Propossal for pilot in large scale centralised hap fluoride removal naivasha, kenya

HUGO VREUGDENHIL
11/5/18
HAP DEFLUORINATION NAIVASHA, KENYA
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Proposal for a pilot with large-scale centralised
HAP fluoride removal in Naivasha, Kenya
Fluoride is a useful element that can protect teeth against carries when used in low concentrations (< 1
mg/l). For example in your toothpaste or mouthwash. However high concentrations of fluoride have
harmful health effects (Table 1).
In the Ethiopian, Kenyan and Tanzanian rift valley (Figure 1)
volcanic rocks contain high concentrations of fluoride1
. This
fluoride washes out over time and is dissolved in the
groundwater. For many people, town cities or even whole
counties, groundwater is the only sustainable source of drinking
water. This causes large populations to consume high levels of
fluoride during their childhood. The fluoride makes children’s
growing teeth to develop a thin porous enamel layer, instead of
a more durable thick layer. This enamel layer is meant to
protect their teeth. Over time the affected layer is stained and
pitted causing carries, chipping and breaking teeth over time.
“Young girls cannot afford a smile, because of the brown teeth”
(Paula Connita, resident of Karagita, a fluoride affect low income area)
Table 1 Table 1 Effects of excess fluoride concentrations
1
Nair (1984) sampled 1286 boreholes in Kenia one fifth had more than 5 mg/l of fluoride. The distribution of high
fluoride concentrations overlaps with the distribution of volcanic rock in the riftvalley.
Concentration of fluoride in drinking water Effects (based on WHO, 2006)
Less than 1 mg/l Beneficial protection of teeth
More than 1 mg/l Increased risk of dental fluorosis
More than 2 mg/l Increased risk of skeletal fluorosis
More than 4,3 mg/l Clear excess risk of skeletal adverse effects
Figure 1 East African Rift Valley
Figure 2 Dental fluorosis

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Affected teeth are a visible characteristic of a chronical excess
dose of fluoride (dental fluorosis). However, there is a more
hideous effect of excess fluoride; it is called skeletal fluorosis
(Figure 2). With high uptakes of > 6 mg/day fluoride affects the
growing skeleton of children and adolescents. Bone density
increases, bony spurs start to develop and ligament and tendons
start to calcify. Bones get hard and breakable. This causes people
to have weak bones and tendon pain.
The social and economic effect of fluorosis is large. A lot of people
don’t dare to smile fully out, because they are ashamed of their
teeth. It affects their social status. It also effects their ability to get
jobs. Employers know that people with brown teeth have weak
bones. For example, the Kenyan police and army do not recruit
people with stained teeth.
One of the towns suffering from fluorosis is Naivasha. The
boreholes for their drinking water supply contain excess levels of
fluoride (Table 2) and a large part of the population has brown
teeth and potentially skeletal fluorosis.
“It is really easy identify someone from Naivasha, you only need to ask them to smile”
(resident of Naivasha)
Table 2 Fluoride concentrations Jan 2015- June 2017
The impact of fluorosis in Naivasha so far is large, but the local drinking water company ‘Naivasha Water,
Sewerage and Sanitation Company’ is dedicated to fight this problem in the future. In collaboration with
the Nakuru Defluorination Company, Dr. Ecker GmbH and Vitens Evides International investigated a new
way of removing fluoride. The innovation is called Hydroxy Appite (HAP) and is a low-cost, effective,
durable and scalable solution to the fluoride problem in Naivasha. But it also has potential to help the
whole rift valley. This paper describes the outcome of a pilot installation and proposes a business case for
a large-scale pilot plant (ca 900.000 m3
/year). This pilot plant could prove the feasibility of large scale
centralized HAP fluoride removal in the Rift Valley. The objective is to interest any potential donor to share
the financial cost and help spread this life changing technology.
Production site Max fluoride (mg/l) Average fluoride (mg/l)
Karate 2,32 1,50
DTI 3,34 1,97
DCK 3,72 2,68
WWS 8,90 6,00
Figure 3 Skeletal fluorosis

