In September 2000 water fluoridation became mandatory in South Africa. Since then water service providers like Umgeni Water (UW), a bulk water supply authority in the KwaZulu-Natal (KZN) province of South Africa began the process of implementing the legislation. This study was undertaken to establish the spatio-temporal variations of fluoride concentrations in surface and ground waters within the Umgeni Operational Area, to establish whether these waters would require fluoridation or defluoridation to meet a fluoride concentration of 0.70 mglf, and to assess the potential impacts of water fluoridation. Baseline fluoride concentrations of surface and ground water: It was concluded that the fluoride concentration of all sample types (rivers, dams, water works raw and final waters, wastewater influent and effluents, and boreholes), except pollution point sources, is less than O.S; mglR, 50 percent of the time. Some rivers (Mshazi, KwaNyuswa, KwaNgcolosi,·Mshwati and the MgoShongweni) exhibited high fluoride concentrations, while someboreholes also exhibited high fluoride concentrations. Temporal Variations and Seasonality: There are seasonal variations in the fluoride concentrations for surface waters, with higher fluoride concentrations in winter than in summer (64 out of 125 occasions). This low fluoride concentration in summer can be attributed to the dilution effects caused by rainfall runoff. Identification of "Hot Spots": "Hot Spots", sites where the fluoride concentration exceeds 1 mglR are present within the study area, for surface and borehole water. For surface water, the MgoShongweni exhibited fluoride concentrations in excess of 1mglRat least 75% of the time. The KwaNgcolosi and Mshwati exhibited fluoride concentrations In excess of 1mglR at least 25% of the time, while the Mshazi and the KwaNyuswa exhibited fluoride concentrations in excess of 1mglR only 5% of the time. The storm water discharge below AECI had high fluoride concentrations in excess of 1mg/R at least 20% of the time and the concentrations exceeded the fluoride concentration for seawater (1.4 mglf) at least 5% of the time. Of the 286 boreholes sampled, 17 boreholes (6% of all boreholes sampled) had fluoride levels in excess oft mglf . The impacts of long term consumption of water from these boreholes could range from slight mottling of the dental enamel in sensitive individuals (boretioles JD26, C29, H19, CB7, 112/1, 69/5, Thembeni 108 and EC (Thembeni 105, Keats Drift boreholes 1 and 2). Spatial patterns and possible sources of high fluoride concentrations: With respect to spatial patterns, relatively high concentrations of fluoride (300 IJglR to 1000 IJglR) can be found in surface water in the Msunduzi river, the Mgeni river downstream of the Msunduzi confluence and along the coastal belt. No spatial patterns are evident with respect to borehole water. For surface water, high fluoride concentrations in the Mshazi, KwaNyuswa and the KwaNgcolosi streams (inflows to the Inanda dam) appear to be associated with the catchment geology. The ~igh fluoride concentrations in Mshwati and the MgoShongweni are most likely as a result of industrial activities in the respective catchments. For borehole water, high fluoride concentrations may be attributed to catchment geology. Additional fluoride dosaqe ' at water treatment works: Since the fluoride concentrations at the water works were low (mean ranging between 0.5 mglf to 0.38 mglf) , fluoride would need to be added to meet the fluoride standard of 0.7 mgl£ . For most of the water works, the additional fluoride (sodium fluoride) requirement to meet the fluoride standard of 0.7 mgl£, ranged from 1.201 kglMRto 1.555 kg/MR. For the water works, Imfume and Umzinto, the additional fluoride , requirement is 0.768 kg/MR and 0.109 kg/MR respectively. In final water, the fluctuations in fluoride concentrations observed would translate to continuous testing being required to maintain optimal dosing of fluoride. Comparison of influent and effluent fluoride concentrations at wastewater works: There was no evidence of fluoride removal at the Mpophomeni Wastewater Works . There was evidence of 22.4% fluoride removal at the DarvHI Wastewater Works possibly due to the activated sludge treatment process at the wastewater works. Future