Bioremediation of contaminated soils

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Information about Bioremediation of contaminated soils

Published on December 7, 2013

Author: WaqasAzeem1



Soil can be contaminated by Heavy metals. Its remediation can be done biologically in environment friendly way by the method... bioremediation..!

Submitted To Dr. Sher Muhammad Shahzad Submitted By Waqas Azeem Reg No PAGF12E033 University College of Agriculture University of Sargodha

THE BASIC PROBLEM: RELEASE OF HAZARDOUS MATERIALS  Enormous quantities of organic & inorganic compounds are released into the environment each year as a result of human activities.  The release may be:  Deliberate and well regulated (industrial emissions)  Accidental and largely unavoidable (chemical/oil spills)  US EPA estimated that in 1980 at least 57 millions metric tons of the total waste can be categorized into three general groups:

 Heavy metal, Pb, Cd, Ni and Be can accumulate in various organs, interfere with normal enzymatic reactions and cause disease including cancer  Chlorinated hydrocarbons, also known as organochlorides including pesticides and other organic compounds such as PCB (polychlorinated biphenyls)  Research proven a positive correlation between cancer in lab animals and organochlorides.  Nuclear waste including radioactive material such as plutonium which are dangerous for thousands of years

What Is Bioremediation?  Biodegradation - the use of living organisms such as bacteria, fungi, and plants to degrade chemical compounds  Bioremediation – process of cleaning up environmental sites contaminated with chemical pollutants by using living organisms to degrade hazardous materials into less toxic substances

What are environmental contaminants?  pollutants  naturally-occurring compounds in the environment that are present in unnaturally high concentrations.  Xenobiotics  chemically synthesized compounds that have never occurred in nature.  Examples:   Examples:     crude oil refined oil phosphates heavy metals   pesticides herbicides plastics

Contaminants Potentially Amenable to Bioremediation ____________________________________________ Readily degradable ____________ _ Somewhat Difficult to Generally degradable degrade recalcitrant _____________ _____________ _____________ fuel oils, gasoline creosote, coal tars chlorinated solvents (TCE) dioxins ketones and alcohols pentachlorophenol (PCP) some pesticides and herbicides polychlorinated biphenyls (PCB) monocyclic aromatics bicyclic aromatics (naphthalene)

Current Situation in Pak Pak is an agricultural country. But still most of its agricultural fields are already deficient in fertilizer and pesticides application. So, soil toxicity due to fertilizer or pesticides application are very rare. But water contamination cases can be seen.

 Karachi, a hub of industrial activity, houses seven major industrial estates in Korangi, Landhi, SITE, Federal B Area, North Karachi, Superhighway and Port Qasim.  At present, Karachi coastal region has become a dumping ground of hazardous waste, receiving huge quantities of untreated domestic & industrial wastewater through Lyari & Malir Rivers.  Since most industries have no treatment facility or have grossly inadequate arrangements. .

 Accelerated rate of fresh water contamination in the city is exposing the problem of water scarcity.  Continued practice will ultimately threatens fresh water availability and food security for future as well as health hazards and economic losses.

Current Concern  Contaminated water is responsible for over 12 million deaths per year world over.  More than 40% hospital beds in Pakistan are occupied by patients with water related diseases.  According to Economic Survey of Pakistan 2008-09, economic losses due to water pollution in the country are estimated at Rs.109.5 billion per year.  While National Drinking Water Policy Document 2009 mentions the same at about Rs.112 billion per year, over Rs.300 million a day, in terms of health costs and lost earnings.

Water Pollution in Karachi  Karachi, population over 18 million discharged around 446 MGD of wastewater.  About 70% untreated wastewater discharged into the Arabian sea.  All most all chemical waste are dumped untreated into storm-drains, open nallahs or in the lyari and malir rivers which ultimately fall into the Arabian Sea.  The coastal zone, extended up to 135 Km, is exposed to heavy pollution load of both domestic and industrial origin.

With new regulations and a greater environmental concern, industrial effluent treatment need especial attention.