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HAP fluoride treatment
Dr. Ecker invented HAP pellets (Figure 1 ) that absorb fluoride
and can be regenerated. HAP (hydroxyl apatite) is a mineral filter
material. The main components are calcium, phosphate and
water. Dr. Ecker has extensive experience with HAP treatment in
Germany and Italy. One HAP treatment plant in Italy is already
running for more than ten years. It is expected that HAP
treatment is a viable technique with low operational cost, low
complexity and one that can be built by using mainly local
materials.
HAP pellets can be used in a simple filtration process comparable
to the process of sand filtration. The process does not require a
lot of pressure, which keeps electricity costs low. When the HAP
pellets are saturated, they can be rinsed with caustic soda.
During this rinsing process, the surface of the HAP pellets
increases. Because of this increased surface, the performance of
HAP does improve or at least remains stable over time. The
process creates a small residual flow of concentrated fluoride
(500-1000 mg/l). This fluoride residue can be precipitated into
harmless calcium fluoride (solubility of < 2 mg/l in water). It can
also be diluted and disposed in a sewerage treatment plant.
Annex I describes the chemical processes of HAP fluoride
treatment in more detail.
Dr. Ecker created a foundation to spread his technology in Africa. He has built a relationship with NDC Ltd.
teaching them how to produce the HAP pellets themselves. At this moment, with the help of Dr. Ecker,
NDC Ltd. is ready for the next step in upscaling HAP treatment.
NAIVAWASS, NDC Ltd. Dr. Ecker GmbH and VEI investigated the possibilities of a large-scale pilot that will
test the efficiency of centralised defluorination. On the next page, the details of such an investment will
be discussed.
CHARACTERISTICS OF HAP
- Fluoride holding ratio: 6
g/kg
- Recommended contact
time: 10-20 minutes
- Recommended flowrate:
3-6 meter/hour
- HAP loss due to
degradation ca. 2% / year
Figure 1 HAP pellets

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HAP defluorination plant at production site “DTI”
The proposed treatment plant is designed for the production site “DTI” (Figure 2). The plant has the
capacity to produce 900.000 m3
of water, with a concentration of less than 1 mg/l fluoride, per year. The
invested cost is estimated to range between €200k and €300k or KES 24-36 mln. The design is made to get
more insight in the OPEX and daily operations of such a plant. The design could be downscaled or applied
to other production sites if required. Annex II and III provide a rough process design of the proposed plant.
Figure 2 The town of Naivasha and production site "DTI"

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Impact
The biggest impact of the full-scale HAp pilot will be the dissemination of HAp technology over the Rift
Valley and beyond. A working full-scale HAp plant demonstrates the effectiveness of HAp technology. It
will inspire water companies, government and NGO’s struggling with fluoride problems. It gives a viable
alternative to more costly and complex solutions as granulated alumina or reverse osmosis, making
healthy drinking water available for large populations. The small scale pilot already attracted the attention
of other drinking water companies and the local government. If the full-scale pilot works it is a relatively
easy step to copy it to other production sites, other cities and even other countries.
Besides the impact of demonstrating HAp technology, the pilot will also provide good quality drinking
water to an estimated 48.000 residents (Figure 3 and see Annex IV for the calculations).
Figure 3 Distribution zones DTI
Operational expenditure
There are three different scenarios to calculate the OPEX (Table 3). They all depend on the way the
concentrated fluoride residue is treated. The residue can be diluted in a sewerage treatment plant
(scenario 1) or it can be precipitated into calcium fluoride. This later can be done in a conventional method
with hydrochloric acid (scenario 2) or with an improved treatment method (scenario 3). In the improved
method, the concentrated fluoride residue is partly recycled and alternatives chemicals are used.
However, the efficiency of this improved waste treatment still needs to be confirmed in a pilot installation
under local circumstances.