fluoride levels in surface water that will receive return flows: Once water fluoridation is implemented, the Darvill Wastewater Works would receive fluoridated return flows, and discharge its fluoride rich effluent into the Msunduzi river. The average monthly fluoride road discharged from Darvill Wastewater Works would increase from 0.23 tons to 1.46 tons, an additional 1.23 tons per month on the aquatic environment of the Msunduzi river. The sludge fluoride load, disposed to land, could increase from 4 056 tons/month to 27 863 tons/month, which implies an increase in the fluoride runoff potential from the sludge-lands to the Msunduzi river. Number of people in sensitive groups that could be affected by water fluoridation: A significant number of people in KZN could be sensitive to water fluoridation. This has been estimated to be at least one third of KZN's population that are HIV infected. Recommendations were made and the most important ones are as follows: In the light of the large number of people, one-third the population of KZN, that is HIV positive and therefore could be sensitive to fluoridated water, it is recommended that the South African legislation mandating water fluoridation be withdrawn. Examination of the most recent literature indicated a significant lack of confidence in the best available studies that researched the safety and efficacy of water fluoridation. In the light of this it is recommended that the South African Department of Health re-examine and withdraw its legislation that mandates water fluoridation. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

MENVSC / Department of Hydrology and Water Resources / See the attached abstract below

Text in Afrikaans / Die tydruimtelike variasie in die fluoriedinhoud vannatuurlike drinkwater en in die voorkoms van tandfluorose, die verband tussen hierdie veranderlikes asook hulle kovariasie is op 'n hoe resolusievlak in geselekteerde endemiese gebiede ondersoek. Die drie studiegebiede verskil grootliks van mekaar wat sommige fisies- en menslik-geografiese kenmerke betref, maar ondergrondse water was oral die belangrikste bron van drinkwater. Ioonspesifieke analise en laboratoriumtegnieke is gebruik om die fluoriedinhoud van die drinkwater uit 517 bronne te bepaal. Die tande van 3 068 kinders is klinies en fotografies ondersoek. Die erkende Tooth Fluorosis Index en die indeks van Dean is gebruik om die voorkoms van fluorose te beskryf. Grafiese tegnieke, beskrywende statistieke en nieparametriese analise van variansietoetse is gebruik om die voorkoms en tydruimtelike variasiepatrone van die sleutelveranderlikes in elke studiegebied, asook die verskillende ruimtelike eenhede binne die studiegebiede, te beskryf. Die verband tussen die sleutelveranderlikes asook hul intra- en interareale kovariasie is ontleed. Daar is gevind dat die fluoriedinhoud van die ondergrondse water in die Pilanesberg- en Hammanskraal-studiegebied relatief hoog tot hoog is en die in die Vrystaat-studiegebied relatief laag. Ruimtelike veranderlikheid met groot verskille oor klein afstande kenmerk die fluoriedinhoud van ondergrondse water ongeag die gesteentes waaruit dit onttrek word. Middelwaardes bied ontoereikende beskrywings van die fluoriedgehalte van die drinkwater. Die skep van nuwe drinkwaterbronne veroorsaak langtermynvariasie in die fluoriedinhoud van die beskikbare drinkwater. Fluoroseprevalensie in die studiegebiede bet van 62% tot 87% gewissel, met meer ernstige aantasting in die Pilanesberg- en Hammanskraal-gebied as in die Suid-Vrystaat. Beduidende intra-areale ruimtelike variasie is 'n wesenlike kenmerk van die voorkoms van fluorose in al drie studiegebiede. In alle gevalle het die variasiepatroon in die fluoriedinhoud van die drinkwater die in die voorkoms van fluorose slegs gedeeltelik verklaar. Sporadiese en/of periodieke kortstondige blootstelling aan hoe fluoriedkonsentrasies lei tot emstige aantasting ten spyte van die gereelde gebruik van water met 'n laefluoriedinhoud. Ligte fluorose ontwikkel geredelik in assosiasie met <0,5 mgF-/l en matige fluorose in assossiasie met 0,5-0,7 mgF-/l, die optimum konsentrasieinterval vir fluoridasie in Suid-Afrika. / The spatiotemporal variation in the fluoride content of natural drinking water and the occurrence of dental fluorosis, the