Removal of Arsenic from Drinking Water

This article discusses the harmful effects of arsenic in drinking water and various techniques for its removal. It covers commonly used techniques like coagulation and filtration, membrane technology, sorption methods, precipitation methods, and the C/MF process. The article also justifies the need for arsenic removal and highlights the severe health problems caused by arsenic exposure. Subject: Environmental Science, Course Code: NA, College/University: NA

Removal of Arsenic from Drinking Water 1
REMOVAL OF ARSENIC FROM DRINKING WATER
Name of the student
Name of class
Name of Professor
Name of School
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Date

Removal of Arsenic from Drinking Water 2
Table of Content
Removal of Arsenic from drinking water........................................................................................3
1.0 Introduction................................................................................................................................3
Justification of the Study..............................................................................................................3
Severe Health Problems...............................................................................................................4
The chemical composition of arsenic...........................................................................................5
2.0 Commonly Used Techniques in the Removal of Arsenic from Water......................................5
Arsenic Removal by Coagulation and Filtration..........................................................................6
Arsenic Removal by Membrane Technology..............................................................................6
Arsenic Removal through Sorption Methods...............................................................................6
Arsenic Removal by Precipitation Methods................................................................................7
Coagulation Followed By Microfiltration (C/MF Process).........................................................7
Lime Softening.............................................................................................................................8
3.0 Advanced Treatment Methods...................................................................................................8
Hybrid Membrane Systems..........................................................................................................8
Iron –Modified Bamboo Charcoal...............................................................................................9
Electrocoagulation.......................................................................................................................9
4.0 Conclusion...............................................................................................................................10
5.0 List of References....................................................................................................................11

Removal of Arsenic from Drinking Water 3
Removal of Arsenic from drinking water
1.0 Introduction
The spread of arsenic in the environment is more than it was imagined. Currently, it is distributed
on a wide scale in the environment. The natural processes that introduce arsenic in surface water
include mineral leaching, soil erosion as well as weathering. Industrial arsenic and enriched
arsenic geothermal waters significantly contribute to the growth of arsenic amounts in surface
waters (Dimitrovski et al 2012, p.14). Arsenic also exists in oxidation states resulting in a variety
of compounds. Inorganic form, arsenic contains elements such as carbon. The inorganic types of
arsenic mixes are more lethal than natural ones. The inorganic forms of arsenic readily react with
body cells, displacing certain elements in the cell and consequently altering the function of the
cell.
Arsenic is applied in a variety of ways to produce certain products. It is used in the
production of CCA, the common wood preservative in the world. It is also used in the production
of alloys that are used in lead-acid batteries as well as semiconductor material manufacture.
Additionally, metallic arsenic can be added in alloys that are involved in metal, automotive
solder and ammunition production. Arsenic gets into surface water through industrial waste
discharge or geothermal waters. Initially, groundwater was regarded as safe but after extensive
research, it has been noted that groundwater has started to be contaminated with arsenic (WHO
2008). Arsenic is an inorganic substance that is found in numerous drinking water resources in
the world.
In Malaysia, the spread of arsenic contamination is caused by tin mining tools which
leach into river waters and groundwater. These waters subsequently contaminate local vegetables
as well as fish stocks in Malaysia. In polluted water, arsenic concentration ranges between 0,001
and 0.55mg/l. The maximum arsenic concentration levels that have been reported are 0.125mg/l
in sediment and 0.003 and 0.08 mg/l in plant and fish (Howard 2003, P.23). China, Chile,
Australia, Hungary, Thailand and the USA are among the countries that reported a serious health
hazard from arsenic in drinking water.

