Groundwater is water present below the ground surface that saturates the pore space in the subsurface. At least 50% of the world population depends on groundwater as a source of drinking water. Other uses of groundwater includes Irrigation of crops, Industrial uses etc. Groundwater is a part of natural water cycle therefore, it can spread throughout the cycle and if contaminated, can cause damage to other entities ( Sea life, lakes, human health etc) Groundwater can be polluted / contaminated as a result of HUMAN activity and Natural conditions. Contaminations found in the groundwater cover a broad range of physical, chemical (Organic & Inorganic), bacterial and radioactive parameters.

1. Groundwater Contamination
Causes and prevention
By-
MOHIT DWIVEDI
12BCL0172
( G2- Slot)
Fall Sem ‘13

2. Contents
Introduction
Importance of Groundwater
Sources of Groundwater Contamination
Prevention from Groundwater Pollution
Actions by Industries and Community
Groundwater Remediation
Conventional and Innovative Remediation Techniques
Some Groundwater Contaminants
Remediation Technologies
Conclusion

3. Introduction
Groundwater is water present below the ground surface that saturates the pore
space in the subsurface.
At least 50% of the world population depends on groundwater as a source of
drinking water.
Other uses of groundwater includes Irrigation of crops, Industrial uses etc.
Groundwater is a part of natural water cycle therefore, it can spread throughout
the cycle and if contaminated, can cause damage to other entities ( Sea life,
lakes, human health etc)
Groundwater can be polluted / contaminated as a result of HUMAN activity and
Natural conditions.
Contaminations found in the groundwater cover a broad range of physical,
chemical (Organic & Inorganic), bacterial and radioactive parameters.

4. Sources of Groundwater Pollution
Improper use of contaminated water
Leaking Fuel and Chemical Tanks
Extensive use of Pesticides,
Herbicides and fertilizers
Drainage of house hold chemicals
Industrial Chemical spills
Badly Managed Landfill
Industrial Emissions

5. Prevention of Groundwater Contamination
Participation of Industries:
•Minimize use of Toxic / Hazardous Raw Materials
•Maintain Integrity of the Storage Tanks, Pipelines, surface impoundments
•Adopt Good Engineering Practices for selecting proper material for tanks and pipes.
•Implement monitoring programs: Leak Detection and repair program, spill detection, spill control,
emergency response plan etc.
•Manage Properly: Waste materials, their transport and disposal.
•Install Monitoring Wells
•Monitor Periodically: Groundwater quality

6. Prevention of Groundwater Contamination
Participation of Community:
•Minimize use of house hold chemicals containing Hazardous substances.
•Avoid draining chemicals, motor oil, insecticides in community areas.
•Reduce pesticide application
•Use proper procedures for handling chemicals (Paints, Pesticides, Insecticides, polishing materials,
cleaning chemicals and detergents).
•Immediately clean any spills and report any leakages to concerned department.

7. Groundwater Remediation
Groundwater remediation is the process that is used to remove pollution from groundwater.
Pollutants and contaminants can be removed from groundwater by applying various techniques
thereby making the groundwater safe for use.
Groundwater remediation techniques are mainly divided into two technologies:
Ex-Situ Technology involves treatment of groundwater by de-watering the
polluted aquifer (pumping out), then treating the water on surface by Physical,
chemical or biological technology and finally re-injecting the treated water to the
aquifer.
In-Situ Technology involves treatment of groundwater within the aquifer (in
the sub-surface) by using thermal, chemical and biological treatment technology.

8. Remediation Techniques
Ex-Situ Technology:
Extraction of groundwater from aquifer , treat above ground. and return the treated water to the aquifer.
Extraction is done by pumping groundwater from the well or trench and treat it with a variety of techniques
such as :
Stream stripping
Involves treatment by introducing steam which extract the contaminants from the pumped out groundwater.
The extracted steam (along with contaminants can be recovered from the condensate or treated further by
incineration.
Oxygen Sparging
Involves introduction of oxidizing/reducing agents ( O3, H2O2, Hypochlorite) to chemically convert the toxic
contaminants to less toxic compounds.
Bioremediation
Involves treatment of pumped up groundwater by air (biodegradation) with careful control of moisture, heat
nutrients, oxygen and pH.
Carbon Adsorption
Involves passing the contaminated pumped up groundwater through activated carbon column in which
contaminants gets adsorbed.

