This document provides background information on arsenic contamination in drinking water in Cambodia. It discusses that groundwater in certain Cambodian provinces along the Mekong and Tonle Sap rivers often contains high levels of arsenic exceeding safe drinking water standards. Long-term consumption of arsenic in drinking water can cause severe health issues. The document reviews existing literature on arsenic contamination globally and in Cambodia. It provides details on water sources and usage in Cambodia to understand the context. The aim of the document is to inform the design of an affordable water filtration system that can remove arsenic from groundwater in Cambodia.

1. 1
Cambodia:
Arsenic Removal
from Drinking Water
through a Variety of Options
Molis O’nilia Nou
FEBRUARY 2016
ARSENIC
MITIGATION
OPTIONS

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3. iii
1 INTRODUCTION
Table of Contents
1 Introduction .....................................................................1
1.1 Problem Statement..............................................................................1
1.2 Background on Cambodia ...................................................................1
1.3 The Solution ........................................................................................2
1.4 Aims and Objectives............................................................................2
1.5 Significance of Research.....................................................................2
2 Literature Review ............................................................ 3
2.1 Arsenic Contamination in Groundwater ...............................................3
2.2 The Cambodian Context......................................................................5
2.3 Factors to Consider in Water Filtration Design...................................11
3 Arsenic Mitigation Options........................................... 12
3.1 Arsenic Mitigation Techniques...........................................................12
3.2 Existing Projects in Cambodia ...........................................................14
3.3 Projects Outside of Cambodia ...........................................................16
3.4 Overview of Existing Arsenic Mitigation Projects ..............................20
4 Recommendations ........................................................ 23
5 Conclusions................................................................... 24

4. iv
Executive Summary
The research paper investigates a variety of filtration technologies and
systems for producing drinking water that is safe for human consumption.
The purpose of the research is to provide background information and a
review of existing literature that could potentially be used to design a water
filtration system for locals in Cambodian provinces such as the Kandal, Prey
Veng and Kampong Cham provinces.
The two primary sources of drinking water in Cambodia are groundwater
and surface water with groundwater being particularly prone to
contamination by arsenic. Hence, the research focuses on mitigation options
for the removal of arsenic from groundwater. Arsenic contamination has
been linked to various health problems including skin lesions and skin
cancer
This research paper describes 5 different arsenic removal technologies that
exist as well as practical applications of these technologies. From these
technologies, it was recommended that a household or community scale
design for a water filtration system should be used given the poor economic
state of the aforementioned Cambodian provinces.

5. 1
1 INTRODUCTION
1.1 Problem Statement
Whilst the vast majority of people living in developed countries have abundant access to
clean water supply, with an average of 90% of Australian’s having access to clean drinking
water, this is not the case for most developing nations (Sydney Water 2014). In particular,
access to clean water supply is a major issue in Cambodia. Although copious amounts of
water exist, from the two converging rivers, the Mekong and the Tonlé Sap, that flow across
Cambodia, to the 16 km of ocean water that borders Cambodia, much of it is contaminated.
During monsoonal season, both the Mekong and Tonlé Sap River serve as the primary
source of water supply in Cambodia and as rivers drain and the dry season arrives, locals
turn to groundwater extracted from wells. Among these water sources, groundwater presents
issues discovered only in the past two decades. Rivers are often used for washing pets as
well as clothes and household appliances resulting in bacteriological contamination.
Statistics have emphasised the significance of bacteriological contamination in rivers where
86% of deaths in Cambodia were related to preventable waterborne diseases in 2014 (RDIC
2014). In the case of groundwater, a study has shown that 73% of groundwater extracted
from wells along the Mekong and Bassac river banks contain high levels of naturally
occurring arsenic, exceeding 10µg/L, a guideline set by the World Health Organisation for
safe arsenic consumption (WHO 2014). Up to 1340 of arsenic per litre of water has been
recorded along these banks and a survey have shown that 1 in 10 people who drink water
containing 500µg of arsenic per litre of water may ultimately die from cancers caused by
arsenic including skin, lung, bladder and kidney cancers after long term consumption (A. H.
Smith 2004 and Buschmann et al 2007). There have been a number of efforts focused on
the removal of pathogens, however little has been done to address arsenic contamination.
1.2 The Solution
An affordable yet efficient water treatment system is essential to address the issue of
bacteriological and arsenic contamination in groundwater and ensure freshwater supply is
met across Cambodia, as well as other countries in the same situation.
1.3 Background on Cambodia
Cambodia, officially known as the Kingdom of Cambodia, is a country located in the
southern portion of the Indochina Peninsula in Southeast Asia. It is bordered by Thailand to
the northwest, Laos to the northeast, Vietnam to the east, and the Gulf of Thailand to the