Removal of Arsenic from Drinking Water 4
The occurrence of cancer of the skin, kidney, bladder and lungs are some of the severe
consequences of arsenic intoxication (Mass et al. 2001, p.18). As much as Bangladesh consumes
groundwater, the problem of arsenic contamination is not different to Bangladesh. The problem
of groundwater arsenic contamination is increasingly soaring in many developed and developing
countries. In the Western US, the use of groundwater for drinking purposes has been adversely
affected as well as Mexico (Shih 2005, p.39). The Australia, Europe, Asia, North and South
American communities are likewise confronting the issue of arsenic-debased drinking water. The
communities in Chile, Brazil, Argentina, Peru and Mexico are also affected (Shevade and Ford
2004, p.21). The arsenic drinking water problem in Mexico and Argentina has been so severe to
an extent of achieving state acknowledgement as a public health concern. The impacts of arsenic
on drinking water are the worldwide problem and have affected millions of people. It is projected
that the affected population is likely to rise in future.
Justification of the Study
The contamination of arsenic in both groundwater and surface water is a global problem
which has been reported by several studies in the world. Some of the countries that have been
affected include New Zealand, the USA, Italy, Argentina, India and Malaysia. Studies have
indicated that arsenic causes numerous damages to human health. The increased consumption of
water that contains arsenic contributes to the development of kidney, bladder and liver tumour
alongside skin and circulatory system damages. From these studies, it clear that arsenic
contributes to numerous health problems to people and its removal from drinking water will
immensely reduce health problems in human. The removal of arsenic in drinking will be
achieved through the use of the conventional methods such as ion exchange, adsorption,
coagulation and precipitation. Other advanced techniques have been established for the same.
Therefore, the removal of arsenic in drinking will be of significance to the health of people.
Severe Health Problems
Over the past three decades, arsenic occurrences in drinking water have been recognized as
one of the main public health issues in the world. The irritation of the digestive tract, vomiting,
diarrhoea and nausea are some of the symptoms that are related to severe arsenic exposure. The
distinct skin abnormalities contributed by acute arsenic consumption include the appearance of
small corns on the sole, trunk and the dark or light spots on the skin which progress to skin
cancer. The use of chronic arsenic is related to increase liver, cancer and kidney risks (Choong et

Removal of Arsenic from Drinking Water 5
al. 2007, p.14). The continuous consumption of low concentration of arsenic can lead to stroke,
diabetes mellitus, and hypertension and heart attacks (Liu et al 2010, p.7). Inhalation of arsenic
can lead to lung throat and lung irritation and continuous exposure may result in lung cancer and
skin conditions.
The most vulnerable populations are infants and children. The indications of the toxic
effects of arsenic exposure in children are evidenced on infant birth weight, neurological
developments and congenital malformations. In Chile, the deadly, neonatal and post-neonatal
mortality dangers have been ascribed by low arsenic levels in drinking water (Author 2004,
p.26). According to (Karim 2000, p. 34), the higher incidences of stillbirths, pre-term births and
abortions have been related to arsenic in drinking water. To reduce the above risks, it is of
importance to involve arsenic in the gauges for drinking water quality. This can only be achieved
if appropriate techniques are devised to remove or reduce the amount of arsenic in drinking
water.
The chemical composition of arsenic
Arsenic is found in more than 200 different minerals in different oxidation states such as -
3, 0, +3 and +5 (Yong 2009, p.21). It additionally happens in different structures in water
contingent upon the pH esteem and redox response potential. The common pH value of arsenic
ranges between Ph. 5 to 8. The pH value determines the major species that dominate in water and
this plays a crucial parameter during the arsenic removal treatments. When As (III) is a
hydrolysed, it forms arsenic acid which exists as a free acid or a species that result from
dissociation. On the hand, As (V) can also hydrolyse to H3AsO4 acid but occurs as a non-
dissociated acid. In this regard, the quantity of arsenic that can cause severe effects relies upon
the physical and also synthetic type of the ingested arsenic. The dissolvable types of arsenic are
more harmful as compared to the insoluble forms. More so, the states of oxidation also affect
toxicity to humans. The reduced form of arsenic is more toxic than the oxidized form.
2.0 Commonly Used Techniques in the Removal of Arsenic from Water
Different techniques have been developed and implemented in fields and laboratory to
expel arsenic from drinking water. The procedures have been characterized in light of the
standards include, for example, coagulation, adsorption, ion exchange and layer innovation. In