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Table 3 Cost scenarios
Scenario 1 2 3
Waste
handling
Waste disposal in
sewerage
treatment plant
Conventional waste
treatment
Improved waste
treatment
OPEX 7,0 KES/m3 13,0 KES/m3 8,2 KES/m3
Economic
depreciation
2,3 KES/m3 (Based on 15 year economic life)
Table 4 gives a more detailed breakdown of the operational cost for the first scenario. The cost are
calculated for a filter cycle of one vessel producing 1.3529 m3
. The whole OPEX calculations can be found
in Annex VI.
Table 4 OPEX for scenario 1
Figure Unit
Electricity cost 56 EUR
NaOH 300 EUR
Co2 60 EUR
HR 76 EUR
Laboratory 10 EUR
Maintenance 181 EUR
Logistics 30 EUR
Total 713 EUR
M3 water produced 12216 m3
Cost 0,06 EUR/m3
7,01 KES/m3

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Tariff increase
The operational costs could be compensated by a tariff increase (Table 5). To have some margin, an OPEX
of 10 KES/m3 is used. The 2018-2019 tariff, for a user with a consumption of 0-6 m3 / year is KES 50 or €0,
42. With HAP treatment, the tariff will be KES 56 or €0.47.
Table 5 Proposed tariff increase with 10 KES operational cost
Residential consumption
block in m3 / year
Tariff KES/m3
Tariff with defluorination KES/m3
Difference
KES/m3
Block 1 0-6 m3 50 56 6
Block 2 7-20 m3 65 73 8
Block 3 21-50 m3 85 96 11
Block 4 51-100 m3 105 118 13
Block 5 101-300 m3 125 141 16
Block 6 301 m3 and above 140 158 18
CAPEX
An economic depreciation of 2,3 KES/m3
is not included in the tariff neither is a rate of interest on a
possible loan. Whether this need to be included depends on the type of financial support the project will
acquire. It is hoped for that a donor could share the financial risk for the customers of Naivawass. This type
of innovative project could change many lives in the rift valley; however, it might be one-step to far for
Naivawass to realise it all on their own.
Human Resources.
One challenge of such a large-scale treatment plant could be the daily operations. However, the staff of
NAIVAWASS has proved to be able to run the small-scale pilot plant themselves and fix any technical issues.
To be sure of good operations it is advised to (temporarily) hire one process supervisor with a chemical
engineer background (fulltime hiring cost is accounted for in the OPEX calculations). Besides that,
NAIVAWASS staff should receive ample training on the new large-scale plant.
Environmental risk
There is an increased environmental risk with a treatment plant using chemicals. However, it is expected
that the risk is manageable with good safety measures and training of the staff involved. NAIVAWASS is
currently investigating the environmental effects of the dilution of the concentrate fluoride residue in the
sewerage treatment plant. It is expected that the effects are limited since only 1 mg of fluoride per litre
sewage is added.
Design and construction
For the construction of the large-scale treatment plant it is advised to collaborate with NDC Ltd. The
company can provide local knowledge, laboratory analysis and can assist with maintenance of the plant.