relation between these variables as well as their covariation were investigated at a high resolution level in selected endemic areas. Groundwater was the most important source of drinking water in all three study areas, but they differed markedly in respect of some physical and human geographical characteristics. Ion specific analysis and laboratory techniques were used to determine the fluoride content of the water from 517 sources. The teeth of 3 068 children were examined clinically and photographically. The fluorosis was scored according to the Tooth Fluorosis Index and Dean's classification. Graphical techniques, descriptive statistics and nonparametric analysis of variance were used to describe the occurrence and variation patterns of the key variables in the different spatial units is each study area. The relation between the variables as well as their intra and interareal covariation were analysed. The fluoride content of the groundwater in the Pilanesberg and Hammanskraal areas was relatively high to high; in the southern Free State it was relatively low. Spatial variability and significant differences over small distances typify the fluoride content of the groundwater, irrespective of the aquifer. Central statistics inadequately describe the fluoride quality of the natural drinking water. The development of new water sources causes long term variation in the fluoride content of the available drinking water. Fluorosis prevalence varied form 62% to 87%, with more severe fluorosis in Pilanesberg and Hammanskraal than in the southern Free State. Significant intra-areal spatial variation is an attribute of fluorosis in all three study areas. In all cases the variation pattern in the fluoride content of the drinking water partly explained the spatial pattern in the occurrence of fluorosis. Sporadic and/or periodic brief exposure to high fluoride concentrations leads to severe fluorosis despite regul~ usage of water with a low fluoride content. Mild fluorosis readily develops in association with <0,5 mgF-1~ and medium fluorosis in association with 0,5-0,7 mgF-/l, the optimum concentration interval for fluoridation in South Africa. / Geography / D. Phil. (Geografie)

Text in Afrikaans / Die tydruimtelike variasie in die fluoriedinhoud vannatuurlike drinkwater en in die voorkoms van tandfluorose, die verband tussen hierdie veranderlikes asook hulle kovariasie is op 'n hoe resolusievlak in geselekteerde endemiese gebiede ondersoek. Die drie studiegebiede verskil grootliks van mekaar wat sommige fisies- en menslik-geografiese kenmerke betref, maar ondergrondse water was oral die belangrikste bron van drinkwater. Ioonspesifieke analise en laboratoriumtegnieke is gebruik om die fluoriedinhoud van die drinkwater uit 517 bronne te bepaal. Die tande van 3 068 kinders is klinies en fotografies ondersoek. Die erkende Tooth Fluorosis Index en die indeks van Dean is gebruik om die voorkoms van fluorose te beskryf. Grafiese tegnieke, beskrywende statistieke en nieparametriese analise van variansietoetse is gebruik om die voorkoms en tydruimtelike variasiepatrone van die sleutelveranderlikes in elke studiegebied, asook die verskillende ruimtelike eenhede binne die studiegebiede, te beskryf. Die verband tussen die sleutelveranderlikes asook hul intra- en interareale kovariasie is ontleed. Daar is gevind dat die fluoriedinhoud van die ondergrondse water in die Pilanesberg- en Hammanskraal-studiegebied relatief hoog tot hoog is en die in die Vrystaat-studiegebied relatief laag. Ruimtelike veranderlikheid met groot verskille oor klein afstande kenmerk die fluoriedinhoud van ondergrondse water ongeag die gesteentes waaruit dit onttrek word. Middelwaardes bied ontoereikende beskrywings van die fluoriedgehalte van die drinkwater. Die skep van nuwe drinkwaterbronne veroorsaak langtermynvariasie in die fluoriedinhoud van die beskikbare drinkwater. Fluoroseprevalensie in die studiegebiede bet van 62% tot 87% gewissel, met meer ernstige aantasting in die Pilanesberg- en Hammanskraal-gebied as in die Suid-Vrystaat. Beduidende intra-areale ruimtelike variasie is 'n wesenlike kenmerk van die voorkoms van fluorose in al drie studiegebiede. In alle gevalle het die variasiepatroon in die fluoriedinhoud van die drinkwater die in die voorkoms van fluorose slegs