Development of affordable adsorbent systems for arsenic and fluoride removal in the drinking ...

84 Pages·2015·2.83 MB·English

by  Rajabu Hamisi

Development of affordable adsorbent systems
for arsenic and fluoride removal in the
drinking water sources in Tanzania
(DAFWAT)

Felix Mtalo, Joseph Mtamba

Department of Water Resources Engineering,
University of Dar es Salam (UDSM), Tanzania,
E-mail: [email protected].

Prosun Bhattacharya, Berit Balfors, Roger
Thunvik, Helfrid Schulte-Herbrüggen,
M. Annaduzzaman

Department of Sustainable Development, Environmental Science and Technology KTH-
International Groundwater Arsenic Research Group Teknikringen 76, SE-10044
Stockholm, Sweden
E-mail: [email protected]

Project reference: .........2235............
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

Popular Summary:
There is a serious problem of elevated concentration of Arsenic and Fluoride containing
waters in parts of the Tanzanian Rift valley, particularly in the Northern regions. The elevated
concentration of these elements has posed a serious medical problem for dental, skeletal and
skin cancer. About 90% of the population living along the Great Rift Valley are affected by
dental fluorosis at some point. Fluoride issues have been having a lower priority and less
action has been taken to overcome the problem. In some communities there is no reliable
source of low-fluoride water and people may not realise the effects it has on their daily lives.
Current defluoridation technology employed in northern Tanzania is based on household and
community scale units. The units use bone char for sorption of fluoride. While this technology
reduces the fluoride level, it cannot produce water that complies with WHO guideline values
especially due to colouration and in some cases smell. There is also the problem of
preparation of the bones, collection of sustainable quantities and some religious beliefs.
Furthermore, high concentrations of arsenic in hand dug wells and deep wells were reported
in the gold mining areas around lake Victoria Basin
Alternative promising adsorbent materials investigated at UDSM, is a combination of
calcined gypsum, bauxite, and magnesites which are available naturally in Tanzania. Other
pollutants such as colour will be removed using membrane technology.
In this study, investigation and optimisation of the use of low-cost affordable adsorbents to
remove fluoride and Arsenic from water will be perfected at laboratory scale, and a pilot
water defluoridation plant will be constructed and tested at one of the places with excess
fluoride under the Arusha Urban Water Supply and Sewerage Authority (AUWSA). This will
also involve a pilot plant for preparation (crushing, sieving and calcination) of adsorbents
from locally available adsorbents rawmaterials (gypsum, bauxite and magnesite). The other
impurities such as colour, organic matter and trace elements will be removed by appyling the
membrane technology.

2
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

Table of Content
Popular Summary ............. 2
Popular Science description ............. 4
1. Introduction ............. 5
2. Background ............. 6
3. Benefits and added value for the partnership between the target
University and Swedish university ........... 15
4. Plans and expected outcome of the selected research training area of
focus/ the research supporting component ........... 16
5. Capacity Development Process: Brief outline of planned activities ........... 16
6. The planned contribution and responsibility of each of the
partners/participants/positions in the proposed research training
programme ........... 22
7. Management ........... 22
8. The operational issues of the research training programme/ research
supporting component ........... 24
9. Organisation of the Personnel Welfare ........... 26
10. Ethical consideration
........... 26
11. References
........... 26