9. Ex-Situ Technology

10. Remediation Techniques
In-Situ Remediation Technology:
Involves treatment of groundwater (in-place) without extracting the water from aquifer. There are several treatment
techniques used for in-situ groundwater treatment such as:
Air Sparging:
Involves the injection of contaminant-free air into the subsurface saturated zone, enabling a phase transfer of hydrocarbons from a
dissolved state to a vapor phase.
Bioremediation:
Involves injection of oxygen to enhance the biodegradation. This treatment also combines injection of degrading bacteria and
nutrients into aquifer to stimulate biodegradation.
In-well air stripping:
Involves injection of air in double screened well, lifting the water up the well and force it out in upper screen. VOCs in the
contaminated water are transferred from dissolved phase to vapor phase in air bubbles and drawn off and treated.
Chemical Oxidation:
Involves Reduction-Oxidation reactions that chemically converts hazardous contaminants to less toxic compounds. Cyanide oxidation
and de-chlorination are the typical examples of chemical oxidation.
Thermal Treatment:
Involves increase in temperature of the source zone to increase the mobility of the pollutants. The mobility facilitate removal of
pollutants and can also results in In-Situ destruction of contaminants.
Phythoremediation
It involves the use of macroscopic plants to destroy, remove, immobilize and treat contaminants. This process does not use
microorganisms.

11. Remediation Techniques
In-Situ Bioremediation

12. Selection of Remedial Technology
The selection of the remedial technology depends upon several
parameters such as:
Contaminant Profile:
Types of compounds ( DNAPL, LNAPL, Ammonia, Virus, Bacteria)
Quantity and Solubility ( Solubility in Water)
Toxicity and volatility ( VOCs , SVOCs, Metals, etc)
Biodegradability
Aquifer Profile:
Soil Type (permeability, homogeneity, chemistry, confined or open, etc)
Groundwater Flow direction
Water Table location
Recharge location ( seasonal Rainfall)
Feasibility Profile:
Cost of technology
Time of completion

13. Groundwater Contaminants
Several man made chemicals are referred to as Groundwater contaminants because of their
extensive use, accidental spills and leaks, mismanagement and illegal dumping. Some of the
popular contaminants are the following:
DNAPL (Dense Non Aqueous Phase Liquids )
LNAPL (Light Non Aqueous Phase Liquids)
Inorganic Chemicals ( Ammonia, Cyanide, Fluoride)
Metals
Bacteria and Viruses

14. Groundwater Contaminants
DNAPL :
Dense Non Aqueous Phase Liquids are organic compounds heavier than water and having less
absolute solubility. These compounds include chlorinated solvents (EDC) and halogenated
aromatics (TCB)
DNAPLs migrate very fast through the soil formation and reach water table because of their high
density and low viscosity. They sink steeply to the bottom of the aquifer till they reach the
impermeable bed rock.
Treatment of DNAPL
The following types of technologies are increasingly being used to treat DNAPLs:
 In situ thermal treatment
 In situ chemical oxidation
 Surfactant/co-solvent flushing
 In situ bioremediation
Ground water extraction (P&T or recirculation)
 Excavation
Containment (Engineered caps and slurry walls).

15. DNAPL Dense Non Aqueous Phase Liquid Migration Pattern

16. Groundwater Contaminants
LNAPL
Light Non Aqueous Phase Liquids are organic compounds lighter than water
and having low solubility. These liquids include Gasoline, fuel oil and other
petroleum products.
LNAPL Remediation:
Remediation may require the use of more than one technology.
It is likely that several remediation techniques, used in series and/or parallel
applications, will be required for maximum contaminant removal.
This collaborative effort may be referred to as a treatment train approach. A
conceptual example of a treatment train which might be effective at an
LNAPL site includes:
Pump and Treat for mobile LNAPL removal followed by vapor extraction for
removal of residual LNAPL .
Additional technologies such as bioremediation might be used to further
reduce contaminant concentrations.

