahi 2016 Pindjou 2015)Although the study demonstrates that theconstructed defluoridation system can be usedto reduce fluoride concentrations in water to

below both the WHO (1994) upper limit of 15mgl and locally estimated upper limit of 07 mgl the following challenges remain a prerogativein the next phase of this study (1) regularmaintenance of the furnace that chars the rawbones (2) establish how much volume of waterand time are needed to saturate the 300 g of bonechar in the filter with fluoride before proposinghouse hold usage and (3) elaborate a strategy forsustainable management of the filter beforerecommending it for general use

6 ConclusionsConsumption of raw groundwater remains a threatto the health of the population in Meri SubDivision as 90 of investigated groundwaterpoints contain fluoride concentrations higher thanthe established local upper limit of 07 mgl andWHO upper limit of 15 mgl

23


Although a few of the groundwater points showedCa+Mg-NO3 type and four Na+K-HCO 3

signatures the groundwater chemistry isdominantly Ca+Mg-HCO3 type Incongruentdissolution of granites that host secondaryminerals such as fluorapatite (Ca10F2(PO4)6)fluorite (CaF2) and fluoropyromorphite(Pb5(PO4)3F are the pristine sources of fluoridein groundwater Climatic and geochemical factorsthat favor fluoride concentration in groundwaterare increasing atmospheric temperature and pHrespectively Locally available cow bones weresuccessfully charred powdered and sieved to 02-08 mm grain size and used as a major componentin household drinking water defluoridation filtersA household filtration system into which wasintegrated 300 g of locally powdered charred cowbones defluoridated the fluoride-rich groundwaterto concentrations below the local upper limit of07 mgl However the establishment of theduration of use of the bone char in the filterbefore it is replaced remains a target for the nextphase of this study The effective defluoridationof fluoride in fluoride-rich groundwater toconcentrations less than 07 mgl can improvesresilience of the population in the study area toimpacts of climate change

AcknowledgementsWe are thankful to UNICEF and Global WaterPartnership Cameroon for mobilizing funds forthis pilot study Thanks to Centre drsquoEtude deLrsquoEnvironnment et du Developpement auCameroun (CEDC) for providing space for theconstruction and housing of the furnace We arealso thankful to the University of Maroua andthe Regional Delegation for the Far North Regionfor availing students lecturers and workforce whoassisted during fieldwork of this study

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A 2011 Groundwater and Health Meeting

Unmet Needs in Sub-Saharan Africa InSustaining Groundwater Resources JAnthonyAJones (Ed) Springer Heidelberg -Germany 228pp

Appelo CAJ Postma D (2005) Geochemistrygroundwater and pollution 2nd edn BalkemaPublishers Rotterdam 649 pp

Betah SM 1976 Compliment sur la monographienationale de lrsquoeau (aspect eaux souterraines)Diredtion des mines et de la geologie Cameroon

Boutrais J 1984 Le milieux naturels etLrsquooccupation du sol In Jean B (ed) Le Nord duCameroon des homes une region pp 63ndash 100Collection memoires 102 Editions deLrsquoORSTOM Paris

Chae G T Yun S T Kim K amp Mayer B2006a Hydrogeochemistry of sodiumbicarbonate type bedrock groundwater in thePocheon spa area South Korea water rockinteraction and hydrologic mixing Journal ofHydrology (Amsterdam) 43 321ndash326

Chae G T Yun S T Kwon M J Kim S Y ampMayer B 2006b Batch dissolution of graniteand biotite in water implication for ucircuorinegeochemistry in groundwater GeochemicalJournal 40 95ndash102 doi102343geochemj4095

Dahi E 1997 Development of the ContactPrecipitation Method for AppropriateDefluoridation of Water Proceedings of the 2ndInternational Workshop on Fluorosis andDefluoridation of Water Nazreth Ethiopia

Fantong WY Satake H Ayonghe SN AkaFT Kazuyoshi A 2009 Hydrogeochemicalcontrols and usability of groundwater in thesemi-arid Mayo Tsanaga River Basin Far northprovince Cameroon Journ Environ Geol Vol58 12811293

Fantong WY Satake H Ayonghe SN SuhCE Adelana SMA Fantong EBSBanseka HS Gwanfogbe CD WoinchamLN Uehara Y Zhang J 2010Geochemical provenance and spatial

24


distribution of fluoride in groundwater of MayoTsanaga River Basin Far north RegionCameroon implications for incidence offluorosis and optimal consumption doseEnviron Geochem Health Vol 32 147-163

Fantong WY Fouepe A T Emilia B FBanseka S H Gwanfogbe CD AyongheSN and Tanyileke GZ 2013 Increased riskof fluorosis and methemoglobinemia diseasesfrom climate change evidence fromgroundwater quality in Mayo Tsanaga RiverBasin Cameroon Journal of the CameroonAcademy of Sciences 11(1) 49-54

IAHS 2008 Groundwater and Climate in AfricaProceedings of the Kampala ConferenceUganda 24 - 28 June 2008 Edited by RichardTaylor Callist Tindimugaya Michael OworMohammad Shamsudduha IAHS PressWallingford UK 272 pp

IAHS 2009 Groundwater and Climate in AfricaSpecial Issue Hydrological Sciences JournalVolume 54 Issue 4 Edited by Zbigniew WKundzewicz amp Koutsoyiannis IAHS PressWallingford UK Pp 655-804Demetris

Kaseva ME 2006 Optimization ofregenerated bone char for fluoride removal indrinking water case study of Tanzania Journalof Water and Health 041 139-147

McEachern S 2003 Processes of montagnardethnogenesis in the northern mandarasmountain Cameroon PhD thesis 433pUniversity of Calgary Canada ISBN 0-9544730-1-9 Mandaras Publishing