3
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

Popular Science description:
The problem of fluoride and arsenic contaminated water has been reported in several studies
for water collected around the volcanic mountains, the Rift valley and the mining areas
around lake Victoria in Tanzania. The occurrence is geogenic and methods of reducing or
cleaning the water from the contaminants require a lot of energy or highly sophisticated
technologies which are not common or affordable within the communities living in these
areas. They are therefore forced to drink the contaminated water resulting in illhealth
conditions as observed in the reports from the hospitals and the community in general. 90% of
the people and animals living in these areas are surfering from fluorosis and those close to the
gold mining areas have been reported suffering from skin disorders.
The elevated concentration of these elements has posed a serious medical problems for dental,
skeletal and skin cancer. Fluorosis due to a high intake of fluoride from drinking waters has
previously been reported from several parts of the Tanzania, especially in the Great Rift
Valley and volcanic mountaneous areas of Meru and Kilimanjaro. The ground waters
especially around lake Victoria are characterized by elevated arsenic concentrations which
impair the drinking water quality; however studies are meagre to assess the severity of the
health outcomes. Focussed study will be undertaken to assess the extent of arsenic
contamination atround lake Victoria and in the rift valley groundwaters in order to design
suitable measures for mitigation and alleviate the safe drinking water access to the population
living in these regions.
The present project is focused on investigating the sorption performances of affordable
adsorbent systems for fluoride and arsenic removal in drinking water sources in Tanzania. A
pilot water defluoridation plant will be constructed and tested at one of the boreholes with
excess fluoride under the Arusha Urban Water Supply and Sewerage Authority (AUWSA).
This will also include a pilot plant for preparation (crushing, sieving and calcination) of
adsorbents from locally available adsorbents raw materials (gypsum, bauxite and magnesite).
The membrane technology will be tested for removing colour and othe organics form the raw
water.. AUWSA is interested in this project, since it will provide possible solutions to
alleviate the problem of potable water supply to Arusha city where several boreholes have
been condemned due to elevated Fluoride levels. The urgent need of investigating the
severity and distribution of geogenic contaminants such as arsenic and fluoride in the
Tanzania drinking water supply sources has been little documented in the country. From the
limited information available, groundwater compositions appear to be spatially variable and
highly dependent on the aquifer lithology. The arsenic and fluoride concentration in the
drinking water supply of are much higher than the WHO recommendations for drinking water
quality.

4
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

Enclosure 1
1. Introduction
There is a serious drinking water quality problem related to the presence of elevated gigantic
concentrations of fluoride and arsenic in some parts of Tanzania. High flouride concentration
is a significant water quality problem in the Great Rift Valley, particularly in Arusha (10
mg/l), Shinyanga (2.9 mg/l) and Singida (1.8 mg/l) region (Shedafa and Johnston, 2013;
Mjengera et al. 2003). About 90% of the population living along the Great Rift Valley are
affected by dental or skeletal fluorosis and bone crippling because of drinking water with
high levels of fluoride concentration (Smedley et al. 2002).
The adverse health effects of skin disorder and cancer due to an elevated arsenic
concentration were recently reported around the North Mara gold and Geita mining area in the
Lake Victoria Basin. About 30% of the water sources used for drinking in the country exceed
the maximum acceptable WHO limit of 1.5 mg/l fluoride and 0.01 mg/l arsenic. There is
scarcity of information and understanding of the fate and mobility of geogenic contaminants
in the ground water aquifers and surface water supply sources. This information is crucial in
exploring sources of safe drinking water aquifers, associated human health risks of arsenic
and fluoride pollution and scaling-up innovative technologies for water purification and
policy strategies to overcome the problem. In some communities there is no reliable source of
low-fluoride and arsenic water and people exposed to the high levels of fluoride may not
realize the effects it has on their daily lives.
Arsenic is a very toxic substance. Looking back at the history of WHO`s recommendations
for maximum permissible levels, a gradual lowering of maximum allowable Arsenic
concentration in drinking water can be observed since 1958, when maximum Arsenic
concentration of 200 µg/L was suggested, till 1993, when the guidelines for Drinking water
Quality (GDWQ) recommended 10 µg/L in a provisional definition. The legislative drop in
the maximum permissible Arsenic concentration in drinking water depends upon
technological developments in two principle areas; 1) measurement and quantification and 2)
removal processes.
In the past decade (after 1993), marked developments in both these areas have been made
which strongly indicate that another revision in drinking water Arsenic guidelines by WHO in
near future may be expected, which will of course affect the world-wide Arsenic standards.
The WHO has a general rule that no substance may have a higher life time risk of more than 1
in 100,000. However, several studies on toxicity of Arsenic suggest that purely based on
health effects the drinking water arsenic limit of 10 μg/L may not be sufficient.Thus, today
there exists a general consensus that, if possible, it is necessary to remove Arsenic as far as
possible, not only for the safety of human health from the toxicity of Arsenic, but also for
avoiding future non-compliance issues.The US Environmental Protection Agency (USEPA,
1998) and the US Natural Resources Defense Council (NRDC, 2000) has already
recommended Arsenic guidelines below 1 μg/L to attain an acceptable lifetime cancer risk.
Therefore, in this study achieving residual Arsenic concentrations of lower than 1 µg/L was
set as a target to be within the expected future lowering of drinking water Arsenic standard.
In order to provide safe drinking water supplies, there have been limited defluoridation
attempts during the past decades. The current treatment technology employed in northern
Tanzania is based on household and community scale filter units. The units use bone char for
sorption of fluoride. While this technology reduces the fluoride, it cannot produce water that
complies with the WHO guideline values,especially due to colouration and smell. There is
also the problem of preparation of the bones, collection of sustainable quantities and some
religious beliefs. Alternative promising adsorbent materials investigated at UDSM, constist of
5
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