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The final designs can be drawn by Dr. Ecker in close
collaboration with a process technologist and a chemical
engineer.
Time frame
In the future, all drinking water in and around Naivasha
should contain less than 1 mg/l fluoride. It is advised to
first realise a single treatment plant at the production
site “DTI” and use this experience to develop treatment
plants at the other two productions sites as well.
Ongoing research
To prove the effectiveness of HAP Dr. Ecker GmbH, NDC
Ltd. NAIVAWASS and Vitens Evides international realised
a HAP pilot installation at the production site “Karate.”
The pilot installation has a maximum flowrate of 10 -15
m3
/hour and includes an installation to rinse the filters
with caustic soda. The pilot became operational at end
of November 2017. Both filters in the pilot are now
successfully rinsed with caustic soda by the staff of
NAIVAWASS and the removal rate is up to 96%. It is
planned to let the pilot run until May 2018 to produce
more data and train the local staff in operating a
relatively complex treatment plant. If the pilot remains
successful it proves that HAP treatment is a suitable
technology to remove the fluoride in Naivasha and stop
fluorosis. If the pilot is successful NAIVAWASS and VEI
would like to draw proposals in May 2018 to attract
funding for a large-scale pilot
For more information: Hugo.vreugdenhil@vitens.nl
SMALL SCALE PILOT NAIVASHA
Investment cost € 12.000
Operation method: manual operation
combined with PLC
HAP content: 2 m3
(two vessels)
Regeneration chemicals: 30 kg NaOH, 5 kg
Co2
Regeneration time: 7 hours / vessel
Results first serie
One vessel of 1 m3
Flow velocity 4 m/h
Average fluoride content raw water: 2.12
mg/l
Max removal rate up to now: 96%
Average removal rate: 77%
Saturation point: 742 m3
Theoretical saturation point: 891 m3
Efficiency compared with theoretical
performance: 83%

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Figure 4 the pilot installation at Karate

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Annex I Technical background
The main processes of fluoride removal are known. More research is needed to better understand the
effects of pH and temperature changes. The description below from a USAID brochure2
about HAP fluoride
removal describes the processes in more detail.
Synthetic hydroxyl apatite (HAp) is a colourless - white granulate which is insoluble in water mainly
composed of CaO, P2O5 and H2O. The various compositions of Hap may be summarized by the formula
Ca(10-x)(HPO4)x(PO4)(6-x)(OH)(2-x) where x varies from 0 to 1. Apatites are found primary as natural minerals
in magmatic rocks as well as secondary in phosphate containing sediments. Hydroxyapatite is an
essentially component of dental enamel and of bones. The extreme compositions are x = 0, which gives
stoichiometric hydroxyapatite, Ca10(PO4)6(OH)2, with a Ca:P ratio of 1.67, and x = 1, which corresponds to
Ca9(HPO4)(PO4)5(OH), which has a Ca:P ratio of 1.50. HAp removes fluoride from water due to its chemical
structure similar with bone char but it is reported to have better removal capacity and it can also be
regenerated several times. HAp has a high affinity for fluoride, three mechanisms for fluoride uptake
where described: surface adsorption, substitution into the crystal lattice, and dissolution and precipitation.
a) Substitution into the HAP crystal lattice: Fluoride sorbed on the HAP surface can diffuse into the HAP
crystal and substitute for hydroxide (OH-), forming fluoroapatite (FAP, Ca10(PO4)6F2). This substitution is
thermodynamically favored because F- has a smaller ionic Radius (0.133nm) than OH- (0.137nm) and
therefore fits better into the crystal structure of HAP. In contrast to the surface adsorption, substitution
into the crystal lattice is independent of surface charge. Its kinetic is primarily controlled by the diffusion
rate of fluoride into the crystal.
b) HAP dissolution and precipitation of fluoride bearing minerals: HAP dissolves, particularly under acidic
conditions, liberating dissolved calcium (Ca2 +) and phosphate (PO43-). If the solution becomes
supersaturated with respect to fluoride bearing minerals, FAP and CaF2, they precipitate. Given sufficient
time to equilibrate, the thermodynamically less stable CaF2 re-dissolves in favour of the most stable phase,
FAP.
c) Surface adsorption: The fluoride anion forms surface complexes with reactive sites on HAP, such as
=CaOH and =OPO3H2. The charge of surface groups is controlled by chemisorption and release of protons.
The first two mechanisms are reasonably well established, and although much is known about them. These
different fluoride uptake mechanisms could be influenced by pH, presence of dissolved calcium and
temperature. pH influences surface adsorption because OH- ions competing with F- ions for surface sites.
Consequently fluoride uptake due to adsorption increases with decreasing pH. On the other hand
dissolution-precipitation is influenced because the dissolution of HAP increases with decreasing pH, which
enhances recrystallization of fluorite and fluoroapatite. An impact could also come from competitive ions.
These are anions with comparable size to fluoride, which can also bind to the hydroxyl apatite surface or
2
Hydroxyl Appatite. USAID.

