WELCOME

A PRESENTATION ON

BIOREMEDIATN

COURSE TITLE: Advanced Agricultural & Environmental BiotechnologyCOURSE NO: GEBT 5105

PRESENTED TOForhad Karim SaikotLecturerDept. of Genetic Engineering and BiotechnologyJessore University of Science and Technology, Jessore

PRESENTED BYMd. ShoyebRoll No: MS-130611Session: 2013-14Dept. of Genetic Engineering & Biotechnology

Jessore University of Science and Technology , Jessore 7408, Bangladesh

BIOREMEDIATION

Bioremediation is the beneficial form of biodegradation.

In general bioremediation can be defined as the process by which organisms transform chemicals.

For our purposes it is the transformation of chemicals considered to be contaminants or pollutants.

Bioremediation is any natural, environmentally friendly process that uses organisms (microorganism, algae and plant) or their enzymes (process known as Cometabolism) to return the polluted environment to its original condition.

MECHANISMS OF BIOREMEDIATION

Contaminant compounds are transformed by living organisms through reactions that take place as a part of their metabolic processes

Organic compounds (contaminants) act as the source of carbon and electrons

Carbon act as the source of cell building material and electrons as the source of energy

Basic mechanism of bioremediation is that microbes catalyses the oxidation of the organic compounds (contaminants) that cause transfer of electrons from organic chemicals to some electron acceptor

ELECTRON ACCEPTORS

In cases where the contaminant preferentially degrades faster aerobically, enhancing bioremediation can be easily accomplished by adding an electron acceptor

There are a number of electron acceptors but oxygen is usually the most efficient

Other electron acceptors include nitrate, iron, and sulfate are used in anaerobic condition

Many chlorinated solvents degrade faster as electron acceptors. In these cases, an electron donor is added to the system to begin the process. As the substrate is metabolized under anaerobic conditions, an electron is released and is then used to replace a chlorine atom on the chlorinated solvent

The ability to cost-effectively provide sufficient electron acceptor adequately distributed through the system is critical to successfully meeting the goals

PRINCIPLE OF BIOREMEDIATION

The principles of bioremediation are based on- Natural attenuation is the simplest method of bioremediation in which

soils are only monitored for variations in pollution concentrations to ensure that the pollutant transformation is active

Bioaugmentation is usually applied in cases where natural active microbial communities are present in low quantities or even absent, wherein the addition of contaminant degrading organisms can accelerate the transformation rates

Biostimulation:The capacity of a microbial population to degrade pollutants can be enhanced also by stimulation of the indigenous microorganisms by addition of nutrients or electron acceptors

RELATIVE BIODEGRADABILITY

The chemical structure of a compound affects biodegradability in following ways-

Degradability decreases as molecular weight increases

Degree of branching decreases degradability

Substitution makes a compound harder to degrade. For example, benzene rings are easier to break down than benzene rings that have undergone substitution

RELATIVE BIODEGRADABILITY

Pesticides

Chlorinated hydrocarbons

Nitrobenzenes and ethers

Alcohols, esters

Aromatic hydrocarbons

Simple hydrocarbons and petroleum fuels

BIOREMEDIABLE CONTAMINANTS

There are a huge number of bioremediable contaminants in the environment

Many of the contaminants are degraded in aerobic condition with the presence of oxygene

Some are degraded in anaerobic condition in absence of oxygene

LIST OF BIOREMEDIABLE CONTAMINANTS

BIOREMEDIATION STRATEGIES

Different techniques are employed depending on the degree of saturation and aeration of an area

There are two strategies for bioremediation:

In situ bioremediation

Ex situ bioremediation

IN SITU BIOREMEDIATION

In situ bioremediation is the application of biological treatment to the cleanup of hazardous chemicals present in the subsurface

The treatment in place without excavation of contaminated soils or sediments

Applied to soil and groundwater at the site with minimal disturbance

The most desirable options due to lower cost and less disturbance

TYPES OF IN SITU BIOREMEDIATION

There are four basic types in situ bioremediation

Bioventing It involves venting of oxygen to stimulate growth of natural or introduced microorganisms.

Bioventing typically uses low air flow rates to provide only enough oxygen to sustain microbial activity.

Oxygen is most commonly supplied through direct air injection into residual contamination

This technique shows considerable promise of stabilizing or removing inorganics from soil

In situ biodegradation It involves the infiltration of water-containing nutrients and oxygen or other electron acceptors

for groundwater treatment

In situ biodegradation involves supplying oxygen and nutrients by circulating aqueous solutions through contaminated soils

TYPES OF IN SITU BIOREMEDIATION

Biosparging In situ air sparging is a remediation technique that has been used since

about 1985

Biosparging is used for the remediation of volatile organic compounds (VOCs) dissolved in the groundwater

Biosparging involves the injection of air under pressure below the water able to increase groundwater oxygen concentrations

The ease and low cost of in the design and construction of the system

TYPES OF IN SITU BIOHRMEDIATION

Bioaugmentation It Involves the addition of microorganisms indigenous or exogenous to the

contaminated sites

Two factors limit the use of added microbial cultures in a land treatment unit:

I. Non indigenous cultures rarely compete well enough with an indigenous population to develop and sustain useful population levels

II. Most soils with long-term exposure to biodegradable waste have indigenous microorganisms that are effective degrades if the land treatment unit is well managed

EX SITU BIOREMEDIATION

Ex situ refers to a technology or process for which contaminated material must be removed from the site of contamination for treatment.

Soil must be excavated or groundwater must be pumped to an above ground treatment system in ex situ bioremediation.