a combination of calcined gypsum, bauxite, and magnesite which are naturally available in
Tanzania. Other pollutants such as colour and organics will be removed using the membrane
technology.
There is little information and knowledge on the fate and distribution of geochemical
contaminants in the drinking groundwater supplies sources and human health impacts in
Tanzania.
This project gives emphasis on generating local knowledge through specialised training of
staff and students from Department of Water Resources Engineering (WRE-UDSM) at PhD
level. The graduating staff will immediately join the faculty and increase the teaching and
research capability of UDSM. They will be exposed and understand how to realize a problem,
which data and tools are required for possible mitigation measures. The program also
envisages enhancing analytical capabilities through improved laboratory infrastructure to deal
with water quality problems towards affordable and innovative treatment systems for
inclusive development and human health in Tanzania. This initiative is crucial for developing
innovative technologies and transfer of knowledge and best practices, for controlling arsenic
and flouride pollution, from university laboratories to the local users and companies. The
long-term target of this project is to accelerate and advance science, technology and
innovation (STI) through strengthening research collaboration between Department of
Sustainable Development, Environmental Science and Engineering (SEED-KTH) and WRE-
UDSM for sustainable socio-economic growth and policy decision supporting system.
2. Background
2.1. The context of the programme in relation to the university concept paper
This research and training programme is proposed according to the UDSM demand of
strengthening human resource capacity and developing new affordable innovative systems for
pollutants (e.g. Arsenic and Fluoride) removal in the natural drinking water sources. It
responds to Item 5.1.5 Research and human resource capacity development in Natural
Resources (Wildlife, Forestry, Water, Mineral and Materials) and Tourism of the UDSM
concept note.This theme is important to Tanzania Development Vision (TDV 2025) and Big
Results Now (BRN) and teh Millenium Development goals (MDG) initiatives as it removes
the constraint of human access to adequate water of good quality and quantity. The present
programme is geared towards training four PhD and six Master Students in the field of water
resources engineering - biogeochemical analysis and modelling through developing
affordable technologies which can reduce the vulnerability of toxic elements (e.g. arsenic and
fluoride) in the drinking water sources.
The implementation of this programme will be administered in a joint collaborative
partnership by interdisciplinary research teams from the departments of Water Resources
Engineering (WRE-UDSM) and Sustainable Development, Environmental Science and
Engineering (SEED-KTH) in Sweden. Such approach is crucial to facilitate valuable scientific
research, exchange of expertise and specialised supervision to the trained PhD and Master
students and improve our understanding on the affordable techniques for arsenic and flouride
removal in the drinking water supply. The project organization also aspires to work closely
with private companies and local stakeholders such as Arusha Urban Water Supply Authority
(AUWSA) and Ngurdoto Defluoridation Research Station (NDRS) which is a joint
Defluoridation laboratory beteen UDSM and the ministry of Water. A pilot water
defluoridation plant will be constructed and tested at one of the boreholes with excess fluoride
under the Arusha Urban Water Supply and Sewerage Authority (AUWSA). This will also
involve a pilot plant for preparation (crushing, sieving and calcinations) of adsorbents from
locally available adsorbents raw materials (gypsum, bauxite and magnesite). AUWSA is
6
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