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diffuse into the crystal lattice. The anions most similar in size to fluoride are OH- and CO3 2-. Bigger anions,
Cl- and SO4 2- have not been found to have an influence on fluoride uptake; they are suspected to be too
large to replace the smaller fluoride anion. However, dissolved calcium may influence the dissolution-
precipitation mechanism of fluoride uptake. It is suggested that initially CaF2 precipitates, which later is re-
dissolved and substituted by the thermodynamically more stable fluoroapatite. This mechanism is thought
to occur in the period of several days to weeks. Finally, temperature can influence the kinetics of fluoride
uptake. Fluoride uptake is endothermic, and increases with temperature. In addition the kinetically limited
fluoride diffusion into the crystal lattice is enhanced at higher temperature. One or the other factors
indicated above may thus affect fluoride uptake capacity of synthetic hydroxyl apatite under field
conditions.

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ANNEX II Interviews
2018-05-02 Interviews in the Neighbourhoods, Karagita, KCC and Hopewell in Naivasha, Kenya
Intro
Wednesday the second of May we have been interviewing resident of Naivasha. We want to answer
the following questions:
1. Are people aware of the problems with high fluoride levels in drinking water?
2. What is the impact of fluorosis on the peoples live?
3. What is their willingness to pay?
People described health problems that resemble the symptoms associated with fluorosis. However,
they also describe the problem of “stomach issues” this is more likely to be caused by bacteria or other
pollution of the drinking water by other pollutants than excess fluoride. The willingness to pay for
defluorinated water differs per income category. Paying one KES more for defluorinated water might
be too much for poor people. This compared to a relatively rich man who said that price does not
mean anything for him.
Results
Karagita
Paulina Onita, resident of the Karagita low income area, tells us that she noticed the effect fluorides has
on the children: “Young girls cannot afford a smile, because of the brown teeth”. Young boys cannot join
the police or army. (This has a significant effect on their livelihood strategies because these jobs could
provide good income for the boys and their families red.)
Paulina Conita tells us that the fluoride gives brown teeth. “very bad ones”. Even the young boys have
teeth coming out very early (instead of at an old age red.) This tooth decay is caused by the fluoride.
She also knows that fluoride can give stomach ache and excess gas problems. (These effects cannot be
described to fluorosis. It shows that the people are not totally knowledgeable about fluorosis and its
symptoms red.)
Paula Conita also tells that old people cannot sit down or get up easily because fluoride has affected
their bones and joints.
Harron Mwaura also a resident of Kargita tells us that people that have been drinking fluoride water look
very tired. (This is also not likely caused by excess fluoride, showing they do lack knowledge about the
effects of fluoride).

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Harron tells that the fluoride levels can reach up to 6 mg/l. (> 6 mg daily intake gives increased risk of
skeletal fluorosis, >1.5 mg/l gives increased risk for dental fluorosis red.)
The kiosk sells their defluorinated water for 5 KES per 20 litres (a gallon)
Alice Wanjiru an old lady of the Karagita low income area tells that she got the brown teeth when she
was a child. She tells she has weak bones because the water is very salty (You cannot taste fluoride so
saltiness cannot be a cause of the weak bones. This show the people are not very knowledgeable about
fluoride red.)
Alice Wanjiru: “When you do a job you will have pain in your wrists so you cannot finish the job”
To regenerate the bone char of the kiosks cost 500.000 KES for 2.5 m3
Eric Wekesa: “Most of the time I use the water with fluoride. I use it for washing clothes and utensils”
For drinking water he goes to a water vending shop from “Pure Fresh”

