chapt£raw1 - shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/31494/7/07... · 2018. 7. 2. ·...
TRANSCRIPT
CHAPT£RAW1 Introduction
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
CHAPTER 1
INTRODUCTION AND PRESENT STATUS OF
KNOWLEDGE
PREAMBLE
Water is one of the most essential needs of every living being. This need stems from
the fact that it is the water which causes and sustains any life form. The first living
creature of earth took birth in the water only and even today the maximum number
of life forms and their population is supported by water only. The terrestrial life
forms came on the earth in view of the fierce competition for the life supporting
parameters within the water. The most notable among such limiting parameters was
the sunlight and the nutrients. This shifting to the land provided the ample quantity
of sun light and the nutrients which resulted into their fast growth and today we can
find the various life forms even in the supposedly inhospitable areas of the earth.
Yet these life forms could not alter their great dependence on water. It is the reason
that every life form be it is human; plant or animal cannot keep themselves away
from water.
However the success of human race in the matters of survival has brought
about many problems in its wake. The biggest among them is the serious shortage of
usable water for various human purposes. This shortage led the man to explore a
particular source which other living beings can never do i.e. the exploitation of the
groundwater. The groundwater is termed as mother's milk also by some poetic
scientists. Yet the overexploitation of this scarce source is poisoning this precious
and sacred source. A large number of human problems could be attributed to the
misuse of this resource. Severe depletion of the groundwater and its contamination
are the two broad categories of the problem. This thesis is an attempt to study some
------------ --------------------8
Studies On Technology Oriented Methods For Water Contaminants And The Geochem/co/Jnfluences On Contaminated Plume
of the aspects of the groundwater contamination and what could be done by the
scientific community to reduce or eliminate such contaminations.
INTRODUCTION
When even a simple change occurs in the physical environment, its effects percolate
through a complex net-work of physical, biological and social interactions, that feed
back and feed forwards. Sometimes the immediate effect of a change is different
from the long term effect, sometimes the local changes may be different from the
region-wide alterations. These environmental changes entail unusually large spatial
scales. They also entail temporal scales that extend decades, or further, into the
future. Some entail irreversible changes. In case of groundwater the extent,
magnitude and the enormity of problem may sometimes defy the human cognition.
Reason for such behaviour lies in the intricacies associated with groundwater.
WHAT IS GROUND WATER AND HOW CAN IT BE POLLUTED?
Ground water is a resource found under the earth's surface. Most ground water
comes from rain and melting snow soaking into the ground. Water fills the spaces
between rocks and soils, making an "aquifer".
Ground water- its depth from the surface, quality for drinking water, and chance of
being polluted -varies from place to place. Generally, the deeper the well, the better
the ground water. The amount of new water flowing into the area also affects
ground water quality. Worldwide, according to a UNEP study (UNEP, 2003), over 2 B
people depend on aquifers for their drinking water. 40 per cent of the world's food
is produced by irrigated agriculture that relies largely on groundwater.
Ground water may contain some natural impurities or contaminants, even with no
human activity or pollution. Natural contaminants can come from many conditions
in the watershed or in the ground. Water moving through underground rocks and
9
Studies On Technology Oriented Methods For Woter Contaminants And The Geochemkallnfluences On Contamlnoted Plume
soils may pick up magnesium, calcium and chlorides. In addition to natural
contaminants, ground water is often polluted by human activities such as
• Improper use of fertilizers, animal manures, herbicides, insecticides, and
pesticides
• Improperly built or poorly located and/or maintained septic systems for
household wastewater
• leaking or abandoned underground storage tanks and piping
• Storm-water drains that discharge chemicals to ground water
• Improper disposal or storage of wastes
• Chemical spills at local industrial sites
WHERE DO GROUND WATER POLLUTANTS COME FROM?
Understanding and spotting possible pollution sources is important. It's the first step
to safeguard drinking water for our family. Some threats come from nature.
Naturally occurring contaminants such as minerals can present a health risk. Other
potential sources come from past or present human activity - things that we do,
make, and use such as mining, farming and using chemicals. Some of these activities
may result in the pollution of the water we drink.
Metal Leaching and Acid Rock Drainage
Metals are a natural part of our environment. Life has evolved in this natural milieu
and requires that metals be present in appropriate levels and combinations.
Concentrations of metals that are too low can lead to health problems as a result of
nutrient deficiencies, whereas metal concentrations that are too high can be toxic to
plants, animals, and humans.
Metal leaching and acid generation are naturally occurring processes, which may
have negative impacts on the receiving environment. The environmental impact of
Ml/ ARD will depend on their magnitude, the sensitivity of the receiving
environment and the degree of neutralization, dilution and/or attenuation. Factors,
-------- -------------------------10
Studies On Technology Oriented Methods For Water Contom/tJQnts And The Geochemical Influences On Contaminated Plume
which enhance metal leaching, include rapidly weathering metal-containing
minerals, drainage conditions that increase solubility and high flow rates through
contaminated materials. Elevated metal leaching is associated with acidic drainage
due to high metal solubility and sulphide weathering rates under acidic conditions
(Pons et al., 1982). For many rock types/environmental conditions, metal leaching
will only be significant if drainage pH drops below 5.5 or 6.
However, neutral pH drainage does not necessarily prevent metal leaching from
occurring in sufficient quantities to cause negative impacts. While the solubility of
aluminum, iron and copper is greatly reduced in neutral pH drainage, elements such
as antimony, arsenic, cadmium, molybdenum, selenium and zinc remain relatively
soluble and can occur in significantly high concentrations. Unlike ARD, neutral pH
metal leaching is generally only a concern if discharge is into a sensitive resource
and/or with little dilution. High concentrations of metals in neutral pH drainage
often result from localized relatively small zones of acidic weathering (William and
John, 1998). Human activity can greatly enhance acid generation and metal leaching.
Sulphide oxidation resulting in very acidic pH values is common worldwide in marine
soils drained for activities such as farming (Pons et al., 1982). ARD also occurs where
mineralized bedrock is excavated for use in construction. While sulphide mineral
oxidation results in acid generation, mining operations that expose sulphide-bearing
rock do not always create Ml/ ARD. In many cases, drainage alkalinity or other
minerals neutralize the acid. Acid neutralization and the consequent reduction in
metal solubility can occur immediately or at some downstream point. Acidity will
only persist if acid generation is faster than the rate of neutralization or continues
after the available neutralization is exhausted. Even if net acid conditions result,
ML/ARD may not be a concern if there is adequate neutralization or dilution prior to
discharge, or if insufficient water exists to transpc;>rt acid weathering products
(Morin and Hutt, 1997).
11
WHAT HUMAN ACI!VmES CAN POUUTE GROUND WATERl
Bacteria and Nitrates
These pollutants are found in human and animal wastes. Septic tanks can cause
bacterial and nitrate pollution. So can large numbers of farm animals. Both septic
systems and animal manures must be carefully managed to prevent pollution.
Sanitary landfills and garbage dumps are also sources. Children and some adults are
at extra risk when exposed to water-born bacteria. These Include the elderly and
people whose immune systems are weak due to AIDS or treatments for cancer.
Fertilizers can add to nitrate problems. Nitrates cause a health threat in very young
infants called "blue baby" syndrome. This condition disrupts oxygen flow in the
blood (EPA, 2002).
Heavy Metals
Activities such as mining and construction can release large amounts of heavy
metals into nearby ground water sources. Some older fruit orchards may contain
high levels of arsenic, once used as a pesticide. At high levels, these metals pose a
health risk.
Fertilizers and Pesticides
Farmers use fertilizers and pesticides to promote growth and reduce insect damage.
These products are also used on golf courses and suburban lawns and gardens. The
chemicals in these products may end up in ground water. Such pollution depends on
the types and amounts of chemicals used and how they are applied. local
environmental conditions (soil types, seasonal snow and rainfall) also affect this
pollution. Many fertilizers contain forms of nitrogen that can break down into
harmful nitrates. This could add to other sources of nitrates mentioned above. Some
underground agricultural drainage systems collect fertilizers and pesticides. This
polluted water can pose problems to ground water and local streams and rivers. In
12
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contomlnated Plume
addition, chemicals used to treat buildings and homes for termites or other pests
may also pose a threat. Again, the possibility of problems depends on the amount
and kind of chemicals. The types of soil and the amount of water moving through
the soil also play a role (EPA, 2002).
Industrial Products and Wastes
Many harmful chemicals are used widely in local business and industry. These can
become drinking water pollutants if not well managed. The most common sources of
such problems are:
a} Leaking Underground Tanks & Piping
Petroleum products, chemicals, and wastes stored in underground storage tanks and
pipes may end up in the ground water. Tanks and piping leak if they are constructed
or installed improperly. Steel tanks and piping corrode with age. Tanks are often
found on farms. The possibility of leaking tanks is great on old, abandoned farm
sites. Farm tanks are exempt from the EPA rules for petroleum and chemical tanks.
b) Landfills and Waste Dumps
Modern landfills are designed to contain any leaking liquids. But floods can carry
them over the barriers. Older dumpsites may have a wide variety of pollutants that
can seep into ground water.
Household Wastes
Improper disposal of many common products can pollute ground water. These
include cleaning solvents, used motor oil, paints, and paint thinners. Even soaps and
detergents can harm drinking water. These are often a problem from faulty septic
tanks and septic leaching fields.
Water Treatment Chemicals
Improper handling or storage of water-well treatment chemicals (disinfectants,
corrosion inhibitors, etc.) close to a well can cause problems.
----------------- -----------------~ u
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
METALS AND THE GROUNDWATER CONTAMINATION
Metals, radionuclides and other inorganic contaminants are among the most
prevalent forms of environmental contaminants, and their remediation in soils and
sediments is rather a difficult task (Cunningham et al., 1997). Sources of
anthropogenic metal contamination include smelting of metalliferous ore,
electroplating, gas exhaust, energy and fuel production, the application of fertilizers
and municipal sludges to land, and industrial manufacturing (Raskin et al., 1994;
Cunningham et al., 1997; Blaylock and Huang, 2000). Heavy metal contamination of
the biosphere has increased sharply since 1900 (Nriagu, 1979) and poses major
environmental and human health problems worldwide (Ensley, 2000). Unlike many
organic contaminants, most metals and radio nuclides cannot be eliminated from the
environment by chemical or biological transformation (Cunningham and Ow, 1996;
NRC, 1997). Although it may be possible to reduce the toxicity of certain metals by
influencing their speciation, they do not degrade and are persistent in the
environment (NRC, 1999). It is estimated that all over the world huge areas have
contamination due to metals. Similarly, large number of industrial facilities also has
problems with metals. This, in conjunction with a paucity of innovative approaches
to deal with metal problems, means that metal contamination represents a serious
environmental concern and a significant market opportunity for environmental
service companies (Vance, 2002).
Metals (or other inorganics) typically become groundwater problems under the
following situations:
• Activities associated with plating shops, where a wide variety of metals are
present at high concentrations in forms that are soluble.
• Sites with releases of radionucleides that, due to unique health risks, can
have significant impact at very low concentrations. In addition, the use of
chelating and complexing agents, making these contaminants mobile in the
environment, is common during processing of these materials.
14
Studies On Technology Oriented Methods For Water Contaminants And The GeO(hemlca/lnfluences On Contaminated Plume
• Metals and high levels of inorganic Total Dissolved Solids (TDS) are associated
with leaks from sanitary, solid waste and hazardous waste landfills.
• High TDS impacts are also associated with salt storage areas and petroleum
production activities.
Innovation in the area of hydrocarbon remediation has been significant in the last
decade. Metals may only be mobilized or immobilized, unlike hydrocarbons they
cannot be degraded to less innocuous components (C02 and H20 for example). This
limited reactivity is one of the reasons that innovative remediation technology has
not been developed for soils or groundwater contaminated with metals. This will
likely change between now and the turn of the century.
Often metal contamination is confined to the upper few feet of soil beneath a
contaminated area. However, there are instances where metal contamination has
impacted groundwater. The purpose of this column is to discuss the
physical/chemical behavior of metals with a particular focus on conditions that make
metals mobile and thus able to impact groundwater. The next column will look at
remedial alternatives to metal contaminated groundwater. The important issue with
regards to metals is mobility. Specifically, under what conditions are metals mobile
and what conditions immobile? Metals in the environment can take four
fundamental forms: as raw metallic elements, as hydrated ionic salts, in covalently
bonded molecules termed inorganic complexes, or associated with a chelating
agent.
Elemental metals are not highly soluble under normal groundwater conditions.
Although, particles of elemental metal may cause a soil sample to fail a TClP test.
The mobility of metals as hydrated ionic salts is dependent first, upon which metallic
element is participating as the positively charged ion (termed the cation) and
secondly, which anion makes up the negatively charged component of the salt.
15
Studies On Technology Oriented Methods For Water Contom/nonts And The Geochemical Influences On Contaminated Plume
Following is a brief summary of cationic/anionic solubility relationships:
1. Sodium (Na•), Potassium (K+) and Ammonium (NH/) are cations that form
salts which are all soluble.
2. All metal salts of the Nitrate (No3·), Nitrite (N02.), Acetate (C2H30 2.),
Permanganate (Mn04.), Perchlorate (Cio4·), and Chlorate (Cio3·) anions are
soluble.
3. All Chloride (Cr), Bromide (Br"), and Iodide (r) salts are soluble except those
of Lead (Pb2•), Silver (Ag•), and Mercury (Hg2
•).
