International Journal of Separation for Environmental Sciences
Volume 1, Number 1
ENVIRONMENTAL POLLUTION EFFECTS,
MANAGEMENT AND TREATMENT METHODS
Chintan Pathak1 and Hiren C. Mandalia2
1School of Technology, Pandit Deendayal Petroleum University,
Gandhinagar, Gujarat, India
2 Central Laboratory, Ahmedabad Municipal Corporation,
Kankaria Road, Ahmedabad, Gujarat, India
© 2012 Nova Science Publishers, Inc.
With the rise of an environmental protection movement, the petroleum industry has
placed greater emphasis on minimizing environmental impact of its operations. Improved
environmental protection requires better education and training of industry personnel.
There is a tremendous amount of valuable information available on the environmental
impact of petroleum operations and on ways to minimize that impact; however, this
information is scattered among thousands of books, reports and papers, making it difficult
for industry personnel to obtain specific information on controlling the environmental
effects of particular operations. This paper assembles a substantial portion of this
information into a single reference. This paper has been organized and written for a target
audience having little or no training in the environmental issues facing the petroleum
industry. This paper covers the various aspects of drilling and production and impacts
related to them. Discussion is also emphasis on the toxic materials transport, plan and
manage activities that minimize potential environmental impacts. The treatment of
drilling and production wastes to reduce their toxicity and/or volume before disposal.
Keywords: Environmental Protection, Petroleum Industry, Waste Treatment and Disposal
Drilling is the process in which a hole is made on the earth to allow subsurface HCs to
flow to the surface. The process of drilling oil and gas wells generates a variety of different
types of wastes. Some of these wastes are natural by-products of drilling through the earth,
Corresponding author E-mail address: firstname.lastname@example.org (Dr. Hiren C Mandalia, Mo No: +91-
Chintan Pathak and Hiren C. Mandalia
e.g., drill cuttings, and materials used to drill the well, e.g., drilling fluid and its associated
additives. The major way in which drilling activities can impact the environment is through
the drill cuttings and the drilling fluid used to lift the cuttings from the well. Secondary
impacts can occur due to air emissions from the internal combustion engines used to power
the drilling rig.
1.1 Sources of Waste
All drilling muds generally have a number of unwanted components that can potentially
harm the environment. The most common of these are heavy metals, salt, and HCs. The
concentration of these materials varies significantly. The primary concern arises when the
drilling fluid must be disposed off .
1.1.1 Heavy Metals
Heavy metals can enter into drilling fluids in two ways: (1) many metals occur naturally
in most formations and will be incorporated into the fluid during drilling. These includes
arsenic, barium, cadmium, chromium, lead, mercury etc. (2) also metals are added to the
drilling fluid as part of the additives used to alter the fluid properties. This includes barium
from barite weighing agents and chromium from chrome-lignosulfonatedeflocculants.
Heavy metals may incorporate into the Drilling fluid from the thread compound (pipe
dope) used on the pipe threads when making up a drill string or from the formation containing
The heavy metals encountered during drilling activities are related to a variety of
environmental concerns, depending on the metal and its concentration. At very low
concentrations, some metals are essential to healthy cellular activity. Because most
concentrations encountered during drilling are relatively low, the environmental impact is
generally observed only after chronic exposure.
The environmental impact of heavy metals is manifested primarily through their
interaction with enzymes in animal cells. Enzymes are complex proteins that catalyse specific
Heavy metals affect the action of enzymes. Excess concentrations of metals inhibit
normal biochemical processes in cells. This inhibition can result in damage to the liver,
kidney, or reproductive, blood forming, or nervous systems. These effects may also include
mutations or tumours.
Another unwanted component of drilling fluid at disposal time is salts, like sodium or
potassium chloride, are often added to drilling fluid to protect sensitive formations from
reacting with the drilling fluid.
Salt (sodium chloride) in low concentrations is essential to the health of plants and
animals. At concentrations different from the naturally occurring levels found in a given
ecosystem, however, salt can cause an adverse impact.
1.1.3 Hydrocarbons (HC)
Except for oil-based mud, HCs are normally an undesirable material in drilling mud
because they contaminate the cuttings. HCs enter into mud while drilling through a HC
bearing formation or when oil is used for spotting fluid when a pipe becomes stuck.