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Figure 5 Pure Fresh Shop
At the Pure Fresh shop, they sell water treated by Reverse Osmosis for 1 kes/litre
Eric Wekesa tells that if he drinks the raw water “His body will not respond well”. If he drinks it for a long
time he will get sick.
At a house with a house connection in Karagita the residents pay 5 KES/litre untreated borehole water.
They pay it to the landlord who pays the bill.
A resident of the house with house connections says he is not aware of the problems with fluoride even
though he did see the brown teeth. He is not from here and moved in 4 years ago. When the problems of
fluoride are explained he says he better buy water at the Pure Fresh shop.

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Harron Mwaura tells that a time a go the police and the army looked for new recruits in the Karagita and
Kamere area. However according to him they did not find one suitable candidate. This was because of
the brown teeth and lack of physical strength.
Than we meet a group of youth. There are original residents of the area and born here. Multiple have
affected teeth (figure 2)
Figure 6 Resident of Karagita with fluoride affected teeth

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Figure 7 Kelvin from Karagita, showing chipped teeth caused by fluorosis
Joshep Macheria a grown up, tells about the effect fluoride has on their teeth:
“The area has different categories of richness. Not everyone can afford to buy the water without
fluoride. That’s why the poor people end up buying the salty water (misunderstanding about the taste of
fluoride red.). The salty water makes your teeth change colour. If you continue drinking more of it your
jaws will become weak. The fluoride effects the teeth and jaws. The teeth will come out easily and the
jaws will weaken. It is a kind of weakness/pain that affects them.”
“If a person is not from Naivasha, he is very easily to identify! (laughing)” (People from outside the
riftvalley will have white teeth red.)
“It affects the bones and always the joints”
“your bones will get weak”
“So, if you perform a hard task, your bones get weak (tired/painfully)”.
“You got tired easily, most people do not know why but it is all about the water” (It is difficult to assess
whether this tiredness is really coming from fluoride. It can also be caused by malnutrition or bacteria in
the drinking water red.)
Harron Mwaura tells that when it has been raining less people buy water from the kiosks (due to
rainwater harvesting red.)
We arrive at the Pure Fresh shop. The employee tells that they sell around 2000 litters / day for KES /
litre. They will have around 50 customers / day.
At a construction site we meet Richard. A constructor with visible affected teeth. He tells us that he got
the brown teeth as a child. They were drinking from a public borehole. He says he does not experience
any pain in his joints or bones. He tells us he was not aware the brown teeth are probably caused by
excess fluoride.
KCC
Eunice Kiomni is a resident of KCC. Since the Water Kiosk people have an extra option for getting water
besides the river. There is an income difference however. Some people can afford to buy water that is
defluorinated other will not. “Some people will run away if the water is 1 KES more expensive”.
Hopewell
We speak to an old mother. She tells us what she knows are the effects of fluorosis:
“Browning of teeth”
“Stomach problems” (not likely to be associated with fluoride red.)

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“I heard speculations that it does affects the bones”
“Tooth may even decay”
“Tooth might even be forced to remove”
“The browning occurs when being a kid” (This indicates fluorosis instead of carriers red.)
She buys water piped by Naivasha Water from her neighbour for 5 KES/20 litres
After the old mother we meet a relative rich apartment owner. He uses the water for washing and
laundry. For drinking he uses bottled water. For him “The cost do not mean anything as long as we get
clean water”. If the water of NAIVAWASS would be treated he would leave bottled water. Now he buys
bottled water because of the fluoride.

