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BIO-RESTORATION OF CONTAMINATED LAND

SUBMITTED BY:Jasleen Rajpal

ENVIRONMENTAL BIOTECHNOLOGY

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What is Bioremediation?

Bioremediation is the restoring of a surface or object to a

condition which is not harmful to plant or animal life.

There are four (4) subcategories of bioremediation:

1. Bio degradation

2. Bio restoration

3. Bio stimulation

4. Bio augmentation.

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Bio restoration

Biorestoration deals with restoring or bringing back to an original

or near original state using living micro-organisms. Nature has a

built in check and balance system in everything it does. If there is

too much or too little of something nature will use various life forms

to try to re-establish a balance.

This would mean that once requested by the government or a

land remediation authority, immediate action should be taken as

this can impact negatively on human health and the environment.

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Land contamination

Land may be affected by contamination as a result of historical

land use, principally from industrial processes, waste disposal and

accidental spillages. Land contamination may also be arising from

natural processes, such as where local geologic structures contain

naturally high levels of metals, or an increased potential for ground

gas due to the presence of peat. If land contamination is not dealt

with adequately it can pose risks to human health, the environment

and sustainable economic development.

Land Contamination

• Are defined as the introduction of a substance into the land so that its quality and

function are adversely affected.

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Chemicals of

concern

Agricultural waste,

Human waste,

Industrial waste

Metals (e.g. lead, mercury),

Pesticides,

Petroleum hydrocarbons

Salts,

Soil-acidifying chemicals (e.g.

sulphur)

Health Effects

• Chronic exposure to chromium, lead and other metals, petroleum,

solvents, and many pesticide and herbicide formulations can be

carcinogenic.

• Chronic exposure to benzene at sufficient concentrations is known to

be associated with higher incidence of leukemia.

• Organophosphates and carbomates can induce a chain of responses

leading to neuromuscular blockage.

• Mercury linked to higher incidences of kidney damage.

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The opencast mining has also resulted to destruction of

habitats, particularly for ground flora species, which is essential for

maintaining nutrient cycling and ecological balance.

The ground flora species are themselves capable of modifying

site conditions to some extent.

The floristic composition and luxuriance of ground flora in

degraded ecosystem are largely dependent upon the secondary site

conditions

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As large forest have been clear felled for opencast mining of

coal, the major challenges include loss of top soil, reduction of

forest cover and destruction of habitats of ground flora species,

which is essential for maintaining nutrient cycling and ecological

balance. These are chemically, physically and biologically unstable

and deficient.

The ground flora forms an important structural component of

forest ecosystem. The ground flora community not only indicates

the fertility status but also gives an idea of the growth and

development of tree seedlings as it is intimately related to it

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Site Restoration Steps

Risk Assessment

Preliminary riskassessment

Generic quantitative risk assessment

Detailed quantitative risk assessment

Options Appraisal

Identificationof feasible

remediation options

Detailed evaluationof options

Developing the remediation strategy

Implementation Of The

Remediation Strategy

Preparation of the implementation plan

Design, implementation &

verification

Long-term monitoring & maintenance

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Restoration Technologies

• Restoration technologies are many and varied but can

be categorized into ex-situ and in-situ methods.

• The more traditional remediation approach consists

primarily of soil excavation(disposal to landfill “dig and

dump”) and groundwater(pump and treat).

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Excavation or dredging

• Excavation processes can be as simple as hauling

the contaminated soil to a regulated landfill.

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Fig. 1 Excavated Area

SEAR-surfactant enhanced aquifer remediation

• Also known as Solubilization and recovery, the Surfactant

Enhanced Aquifer Remediation process involves the injection

of hydrocarbon mitigation agents into the subsurface.

• In geological formations that allow delivery of hydrocarbon

mitigation agents, this approach provides a cost effective and

permanent solution.

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Solidification and Stabilization

• Stabilization - involves the addition of reagents to a

contaminated material (e.g. soil or sludge) to produce more

chemically stable constituents.

• Solidification - involves addition of reagents to impart

stability to contain contaminants in a solid product and reduce

access by external agents (e.g. air, rainfall).

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Soil vapor extraction

• SVE utilizes different technologies to treat the off-gas volatile

organic compounds (VOCs) generated after vacuum removal

of air and vapors (and VOCs) from the subsurface.

• Carbon is used for low (<500ppm) VOC concentration,

oxidation is used for moderate (up to 4,000 ppm) VOC

concentration, and vapor condensation is used for high

(>4,000 ppm) VOC concentration.

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• Vapor condensation involves cryogenically cooling the vapor

stream to below 40 ֯C such that the VOCs condensate out of

the vapor stream and into liquid form where it is collected in

steel containers.

• This recovered chemical can then be reused or recycled in a

more environmentally sustainable or green manner.

• This technology is also known as cryogenic cooling and

compression.

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THANK YOU !