1.2. Impact on Plants
The impact of salt on plants arises primarily from an excess salt concentration in the
cellular fluids of the plants or from an alteration in the soil structure in which the plants grow.
The primary impact of an abnormal salt concentration in cellular fluids is the disruption of the
fluid chemistry balance within cells. This disruption inhibits cellular growth, water uptake,
and the overall health of the plants.
Salt can indirectly impact plant growth by altering the physical properties of soil. When
saline water is discharged on land, it can alter the pore structure of the soil by causing
compaction, limiting the access of air and water to the plant roots. The impact varies,
however, with salinity level and plant type.
Excess sodium in soil can also cause clays to disperse, lowering the permeability of the
soil. This can form an impenetrable surface crust that hinders the emergence of seedlings and
limits the availability of nutrients such as iron, manganese, calcium, and magnesium to the
plants. On the other hand, the addition of clays from drilling muds can increase the water
holding capacity of sandy/coarse-textured soils, improving plant growth .
The number of ways to measure the salinity of soils has been developed; these
measurements include directly measuring the electrical conductivity of the soil and various
measurements of sodium concentration.
1.3. Impact on Aquatic Organisms
Most, but not all, produced waters have a salt content higher than that found in the local
ecosystems. The discharge of water having a higher salt content can impact aquatic
organisms. High concentrations of sodium chloride can affect the development of embryos
and foetuses and can cause fetal death. High salt concentrations can also affect the
development of the musculoskeletal system and cause eye, skin, and upper respiratory system
Because the salinity of many produced waters is greater than that of marine waters, the
environmental impact of high salt concentrations is also of concern regarding marine
organisms. Highly saline water has a higher density than seawater and will segregate to the
bottom of any surface waters. This density gradient inhibits the mixing and dilution of the
very salty water.
1.4. Hydrocarbon Toxicity
A number of bioassay tests have been conducted to determine the toxicity of various HCs
on marine animals. The toxicity of HCs has been found to vary considerably and
generalizations cannot be easily made. Factors that affect toxicity include molecular weight,
HC family, the organism exposed to the HC, and life-cycle stage of the organism exposed
(egg, larva, juvenile, or adult). For mixtures of HCs, such as crude oil, toxicity also depends
on the history of the exposure.
For HCs of a similar type (the same family), the toxicity tends to increase with decreasing
molecular weight. Smaller molecules tend to be more toxic than large molecules. Light crude
Chintan Pathak and Hiren C. Mandalia
oils and refined products tend to be more toxic than those of heavy crude oil, because heavy
crude oil has a higher average molecular weight. For similar molecular weight HCs, the
toxicity varies with family. The toxicity of HC families generally increases in the following
order: alkanes, alkenes, cycloparaffins, aromatics, and polyaromatic HCs.
Some of the least toxic HCs include dodecane and higher paraffins. In fact, these high
molecular weight paraffins are used in cooking, food preparation, and candles. The most toxic
HCs are the low-boiling-point aromatics, particularly benzene, toluene, ethylbenzene, and
xylene. Because of their similar properties, these four aromatic molecules are commonly
referred to as BTEX. The most toxic HCs also tend to have a high solubility in water. A high
solubility makes a molecule more accessible for uptake by plants and animals .
1.5. Impact of Crude Oil on Marine Animals
The actual impact of HC exposure on marine animals is more complex than simple
bioassay tests reveal. Oil at sublethal concentrations can significantly alter the behaviour and
development of marine organisms. These effects, however, are difficult to quantify. The
problem of determining sublethal toxicity is further compounded because different species
have different reactions and there is mixed effect when multiple toxins are present.
Behaviour changes from exposure to HCs are primarily those involving motility, while in
higher organisms, changes affect avoidance, burrowing, feeding, and reproductive activities
. Exposure to HCs can adversely affect the development of organisms in some species at
concentrations below 1 mg/l. Some species show no long-lasting damage, while other species
can suffer long-term damage at an oiled site. The impact of HC exposure also depends on
whether the HC is dissolved or dispersed as suspended droplets [4-5].
The most common impact of crude oil on birds is by direct contact, oil coats their
feathers, causing them to lose their water-repellence and thermal insulation. The birds then
sink and drown or die of hypothermia. Oil can also be ingested by the birds during preening
of oiled plumage. Although this oil becomes distributed throughout the body, there is no
evidence that ingested oil is a primary cause of death amongst birds.