4. All Sulfate (So/·) salts are soluble except those of Barium (Ba2•), Strontium
(Sr2•) and Lead (Pb2
•).
5. All Oxides (02.), Sulfides (S2
.) and Hydroxides (OH.) are insoluble except those
of Calcium (Ca2•), Barium (Ba2
•) and Strontium (Sr2•).
6. With the exception of Sodium (Na•), Potassium (K+) and Ammonium (NH/),
all metallic salts of the following anions are insoluble: Carbonate (C03 2");
Phosphate (Pol·), Sulfite (So/·), Borate (BO/), Fluoride (F) and Silicate
(SiO{).
A covalently bonded inorganic molecule that contains several atoms (one of more
of which are metal atoms) is termed an inorganic complex. Of particular interest and
environmental concern are a class of inorganic complexes termed oxyanions. These
are compounds composed of metal and oxygen atoms forming an entire molecule
(rather than just an isolated metal ion) that is capable of forming a hydrated
complex ion. These oxyanionic complexes are often soluble and more importantly
have physical/chemical qualities that make them valuable in various industrial
processes. In a modern industrial environment, metallic and metalloid oxyanions not
rare substances.
The most troublesome and the most common industrial oxyanion is chromate which
contains hexavalent chromium Cr(VI). The chromate molecule in turn forms an
extremely soluble anionically charged ion. Contributing to its high mobility in the
environment is a property of the chromate ion that allows it to be soluble over the
entire range of pH. This high degree of mobility, in conjunction with its common use,
16
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
and the fact that it is a known carcinogen, makes it one of the most common
problem metals found to contaminate groundwater (Vance, 2002).
The ability of chromium to form soluble oxyanionic complexes is not unique to it
only. There are other metals and metalloids that form inorganic complexes having
more or less the same solubility profiles. This includes: molybdenum, vanadium,
tungsten, arsenic, selenium and tellurium. These compounds are not commonly
utilized by our industrial society. Although, arsenic and selenium can have significant
groundwater impact around mining areas and irrigation complexes in the west.
Industrial chemistry often makes use of complexing agents with more that one point
of attachment to a central metal atom in a complex. This type of complexing agent is
termed a polydentate ligand or a chelating agent. Chelating agents form strong
bonds with metals and are in turn extremely soluble. EDTA (ethylenediaminetetra
acetic acid) is a commonly used chelating agent. Chelating agents are used in
industrial chemical systems with transition metals, heavy metals and radionucleides.
If released into the groundwater these metal bearing chelates are extremely mobile.
It should also be remembered that under some conditions metals in groundwater
can be mobile as colloidal sized particles, even though the metal is in an insoluble
form. Although not soluble, colloidal particles are so small they may approach the
size of ionized species within an order of magnitude. As such they are transportable
in the pore spaces of tight aquifer formations.
Lastly, it is important to understand that metals in groundwater will interact with
and adsorb to components of the soil matrix. Clays, other mineral components, and
carbonaceous material (especially humic and fulvic substances) can all act in this
manner. However in the case of metals, the dominant adsorptive component of the
soil matrix is iron. Iron oxides particularly of Ferric (Fe•3) have a very high adsorptive
affinity and total capacity for metal ions and oxyanionic metal complexes. This
capacity is so great that ferric hydroxide is often used in waste water treatment
systems to aid in the removal of soluble metallic species. Knowing the total iron
17
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
content of the soil matrix is paramount in understanding the fate and transport of
metals in groundwater.
CONTAMINANT PLUME
A release of leachate to the groundwater may present several risks to human health
and the environment. The release of hazardous and nonhazardous components of
leachate may render an aquifer unusable for drinking-water purposes and other
uses. leachate impacts to groundwater may also present a danger to the
environment and to aquatic species if the leachate-contaminated groundwater
plume discharges to wetlands or streams. Once leachate is formed and is released to
the groundwater environment, it will migrate downward through the unsaturated
zone until it eventually reaches the saturated zone. leachate then will follow the
hydraulic gradient of the groundwater system.
A number of forces may act on or react with the migrating leachate, resulting
in changes of chemistry and a general reduction of strength from the original
release. These forces are physical (filtration, sorption, advection, and dispersion),
chemical (oxidation-reduction, precipitation-dissolution, adsorption-desorption,
hydrolysis, and ion exchange), and biological (microbial degradation). The extent of
these reactions depends on the materials underlying the landfill, the hydraulics of
the groundwater system, and the chemistry of the leachate (Fred and Jones, 1991).
• Dissolved-metal contaminants in the plume move much more slowly than
the plume water. Neutralization reactions in the carbonate aquifer slows the
rate of advance of the plume's acidic front and most of the dissolved metals
to a about one seventh of the rate of advective ground water-flow (Brown et
al., 2000).
• The oxidation and precipitation of iron is driven by the reductive dissolution
of manganese oxide minerals. This reaction is a source of additional acidity to
the plume and a source of dissolved manganese, which travels ahead of the
plume's acidic front in neutralized ground water.
18
Studies On Technology Oriented Methods For Woter Contaminants And The Geach~mlcallnfluences On Contaminated Plume
• The downgradient decrease in dissolved concentrations of copper, cobalt,
nickel, and zinc was the result of the pH-dependent adsorption to iron
hydroxides in the aquifer.
• The exchange of gases between the plume and atmosphere affects the
geochemistry of the shallow part of the plume. The major controls on
exchange of carbon dioxide and oxygen from the plume across the water
table are (1) neutralization reactions involving carbonate minerals and (2)
oxidation of dissolved iron near the water table as shown in (Fig.l). Continual
movement of perennial streamflow into and out of areas of shallow ground
water beneath the stream (hyporheic zone) increases the contact of
streamflow with sediment surfaces. The increased contact stimulates
precipitation of dissolved manganese as oxide coatings on streambed
sediment (Harvey and Wagner, 2000)
• Chemical reactions in the hyporheic zone are enhanced by the activity of
manganese oxidizing bacteria, which are active in the zone because of input
of oxygenated streamflow, shown in (Fig.l). Approximately 20 percent of the
total load of dissolved manganese flowing out of the drainage basin is
removed in this manner.
• Precipitation of manganese in the hyporheic zone reduces the movement of
dissolved nickel and cobalt because manganese oxides are an excellent
sorbent for those metals. The loads of dissolved nickel and cobalt flowing
from the basin were reduced because of hyporheic exchange (Kay, J., 2000).
19
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
ATMOSPHERE
STREAM
HYPORHEI
DISSOLVED· IVETAL REMOVAL
GROUND WATER
OXYGEN THROUGH
INCREASED CONTACT OF STREAM WATER WITH SEDIMENT &
MICROBES
HIGER pH AND OXYGEN THAN GROUND WATER
LOWER pH AND OXYGEN, HIGHER DISSOLVED METAL CONCENTRATION
DISSOLVED· METAL REMOVAL
Fig.l Hyporheic zone water movement showing removing of dissolved metals
HEAVY METAL TOXICITY
The body has need for approximately 70 friendly trace element heavy metals, but
there are another 12 poisonous heavy metals, such as Lead, Mercury, Aluminum,
Arsenic, Cadmium, Nickel, etc., that act as poisonous interference to the enzyme
systems and metabolism of the body. No matter how many good health
supplements or procedures one takes, heavy metal overload will be a detriment to
the natural healing functions of the body. Some metals are naturally found in the
body and are essential to human health. Iron, for example, prevents anemia, and
zinc is a cofactor in over 100 enzyme reactions. Magnesium and copper are other
familiar metals that, in minute amounts, are necessary for proper metabolism to
occur. They normally occur at low concentrations and are known as trace metals; for
example, high levels of zinc can result in a deficiency of copper, another metal
required by the body. Heavy or toxic metals are trace metals that are at least five
times denser than water. As such, they are stable elements (meaning they cannot
be metabolized by the body) and bio-accumulative (passed up the food chain to
humans). These include: mercury, nickel, lead, arsenic, cadmium, aluminum,
20
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
platinum, and copper (metallic form versus ionic form). Heavy metals have no
function in the body and can be highly toxic. Heavy metals are taken into the body
via inhalation, ingestion, and skin absorption. If heavy metals enter and accumulate
in body tissue faster than the body's detoxification pathways can dispose of them, a
gradual buildup of these toxins will occur. High-concentration exposure is not
necessary to produce a state of toxicity in the body tissues and, over time, can reach
toxic concentration levels.
Symptoms
Toxic metals could be the cause of symptoms like memory loss, increased allergic
reactions, high blood pressure, depression, mood swings, irritability, poor
concentration, aggressive behavior, sleep disabilities, fatigue, speech disorders, high
blood pressure, cholesterol, triglycerides, vascular occlusion, neuropathy,
autoimmune diseases, and chronic fatigue (B-Focasd, 2000).
Mechanism
Heavy metals poison us by disrupting our cellular enzymes, which run on nutritional
minerals such as magnesium, zinc, and selenium. Toxic metals kick out the nutrients
and bind their receptor sites, causing diffuse symptoms by affecting nerves,
hormones, digestion, and immune function. The heavy metals most often implicated
in human poisoning are lead, mercury, arsenic, and cadmium. Some heavy metals,
such as zinc, copper, chromium, iron, and manganese, are required by the body in
small amounts, but these same elements can be toxic in larger quantities. Once in
the body, they compete with and displace essential minerals such as zinc, copper,
magnesium, and calcium, and interfere with organ system function. Toxic heavy
metals may lead to a decline in the mental, cognitive, and physical health of the
individual.
There seems to be a higher level of heavy metal toxicity in children. The
evidence suggests that some children build up more of these toxic metals because of
an inability to excrete them. When they become lodged in the brain the brain does
not function normally, causing autistic symptoms and learning disorders (B-Focasd,
2000).
21
Studies On Technology Oriented Methods F~r Water Contaminants And The Geochemical Influences On Contaminated Plume
ATIENUATION OF POLLUTION
Fundamentally, the objective of any groundwater cleanup (remediation) is to
minimize the risk posed by contaminants to human health and the natural
environment. This is accomplished by reducing the contaminant concentrations to
acceptable levels or controlling the migration of contaminants to other sensitive
receptors. Due to their mobility in natural water ecosystems and their toxicity to
higher life forms, ground water contaminants like soluble organics, soluble metals
(e.g., arsenic, lead) and soluble radio-nuclides (e.g., tritium) in surface and
groundwater supplies have been prioritised as major contaminants in the
environment. Other examples include:
• shallow groundwater contaminated by hexavalent chromium Cr(VI)
from electroplating waste disposal;
• ferrous iron Fe( II) and toxic metals in acidic groundwater as a
consequence of sulphide mineral oxidation in mine milling wastes;
• nitrate contamination from septic and sewage lagoon systems; and,
• contamination by constituents such as chloride and sulphate, and
• organics such as toluene and organic acids, from domestic landfills.
Even if these contaminants are present in dilute, undetectable quantities, their
recalcitrance and consequent persistence in water bodies imply that through natural
processes such as biomagnification, concentrations may become elevated to such an
extent that they begin exhibiting toxic characteristics. These metals can either be
detected in their elemental state which implies that they are not subject to further
biodegradative processes or bound in various salt complexes. In either instance,
metal ions cannot be mineralised. Apart from environmental issues, technological
aspects of metal recovery from industrial waste waters must also be considered
(Wyatt, 1988). Metal resources are non-renewable and natural reserves are
becoming depleted. It is therefore imperative that those metals considered
environmentally hazardous, or which are of technological importance, strategic
significance or economic value, be removed/recovered at their source using
22
Studies On Technology Oriented Methods For Water Contamlnont5 And The Geochemlcollnfluences On Contaminated Plume
appropriate treatment systems. Effluent treatment processes are designed to
ensure that when waste waters are discharged into natural water courses, any
adverse effects are reduced or prevented. The extent of any such effect will be a
function of the volume and composition of the influent waste water and the dilution
capacity of the receiving water. It is for this reason that similarly operated
processing facilities may be required to meet different effluent discharge standards
according to their location (Saunders, 1987). The impact of industry on water
sources is immense and it is only through promotion of good pollution prevention
practices that contamination and deterioration of these waters will decrease. It is
therefore the responsibility of various water authorities to inform industry of the
methods available to them and encourage implementation of such practices to
safeguard the water environment.
There are various technologies currently used for groundwater remediation
at contaminated sites that are discussed below. A remediation program will often
employ more than one technology to achieve the cleanup of a given site.
1. Natural attenuation
Application of natural attenuation of groundwater is similar to that of soil.
2. Oxygen enhanced biodegradation
This is an In-situ Oxygen enhanced biodegradation of the groundwater which
involves pumping air, ozone, hydrogen peroxide, or other oxygen sources through
injection wells to enhance aerobic degradation of organic contaminants. This
innovative technology can remove the following contaminats
• Non-halogenated volatiles and semi-volatiles, fuel hydrocarbons.
• Less effective for some halogenated volatiles and semi-volatiles, pesticides.
Advantages:
• Can be a permanent solution.
• Low capital costs.
• Regulatory and public acceptance is moderate to high.
23
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
Disadvantages:
• Not effective in low permeability, heterogeneous soils.
• High iron content can reduce hydrogen peroxide concentrations
• High 0/M costs.
3. Passive treatment walls
This is also an In-situ degradation method where a permeable treatment wall is
installed in front of a migrating contaminant plume, allowing the plume to passively
move through the wall. The contaminants are degraded by interaction with a
catalyst contained in the porous media of the wall. This innovative technology could
be utilized for the destruction of following contaminants (USEPA, 1994).
