EXCESS FLUORIDE IN WATER IN KENYA BY … · CDN Catholic Diocese of Nakuru ... which relates to...

CCEFW

REPORT OF THE CONSULTATIVE COMMITTEE

ON EXCESS FLOURIDE IN WATER

EXCESS FLUORIDE IN WATER IN KENYA

BY

CONSULTATIVE COMMITTEE

KENYA BUREAU OF STANDARDS

NAIROBI

JUNE 2010

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COMMITTEE MEMBERSHIP

University of Nairobi, Department of Chemistry Chair

Ministry of water and Irrigation

Water Resources Management Authority

Water Services Regulatory Board

Nairobi Water & Sewerage Company

National Water Conservation and Pipeline Corporation

Government Chemist

The Kenya Alliance of Resident Associations

Kenya Society for Fluoride Research

Ministry of Public Health and sanitation

National Environment and Management Authority

Kenya Bureau of Standards Secretariat

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THE REPORT OUTLINE

Abbreviations and acronyms

1 INTRODUCTION

2 FLUORIDE IN WATER SOURCES

2.1 Surface water

2.2 Ground Water 2.3 Incidences of Fluorosis

3 DEFLUORIDATION METHODS

3.1 Existing treatment technologies 3.2 Review of fluoride removal technologies 3.3 International experience 3.4 Review of awareness of existing technologies

4 LEGAL FRAME WORK 4.1 Water Policy 4.2 Legislations on Water

4.3 Regulations

4.4 Conflicts

5. RECOMENDATION/CONCLUSION

6. WAY FORWARD

References

Annexes

Annex I: Map of the six drainage basins

Annex II: Borehole fluoride mapping

Annex III: Surface water fluoride mapping

Annex IV: Possible organogram of the Fluoride Surveillance Group

List of tables: Table 1: Reverse osmosis indicative cost Table 2: methods of removing fluoride in water Table 3: difference in deflouridation treatment, Table 4: comparison of advantages of some deflouridation methods Table 5: awareness of different deflouridattion methods in Kenya

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Abbreviations and acronyms

BAT Best Available Technology BuRec US Bureau of Reclamation CDN Catholic Diocese of Nakuru COD Chemical oxygen demand CP Contact precipitation CSOs Civil society organisations DAK Dental Association of Kenya DCP Dicalcium phosphate (CaHPO4.2H2O) € Euro (€1 = KShs. 104.6) ED / EDR Electrodialysis / Electrodialysis Reversal EnDeCo Environmental Development Co-operation Group, Tanzania GC Government Chemist GoK Government of Kenya ICOH Intercountry Centre for Oral Health, Thailand IGRAC International Groundwater Resources Assessment Centre ISFR International Society for Fluoride Research KARA Kenya Alliance of Residents Associations KEBS Kenya Bureau of Standards KOH Potassium hydroxide KSFR Kenya Society for Fluoride Research MoPHS Ministry of Public Health Services MoWI Ministry of Water and Irrigation NaOH Sodium hydroxide NAIVAWASS Naivasha Water and Sewerage Company Ltd NAWASCO Nakuru Water and Sewerage Company Ltd NCWSC Nairobi City Water and Sewerage Company Ltd NTU Nephelometric turbidity units NWCPC National Water Conservation and Pipeline Corporation O&M Operation and maintenance POU Point of use RO Reverse osmosis RWH Rainwater harvesting TDS Total dissolved solids (expressed as mg/l) TOC Total organic carbon USEPA United States Environmental Protection Agency WASREB Water Services Regulatory Board WHO World Health Organisation WRMA Water Resources Management Authority WSP Water Service Provider

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EXECUTIVE SUMMARY

Kenya is among few countries in the world that have high concentration levels of fluoride in some of their surface and ground water sources and lies in the high fluoride belt. It is note worth to say that Kenya mines and exports fluorspar, a 95% Calcium fluoride mineral from Kerio Valley, in the Rift Valley province. Studies dating back to early 1950’s reveal not only high concentration levels of fluoride in drinking water, but also incidences of fluorosis in these areas. Fluoride levels of 2800 mg/l have been reported in Lake Nakuru, while boreholes in the area have reported fluoride levels in the tens range. While water from saline lakes in the Rift Valley has been known to have highest fluoride water, ground water sources, mainly boreholes, were recognized as the greatest threat (source) of fluoride in drinking water. Boreholes fluoride mapping displayed a more widespread distribution which relates to both dental and skeletal fluorosis in the country. Research has established that a good section of Nairobi, parts of Rift Valley and Central Provinces have ground water with high fluoride levels, of even 50 mg/l per litre. It was also established that there are other sources of fluoride ingestion in human beings particularly from beverages, such as tea, vegetable juices and tooth pastes that have high fluoride in addition to drinking water. Use of Magadi soda (trona) in traditionally cooking vegetables is suspect as one of the un investigated ingestion route of fluoride to human beings. Incidences of fluorosis have been related to oesteosarcoma in Kenya and Malaysia, hence the need to overly look at the fluoride issue more keenly. The committee concluded that preventive measures are required in such areas to ensure that fluoride in drinking water is reduced to acceptable levels of a maximum of 1.5 mg fluoride per litre in order to reduce health impacts caused by exposure to high fluoride levels in drinking water. The committee recommended that: • sensitization programmes should be conducted to educate water service

providers and the public on the dangers of consuming water with high fluoride concentrations, and the need to reduce the fluoride in drinking water;

• identify aquifers that contain water with low fluoride concentration; • appropriate threshold levels for various regions in Kenya should be

established; • a correlation of fluoride levels with geological formations be conducted;

• correlate fluorosis with other ailments • sources other than drinking water that contribute to fluorosis in Kenya be

identified; • a reference method for fluoride testing be established. • rainwater harvesting and use should be encouraged; • public awareness/education at all levels should be implemented on available

defluoridation methods; • defluoridation should be used whenever ground water sources meant to

supply water for drinking purposes are found to contain excess fluoride levels;

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• a surveillance system be established to involve all the water sector players that currently collect water quality data

• regulation and monitoring should ensure that fluoride in drinking water

complies with appropriate drinking water standards while at the same time reflecting the realities on the ground;

• a comparison be conducted of available surface and ground water total

quality (hygiene, heavy metals, nitrates, fluorides etc) to ensure the safety and health of consumers;drinking and cooking water policies, strategies and legislation in relation to quality and safety standards be developed and implemented

WAY FORWARD To ensure the supply of water of acceptable fluoride levels for drinking water and to create awareness of required fluoride levels in water; there is a need to: • Establish and implement a programme for certification and identification of

drinking water supplies (boreholes, kiosks, transporters etc) based on drinking water standards

• Review the Kenya Standard on drinking water to reflect prevailing local fluoride levels in ground water versus other available water sources;

• Develop a Code to guide abstractors and water suppliers to comply with

requirements for fluoride and other quality standards in drinking water. This should capture all the regulatory roles and permit issuance conditions required in the water chain from abstraction to consumption; physical identification of water service providers complying standards and recommendations for use of suitable defloridation methods

• Establish a national water source Fluoride Surveillance Group (FSG) led by the Ministry of Water and Irrigation. and managed by the Water Services Regulatory Board, with representatives from the Water Resources Management Authority (WRMA), National Water Conservation and Pipeline Corporation (NWCPC), Kenya Army Engineers, registered Drilling Contactors, Government Chemist / accredited labs, Water Service Boards, Water Service Providers, Community Water Projects, Kenya Water Industry Association (KWIA), Qualified Water Resource Professionals, academia and the Catholic Diocese of Nakuru, and KEBS to draw up and implement a fluoride surveillance system.

• Establish a reference testing method to ensure accuracy and consistency of results from various laboratories;

• Sensitise the public and service sector on the need to reduce fluoride in water

and available defluoridation methods.

• Advocate for establishment and increased use of rainwater

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CHAPTER ONE

INTRODUCTION

The Consultative Committee on Excess Fluoride in Water was established by the Kenya Bureau of Standards in November 2009 in response to growing public concern over excess fluoride in drinking water. Liaison between key stakeholders in the water sector was needed to identify common approaches to reducing fluoride in drinking and cooking water and to “own” the intervention process. Membership of the Committee covered public and private sectors, and ranged from line ministries and parastatals to academia and Civil Societies Organizations (CSO). It is estimated that about 25-30 million people in about 150 districts in India are suffering from varying grades of fluorosis. Globally, it has been reported that apart from India, there are about 20 other developed and developing nations which have come under the threat of fluorosis. These are Argentina, USA, Morocco, Algeria, Libya, Egypt, Jordan, Syria, Turkey, Iraq, Iran, Pakistan, Kenya, Tanzania, South Africa, China, Australia, New Zealand, Japan and Thailand. In Indian subcontinent, a total of 15 states have been declared endemic for fluorosis. Gujarat is one of the most severely affected states in the country considered to be endemic to fluorosis, where about 18 out of a total of 19 districts are prone to fluorosis due to high fluoride content in drinking water (Barot V, 1998).

The fluoride concentration range associated with the least prevalence of fluorosis in Ghana was 0.4-0.8 mg/l. Higher fluoride concentrations and age were associated with higher prevalence and severity of fluorosis. Children who drank water from boreholes had higher prevalence of fluorosis than those who used wells (Anongura R. et al)

The data from West Africa is consistent with the findings of occurrence and exposure to fluoride in Kenya above. It was concluded that fluorosis was of clinical and public significance. The prevalence of fluorosis was higher among children using boreholes. Correlations were also found between severity of fluorosis, fluoride concentrations and age of individual. (Anongura R. et al)

It was found out that Kenya is within the global fluoride belt. Available data from the Ministry of Water and Irrigation and studies undertaken within the country indicate that there exists high fluoride in some water sources in the country and incidences of dental fluorosis found follow the same pattern of high fluoride in the country. Therefore, preventive measures are required to ensure that fluoride in drinking water is reduced to acceptable levels of a maximum of 1.5mg F/l in order to reduce health impacts caused by exposure to high fluoride levels. It was also found out that surface and rainwater have the lowest fluoride levels and boreholes are among the sources with high levels of fluoride in water.