gedeeltelik verklaar. Sporadiese en/of periodieke kortstondige blootstelling aan hoe fluoriedkonsentrasies lei tot emstige aantasting ten spyte van die gereelde gebruik van water met 'n laefluoriedinhoud. Ligte fluorose ontwikkel geredelik in assosiasie met <0,5 mgF-/l en matige fluorose in assossiasie met 0,5-0,7 mgF-/l, die optimum konsentrasieinterval vir fluoridasie in Suid-Afrika. / The spatiotemporal variation in the fluoride content of natural drinking water and the occurrence of dental fluorosis, the relation between these variables as well as their covariation were investigated at a high resolution level in selected endemic areas. Groundwater was the most important source of drinking water in all three study areas, but they differed markedly in respect of some physical and human geographical characteristics. Ion specific analysis and laboratory techniques were used to determine the fluoride content of the water from 517 sources. The teeth of 3 068 children were examined clinically and photographically. The fluorosis was scored according to the Tooth Fluorosis Index and Dean's classification. Graphical techniques, descriptive statistics and nonparametric analysis of variance were used to describe the occurrence and variation patterns of the key variables in the different spatial units is each study area. The relation between the variables as well as their intra and interareal covariation were analysed. The fluoride content of the groundwater in the Pilanesberg and Hammanskraal areas was relatively high to high; in the southern Free State it was relatively low. Spatial variability and significant differences over small distances typify the fluoride content of the groundwater, irrespective of the aquifer. Central statistics inadequately describe the fluoride quality of the natural drinking water. The development of new water sources causes long term variation in the fluoride content of the available drinking water. Fluorosis prevalence varied form 62% to 87%, with more severe fluorosis in Pilanesberg and Hammanskraal than in the southern Free State. Significant intra-areal spatial variation is an attribute of fluorosis in all three study areas. In all cases the variation pattern in the fluoride content of the drinking water partly explained the spatial pattern in the occurrence of fluorosis. Sporadic and/or periodic brief exposure to high fluoride concentrations leads to severe fluorosis despite regul~ usage of water with a low fluoride content. Mild fluorosis readily develops in association with <0,5 mgF-1~ and medium fluorosis in association with 0,5-0,7 mgF-/l, the optimum concentration interval for fluoridation in South Africa. / Geography / D. Phil. (Geografie)

Vibrio infections remain a serious threat to public health. In the last decade, Vibrio disease outbreaks have created a painful awareness of the personal, economic, societal, and public health costs associated with the impact of contaminated water in the aquatic milieu. This study was therefore designed to assess the prevalence of Vibrio pathogens in the final effluents of wastewater treatment plants (WWTPs) in the Eastern Cape Province, as well as their abilities to survive the treatment processes of the activated sludge system either as free cells or as plankton-associated entities in relation to the physicochemical qualities of the effluents. Three wastewater treatment facilities were selected to represent typical urban, sub-urban and rural communities, and samples were collected monthly from August 2007 to July 2008 from the final effluent, discharge point, 500 meter upstream and downstream of the discharge points and analysed for physicochemical parameters, Vibrio pathogens prevalence and their antibiogram characteristics using both culture based and molecular techniques. Physicochemical parameters measured include pH, temperature, electrical conductivity, salinity, turbidity, total dissolved solid (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), nitrate, nitrite and orthophosphate levels. Unacceptably high levels of the assayed parameters were observed in many cases for COD (<10 - 1180 mg/l), nitrate (0.08 - 13.14 mg NO3- as N/l), nitrite (0.06 - 6.78 mg NO2- as N/l), orthophosphate (0.07-4.81 mg PO43- as P/l), DO (1.24 - 11.22 mg/l) and turbidity (2.04 -159.06 