Types of ex situ bioremediation

There are mainly four types of ex situ bioremediation Landfarming Composting Biopiles Bioreactors

LANDFARMING

Landfarming, also known as land treatment or land application, is an above-ground remediation technology for soils

Landfarming is a simple technique in which contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded.

The effectiveness of landfarming depends on parameters such as soil characteristics, climatic conditions, Soil texture etc

Contaminated Soil Treatment

COMPOSTING

Compost bioremediation refers to the use of a biological system of micro-organisms in a mature, cured compost to sequester or break down contaminants in water or soil.

It involves combining contaminated soil with nonhazardous organic amendants such as manure or agricultural wastes.

The presence of these organic materials supports the development of a rich microbial population

BIOPILES

Biopile”, also known as biocell, bioheap, biomound or compost pile

It means a pile of contaminated soils used to reduce concentrations of petroleum constituents in excavated soils through the use of biodegradation.

This technology involves heaping contaminated soils into piles or “cells” and stimulating aerobic microbial activity within the soils through the aeration or addition of minerals, nutrients and moisture.

It is a hybrid of landfarming and composting

BIOREACTORS

Bioreactor is an apparatus, such as a large fermentation chamber, for growing organisms such as bacteria or yeast under controlled conditions

Bioreactors are used in the biotechnological production of substances such as pharmaceuticals, antibodies, or vaccines, or for the bioconversion of organic waste.

Slurry reactors or aqueous reactors are used for ex situ treatment of contaminated soil and water pumped up from a contaminated plume.

ADVANTAGES

It is possible to completely breakdown organic contaminants into other nontoxic chemicals

Equipment requirements are minimal compared to other remediation technologies.

Bioremediation is perceived positively by the public because it is a natural process.

Does not transfer contaminants from one environment to another Can be implemented as an in-situ or ex-situ method depending on

conditions. Low-technology equipment is required i.e. readily available equipment

e.g. pumps, well drilling equipment etc. Low cost of treatment compared to other remediation technologies.

DISADVANTAGES

Organic contaminants may not be broken down fully resulting in toxic by-products that could be more mobile than the initial contamination

The process is sensitive to the level of toxicity and environmental conditions

Field monitoring to is advised. If an ex-situ process is used, controlling volatile organic compounds (VOCs)

may be difficult. Treatment time is typically longer than that of other remediation

technologies. Range of contaminants that can be effectively treated is limited to

compounds that are biodegradable. Difficult to extrapolate from bench and pilot-scale studies to full-scale field

operations Performance evaluations are difficult because there is not a defined level

of a "clean" site and therefore performance criteria regulations are uncertain.

PERSISTENT POLLUTANTS

Persistent organic pollutants(POPs) are synthetic (man-made) organic chemicals

Low water solubility(they do not easily dissolve in water)

The ability to accumulate in fat (high lipophilicity)

Resistance to biodegradation (they take a very long time to break down and stop being harmful).

High levels in fish and marine mammals

These chemicals come from pesticides, industrial chemicals, and are the unwanted by-products of industrial processes or combustion.

PERSISTENT POLLUTANTS

Examples: Endrin, Heptachlor, Mirex, PCBs: Polychlorinated biphenyls, HCB: Hexachlorobenzene etc

EFFECTS OF POPs

Reproductive impairment and malformations

Long-term effects on intellectual function

Altered liver enzyme function

Increased risk of tumours

THE XENOBIOTICS

Xenobiotics is a compound that is foreign to the body ; a chemical which is not normally produced or expected to be present in body.

These compounds are man-made chemicals that are present in the environment at unnaturally high concentrations.

The xenobiotic compounds are not produced naturally

It is artificially produced by chemical synthesis for agricultural or industrial purpose

Low molecular weight

REASONS OF BEING NON BIODEGRADABLE

The xenobiotic compounds may be recalcitrant due to one or more of the following reasons:

They are not recognised as substrate by the existing degradative enzymes

Inability of the compounds to induce the synthesis of degrading enzymes

They are highly stable, i.e., chemically and biologically inert due to the presence of substitution groups like halogens

They are highly toxic or give rise to toxic products due to microbial activity

Their large molecular size prevents entry into microbial cells

Lack of the permease needed for their transport into the microbial cells

BIOTECHNOLOGY AND MICROBES IN XENOBIOTIC DEGRADATION

Certain microbes on continuous exposure to xenobiotics develop the ability to degrade the same as a result of mutations.

Mutations resulted in modification of gene of microbes so that the active site of enzymes is modified to show increased affinity to xenobiotics.

Use of mixed population of microbes is usually recommended

The modification of certain genes of microbes to break down xenobiotics is also recommended and is seen to produce high level of accuracy.

BIOTECHNOLOGY AND MICROBES IN XENOBIOTIC DEGRADATION

Organic pollutants are degraded by various types of microbial degradations such as-

Bacterial degradation

Microfungi and mycorrhiza degradation

Yeasts degradation

Filamentous fungi degradation

Algae and protozoa

BIOTECHNOLOGY AND MICROBES IN XENOBIOTIC DEGRADATION

Some microbes able to degrade Xenobiotics

SOME MICROBES ABLE TO DEGRADE XENOBIOTICS

GENETIC REGULATION

Genes for the degradation of synthetic pollutants are often associated with plasmids and transposons

Catabolic plasmids are circular, accessory DNA elements present in the cytoplasm of many soil bacteria

They confer on their host the ability to degrade environmental pollutants

The very first catabolic plasmid to be isolated was the CAM plasmid of Pseudomonas putida

The first plasmid that encodes the degradation of synthetic molecules was pJP1

PLASMID BORNE BACTERIA CONTROL XENOBIOTICS; MOSTLY FROM PSEUDOMONAS GENUS

Thanks to All