6. 2
1 INTRODUCTION
southwest and has a landmass of 181,035km2
. With a steadily increasing population and
economy of over 15 million people and GDP of $39.7 billion, respectively, Cambodia once
saw a very traumatic past (IEC, 2013). Led by Pol Pot, the Khmer Rouge regime rose to
power in 1975 and killed approximately a quarter of the population leaving Cambodia in
social and political distrust. At present time, the aftermath of the war has caused major
problems including lack of adequate water, sanitation and hygiene, education,
transportation, and communication. The most common diseases in Cambodia today are
related to problems with water and sanitation (WHO, 2014). Many initiatives for national
development have been employed and in particular within the water sanitation sector.
1.4 Aims and Objectives
The primary aim of this research paper is to assess the suitability of existing arsenic
mitigation technologies to provide safe drinking water to locals in small communities across
Cambodia. Achieving this objective requires clear understanding of the Cambodian context.
This objective will be accomplished through a comprehensive review of primary and
secondary literature of existing arsenic mitigation projects as well as a critical evaluation of
the appropriateness of each project for the context of Cambodia. To compliment this,
interviews may also be conducted to gain more insight and depth into the benefits and
limitations of the projects.
This research paper is being written to assess suitable water filtration systems across
Cambodia to treat arsenic contamination in groundwater.
1.5 Significance of Research
Given the discovery of the harmful health effects associated with prolonged periods of
arsenic consumption, it is necessary to take immediate action to remove arsenic in drinking
water. Studies have illustrated that an alarming number of locals in Cambodian living in
arsenic-affected communities have contracted health problems such as skin lesions, skin
cancer and internal cancers. Thus, the Cambodian population will greatly benefit from the
implementation of a water filtration system designed to remove arsenic as well as
pathogens. This research serves to provide basic knowledge on successful existing arsenic
mitigation technologies and therefore allow designers to make more informed decisions in
the design of a water filtration system to remove arsenic.

7. 3
2 LITERATURE REVIEW
After establishing the correlation between long-term consumption of arsenic in drinking water
and health issues in Bangladesh over two decades ago, emphasis has been placed on the
removal of arsenic in water filtration design. There is ongoing investigation on arsenic
contamination in groundwater across the world. In particular, it has been found that arsenic
contamination is a major issue in Cambodia, affecting over 2.25 million rural dwellers across
seven provinces along the Mekong and Tonlé Sap river banks.
This section provides a literature review containing background information relevant to the
removal of arsenic from drinking water in Cambodia. The literature review aims to facilitate a
wholesome understanding of arsenic contamination in drinking water and the Cambodian
context in relation to arsenic-affected drinking water. The literature review begins with an
investigation of arsenic contamination in drinking water by exploring the sources, behaviour
and distribution of arsenic as well as health effects of long-term consumption of arsenic. The
section concludes with background information on Cambodia including a description of
arsenic-affected areas, primary sources and usages of water as well as the societal scenario
and economic constraints. Section 3 to 4 will explore existing water treatment solutions in
Cambodia and integrate a critical analysis of the suitability of each system for treating
arsenic affected water in Cambodia.
2.1 Arsenic Contamination in Groundwater
2.1.1 Sources and Behaviour of Arsenic in Natural Waters
In some areas of the world, sources of drinking water are contaminated with arsenic, posing
significant health problems after long term consumption. It is typically found that arsenic
concentrations in groundwater are considerably higher than that of surface water, commonly
exceeding 50 mg/L while surface waters are frequently less than 1 mg/L (Smedley, 2002).
Numerous studies have been conducted to determine the cause for this difference. Studies
have revealed that there is a strong correlation between topographic environmental variables
and the content of arsenic in groundwater. These large-scale naturally occurring arsenic
groundwater problem areas tend to be found in two types of environment including inland or
closed basins in arid or semi-arid areas and strongly reducing aquifers often derived from
alluvium. In each of these environments, the groundwater flow is slow where the ground
consists of young sediments. Such environments are usually poorly flushed aquifers and
therefore arsenic released from the sediments builds up in groundwater. The groundwater is
pumped to the surface by wells and consumed by the local population (for long periods).

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2 LITERATURE REVIEW
2.1.2 Health Effects of Arsenic Consumption
Typically, the harmful health effects associated with arsenic consumption occur when
concentrations exceeding 50 μg per litre of water are consumed over prolonged periods. The
effects of arsenic consumption occur over time and no immediate harm is caused.
One of the most common effects of long-term arsenic consumption is the development of
skin lesions. In 1987, K.C. Saha, (Department of Dermatology, School of Tropical Medicine
in Calcutta, India) determined that of his patients from West Bengal whose primary source of
drinking water was contaminated with arsenic had symptoms of skin lesions in their upper
chest, arms and legs as well as keratoses of the palms of the hand and soles of feet.
A study of a large population in Taiwan found a clear dose-response relationship between
arsenic concentrations in drinking-water and the prevalence of skin cancer. In this study, the
average concentration of arsenic in water was about 500 mg/L and by age 60 more than
10% had developed skin cancer (Tseng WP et al, 1968).
Arsenic contamination has also caused life threatening internal cancers. Studies in Northern
Chile revealed that 5-10% of deaths over the age of 30 were a result of arsenic-caused
internal cancers of the bladder and lung. The study revealed that exposure to arsenic
reached 500 mg/L over a 10-20 year period (Smith AH et al, 1998). Similar conclusions have
been identified in Taiwan and Argentina (Hopenhayn-Rich C et al, 1996).
Other health effects associated to prolonged arsenic consumption have been discovered
and include neurological effects, hypertension and cardiovascular disease, pulmonary
disease, peripheral vascular disease and diabetes mellitus (A. H. Smith et al, 2000).
2.1.3 Distribution of Arsenic on a Global Context
Figure 1 illustrates the world distribution of arsenic contamination in groundwater, having
concentrations of more than 50 µg per litre of water. (Smedley, 2002). The most noteworthy
occurrences are in parts of Argentina, Bangladesh, Chile, China, Hungary, India (West
Bengal), Mexico, Taiwan, Vietnam, Cambodia and the USA. This paper will focus only on
arsenic contamination in Cambodia.
The following subsection provides background information on the water sources used by
locals in Cambodia and the areas affected by arsenic contamination. The aim is to facilitate
a better understanding of the Cambodian context so that several designs can be evaluated