• halogenated volatiles and semi-volatiles, inorganics.
• less effective for some non-halogenated volatiles and semi-volatiles,
• fuel hydrocarbons.
Advantages:
• Effective for treating chlorinated hydrocarbons.
• Low 0/M costs.
Disadvantages:
• Applicable only in shallow aquifers with well established flow
direction.
• The wall's reactive media must be replaced on a regular basis.
• High capital costs.
4. Air sparging
This is an In-situ separation technique in which air is injected into the groundwater
through a network of injection wells creating a subsurface air stripping system that
separates contaminants from the groundwater through volatilization. Air sparging
must operate in unison with a soil vapour extraction system to capture the volatiles.
This innovative technology could be used for remediation for the following
contaminants (USEPA, 1994):
• Volatiles, fuel hydrocarbons.
---~-------------------------~
24
Studies On Technology Oriented Methods For Water Contaminants And The G~hemkallnfluenc:es On Contaminated Plume
Advantages:
• Low capital and low 0/M costs.
• Can be a permanent solution.
• Regulatory and public acceptance is high.
Disadvantages:
• Channeling of air flow can occur in layered and fractured terrains,
adversely affecting system performance.
• Not effective in low permeable soils.
5. Free product recovery
This is an Ex-situ removal technique where pumping or passive collection methods
are used to remove undissolved liquid phase organics from the subsurface. This
method is used primarily to extract light non-aqueous phase liquid hydrocarbons
(LNAPLHs) floating on the water table. This is a conventional technique used for the
following contaminants:
• Non-halogenated semi-volatiles, fuel hydrocarbons.
Advantages:
• Low capital and low 0/M costs.
• Can be a permanent solution.
• Regulatory and public acceptance is high.
• Effective for contaminants that float on water.
Disadvantages:
• Large draw down cones associated with pumping may spread the
contaminant to lower levels of soil in the saturated zone.
• If dense non-aqueous phase liquids (contaminants that sink) are
present, then pumping can make the problem worse.
• Reuse or disposal of the recovered free product is required.
• Dissolved plume requires treatment.
25
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On ContamJnoted Plume
6. Bioreadors
In this Ex-situ destruction technique a contaminated groundwater is extracted and
treated with microbes ex-situ in bioreactors. The biological systems in a bioreactor
may be suspended or attached. In suspended growth systems, groundwater is
circulated through activated sludge where suspended particles promote microbe
growth and aerobic degradation of contaminants. In attached growth systems
contaminant degradation takes place on an inert support matrix such as trickling
filters. This method may prove to be a better one for the following contaminants:
• Non-halogenated volatiles and semi-volatiles, fuel hydrocarbons.
• Less effective for some halogenated volatiles and semi-volatiles,
pesticides.
Advantages:
• Can be a permanent solution.
• Low 0/M costs.
• Regulatory and public acceptance is generally high.
Disadvantages:
• Metals may need to be removed prior to treatment.
• Precipitation of in organics (e.g. iron, calcium) may clog treatment systems.
• Solid residuals that settle out in sludge systems may require treatment and
disposal.
7. Air stripping
This conventional Ex-situ separation technique involves the extraction of
groundwater and the trickling of the water through a device that volatilizes
contaminants by inducing air counter-current to the water. Types of aeration
methods include packed towers, diffused aeration, tray aeration, and spray aeration.
The following contaminants may be degraded by this method.
• Volatiles.
• Less effective for some semi-volatiles, fuel hydrocarbons.
Advantages:
• Treats high concentrations.
26
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
• Can be a permanent solution.
• Low capital costs.
Disadvantages:
• Off-gases and residual liquids may require treatment.
• Regulatory and public acceptance is low.
• lnorganics can clog the stripping column packing material which then
requires washing or replacement.
• May require further treatment, by carbon adsorption on activated carbon,
for
example, to meet drinking water standards.
8. Carbon adsorption
Carbon adsorption is an ex-situ process, which involves pumping, contaminated
groundwater through a series of activated carbon cells. The activated carbon
adsorbs dissolved organic contaminants from the groundwater. This conventional
method could be a good one for the remediation of following contaminants:
• Semi-volatiles.
• Less effective for some halogenated volatiles, fuel hydrocarbons,
pesticides, inorganics.
Advantages:
• Can be a permanent solution.
• Low capital costs.
• Regulatory and public acceptance is high.
Disadvantages:
• Activated carbon requires periodic regeneration or disposal.
• Metals can clog the activated carbon.
• High 0/M costs.
• Too expensive for high concentration contaminants, therefore, often
used after contaminants are first reduced by air stripping.
27
Studies On Technology Oriented Methods For Water Contaminants And The Geochemlcollnfluences On Contornlnated Plume
9. UV oxidation
UV oxidation is an ex-situ process where contaminated groundwater is exposed to
ultraviolet radiation to destroy organic contaminants. Ozone or hydrogen peroxide
are commonly used to enhance the oxidation and destruction of the contaminant.
Off-gases are treated by an ozone destruction unit. This innovative method could be
used for the following contaminants:
• Halogenated volatiles and semi-volatiles, pesticides.
• Less effective for some non-halogenated volatiles, fuel hydrocarbons.
Advantages:
• No residual produced.
• Low 0/M costs.
Disadvantages
• lnorganics and naturally occurring soil organics can adversely affect
system performance.
• High capital costs.
10. Slurry walls
A vertically excavated trench is filled with a bentonite-water slurry to form an
impermeable subsurface barrier. These walls are used to contain migrating
contaminant plumes that pose an imminent threat to surrounding receptors. They
are also used to redirect a contaminant plume to targeted extraction zones. This
method can be beneficial for all types of the contaminants:
Advantages:
• Usually a rapid method of dealing with migrating contaminants.
• Relatively simple to implement.
• Low 0/M costs.
Disadvantages:
• Full contaminant containment is difficult in high groundwater flow
regimes. • Bentonite may be degraded by some organic compounds and acid,
base, and salt solutions.
• Regulatory and public acceptance is low.
• High capital costs.
28
Studies On Technology Oriented Methods Ftx Water Contaminants And The Geochemlcailnfluences On Contaminated Plume
11. Permeability enhanced groundwater extra dian
This is a In-situ technique of remediation where fractures are induced into
impermeable sediments or bedrock to improve permeability and the pumping
efficiency of extraction wells. This is accomplished by injecting pressurized water
(hydro-fracturing) through injection wells or by blasting a linear zone. This method
may be helpful for the following contaminants:
• All dissolved or light non-aqueous phase liquid contaminants (less dense than
water).
• More caution required for dense non-aqueous phase liquid contaminants
(heavier than· water).
Advantages:
• Effective for groundwater extraction in highly impermeable materials
such as bedrock.
Disadvantages:
• Care must be taken not to fracture an underlying or adjacent
uncontaminated zone into which contaminants could spread.
• Blasting has high capital costs. Monitoring of groundwater capture
effectiveness will increase costs.
• Regulatory and public acceptance is low for blasting methods.
12. Chemical and physical treatment processes
Conventional chemical {precipitation/neutralisation) or physical (ion exchange,
activated carbon sorption and membrane technology) treatment techniques are
inherently problematic in their application to metal-bearing waste streams.
Chemical treatment methods can prove costly to the user as the active agent cannot
be recovered for reuse in successive treatment cycles. Also, the end product is
usually a low-volume highly concentrated metal bearing sludge that is difficult to
dewater and dispose of. After treatment, total dissolved solids (TDS) values of the
waste-water may still be unacceptably high due to the poor compact ion properties
of the sludge cake. Addition of natural or synthetic polyelectrolyte/flocculant may be
29
Studies On Technology Oriented Methods For Water Contaminants And The G~hemkallnfluences On Contaminated Plume
required to assist with precipitation. Introduction of chemicals increases the
conductivity/salinity of water through the production of soluble sulphates and
chlorides (Kuyucak, 1997).
TRADITIONAL METAL REMOVAL PROCESSES
Hydroxide Precipitation
Traditionally, dissolved metals have been removed from water by the process of
hydroxide precipitation. Since most metal hydroxides are insoluble, it would appear
easy to remove metals by this process. The main problems associated with this
process are that hydroxides of different metals have different pH levels for minimum
solubility and the reactions are of an equilibrium type, i.e., some of the metal
hydroxide will disassociate with the resulting metal ions going back into solution
(Brady and Humiston, 1986). The most common reagents used for hydroxide
precipitation are caustic soda, lime, and magnesium hydroxide.
Sulfide precipitation
Soluble metals can also be removed by precipitating them as a sulfide by the
addition of sodium sulfide to the solution. This method yields more complete metal
removal than hydroxide precipitation but can easily leave toxic sulfides in solution.
This method is much more expensive than hydroxide precipitation since the excess
sulfides are usually regulated and the resulting sludge may be difficult to landfill
(Solomon, 1992). Therefore, it is not as widely used as hydroxide precipitation.
MODERN METAL REMOVAL PROCESSES
Carbamates
Carbamates are chemical reducing agents that can be obtained as either sodium
dimethyldithiocarbamate or sodium diethyldithiocarbamate. Carbamate
precipitation is again an equilibrium reaction that does not go to completion. Metal
residuals of 1.0- 1.5 mgl·1 can usually be obtained. Carbamates are not effective at
acidic pH levels and are not always effective at treating chelated wastes (Hill, 1984).
30
Studies On Technology Oriented Methods For Water Contaminants And Th~ GeocMmlcallnfluen~s On Contaminated Plume
Sodium Borohydride
Sodium borohydride is an extremely strong reducing agent and can reduce both
chelated and non chelated metals. This process has the advantage of producing the
least amount of sludge of any process but it has a number of disadvantages that
almost always preclude its use in an efficient and cost effective system. A major
disadvantage, is that unless the liquid is removed from the sludge immediately,
metals tend to go back into solution with the water. Another problem is that pH
control is critical. Explosive hydrogen gas is evolved at acidic pH values. High cost of
this reagent has also been a problem, and as a result, it has been very difficult to
justify its use.
Organometallic Precipitation
In 1994 Steve Holtzman, pioneered a new more environmentally responsible
method of removing heavy metals. This process revolves around the formation of
insoluble organometallic compounds formed by reacting metal bearing wastes with
a proprietary organic agent. By forming specific types of insoluble organometallic
compounds, all regulated metals can be reduced to non-detectable levels. The
process is easily controlled with an inexpensive ORP controller and can adapt to
changing levels of contaminants in the waste stream influent.
13. Biosorption of inorganic contaminants
Biological methods of metal recovery, termed biosorption, have been suggested as
cheaper, more effective alternatives to existing treatment techniques. Biosorption
entails the use of either living or dead micro-organisms and/or their derivatives
which complex metal ions using ligands or functional groups situated on the outer
surface of the cell (Bolton and Gorby, 1995). This phenomenon has been directly
compared with chemical ion-exchange processes (Chang and Hong, 1994). The
process requires neither an active membrane transport mechanism nor metabolic
energy in order to function and is controlled in a non-directed physiochemical
reaction (Gadd, 1988; 1992). Certain biomass types are evidently more suitable than
others to a specific application. The affinity that a biosorbent material exhibits for a
specific metal cation will dictate the practicality of its implementation for
31
Studies On Technology Oriented Methods For Water Contaminants And Th~ G~och~mlcallnf1umus On Contomlnated Plume
remediation of a particular waste stream. Once laboratory trials are complete and a
potential biosorbent has shown the ability to adsorb and sequester the required
metal ions from solution, several questions need to be resolved in order to assist the
decision concerning its pilot-scale or industrial application.
There are basically two categories of industrial waste liquors that will require
treatment prior to discharge: large volumes bearing low concentrations of metal
contaminants (<100 mgl·1, i.e. mining waste water, and conversely, small volumes
characterized by high TDS values, i.e. metal plating liquors. In the first instance, one
would expect to employ a biosorbent exhibiting high affinity for the metal/s
concerned (Volesky, 1987). In the latter case, the active material should possess high
biosorptive capacity values to ensure saturation of biomass binding sites doesnot
occur prior to cessation of the treatment process (Volesky, 1987).
The use of non-living biomaterials as metal-binding compounds has the advantage of
not being affected by high levels of contamination. Moreover, they require
minimum care and maintenance and can be obtained more cheaply. Biosorption is
an emerging technique for metal sequestration. Nonliving biomass can be
regenerated and reused for many cycles. . The strong metal-binding ability of
biomass has attracted much attention in the fields of wastewater treatment and
environmental remediation contaminated by toxic heavy metals.