The effect of oil on marine mammals is highly variable. Fur-insulated mammals lose their
ability to thermally regulate their temperature as their oil-contaminated fur loses its insulating
capacity. The loss of thermal insulation creates a higher metabolic activity to regulate body
temperature, which results in fat and muscular energy reserves being rapidly exhausted. This
can result in the animal's death by hypothermia or drowning. Many species show no
avoidance response to oiled areas. Chronic contact of marine mammals with oil may also
result in skin and eye lesions.
1.6. Impact of Crude Oil on Ecosystem
Only a few studies have been conducted on the chronic effects of HC releases on
ecosystem. No apparent long-term impacts on the productivity of ecosystem have been
observed. In all cases, the affected areas recovered after the HC source had been removed,
although full recovery could take a number of years. One difficulty with ecosystem studies,
however, is that little is known about ecosystems that have not been exposed to HCs. This
makes it difficult to determine what lasting effects HCs do have on ecosystems [3-4].
One important way to gain information about the effects of chronic exposure of
ecosystems to crude oil is to study areas having natural oil seeps. Studies at natural seeps at
Coal Oil Point in the Santa Barbara Channel, California, have shown that the level of
macrofauna is reduced when the HC content in the sediments is high. The reason for the
lower faunal level is the reduced amount of oxygen, high sulfide content, and high level of
dissolved HCs (mostly aromatics) in the surrounding water .
1.7. Impact on Human Health
The impact of HCs on human health depends somewhat on whether exposure was from
ingestion, inhalation, or dermal (skin) contact and on whether the exposure was acute (short-
term) or chronic (long-term).
The acute effects of ingestion may include irritation to the mouth, throat, and stomach,
and digestive disorders and/or damage. Small amounts of HCs can be drawn into the lungs,
either from swallowing or vomiting, and may cause respiratory impact.
The chronic effects of ingestion may include kidney, liver, or gastrointestinal tract
damage, or abnormal heart rhythms. Prolonged and/or repeated exposure to aromatics like
benzene may cause damage to the blood-producing system and serious blood disorders,
including leukaemia .
A number of PAHs have been linked to cancer of the skin, lung, and other sites on the
body. Most human exposure to PAHs comes from nonpetroleum sources, including cigarette
smoke, fossil fuel combustion products, and food.
The acute symptoms of HC exposure by inhalation may include irritation of the nose,
throat, and lungs, headaches and dizziness, anaesthetic effects, and other central nervous
system depression effects.
Chronic effects of inhalation exposure to HCs containing high concentrations of aromatic
compounds, including gasoline, can be weight loss from loss of appetite, muscular weakness
and cramps, and possible liver and renal damage.
Exposure of eyes and skin to HCs may result in irritation, mechanical or chemical
damage to eye tissue, or dermatitis. Exposure to petrochemicals, particularly polyaromatic
HCs, increases susceptibility to skin infections, including skin cancer when there is
simultaneous exposure to sunlight.
One potential source of HC exposure to humans is ingestion of HC-contaminated food,
particularly seafood. Studies have shown that most organisms cleanse themselves of HCs
within a matter of weeks after being removed from the source of contamination. This
cleansing time, however, depends upon the contaminated organism.
1.8. Impact on Plant Growth
HCs also impact plant growth when released on land. Levels of oil and grease above a
few percent in soils (by weight) have shown degradation of plant growth. Levels below a few
Chintan Pathak and Hiren C. Mandalia
percent have shown an actual enhancement of some crop growth. Airborne HCs emitted
during blowouts can impact plant growth around the wellhead.
Waste was defined as "any material that is surplus to requirement" and “management”
comprises EandP project definition, selection of technology, design of facilities, waste
collection, transport, treatment, and disposal .
Waste management is an integral component of oil and gas exploration and production
that can have a substantial bearing on environmental performance and corporate reputation.
The benefits of sound management of waste can minimize environmental impacts, reduce
operational and capital expenditures, and minimize risk to corporate reputation.