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2 LITERATURE REVIEW
on the basis of what is practicable, socially and economically acceptable and complies with
regulations. The section begins by describing the prevalence of arsenic in Cambodia and is
followed by an overview of the significance of groundwater sources in Cambodia. Data
concerning the average household consumption rate is then provided. The section
concludes with the current Cambodian social and economic scenario.
Figure 1: Arsenic Contaminated Aquifers across the World
2.2 Cambodian Context
2.2.1 Arsenic in Cambodia
Several studies have been conducted to identify the areas in Cambodia where groundwater
is most affected by arsenic contamination. A trend can be observed that elevated arsenic
levels in groundwater are clustered along the Bassac and Mekong river banks and the
alluvium braided by these rivers (Goldschmidt, 2004). In addition, the provinces that are
mostly adversely affected are the Kandal, Prey Veng and Kampong Cham provinces which
are located in the south-east part of Cambodia. Concentrations have been reported to be as
high as 1,300 μg/L, far exceeding the 50 μg/L standard (MIME, 2004). Figure 2 shows the
distribution of arsenic concentration throughout south-east Cambodia.

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2 LITERATURE REVIEW
Figure 2: Distribution of Arsenic in Groundwater throughout South-East Cambodia
Figure 3: Percentage of Water Supply retrieved from Tube Wells by Province in Cambodia

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2 LITERATURE REVIEW
To further exacerbate the issue of arsenic contamination in groundwater, a significant
concentration of tube wells in Cambodia are relied upon during the dry season by south-
eastern provinces such as the Kandal, Kampong Cham and Prey Veng provinces shown in
Figure 3. The figure shows the proportion of water that is retrieved from tube wells during the
dry season.
It can therefore be seen that in south-east Cambodia, groundwater is relied upon as the
primary drinking water supply while at the same time also demonstrating arsenic
concentrations well above safe drinking water standards. The design of an arsenic filter
would therefore be critical for locations such as the Kandal, Kampong Cham and Prey Veng
provinces.
2.2.2 Water Sources
A survey conducted in 2007 by the United Nations Children’s Fund (UNICEF) and the Water
and Sanitation Program has shown that of the people participating in the survey, the primary
source of water in Cambodia is surface water during monsoonal season. The Mekong River
and the Tonle Sap Lake are the predominant sources of surface water. However, as rivers
drain and the dry season arrives, surface water and groundwater usage approximately
equal. The survey has shown that groundwater is the second most critical source of drinking
water at 44%, just behind surface water at 46% during the dry season (UNICEF and Water
and Sanitation Program, 2007). The column chart below (Figure 4) summarises the results
of the survey conducted by UNICEF and the Water and Sanitation Program. The chart
describes the primary source of water supply for households in Cambodia in the dry season.
Figure 4: Primary Source of Water Supply for Households in Cambodia during the Dry Season (Source:
UNICEF and Water and Sanitation Program, 2007)

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2 LITERATURE REVIEW
In addition to these findings, it is important to recognise that approximately 81% of
Cambodia is rural and of this group, many rely solely upon groundwater because of the lack
of access to surface water or shortage of surface water during the dry season. Close to 60%
of rural dwellers use groundwater as their primary source of water supply (Ministry of Rural
Development Department of Rural Water Supply, 2002). Moreover, only 15% of urban
dwellers consume groundwater.
Hence, the significance of groundwater in Cambodia along with the persistence of arsenic in
groundwater throughout the country justifies the need for the research and design of a water
filtration system.
2.2.3 Water Usage
In the case of water usage, Rural Development International Cambodia (RDIC) has found
that on average, one Cambodian will use 35 litres of water per day (RDIC, 2008). Of this
amount, 2 to 3 litres is used for drinking and the remaining amount for cleaning, livestock
and other household activities (RDIC, 2008). An average household in Cambodia contains 5
people (UNICEF, 2007) and thus household usage per day is approximately 175 litres per
day.
2.2.4 Quality of Groundwater Sources
Approximately 1607 villages located in seven provinces with a total population of 2.25 million
in Cambodia are affected by arsenic in groundwater. All seven provinces are located along
the Mekong River Basin and Tonle Sap Basin. Moreover, 38% of tube‐wells in these seven
provinces are contaminated with arsenic above (50 ppb). Since the main source of water
among these areas is groundwater, the water quality concerns that will be investigated is the
natural occurrence of arsenic. It is important to note that the quality of surface waters in
which waterborne diseases occur will not be investigated in this report as surface waters are
not the main source of water in arsenic affected areas.
Extensive field testing has been undertaken by the World Health Organisation (WHO), RDIC
and UNICEF to quantify the extent of the problem.
The WHO guideline for arsenic is less than 10 ppb (parts per billion) with the Cambodian
health standard being 50ppb. The WHO found that one-third of 94 unique samples
exceeded WHO’s Guidelines Values for health concern and 46% exceed Cambodia’s
recently introduced Drinking Water Quality Standards (WHO, 2007).