NATURAL BY PRODUCTS
In addtion to use of wild and cultivated species besides cell cultures, a wide variety
of agricultural and forestry by products have been used as biosorbents of toxic
metals in a bid to develop biofilters for specific applications. i.e.: i) Cotton - Hg;
Groundnut skins- Cu; Tree Bark (Pinus, Acacia etc.)- variety of metals; Agrowaste -
variery of metals; waste tea leaves- Pb, Cd, and Zn; Pinus radiata -U; Apple waste -
Variety of metals; Cellulose - Variety of metals; Rice hulls - Variety of metals;
Exhausted coffee grounds- Hg; Pinus pinaster bark- Zn, Cu, Pb. Saw mill dust (wood
waste)- Cr; Freshwater green algae - variety of metals; Marine algae- Pb, Ni; ii)
Sphagnum (moss peat) - Cr(VI); iii) Immobilized Aspergillus niger, A. oryzae - Cd, Cu,
Pb, and Ni ; Olive mill waste Olea europea Cr, Ni, Pb, Cd, and Zn, Cu and Ni;
---- -------------------------------32
Studies On Technology Oriented Methods For Water Contaminants And The Geochemlcoltnjfuences On Contaminated Plume
Streptomyces rimosus (bacteria); Saccharomyces cerevisiae (yeast); Penicillium
chrysogenum (fungi), Fuscus vesiculosus and Ascophyllum nodosum (marine algae)
Zn, Cu andNi; Phanerochaete chrysosporium, P. versicolar- Pb, Ni, Cr, Cd, Cu; Pinus
radiata - U; Immobilized Pseudomonas putida 5-X and Aspergillus niger, Mucor
rouxxi - Cu; Actionomycetes, Aspergillus niger, A.oryzae, Rhizopus arrhizus, R.
nigricans- Cd; Rhizopus arrhizus - Cr(VI), Pb; Rhizopus nigricans, Phanarochaete
chrysogenum -Pb; Aspergillus niger and Rhizopus arrhizus - Ni (Prasad and Freitas,
2000).
BIOSORPTION: A SOLUTION TO POLLUTION?
The knowledge of matter, how it is formed and how it can be modified was a puzzle
for people for a long time ever since someone took a piece of clay and shaped it into
a pot that could be hardened by fire. That pot, once fired, would retain liquid and
resist deformation even when it was set among hot coals. This happened in the
Neolithic, which started approximately 9,000 BC. Some 7,000 years later, Greek
philosophers speculated that all matter consisted of minute, indivisible particles of
the same basic substance. Those early attempts to understand the nature of
material things can be taken as the beginning of materials science. It was not until
the 19th century that chemistry and physics began to support the empirical efforts
of artisans and engineers with the development of applicable theories and novel
analytical tools. The key contribution of science was, understanding the coupling of
external properties of materials to their internal structure. Modern industry is, to a
large degree, responsible for contamination of the environment. Lakes, rivers and
oceans are being overwhelmed with bacteria and waste matter. Among toxic
substances reaching hazardous levels are heavy metals.
Some inland water bodies in Europe and America are closed for fishing.
Newspapers are full with reports of frequent ecological disasters in marine
environments. In Northern Brazil, fish from fresh waters are contaminated with
mercury as a result of ruthless, illegal, gold extraction. It was only in the 1990s that a
new scientific area developed that could help to recover heavy metals: biosorption.
The first reports described how abundant biological materials could be used to
33
Studies On Technology Oriented Methods For Water Contaminants And The Geothemlcallnfluences On Contaminated Plume
remove, at very low cost, even small amounts of toxic heavy metals from industrial
effluents. Metal-sequestering properties of non-viable biomass provide a basis for a
new approach to remove heavy metals when they occur at low concentrations. Note
that metals can be removed from solution only when they are appropriately
immobilized, the procedure of metal removal from aqueous solutions often leading
to effectively concentrating the metal. That aspect of biosorption makes the
eventual recovery of this waste metal easier and economical.
Many scientific studies are currently under way and contributions to welfare are
welcome in this world which grows each second and which needs to be in
equilibrium with so much progress. Some pollution seems inevitable, and one can
wonder what one should do to minimize it? Human populations need methods and
technologies to clean waters and diminish the environmental dangers related to
progress. Biosorption can be a solution to clean the environment contaminated by
heavy metals. When matter was first tamed, nobody could foresee how many
problems humans would have to face in the future.
To solve the water pollution problem by toxic heavy metal
contamination resulting from humans technological activities has for long presented
a challenge. Biosorption can be a part of the solution. Some types of biosorbents
such as seaweeds, molds, yeasts, bacteria or crab shells are examples of biomass
tested for metal biosorption with very encouraging results. The uptake of heavy
metals by biomass can in some cases reach up to 50% of the biomass dry weight.
New biosorbents can be manipulated for better efficiency and multiple re-use to
increase their economic attractiveness.
Various elements are being studied in this thesis for the bioremediation from the
aqueous solution, an elaborate study of those individual elements are been
discussed here.
34
CADMIUM
Cadmium is a naturally occurring metallic element, one of the components of the
earth's crust and present everywhere in our environment. Its presence results
mainly from gradual phenomena, such as rock erosion and abrasion, and of singular
occurrences such as volcanic eruptions. The natural level of cadmium in the
environment has been given in Tablel. The element's existence was revealed in
1817 and it owes its name to "cadmia fornacum", the "zinc flowers" which formed
on the walls of zinc distillation furnaces. Its industrial applications were developed
particularly during the first half of the 20th century, based on its unique chemical
and physical properties.
Table 1. Natural cadmium levels in the environment
Atmosphere 0.0001x10-6 - 0.005x10'6 mgl'1
Earth's crust 00.1- 0.5 j.lg g'1
Marine sediment - 1 j.lg g·l
Sea water -o.oo1 mgL-1
Even though the average cadmium concentration in the earth's crust is generally
placed between 0.1 and 0.5 11g g-1, much higher levels may accumulate in
sedimentary rocks, and marine phosphates and phosphorites have been reported to
contain levels as high as 500 11g g·1 (Cook and Morrow, 1995; WHO, 1992).
Weathering and erosion of parent rocks result in the transport by rivers of large
quantities, recently estimated at 15,000 metric tonnes (mt) per annum, of cadmium
to the world's oceans (WHO, 1992; OCED, 1994). Volcanic activity is also a major
natural source of cadmium release to the atmosphere, and estimates on the amount
have been placed as high as 820 mt per year (WHO, 1992; OCED, 1994; Nriagu, 1980;
Nriagu, 1989). Forest fires have also been reported as a natural source of cadmium
air emissions, with estimates from 1 to 70 mt emitted to the atmosphere each year
(Nriagu, 1980).
35
ANTHROPOGENIC SOURCES OF CADMIUM EMISSIONS TO AIR, WATER AND SOIL
Industrial and municipal wastes are a major source of cadmium pollution. Heavily
industrialized cities, especially those with nickel or copper smelters have the highest
concentrations of cadmium in the air {Health and Welfare Canada, 1992). Sewage
sludge can also contribute high amounts of cadmium, as well as other toxins such as
mercury and PCBs. These wastes come mainly from industrial effluents {Health and
Welfare Canada, 1992). Solid waste disposal and the application of municipal
sewage sludge on land are two sources. Another source is phosphate fertilizers,
which often have very high cadmium content. The percentage emission of cadmium
in the environment is shown in (Fig.2). Cigarette smoke most likely constitutes the
largest source of exposure for Canadians. The average non-smoking adult may
accumulate as much as 50 mg of cadmium over a lifetime, with this toxin
accumulating in kidney tissue. Cadmium, the most voluminous metal found in cured
tobacco is sprayed on the tobacco plant as a fungicide. A residual concentration of
cadmium in each cigarette averages 1.4 11g {Utell and Samet, 1995). One pack of
cigarettes deposits at least 4 11g of cadmium into the lungs (Casdorph and Walker,
1994).
Cadmium emissions to air arise, in decreasing order of importance,
from the combustion of fossil fuels, iron and steel production, non-ferrous metals
production and municipal solid waste combustion (Cook and Morrow, 1995; ERL,
1990; Jackson and Gillivray, 1993, Jones et al., 1993; Van Assche and Ciarletta, 1992).
In the second case, inputs to non-agricultural soils arise mainly from the iron and
steel industry, non-ferrous metals production, fossil fuel combustion, and cement.
manufacture (OCED, 1994; ERL, 1990; Jackson and MacGillivray, 1993). In the case of
cadmium present in controlled landfills, these amounts can arise from disposal of
spent cadmium-containing products, non-cadmium containing products which may
contain cadmium impurities, and naturally-occurring wastes such as grass, food and
soil which inherently contain trace levels of cadmium (Chandler, 1996). Cadmium
input to agricultural soils is of far greater relevance to human health than cadmium
input to non-agricultural soils, and input to controlled landfalls is of even less
importance because cadmium is largely immobilised in controlled landfills. For
example, numerous studies of the leachate from municipal solid waste landfalls has
36
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contamfnated Plume
conclusively demonstrated that, even after long periods of time, the leachate from
these landfills contains only very low cadmium levels, sufficiently low enough to
meet the world's cadmium drinking water standards (Eggenberger and Waber, 1998;
NUS, 1987).
6%
• Phosphate fertilizer • Non ferrous • CD application El Natural
' 2%2% 8%
42%
o Combustion of fossil fuels o Iron and steel lllllCement lliJ Incineration
Fig. 2 Sources of human exposure to cadmium
CADMIUM APPLICATIONS
Cadmium is intentionally added to six major classes of products where it imparts
distinct performance advantages and is present as an impurity in five major classes
of products where its presence is regarded as an environmental disadvantage but
which generally does not affect the performance of the product. The major
intentional uses of cadmium are Ni-Cd batteries, cadmium pigments, cadmium
stabilisers, cadmium coatings, cadmium alloys and cadmium electronic compounds
such as cadmium telluride (CdTe) as shown in (Fig.3). The major classes of products
where cadmium is present as an impurity are non-ferrous metals (zinc, lead and
37
Studies On Technology Oriented Meth d f w o s or ater Contaminants And The Geochemical Influences On Contam(nated Plume
copper), iron and steel, fossil fuels (coal, oil, gas, peat and wood), cement, and
phosphate fertilisers (Cook and Morrow 1995).
8% 2%
•·Batteries D Pigments • Stabilizers D Coatings • Alloys and others
Fig. 3 Cadmium consumption in the world
Nickel-Cadmium Batteries
Cadmium hydroxide is utilised as one of the two principal electrode materials in Ni·
Cd batteries which have extensive applications in the railroad and aircraft industry
for starting and emergency power and in consumer applications such as cordless
power tools, cellular telephones, camcorders, portable computers, portable
household appliances and toys. Ni-Cd batteries are cost-effective well suited for high
power applications, and have high cycle lives and excellent low temperature and
high temperature performance relative to other battery chemistries (Morrow and
Keating 1997).
Cadmium Pigments
Cadmium sulphide and cadmium sulphoselenide are utilised as bright yellow to deep
red pigments in plastics, ceramics, glasses, enamels and artists colours. They are well
known for their ability to withstand high temperature and high pressure without
38
Studies On Technology Oriented Methods Ftx Water Contaminants And Th~ Geochemical Influences On Contaminated Plume
chalking or fading, and therefore are used in applications where high temperature or
high pressure processing is required (Cook 1994).
Cadmium Stabilizers
Cadmium-bearing stabilisers retard the degradation processes in polyvinylchloride
(PVC) which occur upon exposure to heat and ultraviolet light These stabilisers
contain organic cadmium salts, usually carboxylates such as cadmium laurate or
cadmium stearate, which are incorporated into PVC before processing and which
arrest any degradation reactions during subsequent processing and ensure a long
service life (Cadmium Association and Cadmium Council1991).
Cadmium Coatings
Cadmium coatings are utilised on steel, aluminium, and certain other non-ferrous
metal fasteners and moving parts to provide the best available combination of
corrosion resistance, particularly in salt and alkali media, and lubricity or low
coefficient of friction. They are also employed in many electrical or electronic
applications where a good combination of corrosion resistance and low electrical
resistivity are required. In addition, cadmium coatings exhibit excellent plating
characteristics on a wide variety of substrates, have good galvanic comparability
with aluminium, and are readily solderable (Morrow 1996).
Alloys and Minor Uses
Cadmium alloys include (a) electrical conductivity alloys, (b) heat conductivity alloys,
and (c) electrical contact alloys. Other minor uses of cadmium include cadmium
telluride and cadmium sulphide in solar cells, and other semiconducting cadmium
compounds in a variety of electronic applications (Cadmium Association and
Cadmium Council1991).
Food content
Foods found to be highest in cadmium are: organ meat (liver, kidneys), wheat and
bran cereals, potato chips and peanut butter although the form of cadmium found in
these foods is not thought to be readily absorbable in humans. A diet survey of
39
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical lnPuences On Contaminated Plume
anglers and hunters found that eating fish and venison (deer meat) did increase
blood cadmium levels; however, the factor that contributed towards even greater
blood cadmium levels was smoking cigarettes {Cole and Kearney, 1997). For the
general world population, average daily cadmium intake, from all sources, is in the
range of 10-25 l!g per day and has decreased steadily over the past 20 years. Goyer,
a research scientist who has been monitoring cadmium content in food, reports a
slow but steady increase in concentrations of cadmium in vegetables over the years.
This increase is most likely the result of the growing agricultural use of this metal
(Goyer, 1996).
Cadmium in water
The average cadmium content in the world's oceans has variously been reported as
low as <5 ngl-1 (WHO, 1992) and 5-20 ngl"1 (OCED, 1994; Jensen and Bra
Rasmussen, 1992) to as high as 110 ngl"1 (CRC, 1996), 100 ngl"1 (Cook and Morrow,
1995) and 10 to 100 ngL-1 (Eiinder, 1985). Higher levels have been noted around
certain coastal areas (Eiinder, 1985) and variations of cadmium concentration with
the ocean depth, presumably due to patterns of nutrient concentrations, have also
been measured. Even greater variations are quoted for the cadmium contents of
rainwater, fresh waters, and surface waters in urban and industrialised areas. Levels
from 10 ngl-1 to 4000 ngl-1 have been quoted in the literature depending on specific
location and whether or not total cadmium or dissolved cadmium is measured
(Eiinder, 1985; WHO, 1992; OCED, 1994).
