“Water is the
driving factor of all nature.” The addition of undesirable substances to
groundwater caused by the activities of human is considered to be
contamination. Groundwater contamination is extremely difficult to clean it up.
There are groundwater contamination issues that potentially affect public water
supplies over a large area. It will cause serious health issues to people due
to contamination. In recent years, the increasing threat to groundwater quality
due to the activities of human has become a matter of great concern. Rapid urbanization
and industrialisation in India has resulted in the increase of generation of
wastes. Due to lack of adequate resources and infrastructure the waste is not
properly collected disposed and treated that leads to the accumulation causing
groundwater contamination. Remediation is the only way to clean up the
contamination groundwater and soil. A variety of techniques for environmental
remediation have been compiled and summarized. This paper is intended to
provide an overview of remediation methods currently utilized at various
hazardous waste sites.
Keywords: Remediation, contamination,
treatment, pollution, environment, physical and chemical treatment.
methods are divided for surface and groundwater remediation. Further
categorization results in the consideration of biological, chemical, and
physical treatment technique. Some techniques may be applicable only under
certain environmental conditions. The problem is more severe in large cities
and also various clusters of industries. In many of these areas groundwater is
only source of drinking water and so large population is exposed to risk of
consuming contaminated water. In this background Central Pollution Control
Board with the help of its Zonal offices, the National Institute of Hydrology
(NIH) and the Pollution Control Research Institute (PCRI) of Bharat Heavy Electricals
Ltd. gave a detailed survey of groundwater quality in problem areas of
industries and cities of India. Similar to air
quality, water quality can be improved by two functions: proactive (water
pollution control) or reactive (remediation of polluted water). Examples of
water remediation/purification technology is: Conventional water treatment
plants – having different complexity based on the level of contamination of the
water. The activities related to groundwater pollution with respect to the land
use are as follows in the table1.
Activities related to groundwater contamination
Irrigation using wastewater
Salt water intrusion
Industrial , Commercial
Landfill disposal and hazardous
Land and stream discharge of sewage
Mine drainage discharge
The laws and guidelines specify
acceptable concentrations of different contaminants in water meant for
SOURCES OF GROUND WATER CONTAMINATION:
Ground water can become contaminated
from natural sources or numerous types of human activities. Residential,
municipal, commercial, industrial, and agricultural activities can all affect
quality of ground water. Contaminants may reach ground water from activities in
the land surface, such as releases or spills from stored industrial wastes;
from sources below the land surface but above the water table, such as septic
systems or leaking underground petroleum storage systems; from structures
beneath the water table, such as wells; or from contaminated recharge water.
Some other are:
• Industrial chemical spills
• Badly managed landfill
• Drainage of household chemicals
• Extensive use of Pesticides,
herbicides and fertilizers
Some substances found naturally in rocks
or soils, such as iron, manganese, arsenic, chlorides, fluorides, sulphates, or
radio nuclides, can become dissolved in ground water. Other naturally occurring
substances, such as decaying organic matter, can move in ground water as
particles. Whether any of these substances appears in ground water depends on
local conditions. Some substances may pose a health threat if consumed in
excessive quantities; others may produce an undesirable odour, taste, or
colour. Ground water that contains unacceptable concentrations of these
substances is not used for drinking water or other domestic water uses
unless it was treated to remove these contaminants.
?Improper Disposal of Hazardous Waste:
Hazardous waste should always be
disposed of properly, that is to say, by a licensed hazardous waste handler or
through municipal hazardous waste collection days. Many chemicals should not be
disposed of in household septic systems, including oils (e.g., cooking, motor),
lawn and garden chemicals, paints and paint thinners, disinfectants medicines,
swimming pool chemicals. Similarly,
many substances used in industrial processes should not be disposed of in
drains at the workplace because they could contaminate a drinking water source.
Companies should train employees in the proper use and disposal of all chemicals
used on site. There is many different types and the large quantities of
chemicals used at industrial locations make proper disposal of wastes
especially important for ground water protection.
Several federal laws help protect
ground water quality. The Safe Drinking Water Act (SDWA) established
three drinking water source protection programs: the Wellhead Protection
Program, Sole Source Aquifer Program, and the Source Water Assessment Program.
It also called for regulation of the use of underground injection wells for
waste disposal and provided EPA and the states with the authority to ensure
that drinking water supplied by public water systems meets minimum
health standards. The Clean Water Act regulates ground water that’s
shown to have a connection with surface water. It sets standards for allowable
pollutant discharges to surface water. The Resource Conservation and
Recovery Act (RCRA) regulates treatment, storage, and disposal of hazardous
and nonhazardous wastes. The Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA, or Superfund) authorizes
the government to clean up contamination or sources of potential contamination
from hazardous waste sites or chemical spills, including those that threaten
drinking water supplies. CERCLA includes “community right-to know” provision.