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Tests for the KienSvay and Takhmau districts of Kandal Province found arsenic
contamination to be so high in primary testing that secondary testing was required. 70% of
secondary samples exceeded the WHO guideline of 10ppb (WHO, 2007). Concentrations
exceed 504 μg/L and averaged over 130 μg/L.
Table 1 illustrates the composition of groundwater and the associated concentrations for the
Mekong delta region in Cambodia. The table illustrates the significant levels of arsenic in the
groundwater.
Table 1: Composition of Groundwater in the Mekong Delta in Cambodia (Hug. J.S. et al)
Groundwater Composition Mekong Delta Cambodia
pHinitial 6.9 ± 0.4
HCO3
–
(mM) 5.5 ± 2.5
Ca (mM) 1.1 ± 0.9
Mg (mM) 1.0 ± 0.9
Si (mg/L) 20 ± 7
Fe (mg/L) 2.2 ± 3.3
P (mg/L) 0.5 ± 0.7
As (µg/L) 150 ± 276
As > 50 (µg/L) 40%
As > 10 (µg/L) 49%
Mn (mg/L) 0.7 ± 0.7
NH4–N (mg/L) 4.9 ± 9.1
2.2.5 Safe Drinking Water Guidelines
It is mandatory that the design of all water treatment systems in Cambodia comply with the
Drinking Water Quality Standards (DWS) (MIME, 2004). DWS aims to ensure safe drinking
water to all Cambodians and that there is no associated health risks to the public. The
standards state that drinking water should be safe, clean and clear with pleasant taste and
odour. The safety of drinking water has been determined by microbiological, physical and
chemical quality where the water does not contain suspended matter, harmful chemical
substances or pathogens while the quality of drinking water has been assessed by aesthetic
factors accepted by the public. The DWS describes parameters and their associated
maximum concentration values that the filtered water must not exceed for safe drinking
water in Cambodia. These parameters and maximum concentrations are described by the
Ministry of Industry, Mines and Energy (MIME) as well as the World Health Organisation
(WHO). Note the standards should serve as the basis for the design and planning of the
arsenic filtration system.

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2 LITERATURE REVIEW
2.2.6 Societal Scenario
Multiple field studies have been conducted to assess the behaviour and cultural values of
Cambodians in regards to water consumption. The results of these studies should be used in
the design process of the sand filter to ensure a socially acceptable solution is met.
One such study determined that Cambodians opt to drink water that meets their aesthetic
expectations as well as expectation for odour and taste (RDIC, 2008). This claimed is
supported by another study, which indicated that surface water was preferred over
groundwater sources (Feldman et al, 2007) accounting for 46% of water use in Cambodia
(UNICEF, 2008). The study attributed the lower turbidity as well as cleaner taste and odour
of surface water over groundwater to be the primary reasons that Cambodians preferred not
to drink groundwater (Feldman et al, 2007).
Groundwater sources often contain high levels of naturally occurring minerals that
Cambodian’s feel are unpleasant to drink or use. The most common dissolved minerals
affecting the aesthetic properties of groundwater in Cambodia include iron, manganese,
sodium chloride and hardness (calcium and magnesium) (Feldman et al, 2007). Cases of
high levels of iron and manganese have caused unfavoured taste and odour of the water,
stained clothes when washed in the water and corroded pipes and metal fittings while
calcium and magnesium caused bitter-tasting water and scale deposits in cooking pots
(Feldman et al, 2007). Elevated levels of these minerals have caused consumers to reject
newly installed water supplies in the past (Feldman et al, 2007).
Since dissolved arsenic in water is virtually undetectable as it is odourless and tasteless and
that health problems are only noticeable after decades of consumption, there is an
understandable ignorance in regard to arsenic contaminated water. RDIC concluded that
Cambodian’s are aware of the health issues associated with consuming arsenic
contaminated water but have not acted on this. Moreover, it is a widely accepted belief that
clear water is safe in Cambodia (RDIC, 2008).
Cambodia's poor health standards are exacerbated by a lack of basic health education and
income. In Cambodian culture, the importance of safe hygiene and sanitation are
undervalued which therefore limits the possibility achieving improved health outcomes in
drinking water (WHO, 2004).

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2 LITERATURE REVIEW
2.2.7 Economic Constraints
The continual advancement of technology has seen a variety of water treatment methods
that can produce virtually any desired quality of water from any given source; the limiting
factor being economic rather than technical. For example, water can be obtained from highly
contaminated sources such as seawater or sewage effluent and treated using methods such
distillation, electrodialysis or reverse osmosis to produce extremely high degree of purity,
however the capital and running costs associated with these water treatment methods are
very expensive. In developing countries such as Cambodia, this is impractical. This section
provides data on the average income of rural communities and an overview of the
Cambodian economy. Consequently, design (such as material selection) and
implementation will be restricted to costs affordable for communities in Cambodia.
With a steadily increasing population of 15.4 million people, the Cambodian economy has
also continued to strengthen significantly, seeing high amounts of growth in the agricultural
and tourism industry. In 2013, the Cambodia GDP grew at a rate of 7.0% and was valued at
$39.7 billion (IEF, 2014). In addition, 0.3% of the population are unemployed (IEF, 2014).
Despite these promising statistics, further research revealed many Cambodian’s are still
facing poverty and that a community scale filter may better suit the economic scenario of
Cambodia. Community scale filters are classified as public goods and will allow users free
usage of the filtering system.
It is anticipated that the implementation of a community scale water filter will result in positive
effects to the Cambodia economy. The project will require initial funds for construction to be
sourced by external aid agencies supporting regional or large scale clean drinking water
projects. Hence, this will provide an autonomous injection of investment into the economy. In
addition, since the filter is of a communal or household size, it is appropriate that local
tradespeople will be responsible for the construction and erection of the filter. This will
increase employment opportunities and domestic expenditure for locals in Cambodia.
2.3 Factors to Consider in Water Filtration Design
To be successful, the mitigation strategy must take into account the geological differences in
groundwater; the economic resources of the population; the availability of infrastructure for
water treatment and the acceptability by the community (Hug S.J. et al). Other
considerations include ease of implementation, installation, maintenance and use;
performance; waste removal; limitations; and overall impact to the community.