Cadmium is a natural, usually minor constituent of surface and
groundwater. It may exist in water as the hydrated ion, as inorganic complexes such
as carbonates, hydroxides, chlorides or sulphates, or as organic complexes with
humic acids. Cadmium may enter aquatic systems through weathering and erosion
of soils and bedrock, atmospheric deposition direct discharge from industrial
operations, leakage from landfalls and contaminated sites, and the dispersive use of
sludge and fertilisers in agriculture. Much of the cadmium entering fresh waters
from industrial sources may be rapidly adsorbed by particulate matter, and thus
sediment may be a significant sink for cadmium emitted to the aquatic environment
40
Studies On Technology Oriented Methods for Water Contaminants And The Geochemlc:ollnf/uen«S On Contaminated Plume
(WHO, 1992). Some data shows that recent sediments in lakes and streams range
from 0.2 to 0.9 mgl·1 in contrast to the levels of generally less than 0. 1 mgl·1 cited
above for fresh waters (Cook and Morrow, 1995). Partitioning of cadmium between
the adsorbed-in-sediment state and dissolved-in-water state is therefore an
important factor in whether cadmium emitted to waters is or is not available to
enter the food chain and affect human health.
Rivers containing excess cadmium can contaminate surrounding land,
either through irrigation for agricultural purposes, dumping of dredged sediments or
flooding. It has also been demonstrated that rivers can transport cadmium for
considerable distances, up to 50 km, from the source (WHO, 1992).
HEALTH EFFECTS
It has been well established that excess cadmium exposure produces adverse health
effects on human beings. For virtually all chemicals, adverse health effects are noted
at sufficiently high total exposures. For certain elements such as copper and zinc
which are essential to human life, a deficiency as well as an excess can cause
adverse health effects. Cadmium is not regarded as essential to human life. The
relevant questions with regard to cadmium exposure are the total exposure levels
and the principal factors which determine the levels of cadmium exposure and the
adsorption rate of the ingested/inhaled cadmium by the individual, in other words,
the pathways by which cadmium enters the food chain, the principal pathway of
cadmium exposure for most human beings.
Human Intake of Cadmium
Humans normally absorb cadmium into the body either by ingestion or inhalation. It
is widely accepted (WHO, 1992; ATSDR, 1997) that approximately 2% to 6% of the
cadmium ingested is actually taken up into the body. Much of the cadmium which
enters the body by ingestion comes from terrestrial foods. This is to say, from plants
grown in soil or meat from animals which have ingested plants grown in soil. Thus,
directly or indirectly, it is the cadmium present in the soil and the transfer of this
~------------------------
41
Studies On Technology Oriented Methods For Water Contaminants And The Geochemlcollnfiuences On Contomlnat<M Plume
cadmium to food plants together with the cadmium deposited out of the
atmosphere on edible plant parts which establishes the vast majority of human
cadmium intake, Some have estimated that 98% of the ingested cadmium comes
from terrestrial foods, while only 1% comes from aquatic foods such as fish and
shellfish, and 1% arises from cadmium in drinking water (Van Assche 1998). Because
of cadmium's high volatility, this metal is particularly hazardous for welders
(Shannon, 1998). The tolerable daily cadmium intake established by the World
Health Organization (WHO) is 60 llg per day for adult women and 70 llg per day for
adult men. The analysis acknowledges that most human cadmium exposure comes
from ingestion of food, and most of that arises from the uptake of cadmium by
plants from fertilisers, sewage sludge, manure and atmospheric deposition,
Specifically, (Fig.2) estimated the relative importance of various cadmium sources to
human exposure (Van Assche 1998).
Health effects related to cadmium consumption
Symptoms of acute toxicity are vomiting, choking sensation, abdominal pain and
diarrhea occurring within 30 minutes of exposure. Chronic or low level exposure can
include increased salivation, fatigue, weight loss, muscle weakness, and kidney
dysfunction (as late as 10 to 20 years after chronic exposure). Some late stage
effects may be anemia, hypertension, and skeletal effects which includes, back pain
and pain in the extremities, softening of the bone (an adult form of rickets) and
Japanese "itai-itai" (ouch-ouch) disease. Inhaling cadmium dust may produce
pulmonary emphysema (Pangborn, 1994). Cadmium has also been designated as a
category 1 carcinogen by the_IARC (Smith et al., 1997). An accumulation of cadmium
in kidney tissue has a biological half-life of 18 to 33 years (Pangborn, 1994).
Cadmium, an extremely toxic heavy metal, linked with learning disabilities (Jiang et
al., 1990) and kidney damage, (Pangborn, 1994) enters the environment mainly
through human activity.
Breathing high levels of cadmium may severely damage the lungs and can
cause death. Eating food or drinking water with very high levels severely irritates the
stomach, causing vomiting and diarrhea. The Minnesota Department of Health
(MDH) established a health risk limit (HRL) of 4 J..lgl 1 (parts per billion) for cadmium
42
Studies On Technology Oriented Methods For Water Contaminants And The G~hemlcaltnPuences On Contaminated Plume
(MPCA, 1999). Cadmium mainly accumulates in the kidneys and liver and can lead to
serious kidney failure, nephrotoxicity, renal stone formation, bone disease and
persistent proteinuria at high exposures. Cadmium stays in the body a very long time
and can build up from many years of exposure to low levels. Recent studies have
shown that the effects are reversible at low exposures, once exposure to cadmium is
reduced.
Iron is the most important metal in the universe. It is considered the most abundant
element (by mass, 34.6%) in the earth as a whole and it ranks fourth in abundance in
the earth crust after oxygen, silicon and aluminium. The concentration of iron in the
various layers of the Earth ranges from high at the inner core to about 5% in the
outer crust. Most of this iron is found in various iron oxides, such as the minerals
hematite, magnetite, and taconite. The iron contents in different rocks has been
given in Table.2. The earth's core is believed to consist largely of a metallic iron
nickel alloy (Lenntech, 2006). It occurs as minor constituents of all mineral classes.
Of the major chemical elements in the earth crust, iron is unusual in that it occurs in
several valence states. The fact that it may be oxidized or reduced in natural
environments markedly effects its geochemical cycle. Although iron is locally
markedly enriched in bodies is considered to have been formed by either magmatic
or hydrothermal processes, by far the most extensive anomalous concentrations are
found in groups of sedimentary rocks called iron- formations and ironstones.
43
Studies On Technology Oriented Methods for Water Contaminants And The Geochemlca/lnPuences On Contaminated Plume
Table 2. Average iron contents of various rocks
Rock type Fez03 FeO Total Fe Source
Igneous rocks
Average 2.9 3.3 4.6 Brotzen, 1966
Granites 1.6 1.8 2.5 Daly, 1933
Granodiorites 1.3 2.6 2.9 Nockolds, 1954
Diorites 2.7 7.0 7.3 Nockolds, 1954
Olivine basalts 3.7 8.1 8.9 Poldervaardt, 1955
Peridotites 2.5 9.9 9.4 Nockolds, 1954
Sedimentary rocks
Average 3.5 2.6 4.5 Garrels and Mackenzie, 1963
Sandstones 1.7 1.5 2.4 Pettijohn, 1963
Shales 4.2 3.0 5.3 Clarke, 1924
Limestones 0.36 Clarke, 1924
Iron formations 28.0 lepp and Goldich, 1974
Metamorphic rocks
Quartzo-feldspathic 1.6 2.0 2.7 Poldervaardt, 1955
gneisses
Mica schists 2.1 4.6 5.0 Poldervaardt, 1955
Precambrian slates 4.1 6.7 8.1 Nanz, 1953
The world resources of iron ore have been increasing over the last more than 30
years. This shows that as and when the mining activity intensifies, there is more
exploration and more discoveries of resources of iron ore world-wide. The world
iron ore reserves and reserve base as estimated by U.5.Geological Survey {USGS,
2005) are as under:
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
Table 3. World iron ore reserves
Qty: Million Tonnes
Crude ore Iron content
Reserves Reserve Base Reserve Reserve Base
United states 6900 15000 2100 4600
Australia 18000 40000 11000 25000
Brazil 21000 62000 14000 41000
Canada 1700 3900 1100 2500
China 21000 46000 7000 15000
India 6600 9800 4200 6200
Iran 1800 2500 1000 1500
Kazakhstan 8300 19000 3300 7400
Mauritania 700 1500 400 100
Mexico 700 1500 400 900
Russia 25000 56000 14000 31000
South Africa 1000 2300 650 1500
Sweden 3500 7800 2200 5000
Ukraine 30000 68000 9000 20000
Venezuela 4000 6000 2400 3600
Other 10000 30000 6200 17000
countries
World Total 160000 370000 80000 180000
(Rounded)
Source: U.S. Geolog1cal survey, 2005
45
Grade
Studies On Technology Oriented Methods For Water Contaminants And The Gtoeh~mlca/lnflu~nc~s On Contaminated Plume
Indian Resources
The Indian resources of iron ore have been made compatible with United Nations
Framework Classification (UNFC) which is more scientific and adopted in most
countries of the world. The resource position since 1.1.1980 till 1.4.2000 have been
tabulated in Table 4.
An important issue relevant to India's iron ore reserves is that unlike
Australia and Brazil, in India there have been no exploration programmes
undertaken exclusively for locating new additional deposits of iron ore. Our current
finds are a part of the Geological Survey of India's annual survey routinely carried
out for all minerals within the constraints of manpower and resources.
Table 4. Iron ore resources and production between 1980, 1990 and 2000
Resources Production Resources Difference Production Resources Difference
as on between as on in between as on in
1.1.1980 1980-1990 1.4.1990 resources 1990-2000 1.4.2000 resources
Haematite 11469 12197 +728 a)Reserves +709
6025
b)Remaining
resources
6881
Total12906
Magnetite 6095 10590 +4495 a)Reserves +92
286
b)Remaining
resources
10396
Total10682
Total 17564 470 22787 +5223 656 a)Reserves +801
6311
b)Remaining
resources
17277
Total23588
'--· Source: Indian Bureau of mmes, Nagpur
46
Studies On Technology Oriented Methods For Water Contaminants And The GtroCMmlca/Jnfluences On Contaminated Plume
REGIONAL DISTRIBUTION
Broadly there are two regions which produce iron ore: (a) Central and Eastern India
comprising Chhattisgarh, Jharkhand and Orissa; and (b) South-Western India
comprising Karnataka and Goa.
Region (a) comprising of Chhattisgarh, Jharkhand and Orissa together produced
69.33 million tonnes or 56.44% and 79.77 million tonnes or 55.90% of the total
production of iron ore in India in 2003-04 and 2004-05 respectively. This is the
region where all the integrated steel plants in public or private sectors are situated
who draws all their requirements of iron ore from their captive mines. NMDC looks
after the iron ore requirements of RINl. Gas-based sponge iron plants also draw
their maximum requirements from NMDC and source some quantity from
noncaptive mines in Eastern and Bellary-Hospet (Karnataka) sectors.
Region (b) comprising of Karnataka and Goa contributed 51.88 million tonnes or
42.23 %of the country's total iron ore production of 122.84 million tonnes in 2003-
04. In 2004-05, this was 59.48 million tonnes or 41.68% of the total production of
142.71 million tonnes in the country.
Unlike other metallic ores such as lead, zinc, copper, nickel and gold, where the
metal content in the ore varies from 5-10% to a fraction of even 1% per tonne of
ore, in the case of iron ore, the iron content averages 60% Fe and above. Whereas
other metals have to be concentrated or smelted at or near about the mine site, in
the case of iron ore, it can be transported over long distances where the steel plants
are situated. Since the steel plants are situated in the countries where the domestic
demand for steel is intense, the main raw material for steel such as iron ore and
coke have to be transported to these plants from far away countries.
STEEL PRODUCTION FROM IRON ORE
Nearly all iron produced commercially is used in the steel industry and made using a
blast furnace. Iron oxide, Fe20 3, is reduced with with carbon (as coke) although in
the furnace the actual reducing agent is probably carbon monoxide, CO.
47
Studies On Technology Oriented Methods For Water Contaminants And The G«Jchemlcallnfluences On Contaminated Plume
2Fe203 + 3C ~ 4Fe + 3C02
This process is one of the most significant industrial processes in history and the
origins of the modern process are traceable back to a small town called
Coalbrookdale in Shropshire (England) around the year 1773.
Steel is an alloy of iron usually containing less than 1% carbon. It is used most
frequently in the automotive and construction industries. Steel can be cast into bars,
strips, sheets, nails, spikes, wire, rods or pipes as needed by the intended user.
POLLUTION SOURCES IN STEELMAKING
In the 1980's it became apparent that iron and steel plant wastes, emissions and
effluents were a cause of concern due to, ground water contamination from
stockpiling or land filling, air born particulates were contaminating soils in
surrounding plant areas and there was concern of the greenhouse effect from gas
emissions. As a result, restrictions were put on land filling and stockpiling of wastes
and air born emissions from plants and a new era of monitoring and control was
established. The added cost to iron and steel making then dictated that new
technologies be developed for collecting the emissions and effluents and treating
the collected materials to reduce leaching into groundwater and potential health
hazards.