The Consultative Committee’s Terms of Reference were as follows: i) Review fluoride levels in water sources in ii) Incidence of fluorosis in Kenya iii) Review defloridation methods iv) Review of legal framework in water management

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CHAPTER TWO

FLUORIDE IN WATER SOURCES

2.1 Surface water The territorial area of Kenya is 582,646 Km2 with 11,230 Km2 (1.927%) under surface water while the rest 571,416 Km2 (98.073%) on land. 85% of the land area is classified as Arid and Semi Arid Land (ASAL) therefore making the only remaining 15% sustain more than 75% of the population. The average annual water available is 20.2 billion m3 which corresponds to 647 m3 per person per year. This classifies Kenya as a water scarce country since it falls way below the 1,000 m3 per person per year threshold.

Water Act 2002, the ultimate Kenya’s recent water legislation document has provided for the management of water resources including potential ones in the hands of Water Resource Management Authority (WRMA). The Act defines areas from which rainwater flows into a watercourse as a catchment area. The country has been divided into six catchment areas that are based on the hydrological boundaries, comprising of six major drainage basins.

The Authority does register and license all water users through its six Regional Offices. It also does register boreholes that are sunk in these areas thereby putting under one roof the total output of water in the country. The six drainage basin areas (see Annex 1) are:

i. Lake Victoria North Drainage Basin ii. Lake Victoria South Drainage Basin iii. Rift Valley Drainage Basin iv. Athi River Drainage Basin v. Tana River Drainage Basin vi. Ewaso Ng’iro North Drainage Basin

2.2 Ground Water Boreholes are sunk for various purposes and reasons. They are sunk in ASAL areas where surface water scarcity is severe, for industrial use, for irrigation and for emergency supply where water demand outstrips the surface water supply as in recent past in urban areas of Nakuru, Nairobi, Kiambu just to mention a few. There are about 16,000 registered boreholes throughout the country with 4,000 of them in Nairobi province alone as indicated by the MOWI, data base of 2002. Although the borehole data base is yet to be updated, there is a high percentage of unregistered boreholes in the country. As a whole, the borehole occurrence distribution density takes the population density pattern of the country.

The total output of borehole water in the country is not very well defined as boreholes dry up with time due to none recharging of the aquifers, while others are sunk illegally. In the recent drought period of 2008/2009, most water service providers in various towns including the City of Nairobi, invited water vendors to supplement their over stretched water supply. Most of them sourced water from boreholes across the city, which though registered they would not been authenticated. This brought into sharp focus the quality of water from boreholes with respect to geological formations. Nakuru area too for example has a water supply of 45,000 m3 with only 6,000-10,000 m3 being surface water, the rest 80% is sourced from boreholes. The dilution effect of high fluoridated water from boreholes therefore cannot be realised with this scarcity of surface water.

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2.2.1 Review of Existing Data Data is available on fluoride levels in water, its distribution, incidents of fluorosis and other sources of fluoride in the diet from 1953-2009. GIS mapping of fluoride distribution and done by the Ministry of Water and Irrigation (MoWI) provide coordinates that enable mapping of fluoride levels in Kenya. The mapping provides fluoride distribution up to district level as indicated in Annex 2 and Table 1.

References included in this report provide data on levels of fluoride in water, incidents of fluorosis and fluoride intake in foods from isolated areas of study (Njenga, 1982, Manji, F et al 1986, Gikunju et al, 1992, Njenga, 1994, Njenga et al, 2005, Gikunju et al, 1995, Bailey et al 2006, Chibole, 1987, Neurath, 2005, Nyaora et al, 2001, Kahama et al, 1997, Nielsen, 1999). Data on fluoride situation in other countries is also well provided for by a World Health Organization (WHO) document (Bailey et al, 2006) and other studies (Neurath, 2005, Anongura R. et al).

2.2.2 Fluoride Mapping

The geographical distribution of fluoride in water from drilled boreholes indicates that 96% of the boreholes in the Lake Region, Western, and Coast regions have fluoride of < 1.5 mg F/l (Njenga, 1982). The areas with at least 50% of boreholes with fluoride levels of >1.5 mg F/l are Baringo, Kajiado, Kericho, Laikipia, Nairobi, Nakuru, Narok and Thika. Whereas these areas are known to have water with high levels of flouoride, there are pockets of water with < 1.5mg F/l (See table 1).

Most surface water provided within the country is less than 1.5mg F/l except in some parts of Koibatek and Baringo, Laikipia, Samburu, Turkana, Nandi, Siaya and Marsabit The high concentration of fluoride in water in Nakuru-Koibatek-Baringo cover the fluorspar deposits in Kenya which agrees with a study that indicated that high fluoride areas tended to coincide with geographic locations of volcanic rock in and around the Rift valley region (Manji, F et al, 1984) See Annex 3 surface water fluoride mapping. Water entering Lake Magadi has been reported to have high levels of fluoride 73 mg/l which concentrates to 140 mg/l over a stretch of 400m due to the heat in the area (Gikunju et al, 1992).

2.3 Incidences of Fluorosis Studies in Kenya have established that a greater population in most parts of the country is susceptible to fluorosis from high levels of fluoride in drinking water and other beverages (Njenga, 1994, Njenga et al, 2005, Gikunju et al, 1995, Bailey et al 2006). As early as 1953, studies by Neivell and Brass reported that 30% of European children aged 7-14 years living in Kenya were suffering from dental fluorosis as a result of high fluoride in drinking water. Chibole in 1987 examined representative sample of people (N = 34,287) from all provinces of Kenya and reported high fluorosis incidences (all degrees) amongst the population ranging from 11.7% to 56.5%. He found out that this corresponded closely to drinking water fluoride levels (Chibole, 1987). It has been reported that fluorosis may be a more accurate indicator of bone exposure to fluoride during childhood than levels of fluoride in drinking water. It is probably a more accurate reflection of total fluoride intake and it may also reflect individual susceptibility to fluoride absorption (Neurath, 2005).

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A study conducted on 102 children born and brought up in an area of rural Kenya with 2 ppm fluoride in drinking water for dental fluorosis using the index developed by Thylstrup and Fejerskov (1978) showed the prevalence of dental fluorosis was 100%, 92% exhibited a TFI score of 4 or higher, and 50% of the children had pitting or more severe enamel damage in at least half the teeth present. The high prevalence and severity of dental fluorosis in a 2 ppm fluoride area confirmed other studies on dental fluorosis being very prevalent in Kenya, even in low-fluoride areas of less than 1 mgF/l (Manji F et al, 1986).

In other studies conducted at Njoro Division and Lake Elementaita areas of Nakuru District, examination of children's teeth, showed that 48.3% and 35% respectively, of the children suffer from moderate to severe dental fluorosis (Nyaora et al, 2001, Kahama et al, 1997,).

In 2005, the Fluoride Action Network using study reports conducted independently showed that there may be a correlation between dental fluorosis incidences and osteosarcoma in Kenya. They compared this with fluoridation and osteosarcoma in Malayasia (Neurath C et al, 2005).

Magadi soda, trona, contains fluoride, in form of villiaumite, NaF, kogarkoïte, Na2SO4·NaF12,13, and the concentration varies considerably. Studies have shown that the use of Magadi heavily contaminated with fluoride contributes to the high fluoride intake in fluorosis areas of East Africa. In fact, in some cases the fluoride uptake from Magadi may be higher than that from water (Nielsen, 1999).

The fact that fluoride is widely dispersed in the environment, all living organisms are extensively exposed to it and tolerate it in modest amounts. In human, overexposure of fluoride results in accumulation of the element in the mineralizing tissues of the body. The symptoms become visible even with small exposure. In young people, fluoride accumulates in both teeth (dental fluorosis) and bones (skeletal fluorosis) while in older people overexposure of fluoride causes skeletal fluorosis only. (Naslund J, 2005)

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CHAPTER THREE

DEFLUORIDATION METHODS

3 EXISTING TREATMENT TECHNOLOGIES

This Chapter reviews existing fluoride treatment technologies; assesses the level of awareness of each of these in Kenya; and makes recommendations regarding which are most suitable in the Kenya context. In choosing a technology suitable for the Kenya context, we must consider: – • Efficiency: can defluoridation be achieved to acceptable levels? • Possible negative impacts, such as the consequences of wrong dosing of

chemicals, possible chemical residuals in treated water, etc • Simplicity against complexity • Cost of defluoridation methods (both plant investment, and running costs) • Scale of defluoridation / scale of service. 3.1 Review of fluoride removal technologies Table 1 at the end of this section summarises the sub-sections that follow. We have considered the following methods: – • Aluminium sulphate (alum) • Lime softening (calcium hydroxide) • Alum plus lime (the “Nalgonda” process) • Gypsum plus fluorite • Activated carbon • Plant carbon • Zeolites • Defluoron 2 • Clay pots, earths and clays • Activated alumina • Bone • Bone char • Bone char and dicalcium phosphate (contact precipitation) • Ion-exchange • Bonechar and dicalcium phosphate • Mixing fluoride-rich and low fluoride waters • Find an alternative water source • Electrodialysis (ED/EDR) • Reverse osmosis (RO) • Distillation (solar distillation) We also discuss – briefly – up-to-the minute technologies (cf. IGRAC 2007), more to ensure full coverage of the field than to select one or more of these as an appropriate technology for use in Kenya. Methods That Use Chemical Precipitation Processes 3.1.1 Aluminium sulphate (alum) Description of method: at high concentrations, aluminium sulphate (Al2(SO4)3.18H2O) induces flocculation, which precipitates fluoride ions (amongst

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others). The application rates required are high, and as a consequence residual aluminium (Al) and sulphate (SO4