interested in this project as will provide possible solutions to alleviate the problem of potable
water supply to Arusha city using a range of adsorbents developed earlier at UDSM.
In Lake Victoria Basin, hand dug boreholes and water streams will be selected around the
mining areas at Geita and Mara regions to monitor arsenic mobilisation in soil sediment,
water, shallow and deep aquifers and evaluate the possible hydrogeological factors and
sorption performances of adsorbents at different redox conditions. The sorption modelling and
optimizing performance of adsorbents will be carried out to explain the behavior and
transport of the arsenic in the streams and groundwater aquifers.
The long term plan of this programme deems to establish a taught PhD programme course in
the field of hydrology and biogeochemical modelling at WRE - UDSM and develop a Water
Research Centre at College of Engineering and Technology (CoET) by 2017.

2.1.1 The problem that is to be addressed by the research training / research
strengthening program
There is a lack of capacity in Tanzanian univiersities with regards to assessment of
distribution and impactof geogenic contaminants (arsenic and fluoride) in the drinking water
sources. Likewise, there is a great need to develop local capacity which can understand and
tackle the problems of elevated concentration of arsenic and fluoride in the drinking supply
system.
Field studies carried out by UDSM staff in Arusha region observed surface water samples
which reached Fluoride concentration values as high as 1113 mg/L which exceeds the WHO
guidelines by a factor of 1000. The pH of this naturally occurring water was also high (>8.5)
and the total dissolved organic carbon (TOC) concentration in some of the waters was also
very high (> 100mg/L) and some of the surface water was brackish. The combination of the
above mentioned pollutants makes the water extremely difficult to treat with conventional
methods. The co-existence of high organic matter in high fluoride rich water significantly
compromises the sorbent capacity of typical sorbents used to remove fluoride.
Studies carried out at the Royal Institute of Technology (KTH) (Hamisi et al.2014) on
modelling the sorption performances of reactive filter materials for recovery of nutrients and
that from University of Dar es Salaam (UDSM) (Mtalo et al., 2007) have indicated promising
method for removal of fluoride from water based on the application of potentially cheap
locally available adsorbents such as, calcined bone char, bauxite, gypsum and magnesite at
laboratory scale. In terms of practical applications, however, only cow bone char is being
tried to a small extent to remove fluoride from water for local communities in the Arumeru
district Tanzania as managed by the NgurdotoDefluoridation Research Station (NDRS). On
the other hand, there has been few studies about the arsenic issues.
Randomly collected samples from drinking water sources were analysed for arsenic, among
others. Arsenic was detected in 58% of water sources surveyed and 41% of them had Arsenic
levels equal to/ or exceeding the Tanzania Drinking Water Quality Standards threshold value
of 1 ppm. A new report published by the Norwegian University of Life Sciences finds
potentially life-threatening levels of arsenic around the gold mining areas around Mara in
Tanzania. [http://www.miningwatch.ca/sites/miningwatch.ca/files/FinalTanzania.pdf.].
7
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

d
Figure 1. Health impacts of elevated fluoride concentrations in groundwater a) concentration between
4-10 mg/L cause skeletal fluorosis: bone malformation; b) concentration >10 mg/L leading to
crippling fluorosis, bone junctions growing together, immobility; c) concentration between 1.5-3.0
mg/L can cause dental fluorosis: Browning and mottling of teeth; d) skin disorder and birth effect is
one of the health effects caused by elevated arsenic concentration in the mining areas.