Slag, the limestone and iron ore impurities collected at the top of the
molten iron, make up the largest portion of iron making by-products. Sulfur dioxide
and hydrogen sulfide are volatized and captured in air emissions control equipment
and the residual slag is sold to the construction industry (USEPA, 1985). Blast furnace
flue gas is also generated during ironmaking. This gas is cleaned to remove
particulates and other compounds, allowing it to be reused as heat for coke furnaces
or other processes.
According to Toxic release inventory (TRI) data, the iron and steel industry
released and transferred a total of approximately 695 million pounds of pollutants
during calendar year 2003. About 75% of iron and steel establishments are
respons1ble for releases and transfers. The releases and transfers are dominated by
-~~~-~--~~~~~~~~~~~~~~~~~~~~--
48
Studies On Technology Oriented Methods For Water Contaminants And Th~ Geoclremkallnflumces On ContamJnoted PluTM
large volumes of metal-bearing wastes. The majority of these wastes (70 percent or
488 million pounds) are transferred off-site for recycling, typically for recovery of the
metal content. Transfers of TRI chemicals account for 86 percent of the iron and
steel industry's total TRI-reportable chemicals (609 million pounds) while releases
make up 14 percent (85 million pounds) (TRI, 2005). Metal-bearing wastes account
for approximately 80 percent of the industry's transfers and over fifty percent of the
releases.
HEALTH EFFECTS OF IRON IN WATER
The total amount of iron in the human body is approximately 4 g, of which 70% is
present in red blood colouring agents. Iron is a dietary requirement for humans, just
as it is for many other organisms. Men require approximately 10 mg iron on a daily
basis, whereas women require 18 mg per day (Carson et al., 1987). The body absorbs
approximately 25% of all iron present in food. When someone is iron deficit feed
iron intake may be increased by means of vitamin C tablets, because this vitamin
reduces tertiary iron to binary iron. Phosphates and phytates decrease the amount
of binary iron. In food iron is present as binary iron bound to haemoglobin and
myoglobin, or as tertiary iron. Iron is a central component of haemoglobin. It binds
oxygen and transports it from lungs to other body parts. It then transports C02 back
to the lungs, where it can be breathed out. Iron is a part of several essential
enzymes, and is involved in DNA synthesis (Lenntech, 2006). Normal brain functions
are iron dependent. In the body iron is strongly bound to transferrin, which enables
exchange of the metal between cells. The compound is a strong antibiotic, and it
prevents bacteria from growing on the vital element. When one is infected by
bacteria, the body produces high amounts of transferrin. When iron exceeds the
required amount, it is stored in the liver. The bone marrow contains high amounts of
iron, because it produces haemoglobin. Iron deficits lead to anaemia, causing
tiredness, headaches and loss of concentration. The immune system is also affected.
In young children this negatively affects mental development, leads to irritability,
and causes concentration disorder. Young children, pregnant women and women in
their period are often treated with iron (II) salts upon iron deficits.
Studies On Technology Oriented Methods For Water Contaminants And The Ge«ht!m/c:DIInf/ut!nct!S On Contaminated Plume
When high concentrations of iron are absorbed, for example by
haemochromatose patients, iron is stored in the pancreas, the liver, the spleen and
the heart. This may damage these vital organs. Iron compounds may have a more
serious effect upon health than the relatively harmless element itself. Water soluble
binary iron compounds such as FeCb and FeS04 may cause toxic effects upon
concentrations exceeding 200 mg, and are lethal for adults upon doses of 10-50 g. A
number of iron chelates may be toxic, and the nerve toxin iron penta carbonyl is
known for its strong toxic mechanism. Iron dust may cause lung disease.
FLUORIDE
Fluorine is the lightest member of Group 17 (VIlA) ofthe periodic table. This group,
the halogens, also includes chloride, bromine, and iodine. As with the other
halogens, fluorine occurs as a diatomic molecule, F2, in its elemental form. It has
only one stable isotope and its valence in all compounds is -1. Fluorine is the most
reactive of all the elements, which may be attributed to its large electronegativity
(estimated standard potential +2.85 V) (Hem, 1989). It reacts at room temperature
or elevated temperatures with all elements other than nitrogen, oxygen, and the
lighter noble gases. Fluorine is also notable for its small size; large numbers of
fluorine atoms fit around atoms of another element. This, along with its
electronegativity, allows the formation of many simple and complex fluorides in
which the other element is in its highest oxidation date. F easily combines with
several cations, viz., Al3•, Ca2
• and Fe3• and forms stable complexes. Hence,
partitioning of F between complexed form, and free ionic form !n, in an aqueous
system, is always expected.
GEOGRAPHICAL DISTRIBUTION
Fluorosis has been described as an endemic disease of tropical climates, but this is
not entirely the case. Waters with high fluoride concentrations occur in large and
extensive geographical belts associated with a) sediments of marine origin in
mountainous areas, b) volcanic rocks and c) granitic and gneissic rocks. High fluoride
50
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plumt!
containing groundwater was found in many parts of the developing world and
fluorosis is endemic in at least 25 countries across the globe (Tetsuji et al., 1997).
The worst affected areas are the arid parts of northern China {Inner Mongolia),
India, Srilanka, African countries like Ghana, Ivory coast, Senegal, North Algeria,
Kenya, Uganda, Tanzania, Ethiopia, northern Mexico and central Argentina.
High groundwater fluoride concentrations associated with igneous
and metamorphic rocks such as granites and gneisses have been reported from
India, Pakistan, West Africa, Thailand, China, Sri Lanka, and Southern Africa. In Kenya
and South Africa, the levels can exceed 25 mgl:1. In India concentrations up to 38.5
mgl-1 have been reported (Susheela and Ghosh, 1990). The highest concentration
observed to date in India is 48 mgl-1 in Rewari District of Haryana {UNICEF, 1999).
The high concentrations in groundwater are a result of dissolution of fluorite, apatite
and topaz from the local bedrock, and {Handa, 1975) noted the general negative
correlation between fluoride and calcium concentrations in Indian groundwater.
In 1991, 13 of India's 32 states and territories were reported to have
naturally high concentrations of fluoride in water (Mangla, 1991), but this had risen
to 17 by 1999 {UNICEF, 1999). The most seriously affected areas are Andhra
Pradesh, Punjab, Haryana, Rajasthan, Gujarat, Tamil Nadu and Uttar Pradesh
(Kurnaran, et al., 1971; Teotia et al., 1984). In India alone people of 196 districts in
35 states and union territories are drinking fluoride contaminated water above the
Maximum allowed concentration {MAC) (Susheela, 2001) and are confronte9;~G·~~::< '"·"''-' ... r """ -
the problems of fluorosis especially in rural and semi-urban areas. --~ Y-' ,-,. ..- ,...,
t/r --'r' ,lj, ' '
~·"· > 1 , ' 1 . 7'' . .,. (o . -- ... ' ) ... ~ '•'- '
'•\ FLUORIDE DISTRIBUTION IN WATER ·' .
Some fluoride compounds in the earth's upper crust are soluble in water, fluoride is
found in both surface and groundwater. In surface freshwater, fluoride
concentrations are usually as low as 0.01-{).3 parts per million. In groundwater, the
natural concentration of fluoride depends on geological, chemical, and physical
characteristics of the aquifer, the porosity and acidity of the soils and rocks, the
temperature, the action of other chemical elements and the depth of wells. The
fluoride concentrations in groundwater can range from well under 1 mgl'1 to more
than 35 mgl·l Seawater typically contains about 1 mgl'1 while rivers and lakes
I . . \\ ·jr. ., ....... T 2249!,
51
Studies On Technology Oriented Methods For Water Contaminants And The Geochemlcalln/fuenc~ On Contaminated Plume
generally exhibit concentrations of less than 0.5 mgL-1• In groundwaters, however,
low or high concentrations of fluoride can occur, depending on the nature of the
rocks and the occurrence of fluoride-bearing minerals. Concentrations in water are
limited by fluoride solubility, so that in the presence of 40 mgL-1 calcium it should be
limited to 3.1 mgl-1 (Hem, 1989). It is the absence of calcium in solution, which
allows higher concentrations to be stable (Edmunds and Smedley, 1996). High
fluoride concentrations may therefore be expected in groundwaters from calcium
poor aquifers and in areas where fluoride-bearing minerals are common.
FLUORIDE EXPOSURE TO HUMANS
Air
Due to dust, industrial production of phosphate fertilizers, coal ash from the burning
of coal and volcanic activity, fluorides are widely distributed in the atmosphere.
However, air is typically responsible for only a small fraction of total fluoride
exposure (USNRC, 1993). In non-industrial areas, the fluoride concentration in air is
typically quite low (0.05-1.90 Jlgm"3 fluoride) (Murray, 1986). In areas where
fluoride-containing coal is burned or phosphate fertilizers are produced and used,
the fluoride concentration in air is elevated leading to increased exposure by the
inhalation route. High levels of atmospheric fluoride occur in areas of Morocco and
China (Haikel et al., 1986, 1989). In some provinces of China, fluoride concentrations
in indoor air ranged from 16 to 46 Jlgm -J owing to the indoor combustion of high
fluoride coal for cooking and for drying and curing food (WHO, 1984). Indeed, more
than 10 million people in China are reported to suffer from fluorosis, related in part
to the burning of high fluoride coal (Gu et al., 1990).
Dental products
A number of products administered to, or used by, children to reduce dental decay
contain fluoride. This includes toothpaste (100D-1500 mgkg-1 fluoride), fluoride
solutions and gels for topical treatment (25D-24000 mgkg-1 fluoride) and fluoride
tablets (0.25, 0.50 or 1.00 mg fluoride per tablet), among others. These products
contribute to total fluoride exposure, albeit to different degrees. It is estimated that
-------------------------~
52
Studies On Technology Oriented Methods For Water Contaminants And The GNCMmlcallnPuences On Contaminated PI~
the swallowing of toothpaste by some children may contribute about 0.50 or 0.75
mg fluoride per child per day (Murray, 1986).
Food and beverages other than water
Vegetables and fruits normally have low levels of fluoride (e.g. 0.1-Q.4 mg kg-1} and
thus typically contribute little to exposure. However, higher levels of fluoride have
been found in barley and rice (e.g. about 2 mg kg-1) and taro, yams and cassava been
found to contain relatively high fluoride levels (Murray, 1986}. In general, the levels
of fluoride in meat (0.2-1.0 mg kg-1) and fish (2-5 mg kg-1) are relatively low.
However, fluoride accumulates in bone and the bones of canned fish, such as
salmon and sardines, which are also eaten. Fish protein concentrates may contain
up to 370 mg kg-1 fluoride. However, even Milk typically contains low levels of
fluoride, e.g. 0.02 mgl-1 in human breast milk and 0.02-D.05 mgl-1 in cow's milk
(Murray, 1986). Tea leaves contain high levels of fluoride (up to 400 mg kg-1 dry
weight). Fluoride exposure due to the ingestionof tea has been reported to range
from 0.04 mg to 2.7 mg per person per day
(Murray, 1986}.
HUMAN HEALTH EFFECTS
Fluoride in drinking water is beneficial at lower concentrations but hazardous to
health at higher levels. Health effect from prolonged intake of fluoride contaminated
water have been reported (Dissanayake, 1991) as: <0.5 mgl.1: dental carries; 0.5-
1.5 mgl"1: promotes dental health; 1.5-4.0 mgl-1: dental fluorosis; >4.0 mgl"1
: dental
and skeletal fluorosis; and >10.0 mgl.1: crippling fluorosis. According to the World
Health Organization (WHO), the maximum allowed concentration (MAC) of fluoride
in drinking water is 1.5 mgl·1 but it is not universally accepted. WHO (1984}
suggested that in warm climate the MAC of fluoride should be <1.0 mgl·1 while in
cooler climate it can go up to 1.2 mgl"1. In India the MAC for fluoride in drinking
water was lowered from 1.5 to 1.0 mgl"1 in 1998. There are several million people in
India exposed to drinking water sources with high fluoride content.
53
Studies On Technology Oriented Methods For Water Contomlncmts And The Grochemlcolln/fuences On Contamlfrat«< Plume
Effects on teeth
The beneficial and the detrimental effects of fluoride naturally present in water
were well established by the early 1940s. Fluoride accumulates in bones and teeth
as fluorapatite and causes bone to become brittle (Cauley et al., 1995; Fratzl, 1994;
Grynpas, 1990). High levels of fluoride present in concentrations up to 10 mgl-1 were
associated with dental fluorosis (yellowish or brownish striations or mottling of the
enamel) while low levels of fluoride, less than 0.1 mgl-1, were associated with high
levels of dental decay (Edmunds and Smedley, 1996). Concentrations in drinking
water of about 1 mgl-1 are associated with a lower incidence of dental caries,
particularly in children, whereas excess intake of fluoride can result in dental
fluorosis. In severe cases this can result in erosion of enamel. The margin between
the beneficial effects of fluoride and the occurrence of dental fluorosis is small and
public health programmes seek to retain a suitable balance between the two (IPCS,
2002).
Skeletal effects
It is primarily associated with the consumption of drinking-water containing elevated
levels of fluoride but exposure to additional sources of fluoride such as high fluoride
coal is also potentially very important. This is compounded by a number of factors
which include climate, related to water consumption, nutritional status and diet,
including additional sources of fluoride and exposure to other substances that
modify the absorption of fluoride into the body. Crippling skeletal fluorosis, which is
associated with the higher levels of exposure, can result from osteosclerosis,
ligamentous and tendinous calcification and extreme bone deformity. Evidence from
occupational exposure also indicates that exposure to elevated concentrations of
fluoride in the air may also be a cause of skeletal fluorosis (IPCS, 4002).