2-) may exceed the Kenya Standard. Effectiveness and interferences: • > 90% fluoride removal (IGRAC 2007); • 150 mg per mg of fluoride removed 1; • No interferences reported. Scale of use: from POU to large-scale. Pre-treatment: None required. Operation and maintenance: low levels of input required. Wastes: substantial volumes of sludge. Advantages: • Simplicity; • Effectiveness. Disadvantages: • Generates sludge, which must be disposed of carefully; • Treated water quality may exceed national standards for aluminium and

sulphate; • Relatively high application rates require large amounts of alum, which has

cost and sludge volume implications. 3.1.2 Lime softening (calcium hydroxide) Description of method: lime softening to remove fluoride only works if the raw water contains sufficient magnesium (Mg), as it is the magnesium that adsorbs the fluoride; if necessary, magnesium sulphate (MgSO4) may be added to raise the magnesium concentration. Lime softening is a two-stage process: first, calcium hydroxide (Ca[OH]2) is added to the water until the pH reaches about 10; this precipitates out carbonate hardness. The second stage requires the addition of sodium carbonate (Na2CO3), which precipitates out non-carbonate hardness. Effectiveness and interferences: • Fluoride removal effectiveness improves with higher temperature; • 30 mg lime per mg of fluoride removed; • Removal efficiency >90%; • Will not works without magnesium ions to flocculate; • May require pH adjustment and re-carbonation after the floc is removed. Scale of use: from POU to large-scale. Pre-treatment: none required. Operation and maintenance: low level of technical input required at POU level; some technical inputs required for community and large-scale plant. Wastes: sludge is generated. Advantages: • Established process, proven and reliable

1 This means that 150 mg of alum is required to remove 1 mg of fluoride

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Disadvantages: • Requires technical staff to oversee the process; • Sludge is generated, which needs to be disposed of. 3.1.3 Alum plus lime (the Nalgonda process) Description of method: The Nalgonda process was developed in India for use at the household and community level, and is in widespread use there; it has also seen extensive application in Tanzania. The Nalgonda process is aluminium sulphate-based coagulation-flocculation sedimentation; the dosage rate must be designed to ensure fluoride is removed from the target water (IGRAC 2007). There are numerous studies of the Nalgonda process, both in India (e.g. Nawlakhe et al 1975) and in Tanzania (e.g. Gumbo et al 1995). We have not reviewed these in detail. Effectiveness and interferences: said not to be very high performing (IGRAC 2007); especially when raw water fluoride concentrations are high, residual fluoride in treated water may exceed 1 mg/ℓ: – • In extensive use in India, where its current form was developed by the

National Environmental Engineering Research Institute in Nagpur, India; • 150 mg of alum + 7 mg of lime per mg of fluoride removed; • Removal efficiency 70 to 90% (IGRAC 2007); • Alum application rates may exceed typical water treatment works application

rates for turbidity removal by as much as twenty times (Mjengera et al 2002); • There is evidence that the Nalgonda method is less suitable for removing

fluoride from waters with high dissolved fluoride (<10 mg/l: Mjengera et al 2002), than bonechar defluoridation.

Scale of use: as point-of-use: 20 to 60 litres per mixing cycle; in a small community or institutional filter: 10 to 100 litres per hour; at water treatment works level (megalitres per hour). Pre-treatment: none required; any turbidity in the natural water will be removed by coagulation. Operation and maintenance: at the POU scale none, apart from small-scale, local disposal of the sludge; at the community and water works scale some technical inputs are required as well as more formalised sludge treatment and disposal. Wastes: sludge is generated. Advantages: • Proven and reliable (but not so, based on Meekanshi et al 2006 field

experiences); • Cheap. Disadvantages: • Removal efficiency is limited, so may be unsuitable in areas with very high

fluoride (IGRAC 2007); • Treated water quality may exceed national standards for aluminium and

sulphate; • Requires technical staff to oversee the process when carried out at community

scale; • Sludge is generated, which needs to be disposed of; in cases where large

doses of alum are required, sludge may become a significant disadvantage.

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At least two commentators are critical of the Nalgonda process: Meekanshi et al 2006 listed the following limitations: – • Field experience shows that the process removes a relatively small proportion

of fluoride (18–33%) in the form of precipitate, while converting a larger proportion of ionic fluoride (67–82%) into soluble aluminium fluoride complex ions, which are not removed;

• The soluble aluminium fluoride complex is itself toxic; • The use of alum increases sulphate concentration in treated water, which may

exceed national standards (the Kenya Standard specifies 400 mg/ℓ: KEBS 2007).

• Residual aluminium may also exceed national standards (the Kenya Standard specifies 0.1 mg/ℓ: KEBS 2007).

• The treated water may have a taste that users find unacceptable. • Regular analysis of raw water is required to ensure that the correct dose of

alum and lime. • In the field, the maintenance cost of plant is moderately high: a 10,000 ℓ/d

plant costs about KShs. 5,000 per month in maintenance (2006 cost in Indian Rupees, March 2010 KShs. exchange rate).

• The process requires a regular plant attendant for addition of chemicals and looking after treatment process – it is not automated at the community level.

• Sludge treatment (drying) requires relatively large areas of land. • Silicates have an adverse effect on defluoridation by the Nalgonda method. Narayana et al (2004) noted that 14 of 15 large-scale Nalgonda defluoridation constructed in Nalgonda District in India were not in use, concluding that “… previous attempts to solve the fluorosis problem in Nalgonda by using the alum precipitation technique have been of little success”. 3.1.4 Gypsum plus fluorite Not much info available. Description of method: gypsum (CaSO4) plus fluorite (CaF2) Effectiveness and interferences: • It is reported that 5 mg of gypsum + 2 mg of fluorite will remove 1 mg of

fluoride (IGRAC 2007) • It is not considered terribly efficient (IGRAC 2007); • It is not pH-dependant; • Treatment may result in CaSO4-rich water that may not be acceptable to

consumers on taste grounds. Advantages: • Simple; • Low to medium cost. Methods that use adsorption processes Adsorption is a chemical process in which molecules “stick” to a surface or substrate due to forces of attraction on that surface or substrate. 3.1.5 Activated carbon Description of method: activated carbon (in various final forms) can remove fluoride by adsorption at low pH levels (≈3), meaning that first the raw water

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must be acidified, and after defluoridation its pH must be raised to ≈7. It is better at removing trace metals and inorganic compounds, and is not fluoride-selective. Rao (2003) reported that paddy husk carbon is an efficient defluoridating agent; paddy husk carbon, alkali-digested with 1% KOH & soaked in 2% alum removed 320 mg of fluoride per kg of carbon, and showed maximum removal efficiency at pH 7.0. Effectiveness and interferences: • Removal efficiency >90% (IGRAC 2007); • Efficiency highest at low pH. Scale of use: from POU (as cartridge filters) to water treatment works scale. Pre-treatment: works best at pH of 3, so pre-treatment and post-treatment are required, with the cost implications of doing so (Meenakshi et al 2006). Note however the method cited above by Rao (2003), which does not appear to be pH-dependant. Operation and maintenance: operational inputs are nil at the POU level; if powdered activated carbon (PAC) is used in community level or larger treatment plants, technical inputs will be needed in dosing and filtration. Wastes: spent activated carbon (either as loose media or expended cartridges) will require careful disposal. Advantages: • Simplicity of use. Disadvantages: • Relatively high cost; • Numerous interferences; • Requires medium operator skill, except at the POU level. 3.1.6 Plant carbon Plant carbon is able to remove up to 300 mg of fluoride per kg (IGRAC 2007), but has one obvious disadvantage in Kenya – while plant carbon as wood is widely available, the demand for wood as cooking fuel or as raw material for charcoal may make this method unworkable. Wood must be pre-treated by soaking in potassium hydroxide (KOH). We have been able to find out relatively little about this method, and consider it no further here. 3.1.7 Zeolites Zeolites are a fairly large group of hydrated aluminium silicate minerals, with varying proportions of sodium, calcium, aluminium, silica and oxygen. They form in cavities and fractures of volcanic rocks (basalts and other lavas), for example: – • Heulandite: Ca(Al2Si7O18).6H2O • Chabazite: CaAl2Si4O12.6H2O • Natrolite: Na2Al2Si3O10.2H2O Zeolites can be dehydrated and rehydrated without changing their structure, and with suitable pre-treatment can be used to remove fluoride from water at relatively useful rates (100 mg fluoride per kg of zeolite; IGRAC 2007). However,

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we do not know of any application of zeolites in defluoridation in Kenya; and although the geology of Kenya is likely to include zeolite deposits, we do not consider zeolite-based fluoride removal methods further. 3.1.8 Defluoron 2 Description of method: defluoron-2 is prepared from bituminous coals by partial sulphonation, and works by adsorption-complexation in a reversible reaction. The method is sensitive to alkalinity, with reduced fluoride removal capacity at higher pH values. It is regenerated with 4% alum solution (Akinosi et al 1972). Effectiveness and interferences: • Appears to be an effective, but not widely-used, method; • 150 to 650 mg fluoride removal per litre of media (raw water fluoride 8 to 12

mg/ℓ, alkalinity 160 to 900 mg/ℓ as CaCO3); Scale of use: unknown – a design was prepared for treating Arusha municipal water supply using defluoron-2 as a formal water treatment plant component; fluoride was to be reduced from 5 – 7 mg/ℓ to ≈1.0 mg/ℓ, with treatment rates of 5.5 m3 water/d per m3 of media (op. cit.). Pre-treatment: none, unless source water is significantly turbid: sediment will clog the filter media. Operation and maintenance: at water works scale requires plant operator management (for regeneration). Wastes: regeneration wastes need appropriate disposal. Advantages: • Relatively simple, but requires some technical supervision: not suitable as a

community-level system without a plant operator. Disadvantages: • Apparently little-known and little-used; • Availability of defluoron-2 in Kenya unknown; • Costs unknown. 3.1.9 Clay pots, earths and clays Some clay (both fired and unfired) and earths have fluoride adsorption capacities which have been experimented with at various stages in the past by a number of researchers. In a general review of defluoridation, Dahi noted that a wide variety of natural materials had been tested for their defluoridation potential, including “magnesite, apophyllite, natrolite, stilbite, clinoptilolite, gibbsite, goethite, kaolinite, halloysite, bentonite, verimiculite, zeolites, serpentine, alkalkine soil, acidic clay, kaolinitic clay, China clay, aiken soil, Fuller’s earth, diatomaceous earth and ando soils” (Dahi 2000). These minerals all contain metal compounds with hydroxyl groups (OH-), which can exchange F- under suitable conditions. These materials all have a natural adsorption capacity, but this can be improved by activation (typically by drying, acidification or calcinations). Dahi concluded that these materials do not offer a comprehensive defluoridation solution, but in areas where they are readily available at little or no cost, they could be used either as a flocculant additive as