Figure 2. Map of Tanzania's geology setting

The access of safe drinking water is a pre-requisite to human health and sustainable social and
economic development. In Tanzania, only 57% in the rural communities and 86% in the urban
areas have access to improved drinking water services. However, there are a number of
outstanding challenges which limit access of safe potable water, especially in the large cities,
rift valley and mining areas. These challenges include inadequate knowledge of fate and
mobility of geogenic contaminants, uncontrolled release of pollutants from the pit latrines in
periurban areas, climate change, inadequate supporting policy and lack of innovative
technologies and infrastructure to deal with water quality problems. Groundwater in the Rift
Valley, which extends from Jordan Valley down through to Sudan, Ethiopia, Uganda, Kenya
and Tanzania, is reported to have high levels of Fluoride, which often exceed the local
regulatory limits and the WHO guidelines, and therefore limit the access to safe drinking
water.
8
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

Generally, arsenic and fluorine are a naturally occurring toxic elements which impact human
and ecosystem health (Bundschuh et al., 2004; Bhattacharya et al., 2006; Aullon et al., 2012).
In Tanzania, elevated concentrations of arsenic is prominent around the Lake Victoria Basin,
especially in the mining area where several cases of skin cancer, respiratory and
gastrointestinal problems have been reported (Fig.1d). Such excessive contamination of
arsenic in the drinking water sources has also magnified occurrences of water related conflicts
between the mine investors and surrounding local communities. Fluoride is by far the most
severe and widespread water quality problem in the regions along the Great Rift Valley in the
northern and south-western Tanzania (Bardercki, 1974; Nanyaro et al., 1984). The elevated
concentrations of fluoride have caused several health effects such as dental, crippling and
skeletal fluorosis. The combination of the above mentioned pollutants makes water extremely
difficult to treat with conventional methods.
Systematic water quality data is extremely important for the assessment of risks for human
health and developing appropriate and affordable technologies for drinking water treatment.
and long-term decision making policy against water quality management and protection. This
proposal for research training partnership envisages to built research capacity to understand
the underpinning mechanisms for the water quality problems related to the contaminants from
geogenic and anthropogenic sources and to develop appropriate innovative tools for
evaluation and assessment of the risks related to the drinking water quality in the rift valley
groundwaters. The specific objectives of this project are to investigate the sorption
performances of a number of adsorbents used for removal of fluoride and arsenic in the
drinking water treatment facilities. The hydrological and geochemical factors and mechanisms
controlling fate and mobilisation of aqueous arsenic and fluoride in the drinking water sources
beyond the broad range of redox potential hypotheses will also be investigated in field. Such
investigations will be linked with the assessment of the health impact due to enrichment of
arsenic and fluoride in the groundwater. Understanding the spatial distribution of these
geogenic pollutants and the geochemical factors leading to the mobilisation of the pollutants
from the aquifer matrices in groundwater water systems are crucial for developing affordable
adsorbent systems to treat fluoride and arsenic for drinking water supplies. PhD students
involved as part of research capacity building will be actively involved .in the investigation
on developing and optimizing the adsorption processes and the transfer the results of
laboratory scale studies to the design of pilot scale defluoridation unit. A pilot plant will be
used for investigation and optimisation of the use of low-cost affordable adsorbents to remove
fluoride and arsenic from drinking waters sources in Arusha city in a collaboration between
UDSM and KTH.
Overall, the results obtained in this pilot plant study will alleviate the problem of safe
drinking water availability to communities of Arusha, as well as all other areas where
excessive fluoride is rampant and also contribute to extend the scientific knowledge on
adsorption processes for water treatment. There is a high probability of an Intellectual
Property advancement which will be handled according to the signed MoA and later
commercialization of the same by local entrepreneurs. The project organization also aspires to
work closely with private companies and local stakeholders such as Arusha Urban Water
Supply Authority (AUWSA) and Ngurdoto Defluoridation Research Station (NDRS).