One possible feature of fluorosis is bone fracture, although some studies have
reported a protective effect of fluoride on fracture. In an epidemiological study the
relationship between fluoride intake via drinking-water and all other sources, and all
fractures, followed a U shaped dose response with higher rates of fracture at very
low intakes below 0.34 mgl - 1 and high intakes above 4.32 mgl - 1 (total intake 14 mg
per day) (Li eta/., 2001). It was concluded by the IPCS that for a total intake of 14 mg
-----------------------------54
Studies On Technology Oriented Methods For Water Contaminants And The Geochem/collnfluences On Contaminated Plume
per day there is a clear excess risk of skeletal adverse effects and there is suggestive
evidence of an increased risk of effects on the skeleton at total fluoride intakes
above about 6 mg per day {IPCS, 2002).
FLUORIDES IN INDUSTRY
Fluorides are important industrial chemicals with a number of uses but the largest
uses are for aluminium production, drinking water fluoridation and the manufacture
of fluoridated dental preparations {IPCS, 2002).
• Hydrogen fluoride {HF) is a colourless, pungent liquid or gas that is highly
soluble in organic solvents (e.g., benzene) and in water. It is mainly used
in the production of synthetic cryolite {Na3AIF6), aluminium fluoride
(AIF3), motor gasoline alkylates and chlorofluorocarbons {CFCs). It is also
used in etching semiconductor devices, cleaning and etching glass,
cleaning brick and aluminium and tanning leather, as well as in removing
rust.
• Calcium fluoride {Cah) is a colourless solid that is relatively insoluble in
water and dilute acids and bases. It is used to produce steel, glass and
enamel {because it lowers the melting temperature}, hydrofluoric acid
and anhydrous hydrogen fluoride (as raw material), and aluminium (as
electrolyte).
• Sodium fluoride (NaF) is a colourless to white solid that is moderately
soluble in water. It is used in the fluoridation of drinking water and in the
manufacture of dental preparations such as toothpaste. It is also used in
the production of steel and aluminium (to lower the melting
temperature). glass and enamel, or as an insecticide and a preservative
(for glues and wood).
• Sulfur hexafluoride (SF6) is a colourless, odourless, inert gas that is slightly
soluble in water and readily soluble in ethanol and bases. It is used
extensively in various electronic components and in the production of
magnesium and aluminium.
55
Studies On Technology Oriented Methods for Water Contaminants And rhe G~~mlcalln/luences On Contaminated Plume
• Silicofluorides such as fluorosilicic acid (H2SiF6) and sodium
hexafluorosilicate (Na2SiF6) are also used for the fluoridation of drinking
water supplies.
PROPOSED AND ATTAINED OBJEOIVES OF THESIS
This thesis has attempted to study the genesis of the groundwater contaminants
that are emerging either as a result of industrial activity or may be due to some
geochemical reactions and the possible remediation of the contaminants with the
help of emerging technology. Through the process of biosorption mitigation of
various elements present in the ground water, which show their toxic effects when
present even in small amounts was attempted. This would be certainly beneficial for
the society and also to the industries due to their cost effectiveness.
The main objectives proposed and the objectives attained are enlisted below:
Sr.
no.
1.
2.
'
Table 5. OBJECTIVES PROPOSED AND THE OBJECTIVES ATTAINED
Proposed research work Objectives attained Chapters
concerned
Introduction related to Detailed literature survey of the Chapter 1
elemental contamination in the groundwater contamination
ground water and the possible and the remedial techniques
remediation. has been carried out.
Mineral- water interfacial A complete analysis of ground Chapter 2
reactions and their effect on water of different locations in
elemental mobilisation. Durg -Bhilai region was carried
out to observe the metal L __ ~_L·-~-~~~~~~~~---'L-~~~~~~-~~-~...L~~~~_j
56
Studies On Technology Oriented Methods For Water Contaminants And The GeochemlcollnPuences On Contaminated Plume
3. Adsorption of iron from
groundwater and industrial
wastewater by the plant
biomass.
L_ ···-- -- -- ..
contamination at industrial,
central and boundary region of
Bhilai. Presence of Fe2•, Mn2
•,
As(lll), so/,cr, Alkalinity, Ca2•,
was
determined by analyzing ground
water in the lab. In view of the
frequent prevalence of Fe(ll)
and s2· detailed geo-chemical
interaction was studied to
identify the probable source of
contamination.
Groundwater contamination by
exceedingly high concentration
of iron has been successfully
sequestered by an indigenous
plant material. The effect of
various ions present in ground
water was also studied
simultaneously. Different
parameters like:
1) Effect of pH.
2) Effect of increasing metal ion
concentration.
3) Effect of biomass dosage.
4) Effect of contact time.
5) Effect of various interfering
ions.
6) Study of adsorption isotherm
was investigated using fresh
Chapter 3
57
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contaminated Plume
and the leached biomass.
7) A study on the binding
mechanism of the biomass
with the help of FT-IR studies
was carried out.
8) An application of the biomass
with the synthetic effluent
was carried out.
4. Cadmium removal from A native plant of Chhattisgarh, Chapter 4
contaminated ground water and has been identified whose
industrial effluents by adsorbent cadmium uptake capacity
treatment. surpasses other reported
biosorbents. The biomass was
chemically treated to increase
the sorption capacity. Various
parameters _were optimized
during the experiment to
observe the maximum sorption
capacity of the related biomass.
Mechanism of metal binding
has also been extensively
studied by carrying out its FT-IR
study.Various Parameters like:
1) Effect of pH.
2) Effect of Increasing metal ion
concentration.
3) Effect of Biomass dosage.
4) Effect of contact time.
5) Effect of various interfering
ions. ~-- ____ J_~ _________ __l __________ L_ __ _____j
58
Studies On Technology Oriented Methods For Water Contaminants And The GNChem/calln/luenas On Contaminated Plume
5. Removal of fluoride from
aqueous solution by 'Fiuorofix'.
6) Study of adsorption isotherm.
7) Elution study
were investigated. For
applicability of the biomass a
synthetic solution was
prepared for the adsorption
study.
A metal doped biopolymer has Chapter 5
been synthesised to remove
fluoride from ground water. A
systematic study was done to
optimize the various
parameters so as to achieve
an increased adsorption.
Effect of tempertature on the
sorption behaviour was
investigated. The effect of
interfering ions naturally
present in ground water was
also studied. The parameters
optimized during the
experimental work were
1) Effect of pH.
2) Effect of Increasing metal ion
concentration.
3) Effect of Biomass dosage.
4) Effect of contact time.
5) Effect of various interfering
ions.
6) Study of adsorption isotherm. ··- . - c_ ______________ __L ____________ L_ ____ ..J
59
Studies On Technology Oriented Methods For Water Contaminants And 1M G~ochemlca/lnfluences On Contaminated Plum~
7) Effect of particle size.
8} Elution study.
9} Application of the Fluorofix
for the fluoride contaminated
groundwater was carried out
by preparing a synthetic
solution.
60
REFERENCES
ATSDR, 1997. Agency for Toxic Substances and Disease Registry, Draft Toxicological
Profile for Cadmium, Public Health Service, U.S. Department of Health &
Human Services, Atlanta, Georgia.
B-Focasd, Parent Support Group. e-mail: [email protected].
Blaylock, M.J., Huang, J. W., 2000. Phytoextraction of metals. ln:l. Raskin and B.D.
Ensley eds. Phytoremediation of toxic metals: using plants to clean-up the
environment. New York, John Wiley & Sons, Inc. S3-70.
Bolton, H., Gorby, Y.A. 1995. An overview of the bioremediatlon of inorganic
contaminants. In: Hinchee RE, Means Jl and Burris DR (eds.) Bioremediation
of lnorganics. Battelle Press, Ohio. 1-16.
Bortz en, D., 1966. The average igneous rock and the geochemical balance: Geochim.
Cosmochim. Acta. 30, 863-868.
Brady, J.E., Humiston, G. E., 1986. General Chemistry: Principles and Structure. Wiley,
41h ed., 1986.
Brown, J.G., Bassett, R.l., Glynn, P.O., 2000. Reactive transport of metal
contaminants in alluvium model comparison and column s·imulation: Applied
Geochemistry. 15{1), 35-50.
Cadmium Association, and Cadmium Council, Greenwich, Connecticut, USA, 1991.
"Technical Notes on Cadmium: Cadmium Production, Properties and Uses."
Carson, B.l., Ellis, H.V., McCann, J.l., 1987. Toxicology and biological monitoring of
metals in humans. lewis publishers. Chelsea. 328.
Casdorph, R. Walker, M., 1994.Toxic Metal Syndrome: How Metal Poisonings Can
Affect Your Brain. Avery Publishing Group, New York. 187.
Cauley, J.A, Murphy, P.A., Riley, T.J., Buhari, A.M., 1995. Efffect of fluorinated
drinking water on bone mass and fractures the study osteoporotic fractures.
J. Bone Min. Res.lO, 1076-1086.
61
Stud{~ On Technology Orlentrd Mrthods Frx WCJtl!'r Contomlnonts And n.. Ci«JcMmkallnflwncn On Contomlnatl!'d Plunw
Chandler, A.J., 1996. "Characterising Cadmium in Municipal Solid Waste," Sources of
Cadmium in the Environment, Inter-Organisation Programme for the Sound
Management of Chemicals (IOMC), Organisation for Economic Co-operation
and Development (OCED), Pads, France.
Chang, J.S., Hong, J., 1994. Biosorption of mercury by the inactivated cells of
Pseudomonas aeruginosa PU21 (Rip64). Biotechnol. Bioeng. 44, 999-1006.
Clarke, F.W., 1924: The data of geochemistry: U.S. Geol. Surv. Bull. 770, 841.
Cole D.C., Kearney, J.P., 1997. Blood cadmium, game consumption and tobacco
smoking in southern Ontario anglers and hunters, Canadian Journal of Public
Health. 88(1), 44-46.
Cook, M. E., 1994. "Cadmium Pigments: When Should I Use Them?," Inorganic
Pigments. Environmental Issues and Technological Opportunities, Industrial
Inorganic Chemicals Group, Royal Society of Chemistry, London, January 12,
1994.
Cook, M. E., Morrow, H., 1995. "Anthropogenic Sources of Cadmium in Canada,"
National Workshop on Cadmium Transport Into Plants, Canadian Network of
Toxicology Centres, Ottawa, Ontario, Canada, June 20-21, 1995.
CRC Handbook of Chemistry and Physics 77th Edition, 1996. CRC Press, Inc., Boca
Raton, Florida.
Cunningham, S.D., Ow, D.W., 1996. Promises and prospects of phytoremediation.
Plant Physiol. 110,715-719.
Cunningham, S.D., Shann, J.R., Crowley, D.E., Anderson, T.A., 1997.
Phytoremediation of contaminated water and soil. In: KRUGER, E.L.;
Anderson, T.A. and Coats, J.R. eds. Phytoremediation of soil and water
contaminants. ACS symposium series 664. Washington, DC, American
Chemical Society. 2-19.
Daly, R.A., 1933. Igneous rock and the depth of the earth: Mcgraw-Hill Book Co.,
N ewyork, 598.
Dissanayake, C. B., 1991. 'The fluoride problem in the groundwater of Sri Lanka
Environmental managament and health', Int. J. Environ. Studies. 19, 195-
203.
62
Studies On Technology Oriented Methods FDI' Water Contaminants And The Geothemlcal Influences On Contomlnoted Plume
Edmunds, W.M., Smedley, P.L. 1996. Groundwater geochemistry and health: an
overview. In: Appleton, Fuge and McCall [Eds] Environmental Geochemistry
and Health. Geological Society Special Publication No 113, 91-105.
Eggenberger, U., Waber, H. N., 1998. "Cadmium in Seepage Waters of landfills: A
Statistical and Geochemical Evaluation, "Report of November 20, 1997 for
the OCED Advisory Group on Risk Management Meeting, February 9-10,
Pads.
Elinder, Gustaf, C., 1985. "Cadmium: Uses, Occurrence, and Intake," Cadmium and
Health: A Toxicological and Epidemiological Appraisal, CRC Press, Inc., Boca
Raton, Florida.
Ensley, B.D., 2000. Rational for use of phytoremediation. In: Raskin, I. and Ensley,
B.D. eds. Phytoremediation of toxic metals: using plants to clean- up the
environment. New York, John Wiley & Sons, Inc. 3-12.
ERl, 1990. Environmental Resources limited, Evaluation of the Sources of Human
and Environmental Contamination by Cadmium. Prepared for the
Commission of the European Community, Directorate General for
Environment, Consumer Protection and Nuclear Safety, london, February
1990.
EPA, 2002. Environment Protection Agency, Drinking Water from Household Wells -
EPA 816-K-02-003.water-resource@epa,gov.
Fratzl, P., Roschger, P., Eschberger, J., Abendroth, B., Klaushofer, K., 1994. Abnormal
bone mineralization after fluoride treatment of osteoporsis. asmall- angle X
ray scattering study. J. Bone Min Res. 9, 1S41-1549.
Fred, l. G., Jones, A. R., 1991. "landfills and Groundwater Quality." Groundwater.
29,482-486.
Gadd, G.M., 1992. Microbial control of heavy metal pollution. In: Fry JC, Gadd GM,
Herbert RA, Jones CW and Watson-Craik lA (eds.) Microbial Control of
Pollution. Cambridge University Press.