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) regulates
pesticide use. The Toxic Substances Control Act (TSCA) regulates
PUMP AND TREAT TEST:
It is a primary technique for groundwater and
soil remediation. Here, groundwater are pumped to the surface, and contaminants
are removed by a variety of treatment methods, including air-stripping,
ultraviolet or ozone treatment, precipitation and biodegradation. This
technique is carried out through one or more pumping wells, with the water
being treated by any one of physical and biological methods or their
combinations. Pump and treat systems are relatively easy to design, install and
operate using standard engineering practices. For successful remediation,
surface treatment of pumped groundwater must be in consistence with the type
and concentration of contaminants. It is typically used for contaminants that
are dissolved in groundwater. The pumping systems can accomplish rapid
mass-removal from areas of the groundwater plume where contaminants are most
heavily concentrated. Nevertheless, pump-and-treat is not so effective in area
with low permeability soils as clays and soil.
SOIL VAPOR EXTRACTION:
Extraction uses vapour extraction wells to
remove volatile contaminants from the soil. Vacuum blowers are often installed
to supply the driving force by inducing airflow through the soil matrix. The
extraction wells are prepared within the contaminated area. The screened pipe
is placed in a permeable packing; the unscreened section is sealed in a
cement/bentonite grout to prevent a short-circuited air flow direct to the
surface. The pumped air strips the volatile compounds from the soil and carries
them to the screened extraction well. Gases are collected in perforated pipe
wells or trenches and transported above-ground to a vapor-liquid separator,
where entrained water is separated and contained for subsequent treatment. The
contaminant vapors are moved by a vacuum blower for the vapor treatment
process. Vapors produced by that process are conventionally treated by carbon adsorption
. Other methods including condensation, biological degradation, and ultraviolet
oxidation have been applied thought to a limited extent. In some cases,
air-injection wells are installed in-situ. These wells may enhance the process
efficacy by actively using forced airflow. The system must be designed in a way
Remediation Techniques for Soil and Groundwater – X.H. Zhang ©Encyclopedia of
Life Support Systems (EOLSS) that any air injected into the system does not
allow the escape of volatile organic compounds to the atmosphere. Steam is
often can be used in extraction to remove volatile and semi-volatile hazardous
contaminants from soil and groundwater. It is injected into the ground to raise
the soil temperature and drive off volatile contaminants. Steam injection can
form a displacement front by its condensation to displace groundwater. Steam
can enhance the stripping of volatile contaminants from soil and be used to
displace contaminated groundwater under some conditions.
What makes a biological remediation method
legitimate is that it utilizes microorganisms. These little helpers help
through bioventing, biosparging, or bioaugmentation. In biological water
remediation, biologic materials Water purification starts on a physical level,
with the removal of the largest particles and obstructions that plague the
water you are treating. Air sparging is one physical remediation method that’s
used, which involves using pressurized air to strip water clean. A more common
method is to pump water directly, with filters stripping away and large gravel
or rock materials, and then letting the water be further filtered biologically
or chemically to ensure that it’s in the best shape.
It help to break down unwanted chemicals that
aren’t easily separated from the water, particularly in industrial waste that
forms in groundwater. A plus side to this method is that physically pumping
groundwater out is not required to treat it.
This is most costly type
of water purification, and it can also take the longest to accomplish. Chemical
remediation can be achieved through a variety of methods, including carbon
absorption, ion exchange, oxidation, and chemical precipitation. Chemical
remediation is often used alongside physical water treatment to achieve the
best results, and can help achieve the cleanest groundwater after the fact.
The Groundwater Spatiotemporal Data
Analysis Tool (GWSDAT) is a user-friendly, open source software tool used to
analyze and report trends in groundwater quality monitoring data. It is based
on programming language R and Microsoft Excel. GWSDAT’s primary use is for
interrogation and interpretation of groundwater monitoring data derived from
contaminated sites. It has specific functionality for analyzing dissolved-phase
concentration and Light Non-Aqueous Phase Liquid (LNAPL) .GWSDAT has been used
extensively in the assessment of soil and groundwater conditions a, including
retail and manufacturing sites.
• Improved data transparency to design
and optimize groundwater monitoring or remediation programs;
• Early identification of new releases,
migration pathways, the need for corrective action, and stable or declining
trends that may aid in site closure determinations;
Clarity on the relations between dissolved solute concentrations, LNAPL
thicknesses, and groundwater elevation.
Hardware requirements: Standard PC 1 GB RAM or more, 32-bit or 64-bit
System requirements: Microsoft Windows (XP or later)
Software requirements: R version 3.0.0 (www.r-pro ject.org) or higher and
Microsoft Excel 2003 or higher.
• Program size: 13 MB
Availability: Free from www.claire.co.uk/GWSDAT and http://www.api.org/GWSDAT
This work was funded by Shell Global Solutions
(UK) Ltd. The views expressed are those of the authors and may not reflect the
policy or position of Royal Dutch Shell plc.
ESdat is a specialist environmental
database system; used to validate, import, analyze and report a broad spectrum
of Environmental and groundwater Data as Exceedance Tables, graphs, maps,
statistics and more. It is developed by
Earth Science Information Systems (EScIS) based in Australia.
of ESdat software are:
• More accuracy
• Faster; eliminates redundancy
• Saves money
• Improves collaboration
• Helps assure environmental compliance
• Better results with happier client
users of this software include:
Exploration, Govt and Infrastructure Groups:
• Beach Energy (Adelaide, Australia),
• Carbon energy (Brisbane, Australia)
•AGL (Sydney, Australia)
•CST Minerals Lady Annie (MT lsa,
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