NTU). Temperature, COD and nitrite varied significantly with season (P < 0.05), while pH, EC, salinity, TDS, COD, and nitrate all varied significantly with sampling site (P < 0.01; P < 0.05). In the rural wastewater treatment facility, free-living Vibrio densities varied from 0 to 3.45 × 101 cfu ml-1, while the plankton-associated Vibrio densities vary with plankton sizes as follows: 180 μm (0 – 4.50 × 103 cfu ml-1); 60 μm (0 – 4.86 × 103 cfu ml-1); 20 μm (0 – 1.9 × 105 cfu ml-1). The seasonal variations in the Vibrio densities in the 180 and 60 μm plankton size samples were significant (P < 0.05), while the 20 μm plankton size and free-living vibrios densities were not. Molecular confirmation of the presumptive vibrios isolates revealed V. fluvialis (36.5 percent), as the predominant species, followed by V. vulnificus (34.6 percent), and V. parahaemolyticus (23.1 percent), and V. metschnikovii (5.8 percent) (detected using only API 20 NE), suggesting high incidence of pathogenic Vibrio species in the final effluent of the wastewater facility. Correlation analysis suggested that the concentration of Vibrio species correlated negatively with salinity and temperature (P < 0.001 and P < 0.002 respectively) as well as with pH and turbidity (P < 0.001), in the final effluent. Population density of total Vibrio ranged from 2.1 × 101 to 4.36 × 104 cfu ml-1 and from 2.80 ×101 to 1.80 × 105 cfu ml-1 for the sub-urban and urban communities treatment facilities respectively. Vibrio species associated with 180 μm, 60 μm, and 20 μm plankton sizes, were observed at densities of 0 - 1.36 × 103 cfu ml-1, 0 - 8.40 × 102 cfu ml-1 and 0 - 6.80 × 102 cfu ml-1 respectively at the sub-urban community‘s WWTP. In the urban community, counts of culturable vibrios ranged from 0 - 2.80 × 102 cfu ml-1 (180 μm); 0 - 6.60 × 102 cfu ml-1 (60 μm) and 0 -1.80 × 103 cfu ml-1 (20 μm). Abundance of free-living Vibrio species varied between 0 and the orders of 102 and 103 cfu ml-1 in the sub-urban and urban communities WWTPs respectively. Molecular confirmation of the presumptive vibrios isolates revealed the presence of V. fluvialis (41.38 percent), V. vulnificus (34.48 percent), and V. parahaemolyticus (24.14 percent) in the sub-urban community effluents. In the urban community V. fluvialis (40 percent), V. vulnificus (36 percent), and V. parahaemolyticus (24 percent) were detected. There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, while Vibrio species abundance correlated positively with temperature (r = 0.565; P < 0.01), salinity and dissolved oxygen (P < 0.05). Turbidity and pH showed significant seasonal variation (P < 0.05) in both locations. The Vibrio strains showed the typical multi-antibiotic-resistance of an SXT element. They were resistant to sulfamethoxazole (Sul), trimethoprim (Tmp), cotrimoxazole (Cot), chloramphenicol (Chl) and streptomycin (Str), as well as other antibiotics such as ampicillin (Amp), penicillin (Pen), erythromycin (Ery), tetracycline (Tet), nalidixic acid (Nal), and gentamicin (Gen). The antibiotic resistance genes detected includes dfr18 and dfrA1 for trimethoprim; tetA, strB, floR, sul2 blaP1, for tetracycline, streptomycin, chloramphenicol, sulfamethoxazole and β-lactams respectively. A number of these genes were only recently described from clinical isolates, demonstrating genetic exchange between clinical and environmental Vibrio species. This study revealed that there was an adverse impact on the physicochemical characteristics of the receiving watershed as a result of the discharge of inadequately treated effluents from the wastewater treatment facilities. The occurrence of Vibrio species as plankton-associated entities confirms the role of plankton as potential reservoir for this pathogen. Also the treated final effluents are reservoirs of various antibiotics resistance genes. This could pose significant health and environmental risk to the biotic component of the environment including communities that rely on the receiving water for domestic purposes and may also affect the health status of the aquatic milieu in the receiving water. There is need for consistent monitoring programme by appropriate regulatory agencies to ensure compliance of the wastewater treatment facilities to regulatory effluent quality standards.