Garrels, R.M., Perry, E.A., Mackenzi, F.T., 1973. Genesis of Precambrian iron
formations and the developent of atmospheric oxygen: Econ. Geol. 68, 1173-
1179.
Stud/~ On Technology Oriented Methods For Water Contaminants And The GN>CMmlcoll~nces On ContomJnot~ Piumt!
Goyer, R.A., 1996. Toxic effects of metals: cadmium. In: Casarett and Doull's
Toxicology: The Basic Science of Poisons, 5th ed. Ed. CD Klaassen, New York,
NY: McGraw-Hill. 699-702.
Grynpas, M.D., 1990. Fluoride effects on bone crystals. J. Bone Min. Res. 5, 169-175.
Gu, S.l., Rongli, J., Shouren, C., 1990. The physical and chemical characteristics of
particles in indoor air where high fluoride coal burning takes place.
Biomedical and Environmental Sciences. 3(4), 384-390.
Harvey, J. W., Wagner, B.J., 2000. Quantifying hydrologic interactions between
streams and their subsurface hyporheic zones, 3-44 in Jones, J.A., and
Mulholland, P.J. (Eds), Streams and Ground Waters, Academic Press, San
Diego, 425.
Health and Welfare Canada, 1992. A Vital Link: Health and the Environment in
Canada. Minister of Supply and Services Canada. 99.
Hem, J.D., 1989. Study and Interpretation of the Chemical Characteristics of Natural
Water. Water Supply Paper 2254, 3rd edition, US Geological Survey,
Washington, D.C., 263.
Hill, J. W., 1984. Chemistry for Changing Times. Burgess, 4th edition.
IPCS, 2002. International Programme on Chemical Safety, "Environmental Health
Criteria for Fluorides (EHC227) http:/ /www.greenfacts.org/en/fluoride/.
Jackson, T., MacGillivray, A., 1993. Accounting for Cadmium, Stockholm Environment
Institute, london.
Jiang, H.M., Han, G.A, He, Z.L, 1990. Clinical significance of hair cadmium content in
the diagnosis of mental retardation of children. Chin Med J (Engl). 103(4),
331-334.
Jones, R., Lapp, T., Wallace, D., 1993. Locating and Estimating Air Emissions from
Sources of Cadmium and Cadmium Compounds, Prepared by Midwest
Research Institute for the U.S. Environmental Protection Agency, Office of Air
and Radiation, Report EPA-453/R-93-040, September 1993.
64
Studies On Technology Oriented Methods F'!f' Watt-r Contaminants And Tift' ~ocht!mkallnflwnas On ContomJnoted PJumt-
Kay, J., 2000.The reactive uptake and release of Mn(ll), Co(ll), Ni(ll) and Zn(ll) by
sediments from a mining-contaminated stream, Pinal Creek, Arizona: MS
thesis, University of Arizona. 221.
Kumaran, P., Bhargava, G. N., Bhakuni, T.S., 1971. Fluorides in groundwater and
endemic fluorosis in Raajasthan. Indian Journal of Environmental Health. 13,
316-324.
Kuyucak, N., 1997. Feasibility of biosorbents application. In: Volesky B (ed.)
Biosorption of Heavy Metals. CRC Press, Boca Raton. 371-378.
Lenntech Water treatment & air purification 2006. Netherlands. e-mail:
Lepp, H., Goldich, S.S., 1964. Origin of the Precambrian iron formations: Econ.
Geology. 59, 1025-1060.
Li, Y., Liang, C., Slemenda, C.W., Ji, R., Sun, S., Cao, J., Emsley, C,. Ma, F., Wu, Y., Ying,
P., Zhang, Y., Gao, S., Zhang, W., Katz, B., Niu, S., Cao, S. and Johnston, C.,
2001. Effect of long-term exposure to fluoride in drinking water on risks of
bone fractures. Journal of Bone Mineralisation Research. 16(5), 932-939.
Mangla, B., 1991. India's dentists squeeze fluoride warnings off tubes. New Scientist,
131, 16.
Mell S., Mohira X., Atalah E., 1994. Prevalence of endemic dental fluorosis and its
relation with fluoride content of public drinking water. Revista Medica Chile.
122, 1263-70.
Morin, K.A., Hutt, N.M., 1997. Environmental geochemistry of minesite drainage:
practical theory and case studies. Minesite Drainage Assessment Group. 333.
Morrow, H., 1996. "Questioning the Need to Develop Alternatives for Cadmium
Coatings," Proceedings of 2nd Annual Cadmium Alternatives Conference,
National Defence Centre for Environmental Excellence, Johnstown,
Pennsylvania, USA.l3-15.
Morrow, H., Keating, J., 1997. "Overview Paper for OECD Workshop on the Effective
Collection and Recycling of Nickel-Cadmium Batteries," OECD Workshop on
the Effective Collection and Recycling of Nickel-Cadmium Batteries, Lyon,
France, September 23-2S, 1997. Proceedings to be published by OECD, Paris,
France.
-----------------------------65
Studies On Technology Oriented Methods For W(lterContamlnants And~ GeocMmkolln/l~nas On ContDminoted Plume
MPCA, 1999. Minnesota Pollution Control Agency, Cadmium, Lead and Mercury in
ground water of Minnesota.
http:/ /www.pca.state.mn.us/water/groundwater/gwmap/index.html.
Murray, J.J., 1986. Appropriate Use of Fluorides for Human Health, World Health
Organization, Geneva.
Nair, K.R, Manji, F., Gitonga, J.N., 1984. The occurrence and distribution of fluoride
ingroundwaters of Kenya. In: Challenges in African Hydrology and Water
Resources, Proceedings ofthe Harare Symposium, IAHS Pub I. 144, 75-86.
Nanz, R.H., Jr., 1953. Chemical composition of Precambrian slates with notes on the
geochemical evolution of lutites: Jour.Geol. 61, 51-64.
Nockolds, S.R., 1954. Average chemical composition of some igneous rocks: Geol.
Soc. America Bull. 65, 1007-1032.
NRC, 1999. Metals and radionuclides: technologies for characterization,
remediation, and containment. In: Groundwater and soil cleanup: improving
management of persistent contaminants. Washington, DC, National Academy
Press. 72-128.
NRC, 1997. Challenges of groundwater and soil cleanup. In: Innovations in
Groundwater and Soil Cleanup. Washington, DC, National Academy Press. 8-
41.
Nriagu, J.O., 1979. Global inventory of natural and anthropogenic emissions of trace
metals to the atmosphere. Nature. 279, 409- 411.
Nriagu, J. 0., 1980. "Cadmium in the Atmosphere and in Precipitation," Cadmium in
the Environment, Part 1, Ecological Cycling, John Wiley & Sons. 71-114.
Nriagu, J. 0., 1989. "A Global Assessment of Natural Sources of Atmospheric Trace
Metals," Nature. 338, 47-49.
NUS Corporation, 1987. Characterisation of Municipal Waste Combustor Ashes and
Leachates from Municipal Solid Waste landfills, Monofills, and Codisposal
Sites, Report prepared for the U.S. Environmental Protection Agency, Office
of Solid Waste, R-33-6-7-1, Washington, DC.
OECD, 1994. Organisation for Economic Co-operation and Development, Risk
Reduction Monograph No.5: Cadmium OECD Environment Directorate, Paris,
France.
66
Studies On Technology Oriented Methods For Water Contomlnonts And The Geochemical ln/Juenc~s On ContomJnated Plume
Pangborn, J., 1994. Mechanisms of Detoxication and Procedures for Detoxification.
Chicago ll: Bionetics Inc. 73-78.
Pettijohn, F.J., 1963. Chemical composition of sandstones: U.S. Geol. Surv. Prof.
Paper 440-S, 119-144.
Poldervaart, A., 1955. Chemistry ofthe earth's crust: Geol. Soc. America Spec. paper
62, 119-144.
Pons, L.J., Van Breemen, N.J., Driessen, P.M., 1982. Physiography of coastal
sediments and development of potential soil acidity. in Acid Sulphate
Weathering. Soil Science Society of America. Special Publication Number 10,
1-18.
Prasad, M.N.V., Freitas, H., 2000. Removal of toxic metals from the aqueous solution
by the leaf, stem and root phytomass of Quercus ilex L. (Holly Oak).
Environmental Pollution. 110(2), 277-283.
Raskin, 1., Kumar, P.B.A.N., Dushenkov, S., Salt, D.E., 1994. Bioconcentration of
heavy metals by plants. Current Opinion in Biotechnology. 5(3), 285-290.
Saunders, F.J., 1987. The biomass solution. Food. 43-37.
Shannon, M.W., 1998. The toxicology of other heavy metals. In: Haddad LM,
Shannon MW and Winchester JF (Eds.) Clinical Management of Poisoning and
Drug Overdose 3rd ed. Philadelphia: WB. Saunders Co. 767-783.
Smith, C.J., livingston, S.D, Doolittle, D.J., 1997. An international literature survey of
"IARC Group carcinogens" reported in mainstream cigarette smoke. Food and
Chemical Toxicology. 35(10-11), 1107-1130.
Solomon, T. W., 1992. Organic Chemistry. Wiley, Sth ed., 1992.
Holtzman, S. A., 1994. Cyanide and Heavy Metal Removal. A comparison of different
chemistries with emphasis on an innovative new treatment method.
Advanced Chemical Technology, Inc.
Susheela, A. K., 2001. 'Fluorosis- early detection and management', In Touch 3, 1-
6.Susheela A. K., Ghosh P., 1990. Fluoride: Too much can cripple you. Health
for the millions. New Delhi: Voluntary Health Association of India. 48-52.
Susheela A. K., Ghosh, P., 1990. Fluoride: Too much can cripple you. Health for the
millions. New Delhi: Voluntary Health Association of India, 48-52.
67
Studies On Technology Oriented Methods For Water Contaminants And The Geochemical Influences On Contomlnot~ Plume
Handa, B. K., 1975. Geochemistry and genesis of fluoride containing ground waters
in India. Groundwater. 13, 275-281.
Teotia, 5.P.5., Teotia, M., Singh, D.P., Rathour, R.S., Singh, C.V., Tomar, N.P.S., Nath,
M. and Singh, N.P., 1984. Endemic Fluorosis: change to deeper bore wells as
a practical community-acceptable approach to its eradication. Fluoride. 17,
48-52.
Tetsuji, C., Ning, T., Masamoto, T., Mashahiro, T., 1997. 'An ecotechnological
removal system for fluoride lnwater by activated alumina'. In Proceedings of
4th Asian Symposium on Ecotechnology. 30 September.
TRI, 2005. Toxics Release Inventory, USEPA. Public Data Release.Summary of Key
Findings. http:/ /www.epa.gov/triexplorer.
UNEP, 2003. Groundwater its susceptibility to degradation.
UNICEF, 1999. State of the art report on the extent of fluoride in drinking water and
the resulting endemicity in India. Report by Fluorosis Research & Rural
Development Foundation for UNICEF, New Delhi.
USEPA, 1985. Compilation of Air Pollutant Emission Factors, Volume 1: Stationary
Point and Area Sources, Metallurgical Industry, U.S. Environmental
Protection Agency, Office of Air and Radiation, Office of Air Quality Planning
and Standards, Research Triangle Park, NC, U.S. Government Printing Office,
Washington, D.C., September 1985.
US EPA, 1994. Assessment and Remediation of Contaminated Sediments (ARCS)
Program Remediation Guidance Document. EPA Report 905-894-003.
USGS, 2005. U.S. Geological survey, Mineral Commodity summaries, January 2005.
USNRC, 1993. Health Effects of Ingested Fluoride. National Research Council,
National Academy Press, Washington D.C.
Utell, M.J., Samet, J.M., 1995. Air pollution in the outdoor environment. In:
Environmental Medicine. SM Brooks, M Gochfield, J Hertzstein, RJ Jackson,
MB Schenker (Eds) St. louis, Missouri: Mosby. 462-469.
Van Assche, F. J., Ciarletta, P., 1992. "Cadmium in the Environment: Levels, Trends
and Critical Pathways, Edited Proceedings Seventh International Cadmium
Conference- New Orleans, Cadmium Association, london, Cadmium Council,
68
Studies Ott Technology Oriented Methods For Water Contaminants And The Geoc:hemlcallnfluenc~s On Contaminated Plum~
Reston VA, International lead Zinc Research Organisation, Research Triangle
Park NC.
Van Assche, F. J., 1998. "A Stepwise Model to Quantify the Relative Contribution of
Different Environmental Sources to Human Cadmium Exposure," Paper to be
presented at NiCad '98, Prague, Czech Republic, September 21-22, 1998.
Vance, D. B., 2002. Iron: The Environmental Impact of a Universal Element.
http:/ /2the4.net/iron.htm.
Volesky, B., 1987. Biosorbents for metal recovery. Tibitech. 5, 96-101.
WHO, 1984. Fluorine and Fluorides, Environmental Health Criteria 36. World Health
Organization, Geneva.
WHO, 1992. World Health Organisation, Environmental Health Criteria 134-
Cadmium International Programme on Chemical Safety (IPCS) Monograph.
William, P.A., Errington, J. C., 1998. Guidelines For Metal leaching and Acid Rock
Drainage at Minesites in British Columbia (Ministry of Energy and Mines).
Wyatt, J.M., 1988. Biotechnological treatment of industrial waste water. Microbial.
Sci. 5 (6) 186-191.
69