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Annex III Proposed design
Figure 8 show the (incomplete) fluoride data series of the main production sites of Naivawass. Mainly Karate (blue line) and DTI (orange line) are
used for drinking water production. The companies strategy is to move all production in the long-term to Karate and DTI because of the already
low fluoride level. The red line indicates the safe level of 1.00 mg/l. The average fluoride concentration of DTI is 1,96 and the max is 3.68.
Figure 8 Fluoride level NAIVAWASS
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
9,00
10,00
Fluoride level NAIVAWASS
Karate DTI DCK WWS

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Figure 6 provides an overview of the large-scale treatment plant. It uses an already existing elevated tank to let water under gravity flow filter
through the HAP vessels. An automated valve determines the ratio between raw and treated water so that an end concentration of >1 mg/l is
achieved.
Figure 9 Design filter section of treatment plant DTI

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To account for any future changes in fluoride level, the plant is designed to provide the average production of 2015-2017 being 600.000 m3
/year
by a max fluoride level of 3.68 mg/l. To realise this there are four filters with a combined flow 60 m3
/hour. The treated water is mixed with the
untreated water to reach the safe limit of 1,00 mg/l. However during an average fluoride level (1,96) the plant can mix more raw water and the
capacity will be around 900.000 m3
/year.

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Annex IV Proposed design rinse and waste treatment section
Figure 7 provides an overview of the rinse and waste treatment unit of the plant. The waste treatment is optional since the residue can also be
diluted at the sewerage treatment plant. For the waste treatment, first a mixture of softened water and caustic soda is led through the vessel. This
regenerates the HAP. After that, the caustic soda is neutralised by Co2. The concentrated fluoride residue is mixed up with hydrochloride acid
(31%) and slaked lime. Then it precipitates into calcium fluoride and is cached in a precipitation tank. From there the supernatant containing NaCl
and CaCl can be drained to a drainage pool (not in the design). The calcium fluoride is sucked up by a lorry tanker and transported to a waste
storage facility (not in the design).
Figure 10 Regeneration and waste treatment section of treatment plant DTI

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Not included in the design are the drainage pond, the waste storage facility and three variable speed drives
for the borehole pumps. However, they are accounted for in the investment cost. The variable speed drives
for the borehole pumps are needed because the treatment plant needs continuous flow of water.
Additional benefit of these variable speed drives is that the drawdown of the aquifer and electricity cost
of the borehole pumps can be managed in a more controlled and efficient way.

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Annex V Estimated impact on residents
DTI produced around 600.000 m3
/year in the period of 2015-2017. This equals 68 m3
/hour. NAIVAWASS is
improving their Non-Revenue Water, but the figure is still high (34% in 2016 – 2017). So around 396.000
m3
/year will be supplied to customers. It is difficult to track down every drop pumped in the network but
Figure 12 provides an overview of the estimated water distribution from DTI. It is made by using the billed
water from the distribution zones DTI supplies to (Figure 11).
Figure 11 Distribution zones DTI
Using this distribution, 252.000 m3
/hour is directly supplied to residents. These are the Residents, Bulk
Water Trucks, Schools and Water Kiosks for the poor. The rest of the water is supplied to businesses and
government. This still include hotels and restaurants but the exact use of the water is unclear. When using
the daily water use of an average resident in Naivasha (15 litres). The 252.000 m3
/year equals the daily
water use of 48.000 people. So 600.000 m3
/year will be supplied by the HAp treatment plant of which an
estimated 48.000 people directly benefit. The rest of the water is lost due to NRW or used by businesses
or government agencies.