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a powder or in columns as calcined clay or brick. Media can be regenerated, but more often they are discarded and fresh media used. Padmasiri (2000) noted that burnt brick chips in a simple VLOM domestic column defluoridation system could lower fluoride from 2.14 to 1.2 mg/l F-, a removal efficiency of 57%. Kenyan andosols (soils derived from igneous rock and ash) are reported to have significant defluoridation properties, though this is by no means certain: Dahi (2000) notes that one study concluded that Kenyan andosols had a defluoridation capacity of 5.5 mg/g, while a second concluded that it only had a capacity of 0.2 mg/g under field conditions. In the absence of specific Kenyan experience relating to soils from a know location, we do not examine andosols further, though we recommend that further research into this avenue be encouraged. 3.1.10 Activated alumina Description of method: activated alumina is an extremely porous media made by passing oxidising gases through alumina at very high temperatures. This “activation” process produces the fine pores that result in excellent adsorption properties. Typically, the water to be treated is passed through a cartridge, canister or vessel of activated alumina, which adsorbs the contaminants. Activated alumina is the most successful and most used adsorbent for fluoride removal in developed countries. Effectiveness and interferences: the effectiveness of adsorption depends on a number of factors: – • Physical properties of the substrate (method of activation, pore size

distribution, surface area); • Chemical composition and concentration of contaminants, such as size,

similarity, and concentration; • Temperature and pH – adsorption typically increases as temperature and pH

decrease; • Flow-rate and exposure time to the substrate. Other features: – • Best Available Technology in the USA, because of its highly selective fluoride

removal; • Technical management is required; • Media is lost during each regeneration, and at pH less than 6; • Sensitive to high TDS waters, which foul the media bed; phosphate, carbonate

and sulphate are competitor ions (Meenakshi et al 2006). Activated alumina can remove between 500 and 800 mg/ℓ F- per litre of substrate, depending on pH and temperature. A recent paper (Schoeman 2009) describes the practical application of an activated alumina plant in rural South Africa able to treat 200 m3/d, with a capital cost of KShs. 12.4 million and an O&M cost of KShs. 7.2/m3 (March 2010 exchange rates). Small-scale activated alumina plant – suited to the domestic/small institutional user – are available as cartridge-type systems at costs that range from KShs. 6,200 (total removal capacity 10,000 mg/l fluoride) to KShs. 17,600 (removal

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capacity 20,000 mg/l fluoride); these are the costs of cartridges and filter bodies alone, and exclude VAT and other miscellaneous installation costs. Scale of use: activated alumina treatment can be applied at all scales, from POU to high-volume application for formal water treatment at community scale. Activated alumina plant includes pour-through for treating small volumes; tap-mounted devices for POU treatment; in-line devices for treating large volumes to several taps; and high-volume commercial units for treating community water supply systems, with by-pass and re-activation processes. However, careful selection of the activated alumina to be used is based on the contaminants in the water and manufacturer’s recommendations – there is an element of design required. Pre-treatment: if the raw water is contaminated with bacteria or contains suspended solids, it is advisable to filter and disinfect the water before subjecting it to activated alumina treatment. Operation and maintenance: to ensure that fluoride removal occurs, careful monitoring and testing is required, according to the plant manufacturer’s specification. When the substrate no longer removes fluoride, it must be replaced. Cleaning with the appropriate regenerant will extend the life of the substrate. Flushing is necessary if the plant is not used for several days, and backwashing may prevent or reduce bacterial growth. Wastes: if backwashing or flushing takes place, care needs to be taken over disposal of the waste. Spent media must also be disposed of responsibly. Advantages: • Technically feasible – simple operation • Economically viable • Efficient – 1.4 g fluoride removed per 100 g of product (Azizian 1993) • Suitable for home use, typically inexpensive, with simple filter replacement

requirements. • Improves taste and smell; removes chlorine. Disadvantages: • Careful selection and plant design is required • Effectiveness is based on contaminant type, concentration, and rate of water

usage • Bacteria may grow on alumina surface, so pre-treatment may be required • Monitoring is required. 3.1.11 Bone Degreased and alkali-treated bones are reported to be effective in removing fluoride from waters containing fluoride 3.5 mg to 10 mg/ℓ fluoride, to less than 0.2 mg fluoride/ℓ (Rao 2003). According to IGRAC (2007), this method is able to remove up to 900 g per m3 of substrate. As we have not encountered any references to the use of alkali-treated bone for defluoridation in Kenya, we have considered this method no further. 3.1.12 Bonechar Description of method: bonechar’s ability to defluoridate water has been known for decades (Maier 1947), though it has only relatively recently been applied at

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the practical level in Kenya (since the late 1990s: Korir et al 2009). It may be superseded by the hybrid process described in Section 3.1.14 below. Effectiveness and interferences: • Bonechar alone can remove 1.2 mg/ℓ of fluoride per gramme of media (Korir

et al 2009); • Less retention time required than the hybrid process (see S. 3.1.14 below). Scale of use: thus far, POU to community scale; can be scaled up to hundreds of m3/d. Pre-treatment: none, though significant turbidity will clog filters. Operation and maintenance: minimal, although routine monitoring is recommended for assessing the onset of breakthrough. Regeneration requires technical inputs not available at community level. Wastes: regeneration wastes (from bonechar regenerated by NaOH) need appropriate disposal. Advantages: • Effectiveness; • Simplicity in day-to-day operation; • Based on materials that are readily available locally; • Cheap. Disadvantages: • The use of bonechar may be unacceptable to some communities or cultures,

though Kenyan experience to date suggests general acceptability; • No longer manufactured by the CDN (see S. 3.1.14 below – bonechar and

dicalcium phosphate), though could be re-introduced. 3.1.13 Ion-exchange Ion exchange for soluble fluoride uses charged anion resin to exchange acceptable ions from the resin for dissolved fluoride in the water. The resins provide exchange sites that hold receptor metal ions (usually calcium) that release other anions (typically chloride) and take up fluoride ions. The effective fluoride capacity of such resins is relatively poor compared with other methods. Hybrid Methods 3.1.14 Bonechar and dicalcium phosphate (contact precipitation) Description of method: the bonechar and dicalcium phosphate hybrid process (commonly referred to as contact precipitation) has been developed by the Catholic Diocese of Nakuru over the past few years, and has shown considerable potential for removing fluoride. CDN’s own tests and analysis show that it removes nearly three times as much fluoride, weight for weight, as bonechar alone (Korir et al 2009). Dicalcium phosphate (CaHPO4.2H2O: DCP) pellets are coated with a layer of calcium carbonate to ensure the slow release of the co-precipitation element of the process. DCP extends the bonechar’s ability to adsorb fluoride ions, leading to longer filter life. Members of the Committee visited three Catholic Diocese of Nakuru hybrid defluoridation plants in the Naivasha area. These showed effective defluoridation,

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but this was accompanied by significant increases in pH and dissolved phosphorus. Effectiveness and interferences: • Approximately three times as effective as bonechar alone; 3.4 to 3.7 mg

fluoride removed per gramme of substrate, as against 1.2 mg fluoride removed per gramme for bonechar alone (Korir et al 2009);

• Requires longer retention time than bonechar alone. Scale of use: thus far, POU to community scale; the potential exists to upscale to hundreds of m3/d. Pre-treatment: none, though significant turbidity will clog filters. Operation and maintenance: minimal, although routine monitoring is recommended for assessing the onset of breakthrough. Regeneration processes are not yet fully understood, though they will involve regeneration of the bonechar element and replacement of DCP pellets. Wastes: regeneration wastes (from bonechar regeneration by NaOH) need appropriate disposal. Advantages: • Effectiveness; • Simplicity in day-to-day operation; • Based on materials that are readily available locally; • Cheap (POU [15 to 50 ℓ/d] KShs. 2,500 to 8,000: community level [upto

500,000 ℓ/d] KShs. 800,000 to 3,000,000) (costs pers. comm. CDN 12th March 2010).

Disadvantages: • Lifetime of system not yet understood (though longer than bonechar alone); • Elapsed time before regeneration/replacement is required is uncertain; • Some soluble parameters are changed by the treatment process (e.g. total

phosphorus levels may exceed Kenya standard limits for –2.2 mg/ℓ as PO43-;

pH increases). • Water quality – taste and smell – is sometimes reported to be poor; this does

compromise the use of the filter (pers. comm. Mpala Ranch, 16th March 2010); this may require further post-treatment (e.g. activated carbon filtration);

• Perception by some groups that the use of animal bone for treating water is contrary to traditional and religious beliefs.

Other Treatment Methods 3.1.15 Mixing fluoride-rich and low fluoride waters Where dilution water is available, mixing is the cheapest and most appropriate method to use. However, in many contexts in Kenya it is not possible – all too often, a fluoride-contaminated borehole or spring is the only readily-available water source. Of course, where a low fluoride water is available for mixing, it is an appropriate approach (the Hilton Hotel is using this approach with great success). We do not consider this option any further, as it should be a self-evident option where low-fluoride water exists.