17. LNAPL Light Non Aqueous Phase Liquid Migration Pattern

18. Typical Groundwater Contaminants And Their Treatment Options
Contaminant Main Source Treatment Technology
Trichloroethylene
(TCE)
Degreasing of Metal and Electronic parts, Extract for oil and
waxes, fumigant, carries in paints and adhesives
•Pump and Treat
•Activated Carbon
•Thermal and Biological
MTBE
MTBE can be released to groundwater by leaking
underground storage tanks and piping, atmospheric
deposition, spills during transportation, and leaks at
refineries
•Air Sparging
•In-Situ oxidation ( H2O2 and Fe)
•Bioremediation/Bioaugmentation
•Pump and Treat.
EDC (DNAPL)
From EDC and VCM Plants, storage tanks, pipelines etc. •In-situ Bioremediation.
Gasoline (LNAPL)
Gasoline and other petroleum fuels tanks, petrol stations,
storage tanks and pipelines.
•In-situ Bioremediation
•Vapor extraction
Ammonia
Ammonia Storage Tanks, Landfill leaks, Waste stockpile, etc. •Pump and Treat
•Combination of Air Stripping, Nitrification,
Ion Exchange.

19. Treatment of EDC (Ethylene Dichloride) & Chloroform
Groundwater contaminated by Ethylene Dichloride and Chloroform can be treated through in-situ
bio remediation by using certain types of Enzymes under proper conversion parameters.
This In-Situ process is applicable to both fresh and brackish waters.
50 to 80 percent biodegradation can be achieved by injecting Enzymes in the aquifer within 5 to
10weeks.
Applicability:
EDC (1.3 g/cc), Chloroform (1.5 g/cc) , Chlorobenzene, Vinyl Chloride, VOCs.
Limitations:
Permeability of the ground
Aquifer Matrix
Practical Execution
This In-Situ Bio remediation is practically implemented by two industrial facilities in Jubail to
reduce EDC and other chlorinated compounds from the groundwater.

20. Treatment of MTBE (Methyl Tertiary Butyl Ether )
MTBE is broadly used as Gasoline additive and is one of the
popular contaminant of the groundwater.
The solubility in water is as high as 4.3% comparing to
Solubility of benzene and toluene 0.18% and 0.05%
respectively.
MTBE is very mobile and can spread to very large
subsurface area very quickly.
Groundwater contaminated with MTBE can be treated by :
In-Situ Oxidation
Bioremediation (Enhanced by Oxygen and Nutrients injection)
Pump and Treat by Air Stripping & Activated Carbon Adsorption
Combination of Catalytic Chemical Oxidation with UV Presence.

21. Treatment of Ammonia
Ammonia is one of the major pollutants which contaminates groundwater. Ammonia
contamination could lead to Sea Water Pollution. Being Toxic to Aquatic Organism,
Remediation of Ammonia is very important.
US Department of Energy has successfully conducted pilot studies on the Innovative
Remedial Techniques on an Aquifer near Moab, Utah, USA. Which shows that
technologies are available for treating groundwater contaminated with high levels of
Ammonia to a safe level of 3 mg/L
These technologies includes:
Pump and Treat by Ammonia Stripping
Pump and Treat by Air Stripping and further Nitrification
Pump and Treat by Ion Exchange
Limitation: Needs pH Adjustments,

22. Conclusion
1. Prevention from groundwater contamination is the
best Remedial Option.
2. Mostly, groundwater contaminants are of industrial origin.
3. Royal Commission is closely monitoring the quality of
Groundwater through out the Jubail Industrial City and also have implemented strict
regulation for the prevention of groundwater pollution.
4. Environmental Awareness Programs Including groundwater prevention should be
Implemented for Community.
5. Innovative Technologies are available for the groundwater remediation, for several
common contaminants including EDC and Other Chlorinated Compounds, MTBE and
Ammonia.

23. The Conservation of groundwater is in Our Hands