Ngako V Njonfang E Aka FT Affaton PNnange JM 2006 The northndashsouth Paleozoicto quaternary trend of alkaline magmatism fromNigerndashNigeria to Cameroon complexinteraction between hotspots and Precambrianfaults J Afr Earth Sci 45241ndash256

Ngounou-Ngatcha B Murdry J Wakponou AEkodeck GE Njitchoua R Sarrot-ReynauldJ 2001 The Limani-Yagoua mega sand-ridge

northern Cameroon and its hydrologicalimportance J Afr Earth Sci 32(4)889ndash898

Njitchoua R Ngounou-Ngatcha B 1997Hydrogeochemistry and environmental isotopeinvestigations of the north Diamare plainnorthern Cameroon J Afr Earth Sci 25(2)307ndash316

Piddennavar R and Krishnappa P 2013Review on defluoridation techniques of waterIJES

Sighomnou D 2004 Analyse et redefinition desregimes climatiques et hydrologique duCameroun perspectives drsquoevolution deresources en eau PhD thesis Faculty ofScience University of Yaounde 1 Cameroon292 pages23 86-94

Tillement B 1972 Hydrogeologie du NordmdashCameroun Rapport 6 294p Direction desMines et de la Geologie YaoundeCameroon

UNDP 1975 Recherche et exploitation pilotedlsquoeaux souterraines dans le Nord CamerounContrat 5872 Rapport ucircnal Annexe techniqueNo 1ndash4 Hydrogeo Roma-Pisa Italy

Wilson M 1988 Geomorphology andarchaeological visibility in the northern mandaramountains and mora plain (Cameroon)Preliminary results In Daniel B Henri T (eds)Collection colloques et seminaries Editions deLrsquoORSTOM Paris pp 9ndash50

WHO (World Health Organization) 1994Fluoride and oral health WHO technicalReport Series 846 Geneva

12


ReacutesumeacuteAvec lrsquoenrichissement en fluor causant la fluorose dans le bassin versant du Mayo-Tsanaga lrsquoobjectifprincipal de cette eacutetude est drsquoameacuteliorer la capaciteacute de reacutesilience des habitants de la zone drsquoeacutetude parrapport agrave lrsquoimpact du changement climatique en reacuteduisant agrave des niveaux acceptables la concentrationdu fluor dans lrsquoeau de boisson Les objectifs speacutecifiques eacutetant (i) acceacuteder agrave la chimie des eaux de la zonedrsquoeacutetude afin de reacuteaffirmer que la nappe souterraine est toujours caracteacuteriseacutee par des taux de fluorindeacutesirable (ii) estimer lrsquoimpact des changements de saison sur la concentration du fluor dans la nappe (iii) construire et eacutevaluer la performance drsquoun filtre domestique agrave deacutefluoration par adsorption baseacute surla carbonisation des ossements des bœufs Une combinaison des approches hydrogeacuteochimique ettechnologique a eacuteteacute utiliseacutee pour deacutemontrer que le facies des eaux souterraines est principalement detype Ca+Mg-HCO3 contenant des concentrations pouvant attendre jusqursquoagrave 67 mgl de fluor geacuteogeacuteniqueindeacutesirable Ces concentrations augmentent avec lrsquoeacuteleacutevation du pH la conductiviteacute eacutelectrique et pendentla saison segraveche et sont reacuteduite agrave moins de 02 mgl lorsque lrsquoeau de la nappe est soumise agrave une filtrationagrave travers 300g de couche drsquoossements de bœufs carboniseacutes de 02 agrave 08 mm taille de grain disposeacuteecomme filtre de deacutefluoration Les ossements de boeuf carboniseacutes dans le filtre peuvent reacuteduire laconcentration de fluorure agrave moins de 07 mgl qui est le seuil limite local avec aucun impact neacutegatifsur les caracteacuteristiques organoleptique de lrsquoeau potable Reacutelativement au charbon activeacute vendu lesossements de boeuf ont la capaciteacutee drsquoadsorption de 4 mgl en 30 minutes Ceci implique qursquoavec untemps de saturation connu les ossements de bœufs carboniseacutes peuvent proteacuteger la population des meacutefaitsdu changement climatique induisant lrsquoenrichissement en fluor des eaux de boisson de la nappe souterraine

Keywords Chimie des eaux souterraine Fluor geacuteogeacutenique Fluorose Deacutefluoration Ossements debœufs carboniseacutes Reacutesilience

13


1 Introduction






14








15










16



2- NO3-







17






18











19





3 and Ca+Mg-NO

3 type



20






to the rainy season




21



5 Discussion






22









23
















24


















13


1 Introduction






14








15










16



2- NO3-







17






18











19





3 and Ca+Mg-NO

3 type



20






to the rainy season




21



5 Discussion






22









23
















24


















14








15










16



2- NO3-







17






18











19





3 and Ca+Mg-NO

3 type



20






to the rainy season




21



5 Discussion






22









23
















24


















15










16



2- NO3-







17






18











19





3 and Ca+Mg-NO

3 type



20






to the rainy season




21



5 Discussion






22









23
















24


















16



2- NO3-







17






18











19





3 and Ca+Mg-NO

3 type



20






to the rainy season




21



5 Discussion






22









23
















24


















17






18











19





3 and Ca+Mg-NO

3 type



20






to the rainy season




21



5 Discussion






22









23
















24


















18











19





3 and Ca+Mg-NO

3 type



20






to the rainy season




21



5 Discussion






22









23
















24


















19





3 and Ca+Mg-NO

3 type



20






to the rainy season




21



5 Discussion






22









23
















24


















20






to the rainy season




21



5 Discussion






22









23
















24


















21



5 Discussion






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research article defluoridation of fluoride-rich ...orca.cf.ac.uk/125025/1/published cas.pdf ·...

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