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3.1.15.1 Find an alternative water source As with dilution of high-fluoride water using low-fluoride water, using an alternative water source should be a self-evident measure where it is applicable; in most of water-scarce Kenya – especially where groundwater is the only immediately available water source – there are no alternative water sources. We do not discuss this any further, other than to make the point that rainwater harvesting remains an under-exploited water source across much of the country. The field visit conducted on 12th March 2010 found that at Kinungi, south east of Naivasha, the use of the CDN defluoridation plant was reduced because the community was relying on harvested rainwater; at that time, Kinungi was benefiting from unseasonal rain. 3.1.16 Electrodialysis Description of method: electrodialysis (ED) uses semi-permeable membranes to separate the dissolved solids from the water. The process is driven by electricity (typically 300 to 400 volt direct current), drawing positively charged ions to the cathode (-ve) and negatively-charged ions to the anode (+ve). It works in a similar way to reverse osmosis (see S. 3.1.18 below), except that instead of pressure as the driving force, it uses electricity. It has some marked advantages; membrane clogging by colloids and particularly silica compounds is not a problem, because reversing the polarity across the raw water removes potential clogging agents and discards them to waste (known as EDR). It also wastes less water than reverse osmosis – typically 85 to 94% of raw water is converted to treated water. All information provided herein was provided by General Electric, the inventors of EDR and the principal manufacturer of EDR plant. Effectiveness and interferences: • Undeniably effective, utilising an elegant solution to solute removal; • Requires some pre-treatment to remove iron (>0.3 mg/ℓ); manganese,

aluminium and hydrogen sulphide (>0.1 mg/ℓ); COD (>50 mg/ℓ as O2); TOC (>15 mg/ℓ); oil (>2 mg/ℓ);

• Tolerates free chlorine (0.5 mg/ℓ continuous, 30 mg/ℓ spike) and turbidity (0.5 NTU continuous, 2.0 NTU spike);

• Not sensitive to silica in raw water – no silica clogging of membranes; • With sufficient units (“stacks”), up to 94% of dissolved solids can be removed

from a raw water; • The maximum TDS that EDR can handle is 4,000 mg/ℓ. Scale of use: due to its modular layout, it can be utilised from POU to large-scale application. Pre-treatment: turbidity may need to be reduced, and if raw water is prone to precipitate solids, some pH adjustment or ion-exchange may be necessary. Operation and maintenance: complex, requiring trained specialised technicians and reliable power. Wastes: waste stream (brackish water) needs careful disposal. Advantages: • Proven technology, at all levels of scale; • For small-scale use, has a small footprint; • Less intensive monitoring is required than for reverse osmosis;

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• No concerns about chemical over-dosing or possible residuals in treated water, so no possible negative effects from chemicals.

Disadvantages: • Cost is very high (both capital cost and O&M); • Waste stream must be managed correctly; • Requires technical management; • Not designed specifically for fluoride removal; • Requires reliable and stable power. This technology is not in use in Kenya so far as we are aware, though there are potential suppliers. Indicative costs (EDR stacks only – excluding other required infrastructure and pre-treatment costs) are in the following ranges:– • 3.4 m3/hr, ≈68 m3/d: €40,000 (approx. KShs. 4.2 million) • 10.2 m3/hr, ≈200 m3/d: €60,000 (≈KShs. 6.3 million) • 51 m3/hr, ≈1,000 m3/d: €155,000 (≈KShs. 16.2 million) • 92 m3/hr, ≈1,850 m3/d: €219,000 (≈KShs. 22.9 million) We have not been able to obtain detailed information on operation and maintenance costs. We assume that they are less than given for reverse osmosis in Table 1 below. 3.1.17 Reverse osmosis (RO) Description of method: RO is a physical process in which a range of contaminants are removed by applying pressure on raw water to force it through a semi-permeable membrane. Removal and removal rate depends on ionic size and electrical charge. The raw water is called feed, the treated water is called permeate and the concentrated reject is called concentrate. A typical RO installation includes a high pressure feed pump, membrane elements in pressure vessels, valves, and feed, permeate, and concentrate pipework. Regular maintenance is essential. Membrane selection is based on cost, recovery and rejection, raw water characteristics, and pre-treatment. Membrane performance depends on raw water characteristics, plant pressure and temperature, and regular monitoring and maintenance. Effectiveness and interferences: provided the correct pre-treatment methods and the appropriate semi-permeable membranes are selected, interferences are few. Excessive turbidity and some natural contaminants (such as silica) can create problems. Scale of use: scale of use ranges from simple, single-membrane POU plant to very large scale industrial water treatment works. Pre-treatment: RO plant design requires a careful review of the raw water characteristics, to ensure that the appropriate pretreatment is carried out to maximise membrane life: membranes are susceptible to fouling, scaling and other membrane degradation. Suspended solids must be removed to prevent colloidal and bio-fouling, and removal of some species may be necessary to prevent scaling and chemical attack (in some Kenyan groundwaters for example, silica may co-precipitate with calcium carbonate to form a scale that is very resistant to removal – so silica removal may be required as a pre-treatment).

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Operation and maintenance: rejection percentage must be monitored to ensure fluoride removal to the levels required by national standards – a properly designed and maintained RO system should produce 80% permeate, 20% concentrate. Membrane performance must be monitored regularly for fouling, scaling, or other membrane degradation. Acidic or caustic solutions are regularly flushed through the system at high volume and at low pressure to remove fouling and scaling. The frequency of membrane replacement depends on raw water characteristics, pre-treatment and maintenance; typical large-scale installations in inland Kenya require membrane element replacement every three years or so. Wastes: Pre-treatment waste, concentrate and spent membrane elements require responsible disposal. Advantages: • Well-established; • Produces very high quality water; • Effective in removing a wide range of dissolved salts and minerals, turbidity,

health and aesthetic contaminants, and certain organics; • Low pressure, compact, self-contained, single membrane units are available

for POU applications. Disadvantages: • Very expensive to install and operate (almost all components are imported); • Expensive to operate (requires continuous electrical power); • Frequent membrane monitoring and maintenance is required; • Not fluoride-specific; • Sensitive to chlorine, and excessive silica; • Monitoring of rejection percentage is required to check for fluoride removal; • There may be rigorous pressure, temperature, and pH requirements to meet

membrane tolerances. This technology is fairly widespread use in Kenya, in industry, some horticulture and in the tourism sector. There are numerous suppliers: we contacted M/S Davis & Shirtliff, probably the most experienced of these, and obtained indicative quotations for a range of different volumes and water qualities, all to produce a water with fluoride >1.5 mg/ℓ, all excluding infrastructure and other costs, as follows: –

Table 1: Reverse osmosis – indicative costs

m3/d F- mg/ℓ

TDS mg/ℓ

pH Silica mg/ℓ

Mn mg/ℓ

Fe mg/ℓ

Costs KShs (excl. VAT) Capex O&M

per m3 15 38 1300 8.2 120 0.1 0.1 2,332,000 58.4 30 12 750 ≈7 60 0.1 0.1 2,876,000 43.5 130 7 750 ≈7 60 0.1 0.1 5,745,000 44.2 300 6 750 6.2 60 4.0 1.3 7,731,000 45.7 500 16 500 7.2 60 0.1 0.1 8,937,000 32.91

NOTE: for the above, typical maximum recovery 75%, rejectate 25%. High silica water treatment system does not include pre-treatment for silica reduction. For most of these systems, assume membrane replacement every 2 to 3 years (less for high silica water).

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Domestic-scale reverse osmosis plant is available from the same supplier; cost ranges are as follows (excluding VAT and other miscellaneous costs): – • 12 ℓ/hr: KShs. 21,800 • 24 ℓ/hr: KShs. 51,300 • 100 ℓ/hr: KShs. 61,000. 3.1.18 Distillation (solar distillation) Description of method: Distillation is the physical process that uses heat to convert water to steam, which is condensed in a condenser coil. Dissolved solids remain in the water that is left behind. For both environmental and cost reasons, this form of distillation is inappropriate for widespread application in Kenya (though it could perhaps be used to treat seawater using waste heat generated by the Mombasa fuel refinery, for example). In the Kenya context, solar distillation is, however, an appropriate method in areas where land is readily available and where there is reliable sunlight. A simple solar still is nothing more complex than a more-or-less sealed box with a roof that transmits the energy in sunlight: either plastic or glass roofs are appropriate. The roofs are pitched gently, so as to catch condensed moist air and allow it to drain into gutters along the edge of the roofs, into supply. Effectiveness and interferences: • The method is straightforward and effective, apart from its need for land and

insolation; • It is relatively cheap provided land and insolation are both available; a typical

solar still can generate 5 litres of fresh water per square metre of still in the right solar environment;

• There are no interferences, though a measure of security may be needed to prevent the theft of glass or plastic roof elements;

• Waste water – water left behind is high in dissolved solids, and may need to be disposed of with care;

Scale of use: from POU to large-scale (if land is available). Pre-treatment: none required. Operation and maintenance: brine should be discarded periodically to prevent salt deposition and crystallisation. Wastes: waste brackish water. Advantages: • Simple and low-tech; • Minimum maintenance, no requirement for technical inputs. Disadvantages: • Requires both significant land areas and reliable solar radiation; • Output per unit area small (e.g. the Water Pyramid with an area of 600 m2

produces up to 1,250 litres a day, or 2.1 litres per m2/d: Aqua-Aero Watersystems BV nd).

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New Technologies 3.1.19 IGRAC (2007) new technologies During the literature review conducted for this report, two completely new technologies were encountered (IGRAC 2007). We briefly describe these, for the sake of completeness. Contact precipitation using a Crystalactor® is able to remove fluoride from fluoride-rich waters (>10 to 20 mg/ℓ). It produces calcium fluoride pellets as the waste product, and is reported to be 25% the cost of conventional precipitation methods. Membrane distillation using the Memstill® process uses a combination of flash distillation and membrane filtration (osmosis) to desalinate water. It is reported to do so at a cost that is lower than reverse osmosis or distillation.

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Table 2: Methods of removing Fluoride from water

Removal method

Removal capacity per dose

Working pH

Interferences

Advantages Disadvantages Relative cost

Precipitation

Alum (aluminium sulphate)

150 mg/mg F-

Non-specific

- Established process

Sludge produced; treated water is acidic; residual Al present.

Medium – high

Lime 30 mg/mg F- Non-specific

- Established process

Sludge produced; treated water is alkaline.

Medium – high

Alum + lime (‘Nalgonda’ process)

150 mg alum + 7 mg lime/mg F-

Non-specific, Optimum 6.5

- Low-tech; established process

Sludge produced; high chemical dose; residual Al present.

Medium – high

Gypsum + fluorite

5 mg gypsum + < 2 mg fluorite/mg F-

Non-specific

- Simple

Requires trained operators; low efficiency; high residual Ca, SO4.

Low – medium

Adsorption/ion exchange

Activated carbon

Variable < 3 Many - Large pH changes before and after treatment.

High

Plant carbon

300 mg F- /kg 7 - Locally available

Requires soaking in potassium hydroxide (KOH).