Removal of Arsenic from Drinking Water 6
the recent years, the membrane technology has received much more attention as compared to
other arsenic removal technique.
Arsenic Removal by Coagulation and Filtration
In this technique, alum and ferric chloride are the main coagulants that are used
(Wickramasinghe 2004, p.47). In this case, arsenic is eliminated through sorption onto the fresh
precipitate of Al (OH) 3 and Fe (OH) 3 particles. The iron salts remove arsenic in water better
than aluminium salts. This method is one of the best methods to remove arsenic species from
water. The elimination is more effective in the presence of As (V) but rather unsatisfactory in the
presence of As (III). However, this can be necessitated by pre-oxidizing As (III) by H2O2 and
chlorine to As (V) (Baskan and Pala 2010, p. 11). The ferric chloride is broadly utilized in the
treatment of water because it is of low price and readily available. Ferric chloride has fewer
usability risks. The method produces large quantities of arsenic sludge to be discharged.
Arsenic Removal by Membrane Technology
The working principles that are involved in the elimination of arsenic using membrane
technology include filtration of the arsenic-bearing particles, exclusion depending on the extent
of the hydrated particles or electric aversion by the film. The membrane technology has been
regarded as the most effective method in eliminating arsenic from water but it is less satisfactory
in arsenic (III) cases. According to studies, the membrane technology can remove 95 per cent of
arsenic (V) and approximately 74 per cent of arsenic (III) (Mohan and Pittman 2007, p.19). The
use of reverse osmosis (RO) can offer additional arsenic removal. Nanofiltration process
demonstrates a transcendent evacuation of divalent species and can expel arsenic (III) and
arsenic (V) species productively through size avoidance. The return osmosis (RO) is another
reliable method of eliminating arsenic species. However, the technique is costly to the treatment
plants ranging from membrane costs to operating costs. The membranes also produce a bad
odour during use and this remains a major disadvantage to such a system.
Arsenic Removal through Sorption Methods
In the sorption method, activated carbon, hydrous metal and ion exchange resins are the
conventional adsorbents used in removing arsenic. The proposed arsenic species removal in the
synthetic ion exchange is mostly in chloride form (Kim et al 2004, p.8). The arsenate species of
arsenic can be removed by the resin. The exhausted resin regeneration is achieved by adding

Removal of Arsenic from Drinking Water 7
NaCl solutions. The hydrous metal can be utilized in an expulsion of arsenic in water. At the
point when the hydrous metals are in contact with water, its surface has hydroxyl bunches which
are liable to protolytic responses. At the zero pH charge, the surface is protonated which require
An-adsorption. The proficiency in arsenic expulsion has been seen in the utilization of iron
oxide. Depleted surface recovery can be conveyed by NaOH arrangements pursued by corrosive
washing to change the positive surface charge. The utilization of hydrous metal has restricted
unsteadiness. In the particle trade technique, half breed materials are presented in the polymer
framework. The materials consolidate sorption onto ferric oxide material with quick sorption
onto nano-particles. The moderate rate of sorption is one of the hindrances of utilizing hydrous
metal oxides or hydroxide.
Arsenic Removal by Precipitation Methods
This kind of method is suitable for removing arsenic in some inorganic arsenic compounds
that are insoluble. It is the most common method of removing arsenic from process streams by
precipitation. The arsenic (III) sulphide, ferric arsenate and calcium arsenate compounds are
produced by adding calcium oxide to the contaminated waters. At pH values exceeding 10.5, a
high amount of arsenic precipitate will be formed from the solution. Arsenic (V) can be
eliminated by precipitating it with ferric arsenate to arsenic water (Harper and Kingham1992,
p.4). However, precipitation forms unstable precipitates which are unsuitable for direct disposal
to uncontained sites which can eventually produce arsenic-bearing leachates (Litter et al. 2010,
p.17).
Coagulation Followed By Microfiltration (C/MF Process)
The microfiltration water recovery is higher as compared to other membrane
advancements. The vitality utilization is likewise moderately lower than different techniques
utilized in the arsenic evacuation. Microfiltration, for the most part, expels particulate type of
arsenic since it has the vast particulate pore. In this way, microfiltration is anything but a feasible
strategy for expelling arsenic since it evacuates a low level of the particulate type of arsenic in
the most water source. To enhance arsenic elimination in water, coagulation and flocculation
method is recommended to help the microfiltration technology. Studies have indicated that the
combination of coagulation and microfiltration improves arsenic removal and the combination is
much higher than the separated microfiltration.