MENVSC / Department of Ecology and Resource Management / See the attached abstract below

MENVSC / Department of Ecology and Resource Management / Some boreholes in South Africa which serve as a source of drinking water for rural communities are reported to have high fluoride concentration, much above the WHO guideline of 1.5 mg/L. This study aimed at activating aluminosilicate clay soil mechanochemically, modifying aluminosilicate clay soil with Al-oxide and fabricating porous ceramic granules using Al-oxide modified mechanochemically activated aluminosilicate clay soil/ mechanochemically activated clay soil/ corn starch and evaluating their performances in defluoridation of groundwater. The raw clay materials were mechanochemically activated for 5, 10, 15 and 30 minutes for physicochemical transformation of the solid aggregate. The morphology of the samples showed the honeycomb structure. The surface area analyses of samples using Brunauer–Emmett–Teller (BET) gave the highest surface area of 50.5228 m2/g at 30 min activation time. Hence, the optimum activation time was 30 min. The Fourier Transform Infrared (FT-IR) analysis showed increase in the absorbance of FT-IR by Si-O-H groups at 510 cm-1 with increasing milling time. This is evidence that more surface Si-O-H groups were available at higher particle surface area that would be necessary to interact with fluoride. X-ray diffraction (XRD) analyses revealed that, at 30 minutes milling time, the peak broadening is intensified whereas the reflection peak intensities decreased. The X-ray fluorescence spectrometry (XRF) results for 30 minutes milling time showed that silica and alumina were the highest components in the clay soil. Using the activated clay in batch defluoridation of fluoride-spiked water, a maximum fluoride removal of 41% was achieved at a pHe of 2.41. The initial fluoride concentration was 9 mg/L while the sorbent dosage was 0.6 g/100 mL and the contact time being 30 minutes. The adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption data fitted only the pseudo-second-order kinetic, showing chemisorption. Optimization of Al3+ concentration for modification was carried out by modifying the mechanochemical activated aluminosilicate clay soil with different concentrations of Al3+ from which the optimum modification was achieved with 1.5 M. Characterisation studies on the Al-oxide modified mechanochemically activated aluminosilicate clay soil by SEM, BET, FT-IR, XRD and XRF, analyses were carried out to determine the resultant changes in physicochemical properties of the adsorbent owing to modification. The SEM image of Al-oxide modified mechanochemically activated clay soil showed many small pores and honey-comb structure on the surface of different images. The BET surface area and the BDH adsorption cumulative area of the Al-oxide modified mechanochemically activated v aluminosilicate clay soil were more than double those for the raw clay soil. There was also an increase in pore volume of the Al-oxide modified mechanochemically activated aluminosilicate clay soil. The FT-IR spectra showed that there was increase in the absorbance by the Si-OH, H-O-H, Al-O-H and Si-O-Al. The equilibrium pH of solution was higher than the point-of-zero charge (pHpzc) implying that fluoride removal occurred at solution pH > pHpzc where the net surface charge of the mechanochemically activated clay aluminosilicate soil was negative.The efficiency of 1.5 M Al-oxide modified aluminosilicate clay soil to remove fluoride from water was studied and found to be 96.5 % at pHe 6.86, contact time of 30 minutes and dosage of 0.3 g/100 mL for 10 mg/L fluoride solution at 200 rpm shaking speed. The result shows that Al-oxide modified mechanochemically activated aluminosilicate clay soil is effective for defluoridation. The adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption data fitted only the pseudo-second-order kinetic, showing chemisorption. Al-oxide modified mechanochemically activated aluminosilicate clay soil was tested for fluoride removal on field water and the percentage fluoride removal was 96.5 % at the dosage of 0.6 g/100 mL with the pHe of 6.48. The optimum Al-oxide modified mechanochemically activated aluminosilicate clay soil/ mechanochemically activated clay soil/ corn starch mixing ratio for fabrication of porous ceramic granules was determined by varying ratios and temperature. The optimum ratio found was 20:5:1.The porous ceramic granules were characterised using SEM, BET, FT-IR, XRD and XRF. SEM analysis showed that the porous ceramic granules have the porous structure of the organic foam template. The porous ceramic granule showed an increase in pore surface area and volume as compared to mechanochemically activated aluminosilicate clay soil. The FT-IR showed the presence of a strong broad bending and stretching vibrations band at about 993 cm-1 which shows the presence of Si–O–Si bonds. Mineralogical characterisation showed the presence of quartz, albite, horneblende and microcline as the main minerals of the calcined porous ceramic granules. The major oxides of the porous ceramic granules as shown by XRF analysis were SiO2, Al2O3, MnO and Na2O. The porous ceramic granules reduced the concentrations of fluoride in the water from 10 to 3.31 mg/L. The optimum adsorption capacity was 0.6648 mg/g at a pHe of 6.32 and the percentage fluoride removal was 66.9 % at an adsorbent dosage of 1.0063 g/100 mL and a temperature of 600 ⁰C. The porous ceramic granules were tested for fluoride removal on field water and the percentage fluoride removal was 45.4 % at the dosage of 1.0009 g/100 mL with the pHe of 7.87. Mechanochemically activated aluminosilicate clay soil showed higher adsorption capacity at acidic pH, therefore it is recommended that future work should focus on improving their adsorption capacity at wider range of pH. The porous ceramic granules can also be evaluated in column dynamic flow experiments.