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The literature review briefly touched upon the vast majority of locals in Cambodia living along
the Mekong delta floodplain and Tonle Sap River who are dependent on groundwater
sources. In addition to this, the literature discussed the occurrence of high concentrations of
arsenic in groundwater and that the locals living in these lowland alluvial areas are at high
risk of arsenic poisoning and the associated health effects. As such, schemes have been
implemented across the world endeavouring to remove arsenic from drinking water.
This section describes several techniques that can be implemented for a filter design for the
removal of arsenic in water. Several existing projects that utilise these techniques have also
been described to show their practical applications. Finally, each existing project listed is
neatly summarised in a table. The table provides an overview of the projects against set
criteria (e.g. % of arsenic removed, capital costs etc) and is intended to assist the designer
in applying the appropriate technology to their situation. Educated recommendations on the
technologies used to remove arsenic are then provided for the remainder of the paper.
3.1 Arsenic Removal Techniques
Through the means of laboratory and field testing, there are many techniques that have
been proven to remove arsenic from water. These arsenic removal techniques include
oxidation; adsorption (sorptive filtration); coagulation and filtration; and membrane
techniques. A brief description of each technique has been given below.
(1) Oxidation and Sedimentation
Arsenic removal technologies most effectively remove arsenic in its pentavalent form,
arsenate (As(V)) as it is less mobile than the trivalent form, arsenite (As(III)). This is because
arsenate tends to co-precipitate out with metallic cations or adsorbs onto solid surfaces. As a
result of this, many arsenic removal treatment systems often involve converting arsenite to
arsenate as the first point of action.
In order make this conversion, an oxidation process is required to take place. There are
many oxidising agents that allows for the conversion and include oxygen (most common),
hypochlorite, permanganate and hydrogen peroxide.
Oxidation with oxygen existing naturally in the air will reduce arsenic concentration in stored
water. Oxidation by oxygen is also known as passive sedimentation. For passive
sedimentation, the water needs to be stored for a sufficiently long time allowing the

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3 ARSENIC MITIGATION OPTIONS
exchange of oxygen from the air to the water and is considered to be a very slow process
(Pierce & Moore, 1982).
(2) Adsorption (Sorptive Filtration)
Existing research has reported the success of several sorptive media in removing arsenic
from water. These sorptive medium include activated alumina, hydrated ferric oxide, hydrous
cerium oxide, activated carbon, iron coated sand, kaolinite clay, activated bauxite, titanium
oxide, silicium oxide and many natural and synthetic media.
The process of adsorption involves placing a packed column of sorptive media into the raw
water. Once immersed, the impurities including arsenic present in the water are adsorbed on
the surfaces of the sorptive media grains. Note that larger the surface area (m2
/g) of the
sorptive media, the more effective the adsorption process will be. When the packed column
is saturated and can no longer filter impurities from the water, the sorptive media must be
recharged or replaced. A specified chemical is usually required to recharge the saturated
sorptive media. The recharging or replacement process is quite expensive and would not be
suitable for rural dwellers in developing countries. The process also leaves sludge and is not
a sustainable solution in the long-term.
Examples of sorptive medium used in existing projects to remove arsenic have been outlined
in Section 3.3 and brief descriptions on the process and their success rate have been given.
(3) Coagulation and Filtration
Coagulation technology is an effective technology for the removal of arsenic in water. The
most common methods of coagulation for the removal of arsenic from water are with metal
salts and lime. At present, it is possible to reduce arsenic from 400 μg/L to 10 μg/L at a rate
of 500 L/sec, assuming variables including pH, oxidising and coagulation agents are
controlled (Sancha, 2006). However, it has been reported that the arsenic removal by lime is
relatively low, between 40–70%.
The process of coagulation involves adding the coagulated substance into the raw water and
stirring the water until the substance dissolves. Thereafter, the flocculation process takes
place where all kinds of micro-particles and negatively charged ions are attached to the flocs
by electrostatic attachment. Arsenic is also adsorbed onto the coagulated flocs. The flocs
are then removed partially by sedimentation, followed by filtration to ensure complete
removal of all flocs.

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3 ARSENIC MITIGATION OPTIONS
(4) Membrane Techniques
Membrane techniques are capable of eliminating many contaminants from water including
dissolved arsenic. There are three membrane techniques that are capable of eliminating
arsenic from water including reverse osmosis, nano-filtration and electrodialysis.
The process of using membrane techniques involves raw water passing through special
selective membrane which physically retains the impurities present in the water (Ahmed F.
2011). The membrane has microscopic pores that are specially sized to allow water
molecules through, while trapping larger inorganic molecules like lead, iron, chromium,
manganese and arsenic.
The technique requires very little maintenance and no addition of chemicals. However, using
membrane techniques at household level provides little amounts of purified water while at
community level, it becomes very expensive to operate and maintain. The technique may
cause the water to taste bland due to the inorganic materials removed in the treatment
process.
3.2 Existing Projects in Cambodia
To demonstrate the practical applications on the techniques in the previous section, several
existing projects are described herein. This will aid in discerning the technique that would be
most suitable for removing arsenic in drinking water in Cambodia.
 Kanchan Arsenic Filter (KAF) [adsorption techniques]
Based on 7 years of extensive laboratory and field studies in rural villages of Nepal,
researchers at the Massachusetts Institute of Technology (MIT), Environment and Public
Health Organisation (ENPHO) and Rural Water Supply and Sanitation Support Program
(RWSSSP) have developed the Kanchan Arsenic Filter (KAF), a system to remove arsenic
from drinking water in addition to providing microbiological water treatment (Ngai et al 2006).
The KAF is a household water treatment device that has been adapted from the Bio-Sand
Filter (BSF) and involves slow sand filtration and iron hydroxide adsorption techniques.
Pathogen removal involves standard sand filtration techniques while arsenic removal is
achieved by incorporating a layer of non-galvanised nails in the diffuser basin of the filter
where the arsenic adsorbs on the rusted iron nails surface and is removed from the water.
Figure 5 illustrates the cross-section of a typical Kanchan Arsenic Filter.