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Figure 12 Estimated water distribution production site DTI
64%
18%
4% 4%
4%
3%
2%
1%
Chart Title
Residential (Metered)
Commercial
Water Kiosks
Other (industrial and Parastatals)
Bulk Water Trucks
Government
Local Authorities
Schools (600 unit limit)

HUGO VREUGDENHIL
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26
ANNEX VI OPEX calculations large scale treatment plant scenario 1
OPEX calculations DTI
Scenario 1: Dilute concentrated fluoride residue in sewage
treatment plant
Figure Unit Comments
KES/EURO rate 120 KES/euro
MIXRATIO TREATED UNTREATED WATER
Average
concentration
fluoride raw water 1,97 Mg/l Average of jan-2015-june-2017
Target fluoride
concentration mixed
water 1,00 Mg/l Less than safe limit of 1 mg/l
Removal rate 79% Based on pilot results so far
Fluoride
concentration of
treated water 0,41 Mg/l
mix ratio 0,62
Treated water/per
m3 mixed water (Ctot-Craw)/(Ctreated-Craw)
M3 TREATED BEFORE FILTER IS SATURATED
Calculations made using one filter
cycle (start-saturation-
regeneration)
HAP content 2500 Kg/filter
Fluoride holding
capacity 15 Kg/filter
Average fluoride
concentration raw
water 1,97 Mg/l Average of jan-2015-june-2017
Volume treated
before saturation 7614 M
Volume mixed water
produced 12216 M3
Mixed water of one 1 mg/l s
produced by mixing treated and
raw water

HUGO VREUGDENHIL
11/5/18
27
TIME TO REGENERATE ONE FILTER
Flowrate 15 M3/hour
Time 21 Days/filter
ELECTRICITY COST
Electricity for
regeneration 20 Euro/regeneration
Electricity for
filtration 36 Euro
High estimate. Water needs to be
pumped to an elevated tank of
10m
Total electricity cost 56 Euro
REGENERATION COST
NaOH 300 Euro/regeneration 300 kg of NaOH per regeneration
Co2 60 Euro/regeneration 30 kg of Co2 per regeneration
Total 360 Euro/regeneration
LORRY TANKER COST FOR WASTE DISPOSSAL
Concentrated fluoride needs to be
disposed in to the sewerage
treatment plant
Amount 1 Lorries/regeneration 40 - 60 m3 per regeneration
Price 30 Euro/lorry Yearly contract or own lorry
Cost 30 Euro/regeneration
HUMAN RESOURES

HUGO VREUGDENHIL
11/5/18
28
Price 433 Euro/month
It is advised to hire one process
supervisor with a chemical
engineering background
Cost 76 Euro/filter cycle
LABORATORY COST
Cost 10 Euro
Cost of reagents for analyses and
calibration of sensors
MAINTENANCE COST
Percentage of
investment cost 5,0%
Adopted from Kenya engineering
manual 2005. High estimate
Investment cost 250.000 Euro
Investment cost are estimated
between 200.000 and 300.000
yearly maintenance
cost 12.500 Euro/year
maintenance cost
per filter cycle 181 Euro
TREATMENT COST PER M3
Water produced 12216 M3
Total cost 713,5 Euro
Cost per m3 0,06 Euro
7,0 KES
COST INCLUDING NRW
Non Reveneu Water 34,00% Average 2015-2016
Cost including NRW 10,6 KES/m3

HUGO VREUGDENHIL
11/5/18
29
TARIFF
Current tariff
Residential
consumption block
in m3 / year Tariff KES/m3 Ratio to average
Block 1 0-6 m3 50 0,5
Block 2 7-20 m3 65 0,7
Block 3 21-50 m3 85 0,9
Block 4 51-100 m3 105 1,1
Block 5 101-300 m3 125 1,3
Block 6
301 m3 and
above 140 1,5
Average tariff 95 KES/m3
Average tariff
including fluor
removal 106 KES/m3
Residential
consumption block
in m3 / year
Tariff with fluoride
removal KES/m3 Difference KES/m3
Block 1 0-6 m3 56 6
Block 2 7-20 m3 72 7
Block 3 21-50 m3 95 10
Block 4 51-100 m3 117 12

HUGO VREUGDENHIL
11/5/18
30
Block 5 101-300 m3 139 14
Block 6
301 m3 and
above 156 16

Propossal for pilot in large scale centralised hap fluoride removal naivasha, kenya

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