2.2 The scientific issues involved, and basis for the layout of the training programme for
the problem that is to be addressed by the research training and /or research supporting
component.
9
Development of affordable adsorbent systems for geogenic contaminant removal (2015-2020)

Provision of good water quality and quantity is the key indicator for human health, improving
livelihood standards, socio-economic and agricultural development. In Tanzania, just to
mention a few factors, the access to clean water supply and sanitation services are challenged
by dilapidated infrastructure in the urban areas, pollution from geochemical composition
processes, anthropogenic activities, climate change, inadequate policy and affordable
technology for water treatment and water protection. About 86% of residents in regional
towns and 57 % in the rural communities have access to clean drinking water.
The surface and groundwater pollution is primarily influenced by mineralization and
dissolution within the aquifer matrix, evaporation and anthropogenic processes (Fass et al.
2007).The investigation made by Norwegian University of Life Science in the vicinity of
North Mara Gold Mine in the Lake Victoria Basin has recently found excessive level of
arsenic concentration between 111µg/l to 1142 µg/l (Almås and Manoko, 2012) and the area
used for cattle grazing contained 40 times higher, the current WHO guideline for safe
drinking water of 10 µg/l. The anthropogenic activities like large scale mining, smelting of
arsenic bearing minerals and phosphate detergents made with arsenic bearing rock phosphate
may locally elevate the arsenic concentration in the drinking water sources. The geochemical
processes controlling groundwater mineralization need a special investigation and evaluation
in order to understand the problem of arsenic and fluoride pollution. Mapping the spatial
distribution the pollutants would help to identify the safe sources of groundwater for drinking
water supplies and help to provide guidelines for effective management to protect these
sources.
The most common sources of arsenic bearing minerals are arsenopyrite (FeAsS), cobaltite
(CoAsS), realgar (As S ) and tennantite (Cu As S ). Human activities such as mining,
4 4 12 4 13
smelting of arsenic bearing minerals and burning of fossil fuels (coal) may locally elevate the
arsenic concentration in the drinking water sources. The toxic and mobility of arsenic in the
groundwater sources is influenced by redox potential, pH and the presence of adsorbents such
as oxides, hydroxides of clay minerals and humic substances (Robinson et al., 2012). On a
large-scale, arsenic concentration in the groundwater is mainly found in strong reducing
aquifers or in closed basins with excessive evaporation, especially in the arid and semi-arid
regions. The greenstone belt east of Lake Victoria Basin, characterized by Nyanzian volcanic
rocks, containing gold mineral holds as the major source of arsenopyrite and sulfides
(Geosurvey, 1981, Bowell et al. 1995).The mobilisation and immobilisation of arsenic and
fluoride is potentially controlled by redox processes which may occur in the groundwater
aquifers.
Various studies have assessed the availability of safe groundwater for domestic, industrial and
agricultural development (Kashaigili, 2010;Almås and Manoko, 2012). However, not much
has been done on investigating the effects of arsenic and fluoride in the soil, sediment, surface
water and groundwater aquifers with regards to the variation of hydrological conditions or
geochemical factors (e.g. evaporite dissolution, cation exchange and carbonate weathering)
and redox potential. On the other hand, there has been virtually no study on technology for
arsenic removal using local adsorbent media.
In order to respond to the UDSM concept note (2015 - 2020) and Tanzania Development
Vision 2025, Science, Technology and Innovation (STI) deemed to play a special role in
improving water quality and living standard and contribute to better water management and
water quality protection without impairing positive health effects. Characterization of the
drinking water supplies and more specifically the trace element contaminants in the rift valley
settings and mining area are typically important for national and regional poverty alleviation.
The overall research training programme encompasses five main technical research issues:
10