Low – medium

Zeolites 100 mg F-/kg Non-specific

- Poor capacity. High

Defluoron 2 360 g F-/kg Non-specific

Alkalinity

Disposal of chemical used in resin regeneration.

Medium

Clay pots 80 mg F-/kg Non-specific

- Locally available

Low capacity; slow. Low

Activated alumina

1200 g F-/m3 5.5 Alkalinity

Effective; well-established

Needs trained operators; chemicals not always available.

Medium

Bone 900 g F-/m3 >7 Arsenic Locally available

May give taste; degenerates; not universally acceptable.

Low

Bone char 1000 g F-/m3 >7 Arsenic Locally available; high capacity

Not universally accepted.

Low

Ion-exchange using resins

Variable Non-specific

- Locally available

Not known to be available in Kenya

Low - medium

Hybrid methods

CDN hybrid 3.4-3.7 mg F-

/g > 7

Alkalinity

Locally available; high capacity

pH of treated water high; dissolved phosphorus high

Medium

Other methods

Mixing Variable Non-specific

Water chemistry

Simple Requires other low fluoride water source

Variable

Find N/a N/a N/a Simple. Cost Very high

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Removal method

Removal capacity per dose

Working pH

Interferences

Advantages Disadvantages Relative cost

alternative water source

Electrodialysis

High Non-specific

Turbidity

Can remove other ions; used for high salinity waters

Waste liquid produced; skilled operators; high cost; not much used.

Very high

Reverse osmosis

High Non-specific

Turbidity

Can remove other ions; used for high salinity waters

Corrosive brine produced; skilled operators; high cost.

Very high

Distillation (solar)

N/a Non-specific

Low insolation

Simple, non-technical

Requires relatively large land areas; requires strong insolation

Low

3.2 International experience

3.2.1 World Health Organisation The World Health Organisation (WHO 2006b) does not make specific recommendations for fluoride removal, instead acknowledging that industrialised and developing countries have different requirements and different scales of treatment. Table 3 below outlines these differences.

Table 3: Differences in defluoridation treatment – industrialised and developing countries

Criteria Industrialised countries Developing countries Set-up and water flow

Always continuous, often in columns

Often discontinuous, in columns Batch processes

Scale and treatment site

Always at water treatment works, usually close to water source

At water works; At village / community level At household level

Treatment media / processes

Contact precipitation; Activated alumina; Syhthetic resins (ion exchange); Reverse osmosis; Electrodialysis.

Bone char; Contact precipitation; Nalgonda process; Activated alumina; Clay; Other naturally-occurring media.

Source: WHO 2006b) WHO also list some of the advantages and disadvantages of some of the more common processes (bone char, contact precipitation, the Nalgonda process, activated alumina and calcined clay): –

Table 4: Comparison of advantages of some defluoridation methods (WHO 2006b)

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Advantages BC CP Nal AA Cl No daily dosage of chemicals i.e. no daily working load

+ – – + +

Dosage designed for actual F- concentration independent of unit or plant

– + + – –

No risk of false treatment due to break point – + + – – Removal capacity of medium is independent of F- concentration

– + – – –

No regeneration or renewal of medium is required – + + – – High removal efficiency can be ensured + + – + – Easy to construct, even by users + + ++ + + Construction materials are cheap and widely available + + ++ + + Can be sized for one or several families or a group, e.g. a school

+ ++ + + –

No risk of medium or chemicals being considered unacceptable

– –/+

+ + –

No risk of deterioration of original water quality –/+

+ –/+

–/+

–

(Source: WHO 2006b) NOTE: BC – bone char: CP – contact precipitation: Nal – Nalgonda method: AA – activated alumina: Cl – calcined clay. As we have stated above, WHO does not make recommendations regarding different methods. However, WHO (2006b) does present six aspects that must be taken into account when considering different methods in different contexts: – 1. Cost and technology; where capital and/or O&M costs are high, or when the

technology is complex, some of the methods described above are unsuitable in rural contexts. This category includes reverse osmosis, electrodialysis, ion exchange and activated carbon.

2. Limited efficiency; some methods are of limited efficiency, or are unable to treat high-fluoride waters to acceptably low levels without excessive dosages of compounds that make the treated water unacceptable to users. This includes the alum, lime and Nalgonda processes.

3. Unobserved break through; fluoride concentrations in treated water will rise when the media are exhausted or active sites fully taken up; or if throughflow rates exceed the capacity of the system to treat. This is a particular problem when treatment systems that will “break through” at some stage of their lives are not monitored with sufficient frequency. This applies to all the column methods (i.e.bonechar, loose activated alumina, calcined clay; and to bed methods such as activated carbon and defluoron-2. It also applies to the bonechar/contact precipitation hybrid process.

4. Limited capacity; some methods have relatively high removal capacities, others low. This means that to obtain the equivalent fluoride-stripping capacity of the more efficient methods, the scale of less efficient methods must be larger. This applies to calcined clay and soils, for example.

5. Poor water quality; some methods are more prone to suffer deteriorating water quality as a result of technical problems than others. For example, poorly-prepared bonechar leads to taste and aesthetic problems; the alum and Nalgonda methods may suffer elevated aluminium and/or sulphate concentrations leading to acceptability problems; or if medium/leachate escapes from the vessel that is meant to contain it, such as ion exchange,

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activated alumina or Nalgonda sludge. These problems may lead to treated water infringing national standards for some parameters (e.g. sulphate, aluminium, phosphorus).

6. Taboo limitations; apart from the bonechar and bonechar/contact precipitation methods, none of the methods described above are likely to transgress cultural or taboo mores.

The wide range of technologies, costs and complexity makes it vitally important that each potential defluoridation scenario is examined in its context, listing the advantages and disadvantages of each method and so leading to a logical conclusion and recommendation for each situation. WHO (2006b) lists four criteria: – 1. The method selected must adequately deal with actual raw water quality and

the methods’ social acceptability (e.g. bonechar vs. Nalgonda).

2. Proper design and an understanding of treatment processes must exist in the management of each facility, irrespective of which is selected (e.g. the operators of activated alumina or bonechar systems must understand that at some stage there will be a fluoride breakthrough).

3. Media or spare parts must be available in the community context (e.g. a user of reverse osmosis or activated charcoal cartridges must know where replacement membranes or cartridges can be obtained; similarly, a VLOM system using a bonechar process must know where to obtain fresh media).

4. Appropriate motivation and user/operator training must be a part of any defluoridation installation process. Thus if the Nalgonda process is to be used at household level using buckets, users must know that they have to stir the alum and lime together and then let it stand to allow the floc to settle out before decanting and using the water – and they must know why they should do this.

3.2.2 United States of America The United States Environmental Protection Agency (USEPA) has yet to advise on best available technologies (BAT). The US Bureau of Reclamation has compiled a primer for water treatment, in which are listed the BATs for the removal of a variety of contaminants, including fluoride (BuRec 2009). This states that the following methods have the highest removal efficiencies: – • Reverse osmosis. Benefits: high quality water produced. Limitations: cost;

pre-treatment and feedpump requirements; disposal of concentrate. • Activated alumina. Benefits: suitable for small to large systems; fluoride is

contained within the treatment bed. Limitations: careful selection and design required.

Lime softening is included as an alternative method of treatment. Benefits: proven and reliable. Limitations: technical operation needed for correct chemical dosage; sludge disposal. It must be acknowledged that the US and Kenyan contexts are very different from each other; the latter context is better resourced, and there is probably a better sense of awareness of the risks of fluoride in drinking water. Kenya has to face both a lack of adequate understanding on the part of both the public and parts of Government, and far greater limitations in respect of financial and technical resources available to address excessive fluoride in drinking water.

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3.2.3 India India developed the Nalgonda process for application at the village level, and it appears to have worked reasonably well at the household level. However, community-level defluoridation works have been found to be unsuccessful due to inadequate maintenance (Narayana et al 2004). This has led to alternative methods, including bonechar methods, being explored. 3.2.4 Tanzania Tanzania has long acknowledged that it has a serious fluoride problem and has attempted to introduce defluoridation at the village level in the worst-affected areas. Levels of natural fluoride are typically so high that in 1974 a temporary standard of 8 mg/l was adopted (RWSHSC 1974), though this has since been reduced to 4 mg/l (TBS 2008). The Nalgonda method was first applied in 1975 (WHO 2006b), and since then practical experience and experiment has led to development of both bonechar and contact precipitation methods. 3.2.5 Kenya There are no recommendations in place in Kenya regarding methods for the defluoridation of drinking water – one of the objectives of the Consultative Committee on Excess Fluoride in Water is to establish these. Thus far, only the Catholic Diocese of Nakuru has adopted a coherent and determined approach to tackling fluoride at the practical level. There may be or have been other initiatives to tackle fluoride in drinking water in Kenya, but we have not been able to obtain any information on such initiatives. The Kenya Society for Fluoride Research has been active in the past few years in publicising the fluoride in drinking water issue at high levels in Government. The academic institutions (universities in Nairobi, Egerton and Eldoret; and overseas) continue to research aspects relating to fluoride in water (e.g. Coetsiers et al 2008; Gikunju et al 2002; Moturi et al 2002) and food (e.g. Njenga et al 2005). This research is certainly valid and useful in its own right, but does little to publicise the fluoride in water problem outside academia, the technical press and some water sector professionals. It is important that this research continue, but as important is the need to disseminate it in a form that is understandable to the public. 3.3 Review of awareness of existing technologies Relatively few of the methods outlined above are in use in Kenya; consequently, the awareness of most of these methods is poor to non-existent. There is also a marked dichotomy between “high-tech” solutions – applicable in modern industrial and urban contexts (RO and ion exchange) – and VLOM solutions – simpler methods applicable at the rural household or small institutional level (Nalgonda, bone char, bonechar + DCP). Methods that we believe have been applied in Kenya include the following. These include experimental methods reviewed in the literature but not necessarily adopted in practice: – • Nalgonda • Bonechar • Bonechar plus DCP

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• Reverse osmosis • Activated alumina • Andosol adsorption Levels of awareness depend on what kind of water user is being considered. Thus an industrialist in Nairobi or Thika would be aware of reverse osmosis, and may know about ion exchange and activated alumina; however, while he or she may know about the bonechar method, he or she would probably not consider using it for reasons of ignorance or cultural doubt. On the other hand, the awareness of bonechar defluoridation in the rural parts of the country where high fluoride water are common is almost certainly higher than it is for the high cost, high-tech methods.