MENVSC / Department of Ecology and Resource Management / Fluoride is one of the anionic contaminants which is found in excess in groundwater because of geochemical reaction or anthropogenic activities such as the disposal of industrial wastewaters. Among various methods used for defluoridation of water such as precipitation, ion-exchange processes, membrane processes, the adsorptions process is widely used. It offers satisfactory results and seems to be a more attractive method for the removal of fluoride in terms of cost, simplicity of design and operation. In this work, the preparation of clay polymer nanocomposites (CPNCs) used in defluoridation began by modifying the original natural Mukondeni clay to render the layered silicate miscible with the chosen polymer, microcrystalline cellulose. Clay polymer nanocomposites (CPNCs) were synthesized using the melt intercalation method. Mukondeni black clay with microcrystalline cellulose as polymers was melt mixed at 220 °C for 10 minutes in an extruder for exfoliation of the resulting composite. Physicochemical characteristics and mineralogical characteristics of the CPNC was determined using XRD, XRF, BET, FTIR and SEM. Batch adsorption experiments were conducted to determine the efficiency of CPNCs in defluoridation of groundwater. The pH, EC, TDS and fluoride concentration of field water was determined using the CRISON MM40 multimeter probe and the Orion versastar fluoride selective electrode for fluoride concentration. Elemental analysis revealed that CPNC 1:1 is mainly characterized of cellulose, Quartz and Albatite as the major minerals with traces of Montmorillonite, Ednite and Magnesium as minor minerals constituting CPNC 1:1. The structure of 1:4 CPNC was partially crystalline and partially amorphous showing increased cellulose quantity (1:4 clay to cellulose) as compared 1:1 CPNC, 1:2 CPNC and 1:3 CPNC. Maximum adsorption of fluoride was attained in 10 minutes using 0.5g of 1:4 CPNC removed 22.3% of fluoride. The initial fluoride concentration for the collected field groundwater was 5.4 mg/L, EC 436 μS/cm, and TDS 282 mg/L. The regeneration potential of CPNCs was evaluated through 3 successive adsorption desorption cycles. Fluoride removal decreased after the first cycle for all ratios of CPNCs, a continued decreased can be observed following the second cycle. CPNC 1:2 decreased from 9.32 % at the 1st cycle to 2.84 % and 0.56 % on the 2nd and 3rd cycle respectively. CPNC 1:4 decreased from 8.22 % at the 1st cycle to 4.80 % and 0.72 % on the 2nd and 3rd cycle respectively. The fluoride-rich Siloam groundwater had a slightly alkaline pH of 9.6. iv The low adsorptive characteristic displayed by all 4 CPNCs can be deduced from the BET analysis that revealed low surface area, pore volume, and pore size, it is evident from the BET analysis that less fluoride will be absorb as adsorption sites will be limited. Based on the findings of this study, recommendations are designing of correct preparation techniques to obtain nanocomposites with desirable properties, polymer melting points and evaporation point of the binder should be taken into consideration. / NRF