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3 ARSENIC MITIGATION OPTIONS
Figure 5: Cross-section of Kanchan Arsenic Filter
illustrating the Components
The KAF was tested under two conditions;
the first being under laboratory study in
Cambodia in 2006 by the Institute of
Technology of Cambodia (ITC) and then an 8
month field technical pilot demonstration
project in rural Cambodian communities.
The results demonstrated that the system
was successful as the KAF consistently
removed over 95-97% of arsenic, total
coliforms and E.coli from arsenic
contaminated groundwater. In other words,
the filters reduced arsenic levels from an
average of 637ppb to less than 50ppb.
These successful results allow for a reliable
mitigation option to arsenic affected households. In considering maintenance tasks, the KAF
does not require external energy or material input for operation and replacement parts with
the exception of iron nails (Chea S. et al, 2008). In addition, since the KAF uses biological
material such as sand, it is relatively cheap. Using the KAF results in arsenic-liquid-waste
formation and requires a high standard of waste management for safe disposal.
 Subterranean Arsenic Removal (SAR) [oxidation techniques]
Developed by Professor Bhaskar Sen Gupta and his team of scientists in Queen’s
University, the Subterranean Arsenic Removal (SAR) Technology is a simple and easily
adaptable technology that removes arsenic from groundwater using controlled oxidation.
At present, there are nine SAR plants implemented across India, Cambodia and Malaysia
with more than 13,000 people receiving SAR treated water supply. Of the communities using
SAR Technology, significant signs of recovery from arsenic poisoning have been observed.
In a modified in situ process, water is oxidised above-ground and injected back into the
aquifer, where ferric arsenate particles are then filtered (Sengupta B. et al, 2008). Error!
Reference source not found. illustrates the process taken by SAR Technology.
The results obtained during testing in West Bengal, India illustrated that the arsenic and iron
concentration gradually dropped to a permissible limit (below 0.01 µg/L (WHO guideline))
from an initial very high concentration of 250 µg/L within 45-50 days of operation.

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3 ARSENIC MITIGATION OPTIONS
Figure 6: Diagrammatical Representation of the Process
taken by SAR Technology
The greatest advantage of using SAR Technology is that the filtration process is chemical
free and results in no sludge. As a result, the process not only saves on disposal costs but is
also eco-friendly. The technology
is simple, easy to handle and is
very cost effective (low capital
and operational costs) and hence
SAR is suitable for developing
countries. In addition, the system
also has no restriction on the
volume it can handle.
The only disadvantage is that
SAR takes time to stabilise
because of the slow kinetics of
the oxidation process since the
oxygen rich impregnated
water requires time to create
the adequate oxidising zone
in the deep aquifer. Another consideration is that uncalculated amount of oxidation of the
aquifer can reverse the system resulting in arsenic and iron precipitation rather than
adsorption.
3.3 Projects Outside of Cambodia
Akin to subsection 3.2, this subsection serves to demonstrate the practical applications of
the techniques in relation to projects outside of Cambodia. Note projects that exclusively use
oxidation techniques have not been discussed because arsenic more effectively mitigated
from water in its pentavalent form (arsenate) which requires oxidation as the first point of
action, hence oxidation is discussed in combination with other techniques. This is Note also
that only brief descriptions will be provided for each project and the interested reader is
encouraged to seek further information by referring to the sources indicated.
(1) Adsorption (Sorptive Filtration)
Activated Alumina
Activated alumina can remove arsenic from water and is found to be highly effective as it has
a large sorptive surface and. A packed column of activated alumina is immersed into the

21. 17
3 ARSENIC MITIGATION OPTIONS
contaminated where the impurities including arsenic in the water are adsorbed on the
surfaces of the media. As the column becomes saturated, regeneration through the use of
caustic soda of the saturated alumina is required.
Examples of activated alumina include the Bangladesh University of Engineering and
Technology (BUET) Activated Alumina, Alcan Enhanced Activated Alumina, Arsenic
Removal Units (ARU) of Project Earth Industries Inc, USA and Apyron Arsenic Treatment
Unit. The technologies were found to average an arsenic reduction concentration of less
than 10µg/L.
Read-F Arsenic Removal Unit
Produced by Shin Nihon Salt Co. Ltd in Japan, Read-F is an adsorbent for arsenic removal
in Bangladesh. Read-F is made from ethylene-vinyl alcohol copolymer-borne hydrous cerium
oxide and hydrous cerium oxide is the adsorbent. The product is not classified as hazardous.
Laboratory test at BUET and field testing showed the product is highly sensitive to arsenic
ions under a broad range of conditions and effectively adsorbs both arsenite and arsenate
without the need for pre-treatment. That is, the adsorbent is highly effective in removing
arsenic from groundwater (SNSCL, 2000).
Iron Coated Sand
Iron coated sand is effective in removing both arsenite and arsenate. The preparation of iron
coated sand can be found in a study by (Ahmed, 2011). Field tests in Bangladesh showed
that raw water having 300 µg/L of arsenic when filtered through iron coated sand resulted in
arsenic free water.
The Shapla Filter is an example of an arsenic removal technology using iron coated sand
adsorption processes. As water passes through the filter, the arsenic present in the water is
absorbed to the iron coated sand. The filter can remove arsenic to virtually untraceable
levels. The filter operates at a household level and can hold up to 30 litres of water. The filter
can provide average of 25 to 32 litres of safe water to households per day.
Indigenous Filters
Sorptive media developed using indigenous Bangladesh material such as red soil rich in
oxidised iron, clay minerals, iron ore, iron scrap or fillings and processed cellulose materials
are known to have capacity for arsenic adsorption.