Table 5: Awareness of different defluoridation methods in Kenya

Method Urban context Rural context Industry Household

Nalgonda – – – – + Bonechar – – – ++ +++ Bonechar + DCP 0 0 ++ Reverse osmosis +++ ++ – – Activated alumina ++ + – – – Andosol adsorption – – – – – – 0

NOTES: +++ awareness very high – – – awareness very low 0 uncertain

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CHAPTER FOUR

LEGAL FRAMEWORK 4.1 Water Policy The Ministry of Water Resources in 1999, the precursor of the Ministry of Water & Irrigation developed a Water Policy Paper with the aim of providing an elaborate and efficient mechanism for the development of water resources and water use. This is known as the Sessional Paper Number 1 of 1999 on National Policy on Water Resources Management and Development. The Policy Paper set out to tackle issues pertaining to Water Resources Management, Water and Sewerage Development, Institutional Framework and Financing of the Water sector. It necessitated the overhauling of the existing Water Act (Cap 372) to the current Water Act 2002, which established the water provision and service institutions as they exist today. The Policy Paper stipulates that, the long-term objective of the Government of Kenya is to ensure that all residents in the country are entitled to clean and potable water by protecting the water resources: Section 2.6.2 proposes that the water abstraction and disposal permits be dynamic and economic instruments for the water quality control. Section 2.6.3, states that ‘a process of water quality monitoring of all water bodies and pollution control inspection of existing and potential polluting sources will be put in place. Section 2.7.1, the policy paper stresses that there should be continuous water resources assessments for the determination of sources, extent, dependability and quality of water resources and further states that, monitoring of water quality parameters provides baseline data for the purpose of pollution control. Section 2.7.4 calls for the establishment of fully fledged hydrologic, hydro-geologic, water quality, water permits and socio-economic databases at all water resources management levels for the purpose of establishing comprehensive water resources databases. Section 3.3.1 mandates the Ministry of Water & Irrigation to facilitate formulation of policy framework to guide water sector activities. 4.2 Legislations on Water 4.2.1 Water Act 2002

The Water Act 2002 was enacted in response to the Water Policy of 1999 and as a repeal of the Water Act (Cap.372) and certain provisions of the Local Government Act. It does provide for the management, conservation, use and control of water resources and for the acquisition and regulation of rights to use water; the regulation and management of water supply and sewerage services. The Water Act came into operation on 24th October 2002.

Section 7(1) of the Water Act 2002, thereby establishes the Water Resource Management Authority whose mandate among others is to;

a) Section 8 (1) (b) to monitor, and from time to time reassess, the national water resources management strategy and

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b) Section 8 (1) (e) to regulate and protect water resources quality from adverse impacts

c) Section 8 (1) (h) to gather and maintain information on water resources and from time to time publish forecasts, projections and information on water resources and

d) Section 8 (1) (j) to advise the Minister concerning any matter in connection with water resources.

Thus the Water Act empowers the Water Resource Management Authority (WRMA) to monitor water sources for not only utilization but also for quality.

The Minister for water is further given mandate to classify in terms of quality any water resource within the Republic of Kenya for the sole objective determining its suitable use. In the following sections;

Section 12 (1) The Minister shall prescribe a system for classifying water resources for the purpose of determining resource quality objectives for each class of water resource

Section 12 (2) Under the prescribed classification system water resources may be classified according to type, location or geographical or other factors.

Section 12(3) (b) specify the resource quality objectives for water resource of the class to which it belongs

Section 12 (3) (c) specify the requirements for achieving the objectives, and the dates from which the objective will apply.

Section 18 (1) The national water resources management strategy shall provide for national monitoring and information systems on water resources.

Section 25(1) (a) A permit shall be required for any use of water from a water resource except as provided by section 26.

Section 26(1) Except as provided by subsection (2), a permit is not required-

(a) For abstraction or use of water, without the employment of works, from or in any water resource for domestic purposes by any person having lawful access thereto

(b) For any development of ground water, where none of the works necessary for development are situated,

a. Within one hundred metres of any body of surface water (other than inclosed spring water as defined in subsection (3); or

b. Within a ground water conservation area.

Section 47 The Regulatory Board shall have the following powers and functions

(a) To issue licenses for the provision of water services

(b) To determine standards for the provision of water services to consumers

In essence the jurisdiction of water resources quality and water quality is in the hands of the Water Resources Management Authority.

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4.2.2 Environmental Management and Coordination Act 1999

The National Environment Secretariat established in the early 1990’s developed and established the Environmental Management & Coordination legislation that was enacted into law by the Kenya Parliament in 1999 and commenced on 14th January 2000. This act of parliament was to provide for establishment of an appropriate legal and institutional framework for the management of the environment and for matters connected therewith and incidental thereto’.

The Act defines environment to include the physical factors of the surroundings of human beings including land, water, atmosphere, climate, sound, odour, taste, the biological factors of animals and plants and the social factor of aesthetics and includes both the natural and the built environment.

There was established through this Act, the National Environmental Management Authority that was charged with overall protection of the environment and implementation of EMCA. The Authority carries many tasks pertaining to the environment among them the protection and conservation of the environment under Section 42.

Section 42 (1) of EMCA 1999 states that ‘no person shall, without prior written approval of the Director-General given after an environmental impact assessment, in relation to a river, lake or wetland in Kenya, carry out any of the following activities- which include,

(b) Excavate, drill, tunnel or disturb the river, lake or wetland,

(f) Direct or block any river, lake or wetland from its natural and normal course or

(g) Drain any lake, river or wetland

Section 70 (1) establishes a Standards and Enforcement Review Committee in the Authority. Among the tasks the Committee is engaged in consultation with lead agencies in Section 71 include;

(c) Advise the Authority on how to establish criteria and procedures for the measurement of water quality

(d) Recommend to the Authority minimum water quality standards for all waters in Kenya and for different uses, including-

i. Drinking water ii. Water for industrial purposes iii. Water for agricultural purposes iv. Water for recreational purposes v. Water for fisheries and wildlife and; vi. Any other prescribed water use.

c) Prepare and recommend to the DG guidelines or regulations for the preservation of fishing areas, aquatic areas, water sources and reservoirs and other areas where water may need special protection.

f) Advise the Authority to carry out investigations of actual or suspected water pollution including the collection of data

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g) Advise the authority to take steps or authorise any works to be carried out which appear to be necessary to prevent or abate water pollution from natural causes or from abandoned works or undertakings;

h) Document the analytical methods by which water quality and pollution control standards can be determined and appoint laboratories for the analytical services required or request the DG to establish such laboratories

4.2.3 Standards Act 2002

The Kenya Bureau of Standards commenced its operations on 12th July, 1974 following the enactment of the Standards Act, Chapter 496 of the Laws of Kenya. The Act has undergone several amendments aimed at ensuring that the functions of KEBS are responsive to the prevailing circumstances. In establishing the Bureau, Parliament set out its functions as follows:

To promote standardization in industry and commerce;

To make arrangements to provide facilities for the testing and calibration of precision instruments, gauges and scientific apparatus, for determination of their degree of accuracy by comparison with standards approved by the Minister or on the recommendation of the Council, or for the issue of certificates in regard thereto;

To prepare, frame, modify or amend specifications and codes of

practice;

• To encourage or undertake educational work in connection with standardization;

Since its inception KEBS has developed a number of standards on varied subjects, these include drinking and mineral water (KS 459 parts 1 and 7) and the fluoride levels recommended is in line with WHO guidelines. However, the implementation of the standards does not adequately cover boreholes and related drinking water supplies such as distributers (transporters, kiosks and others). It is necessary that boreholes be identified and certified for suitability of supplying drinking water that complies with Kenya standards, and that suppliers proof that the water in distribution or offered for sale as drinking water also complies with the standards.

4.3 Regulations

4.3.1 Water Resources Management Rules, 2007 (legal notice no 171)

Following the enactment of Water Act 2002, the Water Resource Management Authority (WRMA) came into operation in 2005 and went forth to publish the Water Resources Management rules in 2007. These rules are for the operationalization of the legislation, the Water Act 2002, on the management of water resources in Kenya. Section 4 (2) says the Rules apply to all water resources and water bodies in Kenya, including all lakes, water courses, streams and rivers, whether perennial or seasonal, aquifers, and shall include coastal channels leading to territorial waters.

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Section 73 (1) regulation of the groundwater development, the Authority will determine in the allocation plan for a given aquifer or part thereof, the spacing of boreholes, or wells to be equipped with motorized plant and will be guided by- (a) Existing borehole or well spacing (b) Individual aquifer characteristics, including water quality (c) Existing aquifer use and (d) Existing bodies of surface water Section 79 states that the Authority may from time to time and in carrying out its responsibilities towards groundwater resources management require any person or entity, permit holder or operator, to provide it with abstraction, water levels, water quality or any other specified information within reasonable time or on a regular basis. Section 80 gives the Authority the mandate to maintain groundwater database.

4.3.2 Environmental Management and Coordination (Water Quality) Regulations 2006 (legal notice no 120)

The EMCA (Water Quality) Regulations 2006 are set to apply to drinking water, water used for industrial purposes, water used for agricultural purposes, water used for recreational purposes, water used for fisheries and wildlife, and water used for any other purposes.

4.4 Conflicts

Data Available Discussions revealed that a lot of data available in water laboratories is not analyzed and that various methods of determining fluoride levels are used. Although it is necessary to establish consistency of data from various laboratories, data from studies undertaken within the country show consistent trends with the GIS fluoride in water distribution by MoWI data.