Why use Bioremediation?  Most approaches convert harmful pollutants into relatively harmless materials such as carbon dioxide, chloride, water, and simple organic molecules  Processes are generally cleaner

 Biotechnological approaches are essential for  Detecting pollutants  Restoring ecosystems  Learning about conditions that can result in human diseases  Converting waste products into valuable energy

BIOREMEDIATION  It requires the control and manipulation of microbial processes in surface reactors or in the subsurface.  The contaminants can be biodegraded in situ or removed and placed in bioreactor (at or off the contamination sites).  Idea:  To isolate microbes that can degrade or eat a particular contaminant  To provide the conditions whereby it can do this most effectively, thereby eliminating the contaminant

Bioremediation Basics  What needs to be cleaned up?  Soil, water, air, and sediment  Pollutants enter environment in many different ways  Tanker spill, truck accident, ruptured chemical tank at industrial site, release of pollutants into air  Location of accident, the amount of chemicals released, and the duration of the spill impacts the parts of the environment affected

Groundwater contamination  Groundwater constitutes 96% of available freshwater in U.S.  95% of potable water in rural areas of U.S. comes from groundwater  In 1988, EPA confirmed that 26 states had various amounts of 44 different pesticides in their groundwater  Cost of cleanup is in the $ trillions  Issues that are still hotly debated  How clean is clean?

Bioremediation Basics


Microbial Divisions  Two kinds of cells are recognized, the prokaryotic and eukaryotic. Prokaryotic cell Eucaryotic cell Bacteria Blue-green bacteria or cyanobacteria Plants Animals Protozoa Fungi Most algae  The most important groups to bioremediation are bacteria and fungi.

Microorganisms  Aerobic bacteria:  Examples include: Pseudomonas, Sphingomonas, Rhodococcus, and Mycobacterium  Shown to degrade pesticides and hydrocarbons; alkanes and polyaromatics  May be able to use the contaminant as sole source of carbon and energy.  Methanotrophs:  Aerobic bacteria that utilize methane for carbon and energy  Methane monooxygenase has a broad substrate range  active against a wide range of compounds (e.g. chlorinated aliphatics such as trichloroethylene and 1,2dichloroethane)

 Anaerobic bacteria:  Not used as frequently as aerobic bacteria  Can often be applied to bioremediation of polychlorinated biphenyls (PCBs) in river sediments, trichloroethylene (TCE), and chloroform  Fungi:  Able to degrade a diverse range of persistent or toxic environmental pollutants

Aerobic and Anaerobic Biodegradation

Environmental Factors  Nutrient availability  Environmental Conditions  Metal content

 Microorganisms destroy organic contaminants in the course of using the chemicals for their own growth and reproduction.  Organic chemicals provide: carbon, source of cell building material, electrons, source of energy

TYPES OF BIOREMEDIATION  The two main types of bioremediation are in situ bioremediation and ex situ bioremediation. In addition, another offshoot of bioremediation is phytoremediation.

Forms of Bioremediation  In situ Bioremediation       Bioventing In situ biodegradation Biostimulation Biosparging Bioaugmentation Natural Attenuation  Ex situ Bioremediation     Land farming Composting Biopiles Bioreactors

In Situ Bioremediation  In situ bioremediation is when the contaminated site is cleaned up exactly where it occurred.  It is the most commonly used type of bioremediation because it is the cheapest and most efficient, so it’s generally better to use.  There are two main types of in situ bioremediation: intrinsic bioremediation and accelerated bioremediation.

Five Steps of In Situ Bioremediation 1. Site investigation 2. Treatability studies 3. Recovery of free product and removal of the contamination source 4. Design and implementation of the in situ bioremediation system 5. Monitoring and performance evaluation of the in situ bioremediation system

Intrinsic Bioremediation  Intrinsic bioremediation uses microorganisms already present in the environment to biodegrade harmful contaminant.  There is no human intervention involved in this type of bioremediation, and since it is the cheapest means of bioremediation available, it is the most commonly used.  When intrinsic bioremediation isn’t feasible, scientists turn next to accelerated bioremediation.