22. 18
3 ARSENIC MITIGATION OPTIONS
Examples of filters using these materials include Sono 3-Kolshi Filter, Garnet Home-made
Filter, Chari Filter, Adarsha Filter, Shafi Filter and Bijoypur Clay/Processed Cellulose Filter.
Arsenic can be removed by up to 97 % using these sorptive media.
Since the above mentioned adsorption techniques have not been investigated in
detail, they have not been included in the summary evaluation in this paper. These
techniques have been listed as they could potentially provide an effective solution depending
on the scenario. The interested reader is encouraged to further investigate these techniques.
(2) Coagulation and Filtration
The following examples of coagulation and filtration arsenic removal technologies have been
proposed by DPHE-Danida in Bangladesh and include the Bucket Treatment Unit, Stevens
Institute Technology, Fill and Draw Units and Arsenic Removal Attached to Tubewell.
Bucket Treatment Unit (BTU)
The Bucket Treatment Unit (BTU) removes arsenic from water by using a combination of
oxidation as well as coagulation and filtration processes. BTU is limited to household level
use only. The system works by the use of two plastic buckets, each 20 litres, placed one
above the other. In the upper bucket, chemicals are mixed with the polluted water by hand.
The chemical used includes aluminium, sulphate and potassium permanganate and are
supplied in powder form. Through a plastic pipe and sand filter box, the water in the upper
bucket flows through to the lower bucket. This technique has found cases with higher than
safe levels of aluminum and manganese.
Stevens Institute Technology
This technology also uses two buckets lying side by side. The first bucket mixes chemicals
including iron sulphate and calcium hypochloride which are supplied with the polluted water
while the second bucket serves to separate the flocs by sedimentation and filtration. Field
study illustrated that the Stevens Institute Technology reduced arsenic levels to less than
0.05 mg/L for 80% to 95% of the samples tested (BAMWSP, DFID, WaterAid, 2001). The
problems associated with the technology include quick clogging by floc in the sand bed and
requires washing at least twice a week.
Arsenic Removal Unit Attached to Tubewell
The Arsenic Removal Unit Attached to Tubewell project uses coagulation, sedimentation and
filtration techniques to treat the polluted water. The project has been implemented in villages

23. 19
3 ARSENIC MITIGATION OPTIONS
in West Bengal, India. The project demonstrated a 90% effective arsenic removal from
tubewell water having initial arsenic concentration of 300μg/L. More information about this
project can be found in a study by (Ahmed, 2011).
(3) Membrane Techniques
MRT-1000
A household level reverse osmosis water dispenser named MRT-1000 was promoted in
Bangladesh by Jago Corporation Limited. This system was tested at BUET showing an
As(V) removal efficiency of more than 80%. Experimental results also showed that the
system could reduce other impurities in water effectively.
Reid System Limited
A larger scale reverse osmosis system named Reid System Limited was also implemented
in Bangladesh and showed similar results to MRT-1000. The capital and operational costs of
the system however are much higher due to the larger size.
3.4 Summary of Existing Arsenic Mitigation Projects
This section provides a comparison between of the arsenic filtration techniques and projects
that implement them. The comparison is based on criteria that enable the reader to assess
which design would be most appropriate for any other potential project. Table 2 describes
the criteria that were used to evaluate each of the filter designs so that they could be
compared directly. Table 3 provides an evaluation of the filter design listed in this research
paper.
Table 2: Criteria used to Evaluate Filter Design
Design Attribute Criteria
Technique
 Which technique does the filter use including oxidation; adsorption; coagulation;
or membrane techniques?
Functionality
 Is the filter able to remove arsenic?
 Is able to provide safe drinking water?
Cost
 Capital Cost
 Implementation and installation cost
 Operating and maintenance cost
Resources  Requires skilled trades people to install and/or maintain
Performance
 Percentage of arsenic removed from water
 Percentage of other contaminants removed from water
 Time required to filter water until safe for consumption
Size  Individual/Household/Community/Commercial
Waste Removal  Requires waste removal