2. WASTE MANAGEMENT
The principles of waste management include the incorporation of a hierarchy of
management practices that is integral to the development of the strategy for dealing with
wastes. Waste management begins with prevention. Prevention refers to the
avoidance/reduction of waste by modification of design and operating practices. This
principle should be incorporated into all stages of the project life cycle.
2.1. Waste Treatment and Disposal Methods
The OGP Exploration and Production Waste Management Guidelines document reviews
and describes a wide range of waste handling includes:
2.1.1. Biological treatment is among the most useful and cost-effective methods for
managing EandP waste. Biodegradation is a natural process by which HCs and other organic
materials are consumed by microorganisms (such as bacteria or fungi) that utilize these
materials as food sources. Before beginning a biological treatment operation, one needs to
consider several site-specific parameters to determine the feasibility of successfully
biotreating the wastes. A risk assessment will aid in this decision-making process when
regulations do not exist. Biological treatment includes: Land-farming, Land treatment,
2.1.2. Thermal treatment is useful primarily for organic compounds, but can process
most wastes regardless of form. Thermal processing can be very efficient, but can also require
high maintenance, be very expensive, and complex to operate. Air pollution control
equipment is usually required, or should at least be considered based on a risk-management
approach. Thermal treatment objectives usually include volume reduction, detoxification, or
disinfection and may also include energy recovery. Thermal treatment includes: Incineration,
Fuel blending [10-12].
2.1.3. Chemical treatment processes are those in which materials are altered by chemical
reactions. The chemical reactions can improve or enhance a separation/filtration process or, in
some cases, create a product that is in a more convenient form for further processing or
disposal. It includes: Neutralization, Solidification/Stabilization.
2.1.4. Physical treatment processes are characterized by the ability to separate the
various phases of a waste without performing any chemical reaction or changing the
chemistry of the mixture. Phase separation, such as separating solids from liquids or oil from
water, is useful in concentrating constituents or removing free liquids to render a waste
suitable for land disposal. By concentrating the material, additional treatment can be done
more economically or conveniently, or recycling/re-use options may be possible. Typical
treatments utilized in this waste management process include: Evaporation, Gravity
2.1.5. Waste-specific Treatment. Several waste-specific treatment technologies have
particular relevance for EandP operations, such as: Non-incineration treatment for medical
waste, Waste water.
2.1.6. Waste Disposal Options. Multiple approaches for waste management may be
appropriate depending on local needs and the availability of resources and technology. In any
one region, site-specific factors can be important in deciding which of the available disposal
options is most appropriate and may provide the best environmental benefit in a cost-effective
manner. Typical waste disposal options that may meet legal, risk-based and practicability
criteria include: Underground injection, Landfill, On-site burial
Where it is not practicable to rely on existing waste management infrastructure, it may be
necessary to design a new on-site or off-site waste management facility. The following
considerations are important when addressing specific waste management options.
Community and outreach
Metcalf and Eddy. Inc. Wastewater Engineering; 3rd Edition; TATA McGraw-Hill
publishing company Limited, New Delhi, 1999; 765-915.
Bhatia, S.C. Handbook of Industrial Pollution and Control; CBS publishers. 2002;
Cormack, D. Responses to oil and chemical Marine Pollution; Applied science
publishers, New York.1983.
Noyes, Robert. Unit operations in Environmental Engineering; Jaico publishing house.
Kiely Uwe. Environmental Engineering; Irwin McGraw-hill. 2006; 718.
Noyes, Robert. Pollution Prevention Technology Handbook; Noyes publications,
U.S.A. 1993; 30, 39, 105, 206, 502.
Sharma, B. K. Industrial Chemistry; 14th edition. Goel publishing house. 2004.
Willard, H. H. Industrial Methods of Analysis; 6th edition. CBS publishers. 1986.
Gupta, V. Break-through in oil-water separation; Environment science and
Engineering, 2006; 57-58.
Chintan Pathak and Hiren C. Mandalia Download full-text
 Rao, M. N. and Datta, A. K. Wastewater Treatment; 2nd edition. Oxford and IBP
publishing Co. Pvt. Ltd. 1978.
 Punmia, B. C. and Jain, A. K. Wastewater Engineering; Laxmi publications. 2005.
 Chakravarty, R. N. and Bhaskaran, T. R. Treatment and Disposal of oil refinery wastes;
IAWPC volume 10. 1973; 137-153.