Removal of Arsenic from Drinking Water 8
The use of Al (III) and Fe (III) salts can increase the concentration of metals in the
treated water and anions from the salts. Inorganic arsenic is present as arsenate and arsenite in
the natural aquatic environment. The stable form of inorganic arsenic is arsenate which
dominates in surface water. Arsenite is a reduced form of arsenic which reduces groundwater
(Chwirka et al 2000, p.38). According to (Basu et al 2015, p. 52), it is difficult to eliminate
arsenite from groundwater by the coagulation and microfiltration method. However, arsenite can
be removed by oxidizing it to arsenate by using oxidants such as chlorine. To remove arsenic in
groundwater and surface water, coagulation and microfiltration method should involve an
oxidant to necessitate arsenate from the water.
Lime Softening
The use of lime softening is effective for arsenic elimination but a considerable effort
should be involved to make it successful. The addition of lime in water serves two purposes in
water. As much as it used to eliminate arsenic, it also minimizes water hardness. The process of
adding lime in water removes calcium and magnesium ions as well as removes some
considerable amounts of arsenic through uptake of metal carbonates and hydroxide. Contrary to
its use, an excellent design is needed to pay attention to the possibility of operation and
maintenance costs that may occur, to outweigh the initial savings of installing a cheap physical
plant. Arsenic uptake usually rises at higher pH during the process of lime softening, especially
when magnesium hydroxide is established at the pH exceeding 10.8. The process of uptake
combines co-precipitation, sorption and occlusion of magnesium as well as calcium solids
(Kartinen and Martin 1995, p.78).
3.0 Advanced Treatment Methods
Hybrid Membrane Systems
The introduction of membrane bioreactors in the treatment of wastewater has offered an
alternative to eliminating arsenic from water. The hybrid membrane systems are crucial because
they permit phase separation between particles that bind arsenic and the treated water. In this
technique contact time, pH effect and other ionic compounds existence should be put into
consideration during the design of the membrane bioreactor system for maximum rejection of
arsenic (Nguyen et al. 2009, p. 31). However, researches have not yet established the full
potential of the technology for arsenic removal. The hydraulic as well as removal performances

Removal of Arsenic from Drinking Water 9
of the hybrid adsorption technology ought to assess both the potential of the membrane and
adsorption technology in arsenic elimination.
Iron –Modified Bamboo Charcoal
The technique is effective in the elimination of arsenic from aqueous systems. The method
is exciting for future growth in arsenic removal. The low cost and high adsorption capacity of the
BC-Fe discussed by (Wang et al 2013, p.62) demonstrates that the technique is a promising
option for end of arsenic in polluted water. This method was orchestrated by placing iron into
bamboo charcoal by absorbing the arrangement of ferric salt. The BC-Fe has a porous surface
277895 m2/g surface territory. After the adsorption qualities of arsenic onto BC-Fe researched at
a few pHs, arsenic focuses, contact times and adsorbent dosages in bench tests, it was seen that
the relating most extreme balance times pH ranges of arsenite and arsenate expulsion were 4-5
and 3-4 separately. The balance times of arsenite and arsenate adsorption likewise ran between
30 to 35.5 h. in this strategy, the arsenic end depends on the underlying adsorbent fixation and
additionally the adsorbent dose.
Electrocoagulation
It is a water treatment technology that comprises electrolytic oxidation of anode materials
as well as the in-situ production of coagulant. According to (Kumar et al 2005, p.13), the method
achieved over 99.9 per cent arsenic elimination efficiency. The method has been effective in
eliminating arsenic from drinking water. It is an alternative to chemical coagulant and the
process can oxidize arsenite to arsenate. After the batch electro coagulant experiment conducted,
it was observed that arsenic removal in this method is slower at high pH but arsenate removal is
fast as compared to arsenite (World Health Organization, 2008).
There are numerous considerations to be followed for the elimination of arsenic from
drinking water. Firstly, the expert ought to keenly select the appropriate technology to be used.
However, they have to be aware of the total concentration of arsenic in the source water. They
should access information from the database or send samples to the laboratory to ascertain the
concentration if the information is unavailable. Secondly, the source water quality
characterization will be of help to determine the best treatment option. The water qualities in the
source are known to hinder arsenic removal performance. Besides, the sustainability of the
treatment system should also be considered to know if water quality will be measured in

Removal of Arsenic from Drinking Water 10
compliance with regulatory agencies. Finally, the safe handling and appropriate disposal of the
produced waste from arsenic elimination should be put into the account.
4.0 Conclusion
The drinking water contamination of arsenic is a worldwide problem that will become
apparent in the future. Most of the developing countries have put their attention on the rural,
urban groundwater and agricultural contamination of arsenic contamination in the developed
countries. The severe arsenic poisoning does not only cause physical problems but also acute
social effects. The chronic skin lesions caused by arsenic poisoning have accidentally
stigmatized families and leading to family isolation. Fossil fuels, wood as well as industrial
activities have resulted in air, soil and surface water contamination by arsenic compounds. The
only way to prevent or reduce this hazard is to minimize arsenic chemical use, arsenic
contamination confinement and ensuring complete enforcement through regulatory bodies. To
select the most appropriate technology, the concentrations of arsenic in source water need to be
considered. The elimination of arsenic does not only involve removing arsenic in water but also
proper disposal of the solid wastes.

Removal of Arsenic from Drinking Water 11
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Removal of Arsenic from Drinking Water 13
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