5. RECOMMENDDATIONS AND CONCLUSION

To ensure that drinking water is of safe fluoride quality, the following need to be done:

1. Sensitization of the public on the need to use surface water and rainwater 2. Sensitization of water suppliers and the public on the need of reducing

fluoride in water and available methods. 3. Involving geologists in identification of low fluoride pockets (locations) for

drilling of fluoride safe drinking water. 4. Undertake research to establish appropriate threshold levels for Kenya

based on exposure of populations to varying levels of fluoride in specific regions/locations to facilitate an accurate regulation on fluoride levels and appropriate education on water usage in the country

5. Undertake research to establish correlation of fluoride levels with borehole depths and aquifers.

6. Undertake research to identify factors other than high fluoride in drinking water that contribute to fluorosis in Kenya

7. Identify a reference method for testing of fluoride to ensure accuracy in testing preferably an ion selective method.

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8. A certification programme is urgently needed to provide proof that any water in distribution and offered for sale intended for use in cooking and drinking complies with Kenya Standards and that suitability of boreholes to supply drinking water is periodically validated.

9. There is an urgent need to develop a standard on water destined for other uses other than domestic e.g irrigation, recreational and their respective treatment

10. There is need to build capacities in water companies and regulatory boards to handle surveillance issues

11. Fluoridated tooth paste to be clearly labelled so as to enable consumers make informed choices

12. Fluoride Surveillance System should be established 6. WAY FORWARD To ensure the supply of water of acceptable fluoride levels for drinking water and to create awareness of required fluoride levels in water; there is a need to: • Establish and implement a programme for certification and identification of

drinking water supplies (boreholes, kiosks, transporters etc) based on drinking water standards

• Review the Kenya Standard on drinking water to reflect prevailing local fluoride levels in ground water versus other available water sources;

• Develop a Code to guide abstractors and water suppliers to comply with requirements for fluoride and other quality standards in drinking water. This should capture all the regulatory roles and permit issuance conditions required in the water chain from abstraction to consumption; physical identification of water service providers complying standards and recommendations for use of suitable defloridation methods

• Establish a national water source Fluoride Surveillance Group (FSG) led by the Ministry of Water and Irrigation. and managed by the Water Services Regulatory Board, with representatives from the Water Resources Management Authority (WRMA), National Water Conservation and Pipeline Corporation (NWCPC), Kenya Army Engineers, registered Drilling Contactors, Government Chemist / accredited labs, Water Service Boards, Water Service Providers, Community Water Projects, Kenya Water Industry Association (KWIA), Qualified Water Resource Professionals, academia and the Catholic Diocese of Nakuru, and KEBS to draw up and implement a fluoride surveillance system. See Annex IV Possible organogram of the fluoride surveillance group

• Establish a reference testing method to ensure accuracy and consistency of

results from various laboratories; • Sensitise the public and service sector on the need to reduce fluoride in water

and available defluoridation methods.

• Advocate for establishment and increased use of rainwater References

1. Naslund J, 2005; GIS-Mapping of Fluoride contaminated ground Water 2. in Nakuru and Baringo District, Kenya. A Mater of Science Thesis of the

University of Leae, Sweden

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3. KEBS, 2010; Kenya Kenya Bureau of Standards Inorganic Laboratory 4. MoWI, 2001; MoWI Data fluoride data for 2001 5. WHO, 1970; Eurpean Standards for Drinking Water, Second Edition 6. Manji F et al, 1986; Dental Fluorosis in an area of Kenya with 2 ppm

fluoride in drinking water. Journal of Dental Research, 65 (5) 659-62. 7. Barot V et al, 1998; Occurrence of Endemic Fluorosis in Human Population

of North Gujarat, India: Human Health Risk 8. Anongura R et al undated; Dental Fluorosis in a District of Ghana, West

Africa. 9. Gitonga J et al, 1984; The occurrence and distribution of fluoride in water

in Kenya. East Afri Med Journal 61:503-12. 10. Kahama R et al, 1997; Fluorosis in children and sources of fluoride around

Lake Elmentaita region of Kenya. Fluoride 30:19-25. 11. Bailey K et al, 2006; Fluoride in Drinking Water. World Health Organization

2006 12. Nevill L, et al, 1953; Preliminary Report on Dental Fluorosis in Kenyan

European Children. East African Medical Journal 30 (6), 235-242 13. Neurath C, 2005; Osteosarcoma-fluoride associations in Kenya and

Malaysia. Toxicologic Risk of Fluoride in Drinking Water # BEST-K-02-05-A 14. Gikunju J et al, 1992: Fluoride Levels in Water and Fish from Lake Magadi.

Hydrobiologia 234 123-127 15. Gikunju J et al, 1995; Water Fluoride in the Molo Division of Nakuru

District, Kenya. Fluoride Vol. 28 No. 1. 17-20. 16. Nielsen J. M. 1999; East African Magadi (Trona): Fluoride Concentration

and Mineralogical Composition. J. African Earth Science. 29 423-428. 17. Chibole O, 1987; Dental Carries Among Children in High Fluoride Regions

of Kenya: Journal 18. Njenga L et al 2005; Water –Labile Fluoride in Fresh Raw Vegetable Juices

From Markets in Nairobi, Kenya: Fluoride 2005; 38(3) 2005-2008 19. Njenga L.W, 1994; Fluoride Content in Some Kenyan Tea Leaves:

International; Journal of Biochem Physics 3(1) 20. Njenga L. W, 1982; Determination of Fluoride in Water and Tea Using Ion

Selective Electrode and Colorimetric Methods: MSc. Thesis University of Nairobi.

21. IRC International Water and Sanitation Centre 2002: Small Community Water Supplies: Technology, people and partnership. Eds. Smet J & van Wijk C. Accessed on 9th March 2010 at http://www.irc.nl/page/37797 on 9th March 2010.

22. KEBS (Kenya Bureau of Standards) 2007 (Third Edition): Kenya Standard:

KS 05-459-1: 2007: Drinking water – Specification Part 1: The requirements for drinking water (ICS 13.060.20), KBS Nairobi. ISBN 9966-23-983-9.

23. Korir H, Mueller K, Korir L, Kubai J, Wanja E, Wanjiku N, Waweru J, Mattle

MJ, Osterwalder L & Johnson CA 2009: The Development Of Bone Charbased Filters For The Removal Of Fluoride From Drinking Water. Refereed Paper 189, Water, Sanitation and Hygiene: Sustainable Development and Multisectoral Approaches. 34th WEDC International Conference, Addis Ababa, Ethiopia, 2009.

24. Maier FJ 1947: Methods of Removing Fluorides from Water. Amer. Jour.

Publ. Health Vol. 37, pp. 1559 – 1566 [December 1947].

25. Meenakshi & Maheshwari RC 2006: Fluoride in drinking water and its removal. Jour. Haz. Material 2006, doi: 10.1016/j.jhazmat.2006.02.024.

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26. Mjengera H & Mkongo G 2002: Appropriate Deflouridation Technology for Use in Flourotic Areas in Tanzania. Proc. 3rd WaterNet/Warfsa Symposium Water Demand Management for Sustainable Development, Dar es Salaam, 30-31 October 2002, 10 p.

27. Narayana AS, Khandare AL & Krishnamurthi MVRS 2004: Mitigation of

Fluorosis in Nalgonda District Villages. In: Proc. 4th International Workshop on Fluorosis Prevention and Defluoridation of Water, Colombo, Sri Lanka, May 2 – 6 2004, pp. 92 – 100. Eds. Dahi E & Rajchagool S; published by International Society for Fluoride Research (ISFR), Environmental Development Co-operation Group (EnDeCo) & the Intercountry Centre for Oral Health (ICOH), ISBN 1174-9709.

28. Näslund J & Snell I 2005: GIS-mapping of Fluoride Contaminated Water in

Nakuru and Baringo Districts, Kenya. M.Sc. Thesis 2005: 198 CIV, Luleå University of Technology, Luleå, Sweden. ISSN 1402-1617, 64 pp.

29. Nawlakhe WG, Kulkarni, DN, Pathak, BN & Bulusu KR 1975: Defluoridation

of water by Nalgonda Technique. In: Indian Journal of Environmental Health, 17 (1), pp. 26 – 65. Cited by WHO 2006b and others.

30. Njenga LW, Kariuki DN & Ndegwa SM 2005: Water-labile Fluoride in fresh

raw vegetable juices from markets in Nairobi, Kenya. Fluoride 2005, 38(3), pp. 205 – 208, Research report 205.

31. Moturi WKN, Tole MP & Davies TC 2002: The contribution of drinking water

towards dental fluorosis: A Case Study of Njoro Division, Nakuru District, Kenya. Environmental Geochemistry and Health 24, pp. 123 – 130.

32. Padmasiri JP 2000: Effectiveness of Domestic Defluoridator in Preventing

Fluorosis in Kekirawa, Sri Lanka. In: Proc. 3rd International Workshop on Fluorosis Prevention and Defluoridation of Water, Chiang Mai, Thailand, November 20 – 24, pp. 91 – 96. Eds. Dahi E, Rajchagool S & Osiriphan N; published by International Society for Fluoride Research (ISFR), Environmental Development Co-operation Group (EnDeCo) & the Intercountry Centre for Oral Health (ICOH), ISBN 974-292-073-7.

33. Rao NCR 2003: Fluoride and Environment - A Review. Bunch MJ, V. Madha

Suresh and T. Vasantha Kumaran, eds., Proceedings of the Third International Conference on Environment and Health, Chennai, India, 15-17 December, 2003. Chennai: Department of Geography, University of Madras and Faculty of Environmental Studies, York University, pp. 386 – 399.

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ANNEXES

ANNEX I: MAP OF THE SIX DRAINAGE BASINS (CATCHMENT AREAS)

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ANNEX II: BOREHOLE FLOURIDE MAPPING

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ANNEX III: SURAFCE WATER FLOURIDE MAPPING

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ANNEX IV: POSSIBLE ORGANOGRAM OF THE FLUORIDE SURVEILLANCE GROUP

MINISTRY OF WATER AND IRRIGATION

Policy-making body, as regulator and as custodian of the F- database

WASREB Manager of the FSG FSG o Ministry of Public Health o KEBS o WRMA o WSBs o WSPs o NWCPC o Qualified Water Resource

Professionals o Registered Drilling Contractors o Kenya Army Engineers o Government Chemist o Accredited laboratories o Academia o Others (KWIA, KSFR etc …)

FSG Members (in no order of priority)

EXCESS FLUORIDE IN WATER IN KENYA BY … · CDN Catholic Diocese of Nakuru ... which relates to...

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