Accelerated Bioremediation  In accelerated bioremediation, either substrate or nutrients are added to the environment to help break down the toxic spill by making the microorganisms grow more rapidly.  Usually the microorganisms are indigenous, but occasionally microorganisms that are very efficient at degrading a certain contaminant are additionally added.

 Main advantage is that site disturbance is minimized, which is particularly important when the contaminated plume has moved under permanent structures.  Biggest limitation of in situ treatment has been the inability to deal effectively with metal contaminants mixed with organic compounds.  The goal of in situ treatment is to manage and manipulate the subsurface environment optimize microbial degradation. to

In Situ Bioremediation  Land treatments: Bioventing is the most common in situ treatment and involves supplying air and nutrients through wells to contaminated soil to stimulate the indigenous bacteria.


In situ biodegradation involves supplying oxygen and nutrients by circulating aqueous solutions through contaminated soils to stimulate naturally occurring bacteria to degrade organic contaminants.

 Stimulating Bioremediation  Nutrient enrichment (fertilization) – fertilizers are added to a contaminated environment to stimulate the growth of indigenous microorganisms that can degrade pollutants  Bioaugmentation (seeding) –bacteria are added to the contaminated environment to support indigenous microbes with biodegradative processes

Biosparging involves the injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria. Biosparging increases the mixing in the saturated zone and thereby increases the contact between soil and groundwater.


Ex Situ Bioremediation  which is when contaminated land are taken out of the area to be cleaned up by the organisms.  This type of bioremediation is generally used only when the site is threatened for some reason, usually by the spill that needs to be cleaned up.  Ex situ bioremediation is only used when necessary because it’s expensive and damaging to the area, since the contaminated land is physically removed.

Cleanup Sites and Strategies

Ex Situ Bioremediation Landfarming is a simple technique in which contaminated soil is excavated(dig up) and spread over a prepared bed and periodically tilled until pollutants are degraded. Composting is a technique that involves combining contaminated soil with non-hazardous organic compounds such as agricultural wastes. The presence of these organic materials supports the development of a rich microbial population and elevated temperature characteristic of composting.

Landfarming & Compost

 Bioreactors-Slurry reactors or aqueous reactors are used for ex situ treatment of contaminated soil and water pumped up from a contaminated plume.  Bioremediation in reactors involves the processing of contaminated solid material (soil, sediment, sludge) or water through an engineered containment system.

Advantages and Disadvantages Advantages of bioremediation  Bioremediation is a natural process and is therefore perceived by the public  Bioremediation is useful for the complete destruction of a wide variety of contaminants.  Instead of transferring contaminants from one environmental medium to another, for example, from land to water or air, the complete destruction of target pollutants is possible.

Adv  Bioremediation can often be carried out on site, often without causing a major disruption of normal activities.  Bioremediation can prove less expensive than other technologies that are used for cleanup of hazardous waste

Advantages and Disadvantages Disadvantages of bioremediation  Bioremediation is limited to those compounds that are biodegradable. Not all compounds are susceptible to rapid and complete degradation.  There are some concerns that the products of biodegradation may be more persistent or toxic than the parent compound.

 Biological processes are often highly specific. microbial populations, suitable environmental growth conditions, and appropriate levels of nutrients and contaminants.  Bioremediation often takes longer than other treatment options.

Cleanup Sites and Strategies  Turning Wastes into Energy  Methane gas used to produce electricity  Soil nutrients can be sold commercially as fertilizers  Anaerobes in sediment that use organic molecules to generate energy  Electicigens – electricity-generating microbes.. ?

Applying Genetically Engineered Strains to Clean Up the Environment  Petroleum-Eating Bacteria  Created in 1970s  Isolated strains of pseudomonas from contaminated soils  Contained plasmids that encoded genes for breaking down the pollutants

Applying Genetically Engineered Strains to Clean Up the Environment  E. coli to clean up heavy metals  Copper, lead, cadmium, chromium, and mercury  Biosensors – bacteria capable of detecting a variety of environmental pollutants  Genetically Modified Plants and Phytoremediation  Plants that can remove TNT

Future Strategies and Challenges for Bioremediation  Recovering Valuable Metals  Bioremediation of Radioactive Wastes

Thanks for your attention!

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