24. 20
3 ARSENIC MITIGATION OPTIONS
Table 3: Comparison of Existing Arsenic Mitigation Technologies listed in Research Paper
Arsenic
Mitigation
Project
Arsenic Mitigation
Technique
Oxidation; Adsorption;
Coagulation; Membrane
Techniques
Functionality
Safely removes
arsenic and
contaminants
Cost (in AUD$)
Capital cost;
Operating and maintenance costs
Performance
Removal efficiency; Time efficiency
Size
Household or
Community
Waste Removal
Yes/No
Kanchan Arsenic
Filter (KAF)
Adsorption Yes
 Capital Costs: $40 to $50 per
person depending on
location
 No operating costs (except
replacement of nails)
 95% – 97% arsenic removal efficiency and 60% –
100% total coliform and E.Coli removal
 Initially, just after filter installation, the flow rate can
be as high as 30 L/hr. The flow rate will drop over
time, to about 15 –20 L/hr in a month or two.
Household Yes
Subterranean
Arsenic Removal
(SAR)
Technology
Oxidisation Yes  Not cost effective for
developing countries
 99.9% arsenic removal efficiency
 45 – 50 days of operation
Community No
Bucket
Treatment
Technology
(BTU)
Coagulation Yes  Capital Costs: $10 to $15
 Removes arsenic to below 50 µg/L
 About 5 litres of water per capita per day
Household Yes
Stevens Institute
Technology
Coagulation Yes  Capital Costs: $5 per family
 Arsenic concentration in drinking water was
reduced from 600 µg/L to less than 50 µg/L
Household Yes
Arsenic Removal
Unit Attached to
Tubewell
Coagulation Yes Unavailable data  90% arsenic removal efficiency from tubewell
containing 300 µg/L of arsenic in water
Community Yes
MRT-1000
Membrane Technique
(Reverse Osmosis)
Yes
 High capital and operational
costs and not suitable or
developing countries
 80% arsenic removal efficiency Household Yes
Reid System
Limited
Membrane Technique
(Reverse Osmosis)
Yes
 High capital and operational
costs and not suitable or
developing countries
 80% arsenic removal efficiency Community Yes

25. 21
4 RECOMMENDATIONS
In light of the previous, this chapter will provide recommendations for potential future
pathways for design work, as no formal design work was conducted. Note that many details
are subject to change throughout the project’s life cycle. The work remaining in this project
involves the design of a water filter for provinces in Cambodian such as the Kandal, Prey
Veng and Kampong Cham provinces.
Although many different water filtration systems were described, it is recommended that a
household or community scale water filter is used, given the economic limitations of the
affected Cambodian provinces. A community scale would allow for an affordable means for
providing safe drinking water to a large number of people while household filters allow for the
dismissal of skilled labourers during construction, operation and maintenance and provide
safe drinking water for families.
For these reasons, the Kanchan Arsenic Filter system may be a suitable option, as it is
affordable and easily operated without excessive maintenance costs. More specifically, the
KAF is a household filter that is able to provide essentially arsenic and microbiological-agent
free water (95-97% removal efficiency for arsenic) and meet social acceptance as the filtered
water is free from unpleasant odour, taste and turbidity. Resources including materials and
skilled labour are available locally, that is, there is no need for external aid of obtaining
materials or construction. In addition, the filter is very simple to use and does not require any
training. There is however a waste removal requirement.
Future design work must also conduct detailed requirements analysis for these provinces,
which may require field testing and collecting samples of drinking water. This would provide
a solution for overcoming arsenic contamination that is specific to the provinces that the filter
is to be designed for.
Finally, to ensure acceptability of the water filter design, it is recommended that locals in
Cambodia are surveyed and educated on the use and benefits of the filter. Doing so will
allow the operation and maintenance of the filter without constant aid from external entities.

26. 22
5 CONCLUSIONS
This report has presented a comprehensive review of primary and secondary literature for a
project to provide safe drinking water to locals in small communities located in Cambodia.
More specifically, the aim of the project is to design a water filter to remove contaminants,
and in particular arsenic, from the drinking water sources in order to prevent adverse health
conditions such waterborne diseases and skin cancer.
A literature review was presented that highlighted the areas in Cambodia most adversely
affected by arsenic contamination, which included the Kandal, Prey Veng and Kampong
Cham provinces in south east Cambodia. Existing literature determined that the main source
of drinking water for these provinces is groundwater and that these groundwater sources
contained very high levels of arsenic concentration deemed unsafe for drinking (RDIC, 2008;
WHO, 2004; UNICEF, 2008).
The paper then proposed that a design for a water filter should be investigated in order to
provide such areas in Cambodia with safe drinking water. Several existing water filtration
techniques for arsenic removal were described. Existing projects that have implemented
these techniques were also described to illustrate practical applications of the techniques.
The investigation into the existing projects serves to stimulate further research into suitable
technology to remove arsenic from water in Cambodia and provide base knowledge for
future design work.
With key considerations in mind including the functionality of the filter, economic resources
of the population; the availability of infrastructure for water treatment and the acceptability by
the community as well as an all-encompassing review of the Cambodian context, two
selected technologies have been recommended. It has been recommended that the design
of the water filter should be based on the processes and techniques applied to the Kanchan
Arsenic Filter or the Subterranean Arsenic Removal Technology.

27. 23
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32. 28
About the Author
My name is Molis O’nilia
Nou but most people call
me Mel! I am in my final
year studying to
complete my Civil
Engineering degree at
the University of Sydney.
I have a strong passion
for humanitarian
engineering and as a
result, I became involved
with Engineers Without
mmBorders (EWB) Australia at the University level joining the Usyd
Chapter. I participated in the High School Outreach Program and
Appropriate Technologies Program. Shortly after, I became the
Secretary and Communications Coordinator for the NSW region.
As an avid supporter of humanitarian engineering, I sought to
participate in another initiative by EWB and was assigned to a
research project soon after. This paper is a product of the research
project deliverables. My involvement in this research project is of
particular significance to me as the project seeks to improve the
development of Cambodia as a nation. As Cambodia is the country
where my ancestors orgiinated, I have a deeply rooted personal
connection with the country. In addition, having been indirectly
affected by the Khmer Rouge, I have always wanted to create a
positive change in Cambodia.